CN105195221A - Composite photocatalyst SiO2/g-C3N4 as well as preparation method and application thereof - Google Patents
Composite photocatalyst SiO2/g-C3N4 as well as preparation method and application thereof Download PDFInfo
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- CN105195221A CN105195221A CN201510395064.0A CN201510395064A CN105195221A CN 105195221 A CN105195221 A CN 105195221A CN 201510395064 A CN201510395064 A CN 201510395064A CN 105195221 A CN105195221 A CN 105195221A
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Abstract
The invention provides a composite photocatalyst SiO2/g-C3N4 as well as a preparation method and application thereof. The composite photocatalyst is prepared by compounding a graphite phase, prepared from nitrogen-containing organic matters used as a staring raw material, and silicon dioxide through a thermal polymerization method. The prepared composite photocatalyst can carry out catalytic degradation on azobenzene dyes under the existence of visible light, so that the composite photocatalyst can be used for treating waste water containing azobenzene dyes and is high in catalytic efficiency under visible light.
Description
Technical field
The present invention relates to a kind of composite photo-catalyst and its preparation method and application, particularly composite photo-catalyst SiO
2/ g-C
3n
4and its preparation method and application.
Background technology
Graphite phase carbon nitride, good stability, cost of material higher with its photocatalytic activity are cheap, especially not this outstanding advantages of containing metal, make it become a kind of novel catalysis material, but, the g-C of single-phase
3n
4catalyst makes its photocatalysis performance show usually because quantum efficiency is low not ideal enough.In addition, g-C
3n
4material photo-generate electron-hole recombination rate is higher, causes its catalytic efficiency lower, thus limits its application in photocatalysis.
In order to improve g-C
3n
4catalytic activity, recent years, people have studied a lot of method of modifying.One is to g-C with nonmetalloid
3n
4carry out modification, described nonmetalloid comprises S, N, C, B, F, P etc., it is generally acknowledged that these nonmetalloids instead of C, N, H element in 3-s-triazine structural units, thus forms g-C
3n
4lattice defect makes photo-generate electron-hole to being effectively separated, and effectively improves its photocatalysis performance.As mixed with BmimPF6 (ionic liquid) by dicyandiamide, after high-temperature calcination, obtain P doping g-C
3n
4through XPS analysis, catalyst, shows that P element instead of C in construction unit, although a small amount of P doping can not change g-C
3n
4structure, but it obviously changes g-C
3n
4electronic structure, photogenerated current is also apparently higher than undoped g-C
3n
4.For another example, to adulterate g-C adopting the mixture of heat resolve melamine and boron oxide to prepare B
3n
4, show that B instead of g-C through XPS spectrum analysis
3n
4h in structure, photocatalytic degradation of dye research shows that B doping improves the absorption of catalyst to light simultaneously, and therefore, rhodamine B photocatalytic degradation efficiency is also improved.For another example, by g-C
3n
4at H
2prepare in 450 DEG C of calcinings in S atmosphere and there is unique electronic structure S element doping g-C
3n
4cNS catalyst, XPS analysis display S instead of g-C
3n
4n in structure, as λ > 300 and 420nm, S adulterates g-C
3n
4photocatalysis Decomposition aquatic products hydrogen catalysis efficiency is respectively than single-phase g-C
3n
4improve 7.2 and 8.0 times.For another example, NH is used
4f obtains F element doping g-C as F source and DCDA
3n
4catalyst (CNF), F element mixes g-C
3n
4skeleton in, define C-F key, make wherein a part of sp2C be converted into sp3C, thus cause g-C
3n
4planar structure irregularity; In addition, along with F element doping increasing number, the absorption region of CNF in visible region also expands thereupon, and the band-gap energy of its correspondence drops to 2.63eV by 2.69eV.For another example, BH is used
3nH
3the g-C of B element doping is prepared as boron source
3n
4catalyst (CNB), mixing of B element, instead of g-C
3n
4c element in construction unit.For another example, adopt tetraphenylboron sodium as B source, while mixing B, again because the effect of benzene leaving group makes g-C
3n
4form laminate structure, the thickness of its layer is 2 ~ 5nm, reduces light induced electron and arrives the required energy consumed of catalyst surface, therefore improve photocatalysis efficiency.
But above-mentioned preparation method not only complicated operation, cost of material is high, and obtained its photocatalysis efficiency of modified catalyst increases limitation, can not meet industrial requirements.
Therefore, need exploitation one badly and there is high catalytic efficiency, and preparation method is simple, photochemical catalyst easy to use.
Summary of the invention
In order to solve the problem, present inventor has performed and study with keen determination, found that: carry out compound as the obtained graphite-phase of initiation material and silica by thermal polymerization with itrogenous organic substance, obtained composite photo-catalyst can under visible ray exists catalytic degradation azobenzene dyestuff, thus for administering the waste water containing azobenzene dyestuff, its catalytic efficiency is under visible light high, thus completes the present invention.
