Preparation method of carbon-point composite bismuthyl carbonate visible-light-driven photocatalyst
Technical Field
The invention belongs to the field of nano composite materials, and particularly relates to a preparation method of a carbon dot composite bismuthyl carbonate visible-light-driven photocatalyst.
Background
Nowadays, the environmental pollution problem is more and more serious, and the human health is seriously threatened, so that the environmental pollution problem becomes the first problem to be solved at home and abroad. Solar energy is a clean and renewable natural resource, organic pollutants can be degraded into micromolecular water, carbon dioxide and the like by using a photocatalyst, and the application prospect is good. Bismuth (Bi) -based photocatalysts have been developed, the oxides of bismuth having (BiO)2 2+The layered structure can be self-assembled to form different shapes, and effectively degrade organic pollutants in the wastewater. Bismuth oxycarbonate ((BiO)2CO3) Is a photocatalyst only responding to ultraviolet light, does not contain toxic elements such as halogen and the like, (BiO)2 2+Layer and CO3 2-The layers are alternately stacked in the C-axis direction to form a layered structure. However, the regular layered structure provides bismuth oxycarbonate with a small specific surface area, which greatly limits its photocatalytic performance, and at the same time, its performance is also affected by the limited electron transfer capacity and photoinduced redox capacity. Therefore, bismuth subcarbonate is compounded with a plurality of suitable semiconductor photocatalysts, the morphology of the bismuth subcarbonate is controlled to increase the specific surface area of the photocatalyst to create more catalytic reaction active sites, and a heterojunction is formed to improve the electron transfer capacity in the catalytic reaction process, so that the performance of the visible light photocatalyst for degrading organic pollutants is improved, and the bismuth subcarbonate is an important and urgent problem to be solved.
The Carbon Dots (CDs) are used as a zero-dimensional carbon-based material with wide source, simple preparation and environmental friendliness, and have a wider photoresponse range, stronger electron transfer capability and better photoinduced redox capability. Thus, the coal pitch carbon dots react with bismuth oxycarbonate in situ to form carbon dots and bismuth oxycarbonate heterostructures (CDs @ (BiO)2CO3),The specific surface area of the catalyst can be increased, more catalytic reaction active sites are created, and the heterojunction is formed, so that the electron transfer capability and the photoinduced redox capability in the catalytic reaction process can be improved, and the catalytic performance of the visible-light-driven photocatalyst for degrading organic pollutants is improved. At present, the performance of the visible-light-driven photocatalyst is improved by utilizing the above mode, and particularly, the carbon-point composite bismuth oxycarbonate visible-light-driven photocatalyst (CDs @ (BiO) is prepared under the room temperature environment2CO3) The method (2) has not been reported.
Disclosure of Invention
The invention aims to provide a method for preparing a carbon-point composite bismuthyl carbonate visible-light-driven photocatalyst at room temperature so as to improve the visible-light-driven catalytic performance of the catalyst.
In order to achieve the purpose, the invention provides the following technical scheme:
a preparation method of a carbon-point composite bismuthyl carbonate visible light photocatalyst adopts the following steps:
step 1: preparing a mL of 88% formic acid and b mL of 30% hydrogen peroxide into a mixed solution of the formic acid and the hydrogen peroxide, wherein: b is 9.5-10.5, c mL of mixed solution of formic acid and hydrogen peroxide is poured into a beaker, d mg of coal tar pitch powder is added into the beaker, and suspension is prepared, wherein: d, putting the suspension on a magnetic stirrer, stirring at normal temperature for 18-20 hours, putting the suspension into a centrifugal machine, centrifuging to remove large particles, and taking supernatant to obtain carbon dot solution, wherein c is 5.5-6.5 mg/mL;
step 2: taking e mL of the carbon dot solution prepared in the step 1, adding f mg of pentahydrate bismuth nitrate powder, and preparing the carbon dot-bismuth nitrate solution, wherein: e is 12.5-17.5 mg/mL, then the carbon dot-bismuth nitrate solution is placed on a magnetic stirrer, and is stirred and reacted for 10-12 hours at normal temperature at the rotating speed of 600-800 r/min to obtain a suspension A;
and step 3: placing the suspension A prepared in the step 2 into a centrifuge, centrifuging for 20-30 min at the rotating speed of 8000-10000 r/min, taking solid particles, washing with deionized water for 3-5 times, then placing the solid particles into a vacuum drying oven, and drying at the temperature of 40-50 ℃ to obtain carbon dot-bismuth oxyformate composite powder;
and 4, step 4: and (3) adding g mg of the carbon dot-bismuth oxyformate composite powder prepared in the step (3) into a beaker, pouring h mL of deionized water into the beaker, and preparing a suspension B, wherein: g, h is 25-35 mg/mL, then the suspension B is placed on a magnetic stirrer, and the suspension B is stirred at the normal temperature for 30-40 min at the rotating speed of 600-800 r/min;
and 5: putting i mL of the stirred suspension B prepared in the step 4 on a magnetic stirrer, and adding j mL of sodium borohydride or ammonia borane solution with the concentration of 0.5-1.5 g/L into the magnetic stirrer at the rotating speed of 600-800 r/min, wherein: j is 4.5-7.5, and stirring and reacting for 30-40 min at normal temperature to obtain suspension C;
step 6: and (5) centrifuging the suspension C prepared in the step (5) in a centrifuge at the rotating speed of 8000-10000 r/min for 20-30 min, taking solid particles, washing the solid particles with deionized water for 3-5 times, then putting the solid particles into a vacuum drying oven, and drying at the temperature of 40-50 ℃ to finally obtain the carbon-point composite bismuth oxycarbonate visible light catalyst.