The object of the present invention is to provide following aspect:
First aspect, the invention provides one and prepares composite photo-catalyst SiO
2/ g-C
3n
4method, it is characterized in that, the method comprises the following steps:
(1) itrogenous organic substance is calcined, optionally cool, pulverize, obtain g-C
3n
4;
(2) by g-C obtained for step 1
3n
4mix with silica, the mixture obtained is calcined, optionally cools, then pulverize, obtain composite photo-catalyst SiO
2/ g-C
3n
4.
Second aspect, the present invention also provides the composite photo-catalyst SiO obtained according to said method
2/ g-C
3n
4, it is characterized in that, in described composite photo-catalyst, SiO
2with g-C
3n
4weight ratio be (3 ~ 50): 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
The third aspect, the composite photo-catalyst that the present invention also provides said method obtained, at improvement waste water from dyestuff, particularly administers the application of the waste water aspect containing azobenzene dyestuff.
Accompanying drawing explanation
Fig. 1 illustrates the infrared spectrogram of the sample that embodiment 1 ~ 5 and comparative example 1 obtain;
Fig. 2 illustrates the photoluminescence spectra figure of the sample that embodiment 1 ~ 5 and comparative example 1 obtain;
Fig. 3 illustrates the UV-Vis diffuse reflection spectroscopy figure of the sample that embodiment 1 ~ 5 and comparative example 1 obtain;
Fig. 4 illustrates the photocatalytic activity result figure of the sample that embodiment 1 ~ 5 and comparative example 1 obtain;
Fig. 5 a illustrates the sample catalytic effect interact relation figure that scavenger is obtained to comparative example 1;
Fig. 5 b illustrates the sample catalytic effect interact relation figure that scavenger is obtained to embodiment 3;
Fig. 6 a illustrates that comparative example 1 obtains the ultraviolet-visible light spectrogram of sample degradation methyl orange;
Fig. 6 b illustrates that embodiment 3 obtains the ultraviolet-visible light spectrogram of sample degradation methyl orange;
Fig. 7 a illustrates that comparative example 1 obtains the graph of a relation of sample degradation methyl orange and degradation time;
Fig. 7 b illustrates that embodiment 3 obtains the graph of a relation of sample degradation methyl orange and degradation time.
Detailed description of the invention
Below by the present invention is described in detail, the features and advantages of the invention will illustrate along with these and become more clear, clear and definite.
Below in detail the present invention is described in detail.
According to a first aspect of the invention, one is provided to prepare composite photo-catalyst SiO
2/ g-C
3n
4method, it is characterized in that, the method comprises the following steps:
Step 1, calcines itrogenous organic substance, optionally cools, and pulverizes, obtains g-C
3n
4.
In the present invention, described itrogenous organic substance refers to nitrogenous small organic molecule, refers to the nitrogenous small organic molecule that can decompose in a heated condition especially, and it is being prepared in graphite phase carbon nitride not only as nitrogen source but also as carbon source material.
The present inventor finds, uses the itrogenous organic substance of the small-molecular-weight that carbon-nitrogen ratio is 1:3 ~ 3:1 as raw material, preferably uses the small-molecular-weight itrogenous organic substance that carbon-nitrogen ratio is 1:2 as raw material, in 300 DEG C ~ 800 DEG C environment, can obtain cancellated g-C after roasting
3n
4, as cyanamide, dicyanodiamine, melamine, urea, guanidine hydrochloride etc., be preferably melamine.
The present invention finds through large quantity research, and the decomposition temperature of melamine is lower, and it just can decompose more than 300 DEG C, and the product after decomposition at high temperature can aggregate into graphite phase carbon nitride, i.e. g-C
3n
4, and, with the g-C that melamine is obtained
3n
4during middle accessory substance is few, i.e. g-C
3n
4middle impurity is few, is conducive to the purity improving end-product composite photo-catalyst, and the g-C obtained by melamine
3n
4pattern is homogeneous, and layer structure is obvious, and therefore, the present invention preferably uses melamine to prepare g-C
3n
4.
In calcination process of the present invention, heating rate is selected to be 10 ~ 30 DEG C of min
-1, be preferably 15 ~ 25 DEG C of min
-1, as 20 DEG C of min
-1.The present inventor finds, when heating rate is greater than 30 DEG C of min
-1time, melamine easily distils, and after distillation, it still exists with the form of melamine molecule, and the melamine wherein decomposed is less, thus makes the product morphology that obtains uneven; When heating rate is lower than 10 DEG C of min
-1time, the reaction time is long, and has accessory substance to produce.
In step 1 of the present invention, described calcining is carried out under 300 ~ 800 DEG C of conditions, is preferably 400 DEG C ~ 700 DEG C, is more preferably 500 DEG C ~ 600 DEG C, as 520 DEG C.
In step 1 of the present invention, select calcination time to be 1 ~ 10 hour, be preferably 2 ~ 8 hours, be more preferably 3 ~ 6 hours, as 4 hours.The present inventor finds, be less than 1 constantly little upon calcination, calcination time is too short, reacts insufficient, and raw material is remaining completely still unreacted in reaction system; After being greater than 10 hours upon calcination, raw material fully reacts, the no longer showed increased of the product in system, continues to extend calcination time and can only cause the waste of the energy and the increase of time cost.
In a preferred embodiment of the invention, select in confined conditions to the calcining that raw material carries out, avoid raw material too to contact with oxygen, thus the significant loss reducing raw material complete oxidation and bring.
Optionally, obtained material is carried out cooling down, the method for the present invention to cooling down is not particularly limited to, and any one can be used in prior art by the method for solid cooled, as natural cooling, artificial cooling method etc., to be preferably natural cooling.
Optionally, pulverize calcining the material obtained, the present inventor finds, pulverizing calcining the material obtained, being conducive to fully carrying out of subsequent reactions, the end-product that step 3 also can be made obtained is more even, and performance is more stable.
In the present invention, to pulverize after particle diameter be not particularly limited to, with SiO
2particle diameter be close to preferably.
The present invention is not particularly limited to the mode pulverized, and can use the mode of any one comminuted solids in prior art, as grinding etc., in the present invention, is preferably grinding.
Step 2, the g-C obtained by step 1
3n
4mix with silica, the mixture obtained is calcined, optionally cools, then pulverize, obtain composite photo-catalyst SiO
2/ g-C
3n
4.
The present inventor finds after deliberation, SiO
2carrier has the features such as the large and loose structure of Dispersion on surface effect, specific area, works as SiO
2with g-C
3n
4after compound, photo-generated carrier can carry out transmitting and being separated between different energy level, thus extends the life-span of photo-generated carrier, thus improves the reactivity of composite photo-catalyst.
In the present invention, the g-C that step 1 is obtained
3n
4be g-C with the weight ratio of silica
3n
4weight: weight=(3 ~ 50) of silica: 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
The present inventor finds, as silica and g-C
3n
4weight ratio when being greater than 50:100, the too high levels of silica, the catalytic efficiency of obtained composite photo-catalyst is low; As silica and g-C
3n
4weight ratio when being less than 3:100, dioxide-containing silica is too low, and photo-generated carrier can not be separated by silica wherein effectively, thus the catalytic efficiency of obtained composite photo-catalyst promotes not remarkable.
In the present invention, the particle diameter of silica used is 30 ~ 100nm, is preferably 40 ~ 80nm, is more preferably 50 ~ 70nm.
In the present invention, to g-C
3n
4be not particularly limited to the hybrid mode of silica, can use the mode of any one powder mixing in prior art, as mechanical agitation, grinding etc., the present invention is preferably the mode of grinding.The present inventor find, when adopt grinding mode mix time, not only two kinds of powder can be mixed to get more abundant, and, the mixture particle diameter obtained less evenly, thus in subsequent thermal polymerisation g-C
3n
4obtain more abundant and even with silica compound, thus make the composite photo-catalyst that obtains more even, photocatalysis efficiency is higher, and performance is more stable.
In step 2 of the present invention, described calcining is carried out under 300 ~ 800 DEG C of conditions in temperature, is preferably 400 DEG C ~ 700 DEG C, is more preferably 500 DEG C ~ 600 DEG C, as 520 DEG C.
In step 2 of the present invention, select calcination time to be 1 ~ 10 hour, be preferably 2 ~ 8 hours, be more preferably 3 ~ 6 hours, as 4 hours.Be less than 1 constantly little upon calcination, calcination time is too short, reacts insufficient, and raw material is remaining completely still unreacted in reaction system; After being greater than 10 hours upon calcination, raw material fully reacts, the no longer showed increased of the product in system, continues to extend calcination time and can only cause the waste of the energy and the increase of time cost.
Optionally, in step 2, the product after calcining is cooled, the method of the present invention to cooling is not particularly limited to, any one can be used in prior art by the method for solid cooled, as natural cooling, artificial cooling method etc., natural cooling to be preferably.
Optionally, in step 2, pulverized by the product after calcining, the present invention is not particularly limited to the mode pulverized, and can use the mode that in prior art, any one solid is pulverized, as grinding etc.
One of the present invention preferred embodiment in, in step 2, obtained product being ground to form particle diameter is 40 ~ 100nm, is preferably the particle of 50 ~ 80nm.
In the present invention, the composite photo-catalyst SiO that step 2 is obtained
2/ g-C
3n
4, SiO
2with g-C
3n
4weight ratio be (3 ~ 50): 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
According to infrared spectrum, it is at 810cm
-1neighbouring, 1240 ~ 1640cm
-1between there is absworption peak.
According to photoluminescence spectra, it goes out not only strong but also wide luminous signal at wavelength 400-500nm range performance.
According to UV-Vis diffuse reflection spectroscopy, there is stronger absorption in its UV-visible region at wavelength 300-450nm.