Compared with the prior art, the invention has the advantages of reaction at normal temperature, simple preparation process, contribution to large-scale industrial production and the like; the carbon-point composite bismuthyl carbonate visible-light-induced photocatalyst prepared by the invention has strong visible-light-induced catalytic performance.
Drawings
FIG. 1 is a process flow diagram for preparing a carbon-point composite bismuth oxycarbonate visible-light-induced photocatalyst;
FIG. 2 shows a carbon dot composite bismuthyl carbonate visible-light-induced photocatalyst sample and (BiO)2CO3XRD pattern of standard card;
FIG. 3 is a UV-VISIBLE absorption spectrum of a sample of carbon dot bismuth oxycarbonate visible light photocatalyst;
FIG. 4 is a graph showing pore volume and pore size distribution of a carbon dot composite bismuth oxycarbonate visible light photocatalyst sample;
FIG. 5 is a graph showing the effect of visible light-catalyzed degradation of rhodamine B (RhB) by a carbon dot composite bismuthyl carbonate visible light-catalyzed photocatalyst sample;
FIG. 6 is a graph showing the effect of visible-light photocatalytic degradation of Methylene Blue (MB) for a carbon-point composite bismuthyl carbonate visible-light photocatalyst sample;
FIG. 7 is CDs @ (BiO)2CO3A graph of the effect of photocatalytic degradation of Methyl Orange (MO) on a sample;
FIG. 8 is a graph showing the results of an electron paramagnetic resonance spectroscopy (ESR) test of whether a sample of carbon-point bismuth oxycarbonate photocatalyst produced hydroxyl radical actives;
FIG. 9 shows the results of ESR testing whether a sample of carbon point bismuth subcarbonate visible photocatalyst produces superoxide radical actives;
FIG. 10 shows the photocurrent test results of carbon dot composite bismuth oxycarbonate visible light catalyst samples;
FIG. 11 is a repeatability test of photocatalytic degradation of RhB by a carbon dot composite bismuth oxycarbonate visible-light-induced photocatalyst sample;
FIG. 12 is a graph showing the effect of photocatalytic degradation of RhB by a carbon dot composite bismuth oxycarbonate visible-light-induced photocatalyst sample under different light intensities.
Detailed Description
The detailed technical scheme of the invention is described in the following with the accompanying drawings:
a preparation method of a carbon-point composite bismuthyl carbonate visible light photocatalyst adopts the following steps:
step 1: preparing a mL of 88% formic acid and b mL of 30% hydrogen peroxide into a mixed solution of the formic acid and the hydrogen peroxide, wherein: b is 9.5-10.5, c mL of mixed solution of formic acid and hydrogen peroxide is poured into a beaker, d mg of coal tar pitch powder is added into the beaker, and suspension is prepared, wherein: d, putting the suspension on a magnetic stirrer, stirring at normal temperature for 18-20 hours, putting the suspension into a centrifugal machine, centrifuging to remove large particles, and taking supernatant to obtain carbon dot solution, wherein c is 5.5-6.5 mg/mL;
step 2: taking e mL of the carbon dot solution prepared in the step 1, adding f mg of pentahydrate bismuth nitrate powder, and preparing the carbon dot-bismuth nitrate solution, wherein: e is 12.5-17.5 mg/mL, then the carbon dot-bismuth nitrate solution is placed on a magnetic stirrer, and is stirred and reacted for 10-12 hours at normal temperature at the rotating speed of 600-800 r/min to obtain a suspension A;
and step 3: placing the suspension A prepared in the step 2 into a centrifuge, centrifuging for 20-30 min at the rotating speed of 8000-10000 r/min, taking solid particles, washing with deionized water for 3-5 times, then placing the solid particles into a vacuum drying oven, and drying at the temperature of 40-50 ℃ to obtain carbon dot-bismuth oxyformate composite powder;
and 4, step 4: and (3) adding g mg of the carbon dot-bismuth oxyformate composite powder prepared in the step (3) into a beaker, pouring h mL of deionized water into the beaker, and preparing a suspension B, wherein: g, h is 25-35 mg/mL, then the suspension B is placed on a magnetic stirrer, and the suspension B is stirred at the normal temperature for 30-40 min at the rotating speed of 600-800 r/min;
and 5: putting i mL of the stirred suspension B prepared in the step 4 on a magnetic stirrer, and adding j mL of sodium borohydride or ammonia borane solution with the concentration of 0.5-1.5 g/L into the magnetic stirrer at the rotating speed of 600-800 r/min, wherein: j is 4.5-7.5, and stirring and reacting for 30-40 min at normal temperature to obtain suspension C;
step 6: and (5) centrifuging the suspension C prepared in the step (5) in a centrifuge at the rotating speed of 8000-10000 r/min for 20-30 min, taking solid particles, washing the solid particles with deionized water for 3-5 times, then putting the solid particles into a vacuum drying oven, and drying at the temperature of 40-50 ℃ to finally obtain the carbon-point composite bismuth oxycarbonate visible light catalyst.