According to a second aspect of the invention, the composite photo-catalyst SiO obtained according to said method is also provided
2/ g-C
3n
4, it is characterized in that, in described composite photo-catalyst, SiO
2with g-C
3n
4weight ratio be (3 ~ 50): 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
According to infrared spectrum, it is at 810cm
-1neighbouring, 1240 ~ 1640cm
-1between there is absworption peak.
According to photoluminescence spectra, it goes out not only strong but also wide luminous signal at wavelength 400-500nm range performance.
According to UV-Vis diffuse reflection spectroscopy, there is stronger absorption in its UV-visible region at wavelength 300-450nm.
According to a third aspect of the invention we, the composite photo-catalyst also providing said method obtained, at improvement waste water from dyestuff, particularly administers the application of the waste water aspect containing azobenzene dyestuff.
According to composite photo-catalyst SiO provided by the invention
2/ g-C
3n
4and its preparation method and application, there is following beneficial effect:
(1) described composite photo-catalyst can catalyze and degrade organic pollutants, particularly azobenzene organic pollution under visible light, and its catalytic efficiency is high;
(2) method preparing composite photo-catalyst is easy, easily realizes, and operating condition is easy to control, and can realize large-scale preparation;
(3) when preparing composite photo-catalyst, raw materials used wide material sources, with low cost, the stable performance of obtained composite photo-catalyst;
(4) described composite photo-catalyst does not also produce environmental pollution in the process of catalytic degradation water, is a kind of catalyst of environmental protection.
Embodiment
embodiment 1
(1) accurately take 6.000g melamine with assay balance, be placed in agate mortar the crucible putting into clean dried after grinding 20min, close the lid, then put into Muffle furnace, in 520 DEG C of calcining 4h.After calcining terminates, cooling grind into powder, i.e. flaxen g-C
3n
4powder.
(2) take 0.3g silica, grinding 20min, puts into clean dried crucible, cover lid, puts into Muffle furnace, and after 520 DEG C of calcining 4h, take out cooling, grind into powder, namely makes 4.8%SiO
2/ g-C
3n
4composite photo-catalyst.
embodiment 2 ~ 5
Embodiment 2 ~ 5 method therefor is similar to embodiment method therefor, and difference is only that the weight of silica in step (2) is respectively 0.6g, 0.9g, 0.12g and 0.15g, and obtained product is respectively 9.1%SiO
2/ g-C
3n
4, 13.0%SiO
2/ g-C
3n
4, 16.7%SiO
2/ g-C
3n
4and 20.0%SiO
2/ g-C
3n
4.
Comparative example
comparative example 1
This comparative example specimen in use is g-C obtained in embodiment 1 step (1)
3n
4powder.
Experimental example
experimental example 1 sample infrared spectrum
By doing ftir analysis to sample, can the chemical bonding structure of judgement sample according to absworption peak.
This experimental example specimen in use is the sample that embodiment 1 ~ 5 and comparative example 1 obtain.
Method of operating: take a morsel catalyst sample, adds a small amount of potassium bromide powder (about 1:100) respectively, puts into agate mortar and is ground to and mixes, be pressed into thin slice, drying, carries out infrared spectrum characterization with FTIS to catalyst, and result as shown in Figure 1.
As shown in Figure 1,
G-C
3n
4infrared spectrum form primarily of three parts: at 1240 ~ 1640cm caused by the effect of vibration of CN heterocycle
-1between absworption peak, containing C
3n
4the infrared absorption band of triazine aromatic ring structure molecule is at 810cm
-1neighbouring absworption peak.
Be 1246 ~ 1651cm in wave number
-1between there is more absworption peak, and at 808cm
-1there is absworption peak in place, has-NH in interpret sample
2stretching vibration peak, the stretching vibration peak of C=N double bond, and containing the absworption peak of triazine aromatic ring structure molecule, thus prove that this sample is graphite-phase g-C
3n
4.
Can find in FIG, at 4.8%SiO
2/ g-C
3n
4, 9.1%SiO
2/ g-C
3n
4and 16.7%SiO
2/ g-C
3n
4infrared spectrum in be 2361cm in wave number
-1place's existence absworption peak, be not bound by any theory, the present inventor thinks that this peak is the absworption peak of carbon dioxide.
experimental example 2 sample photoluminescence spectra
Photoluminescence spectra (PL) is research semiconductor nano material electronic structure and the effective ways of optical property, being separated and the information such as compound of the architectural characteristics such as the blemish that can disclose semiconductor nano material and Surface Oxygen room and photo-generated carrier (electron-hole pair).
This experimental example specimen in use is the sample that embodiment 1 ~ 5 and comparative example 1 obtain.
Method of operating: above-mentioned catalyst sample (pulverulence) is taken a morsel respectively and puts into compression mold, then press with sheet glass, sample is pressed to obtain dense uniform, keep the flat smooth of sample surfaces, XRF is utilized to test the photoluminescence performance of various catalyst sample, wherein, excitation wavelength is 400nm, and result as shown in Figure 2.
As shown in Figure 2, g-C within the scope of wavelength 400-500nm
3n
4photochemical catalyst sample (pulverulence) shows not only strong but also wide luminous signal.
The photochemical catalyst sample (pulverulence) that embodiment 1 ~ 5 is obtained, shows similar signal peak equally within the scope of wavelength 400-500nm, but peak intensity will comparatively g-C
3n
4weak, for 13.0%SiO
2/ g-C
3n
4catalyst sample (pulverulence) is that within the scope of 400-500nm, signal peak is the most weak at wavelength.
SiO is demonstrated in Fig. 2
2exist and significantly suppress g-C
3n
4the height at PL peak, may be SiO
2effect has been caught, SiO at the separation of electron-hole and light induced electron
2and g-C
3n
4the chemical bond formed can promote the Charger transfer between two stages.
It is generally acknowledged, fluorescence signal is stronger, and the recombination probability of photo-generated carrier (electron-hole pair) raises, photocatalytic activity just corresponding reduction, in this regard, show in Fig. 2 catalyst activity the strongest be 13.0%SiO
2/ g-C
3n
4secondly catalyst is 4.8%SiO successively
2/ g-C
3n
4, 9.1%SiO
2/ g-C
3n
4, 16.7%SiO
2/ g-C
3n
4, 20.0%SiO
2/ g-C
3n
4catalyst, g-C
3n
4the activity of catalyst is minimum.
experimental example 3 sample UV-Vis diffuse reflection spectroscopy
This experimental example specimen in use is the sample that embodiment 1 ~ 5 and comparative example 1 obtain.
Method of operating: utilize uv-visible absorption spectra instrument to test the ultraviolet-ray visible absorbing performance of various catalyst sample.With tack glass bar, sample is pressed fine and close, firmly evenly, to keep the flat smooth of sample surfaces, can not be uneven, and sample should at least parallel testing twice, ensures the validity of data, result as shown in Figure 3, wherein,
Curve a represents 13.0%SiO
2/ g-C
3n
4,
Curve b represents 4.8%SiO
2/ g-C
3n
4,
Curve c represents 9.1%SiO
2/ g-C
3n
4,
Curve d represents 16.7%SiO
2/ g-C
3n
4,
Curve e represents 20.0%SiO
2/ g-C
3n
4,
Curve f represents g-C
3n
4.
As shown in Figure 3, the catalyst obtained in UV-visible region embodiment 1 ~ 5 and the comparative example 1 of wavelength 300-450nm has stronger absorption.
The catalyst g-C that comparative example is obtained
3n
4the SiO obtained with embodiment 1 ~ 5
2/ g-C
3n
4composite catalyst has absorption in ultra-violet (UV) band and visual field, but the latter increases in the absorption intensity of ultra-violet (UV) band and visual field, is not bound by any theory, and the present inventor thinks SiO
2add and increase g-C
3n
4specific area, enhance the absorption to light.
As seen from Figure 3, to the absorbability of light the strongest be 13.0%SiO
2/ g-C
3n
4photochemical catalyst, be secondly 4.8%SiO
2/ g-C
3n
4, 9.1%SiO
2/ g-C
3n
4, 16.7%SiO
2/ g-C
3n
4, 20.0%SiO
2/ g-C
3n
4, be finally g-C
3n
4catalyst.
Catalyst embodies the photocatalytic activity of catalyst to light absorpting ability, so this figure demonstrates 13.0%SiO
2/ g-C
3n
4the photocatalytic activity of catalyst is the highest.
experimental example 4 sample photocatalytic activity measures
This experimental example specimen in use is the sample that embodiment 1 ~ 5 and comparative example 1 obtain.
Method of operating: accurately take pure g-C respectively
3n
4, 4.8%SiO
2/ g-C
3n
4, 9.1%SiO
2/ g-C
3n
4, 13.0%SiO
2/ g-C
3n
4, 16.7%SiO
2/ g-C
3n
4, 20.0%SiO
2/ g-C
3n
4the each 0.100g of catalyst fines is put in quartz ampoule respectively, respectively adds a stirrer, number consecutively 1,2,3,4,5,6, and adding 40mL concentration is respectively 2.500mgL
-1methyl orange solution, above-mentioned quartz ampoule is put into photochemical reaction instrument, open water intaking valve, opening power, dark treatment 30min under continuous stirring, draw about 8mL solution centrifugal 20min in supercentrifuge, take out after leaving standstill 10min and survey its absorbance respectively with ultraviolet-visible spectrophotometer, be designated as A
0, open light source, visible photo-irradiation treatment 2h, sample centrifugal 20min, survey its absorbance and be designated as A
t, calculate degradation rate W according to following formula.
W(％)＝(A
0－A
t)/A
0×100％。
Draw out the visible light activity figure of different catalysts sample according to gained degradation rate, result as shown in Figure 4, wherein,
Curve 1 represents g-C
3n
4,
Curve 2 represents 4.8%SiO
2/ g-C
3n
4,
Curve 3 represents 9.1%SiO
2/ g-C
3n
4,
Curve 4 represents 13.0%SiO
2/ g-C
3n
4,
Curve 5 represents 16.7%SiO
2/ g-C
3n
4,
Curve 6 represents 20.0%SiO
2/ g-C
3n
4.
As shown in Figure 4, the SiO that embodiment 1 ~ 5 is obtained
2/ g-C
3n
4the photodegradation rate of composite catalyst is all than the pure sample g-C that comparative example 1 obtains
3n
4degradation rate high.
Wherein, 13.0%SiO
2/ g-C
3n
4degradation rate the highest, being secondly 45.8%, is 9.1%SiO successively
2/ g-C
3n
4, 4.8%SiO
2/ g-C
3n
4, 16.7%SiO
2/ g-C
3n
4and 20.0%SiO
2/ g-C
3n
4, g-C
3n
4the degradation rate of photochemical catalyst is minimum, is 18.9%.
experimental example 5 scavenger is on the impact of sample catalytic activity
This experimental example specimen in use is the sample that embodiment 3 and comparative example 1 obtain.
Method of operating: accurately take five parts of 0.100gg-C
3n
4powder be put in the quartz ampoule having put into stirrer respectively, numbering 1,2,3,4,5,6, wherein, any scavenger is not added, as blank in No. 1 quartz ampoule, 0.004g ammonium oxalate is added respectively in 2 ~ No. 6 pipes, 0.004g 1,4-benzoquinone, 3.80 μ L catalases, 5.00 μ L isopropyl alcohols, 0.004g sodium nitrate, then in quartz ampoule, add 40mL concentration be successively 2.500mgL
-1methyl orange solution.Put into photochemical reaction instrument afterwards, under continuous stirring, dark treatment 30min, draws about 8mL solution centrifugal 20min in supercentrifuge, surveys its absorbance respectively, be designated as A
0, open light source, radiation of visible light 2h, draw about 8mL solution centrifugal 20min in supercentrifuge, survey its absorbance, be designated as A
t, calculate degradation rate W according to following formula,
W(％)＝(A
0－A
t)/A
0×100％，
Scavenger is drawn out to catalyst g-C according to gained degradation rate
3n
4interact relation figure, result as shown in Figure 5 a, wherein,
Noscavenger represents and does not add scavenger;
Ammonium oxalate is added during AO represents;
BQ represents and adds 1,4-benzoquinone;
CAT represents and adds catalase;
IPA represents and adds isopropyl alcohol;
NO
3 -represent and add NaNO
3;
Add isopropyl alcohol (IPA) and play the effect that in inhibition system degradation process, OH produces, add ammonium oxalate (AO) and play h in inhibition system degradation process
+the effect produced, adds 1,4-benzoquinone (BQ) and plays O in inhibition system degradation process
2 -the effect produced, adds catalase (CAT) and plays H in inhibition system degradation process
2o
2the effect produced, e
-scavenger NaNO
3also reaction system is introduced respectively.
From Fig. 5 a, when other condition is constant,
(1) with do not add compared with scavenger, after adding above-mentioned scavenger, the activity of the catalyst that comparative example 1 is obtained all has and comparatively significantly reduces, and adding of 1,4-benzoquinone (BQ) makes the activity of catalyst fall minimum;
(2) NaNO
3the impact added catalyst is visible active relatively minimum, can ignore, show e in the process of photo-catalytic degradation of methyl-orange under visible light illumination
-it not main active specy;
(3) the adding visible active the having the greatest impact of catalyst of 1,4-benzoquinone (BQ), O in the process of photo-catalytic degradation of methyl-orange is under visible light illumination described
2 -it is topmost active specy.
In summary, OH, H
2o
2, O
2 -obvious effect is played, especially O in Photocatalytic Degradation Process
2 -main effect is played in photocatalytic process.
With the catalyst 13.0%SiO that same method test scavenger is obtained to embodiment 3
2/ g-C
3n
4catalytic activity interact relation figure, result as shown in Figure 5 b, conclusion and Fig. 5 a conclusion similar, that is, OH, H
2o
2, O
2 -obvious effect is played, especially O in Photocatalytic Degradation Process
2 -main effect is played in photocatalytic process.
the ultraviolet-visible spectrum of experimental example 6 sample degradation methyl orange
Methyl orange dye is a kind of common azobenzene dyestuff, representative.Wherein, it is 464nm place that the absworption peak of azo bond is present in wavelength, and therefore, absworption peak is higher herein, illustrates that in detected solution, the concentration of methyl orange is larger, namely methyl orange be degraded fewer, thus the activity demonstrating photochemical catalyst is less.
This experimental example specimen in use is the sample that embodiment 3 and comparative example 1 obtain.
Method of operating: accurately take g-C
3n
4, 13.0%SiO
2/ g-C
3n
4the each 0.100g of catalyst fines, in the quartz ampoule putting into stirrer, is numbered 1,2, and adding 40mL concentration is respectively 2.500mgL
-1methyl orange solution.Quartz ampoule is put into photochemical reaction instrument, opens water intaking valve, opening power, under continuous stirring, dark treatment 30min, draws about 6mL solution centrifugal 20min in supercentrifuge.Open visible light light source, use visible illumination degrading, every 40min draw solution once, then centrifugal 20min, change a centrifuge tube centrifugal again, to ensure that solution is clarified, get 5 solution altogether, turn off the light after experiment terminates, stir button, power supply, shutoff valve, finally utilize dual-beam ultraviolet-visible spectrophotometer to measure the visible spectrum of each photochemical catalyst respectively, scanning wavelength is 200 ~ 800nm.
Comparative example 1 obtains sample g-C
3n
4test result as shown in Figure 6 a, embodiment 3 obtains sample SiO
2/ g-C
3n
4test result as shown in Figure 6 b, from Fig. 6 a and Fig. 6 b,
When reaction condition is identical, under visible light illumination, 13.0%SiO in same time
2/ g-C
3n
4compare g-C
3n
4the methyl orange of degraded is more, i.e. 13.0%SiO
2/ g-C
3n
4degrading activity better.
In Fig. 6 a and Fig. 6 b, do not have new peak to occur, the reduction gradually of absorption values is mainly because photocatalytic degradation reaction, and along with the carrying out of light-catalyzed reaction, the methyl orange of degraded gets more and more, and concentration is more and more less, so absworption peak is more and more lower.
the relation of experimental example 7 sample degradation methyl orange effect and degradation time
Due to terephthalic acid (TPA) easily and the hydroxyl radical free radical that formed of catalyst surface react that generate can the product 2-hydroxyterephthalic acid of emitting fluorescence, therefore terephthalic acid (TPA) can be utilized as fluorescence probe material, and application fluorescent technique analyzes the hydroxyl radical free radical produced in photocatalytic degradation reaction.
Fluorescence intensity means more by force in photocatalysis system and creates more hydroxyl radical free radicals, it has been generally acknowledged that hydroxyl radical free radical is the important species in photochemical catalytic oxidation, the concentration of hydroxyl radical free radical and the photocatalytic activity of catalyst closely related.
This experimental example specimen in use is the sample that embodiment 3 and comparative example 1 obtain.
Method of operating: accurately take g-C
3n
4, 13.0%SiO
2/ g-C
3n
4the each 0.100g of catalyst fines, in the quartz ampoule putting into stirrer, is numbered 1,2, and adding 40mL concentration is respectively 2.500mgL
-1methyl orange solution, then add 10mL NaOH (2.0 × 10
-3molL
-1) and terephthalic acid (TPA) (5.0 × 10
-4molL
-1) mixed solution is as fluorescence probe material.Above-mentioned quartz ampoule is put into photochemical reaction instrument, opens water intaking valve and power supply, under continuous stirring, dark treatment 30min, then draw the solution after dark treatment respectively, open visible light light source, use visible illumination degrading, once, then centrifugal 20min, changes a centrifuge tube centrifugal again to every 40min draw solution, to ensure that solution is clarified, get 5 solution altogether, utilize XRF to measure its fluorescence property respectively, optical maser wavelength is 315nm.
Comparative example 1 obtains sample g-C
3n
4test result as shown in Figure 7a, embodiment 3 obtains sample SiO
2/ g-C
3n
4test result as shown in Figure 7b, from Fig. 7 a and Fig. 7 b,
Carry out along with light-catalysed, the time lengthening (every 40min sampling once) of Visible Light Induced Photocatalytic methyl orange, fluorescence intensity raises gradually.
Relatively can be found out by Fig. 7 a and Fig. 7 b, 13.0%SiO
2/ g-C
3n
4in composite photo-catalyst same time, spacing is comparatively large, and the hydroxyl radical free radical of generation is more, so 13.0%SiO
2/ g-C
3n
4the visible specific activity pure sample g-C of composite photo-catalyst
3n
4height.
More than in conjunction with detailed description of the invention and exemplary example to invention has been
in detaildescribe in detail bright, but these explanations can not be interpreted as limitation of the present invention.It will be appreciated by those skilled in the art that when not departing from spirit and scope of the invention, can carry out multiple equivalencing, modification or improvement to technical solution of the present invention and embodiment thereof, these all fall within the scope of the present invention.Protection scope of the present invention is as the criterion with claims.
Claims (10)
1. prepare composite photo-catalyst SiO for one kind
2/ g-C
3n
4method, it is characterized in that, the method comprises the following steps:
(1) itrogenous organic substance is calcined, optionally cool, pulverize, obtain g-C
3n
4;
(2) by g-C obtained for step 1
3n
4mix with silica, the mixture obtained is calcined, optionally cools, then pulverize, obtain composite photo-catalyst SiO
2/ g-C
3n
4.
2. method according to claim 1, is characterized in that, in step 1,
Described itrogenous organic substance is nitrogenous small organic molecule, preferred carbon-nitrogen ratio is the itrogenous organic substance of the small-molecular-weight of 1:3 ~ 3:1, more preferably use the small-molecular-weight itrogenous organic substance that carbon-nitrogen ratio is 1:2, as cyanamide, dicyanodiamine, melamine, urea, guanidine hydrochloride etc., be preferably melamine.
3. method according to claim 1 and 2, is characterized in that, in step 1, heating rate is 10 ~ 30 DEG C of min
-1, be preferably 15 ~ 25 DEG C of min
-1, as 20 DEG C of min
-1; And/or
Described calcining is carried out under 300 ~ 800 DEG C of conditions, is preferably 400 DEG C ~ 700 DEG C, is more preferably 500 DEG C ~ 600 DEG C, as 520 DEG C; And/or
Calcination time is 1 ~ 10 hour, is preferably 2 ~ 8 hours, is more preferably 3 ~ 6 hours, as 4 hours; And/or
Select in confined conditions to the calcining that raw material carries out; And/or
The mode of described pulverizing is grinding.
4., according to the method one of claims 1 to 3 Suo Shu, it is characterized in that, in step 2,
G-C
3n
4be g-C with the weight ratio of silica
3n
4weight: weight=(3 ~ 50) of silica: 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
5. according to the method one of Claims 1 to 4 Suo Shu, it is characterized in that, in step 2, the particle diameter of described silica is 30 ~ 100nm, is preferably 40 ~ 80nm, is more preferably 50 ~ 70nm.
6. according to the method one of Claims 1 to 5 Suo Shu, it is characterized in that, in step 2, described calcining is carried out under 300 ~ 800 DEG C of conditions in temperature, is preferably 400 DEG C ~ 700 DEG C, is more preferably 500 DEG C ~ 600 DEG C, as 520 DEG C;
The time of calcining is 1 ~ 10 hour, is preferably 2 ~ 8 hours, is more preferably 3 ~ 6 hours, as 4 hours.
7., according to the method one of claim 1 ~ 6 Suo Shu, it is characterized in that, in step 2, obtained composite photo-catalyst SiO
2/ g-C
3n
4middle SiO
2with g-C
3n
4weight ratio be (3 ~ 50): 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%;
According to infrared spectrum, there is absworption peak in it near 810cm-1, between 1240 ~ 1640cm-1;
According to photoluminescence spectra, it goes out not only strong but also wide luminous signal at wavelength 400-500nm range performance;
According to UV-Vis diffuse reflection spectroscopy, there is stronger absorption in its UV-visible region at wavelength 300-450nm.
8. the composite photo-catalyst SiO obtained according to the method one of claim 1 ~ 7 Suo Shu
2/ g-C
3n
4, it is characterized in that, in described composite photo-catalyst, SiO
2with g-C
3n
4weight ratio be (3 ~ 50): 100, be preferably (4 ~ 30): 100, be more preferably (4.8 ~ 20): 100, as 4.8%, 9.1%, 13.0%, 16.7% and 20.0%.
9. composite photo-catalyst SiO according to claim 8
2/ g-C
3n
4, it is characterized in that,
According to infrared spectrum, there is absworption peak in it near 810cm-1, between 1240 ~ 1640cm-1;
According to photoluminescence spectra, it goes out not only strong but also wide luminous signal at wavelength 400-500nm range performance;
According to UV-Vis diffuse reflection spectroscopy, there is stronger absorption in its UV-visible region at wavelength 300-450nm.
10. the composite photo-catalyst of according to Claim 8 or 9 is at improvement waste water from dyestuff, particularly administers the application of the waste water aspect containing azobenzene dyestuff.
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| CN106582495A (en) * | 2016-10-27 | 2017-04-26 | 江苏大学 | Ternary composite photocatalytic nanometer reactor as well as preparation method and application thereof |
| CN107321375A (en) * | 2017-07-13 | 2017-11-07 | 扬州工业职业技术学院 | A kind of SiO2/ZnO/g‑C3N4Nano material and its application in reduction of hexavalent chromium |
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| CN113083343A (en) * | 2021-03-17 | 2021-07-09 | 江苏索普化工股份有限公司 | Graphite-phase carbon nitride modified silicon oxide porous microsphere rhodium-loaded heterogeneous catalyst and preparation method and application thereof |
| CN113083343B (en) * | 2021-03-17 | 2023-08-29 | 江苏索普化工股份有限公司 | Heterogeneous catalyst of rhodium supported by graphite-phase carbon nitride modified silicon oxide porous microspheres and preparation method and application thereof |
| CN114832803A (en) * | 2022-04-08 | 2022-08-02 | 重庆城市综合交通枢纽（集团）有限公司 | Film-forming composition, preparation method thereof and application of composite photocatalyst |
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