Example 1
A preparation method of a carbon dot composite bismuthyl carbonate visible light photocatalyst is shown in figure 1 and comprises the following steps:
step 1: preparing a mL of 88% formic acid and b mL of 30% hydrogen peroxide into a mixed solution of the formic acid and the hydrogen peroxide, wherein: b is 10, c mL of mixed solution of formic acid and hydrogen peroxide is poured into a beaker, d mg of coal tar pitch powder is added into the beaker, and suspension is prepared, wherein: d, putting the suspension on a magnetic stirrer, stirring at normal temperature for 19 hours, putting the suspension into a centrifuge, centrifuging to remove large particles, and taking supernatant to obtain carbon dot solution;
step 2: taking e mL of the carbon dot solution prepared in the step 1, adding f mg of pentahydrate bismuth nitrate powder, and preparing the carbon dot-bismuth nitrate solution, wherein: e is 15mg/mL, then the carbon dot-bismuth nitrate solution is placed on a magnetic stirrer, and is stirred and reacted for 11 hours at normal temperature at the rotating speed of 700r/min to obtain a suspension A;
and step 3: placing the suspension A prepared in the step 2 into a centrifuge, centrifuging for 25min at the rotating speed of 9000r/min, taking solid particles, washing for 5 times by using deionized water, then placing the solid particles into a vacuum drying oven, and drying at the temperature of 45 ℃ to obtain carbon dot-bismuth oxyformate composite powder;
and 4, step 4: and (3) adding g mg of the carbon dot-bismuth oxyformate composite powder prepared in the step (3) into a beaker, pouring h mL of deionized water into the beaker, and preparing a suspension B, wherein: g, h is 30mg/mL, then the suspension B is placed on a magnetic stirrer, and the suspension B is stirred for 40min at the normal temperature at the rotating speed of 700 r/min;
and 5: i mL of the stirred suspension B prepared in the step 4 is put on a magnetic stirrer, and j mL of sodium borohydride or ammonia borane solution with the concentration of 1g/L is added into the suspension B at the rotating speed of 700r/min, wherein: i, j is 6, stirring and reacting for 40min at normal temperature to obtain suspension C;
step 6: placing the suspension C prepared in step 5 into a centrifuge, centrifuging at 9000r/min for 25min, taking solid particles, washing with deionized water for 5 times, placing the solid particles into a vacuum drying oven, and drying at 50 deg.C to obtain carbon point composite bismuth oxycarbonate visible light catalyst (CDs @ (BiO)2CO3)。
FIG. 2 is CDs @ (BiO)2CO3Sample and (BiO)2CO3The XRD spectrum of the standard card shows that the carbon point and the bismuth oxycarbonate realize heterogeneous combination.
FIG. 3 is CDs @ (BiO)2CO3The uv-vis absorption spectrum of the solid sample shows that the sample has strong absorption over the entire visible range.
FIG. 4 is CDs @ (BiO)2CO3The pore volume and pore diameter distribution curve chart of the sample shows that the sample has abundant mesopores and micropores, which is beneficial to increasing reactive sites.
FIG. 5 is CDs @ (BiO)2CO3The sample degraded rhodamine B (RhB) under visible light catalysis, and the degradation is about 60 percent in 10 minutesThe sample has better capacity of degrading RhB by photocatalysis.
FIG. 6 is CDs @ (BiO)2CO3The sample can be degraded by visible light catalysis to Methylene Blue (MB), and the degradation is about 70% in 10 minutes, which shows that the sample has better photocatalytic MB degradation capability.
FIG. 7 is CDs @ (BiO)2CO3The sample degrades Methyl Orange (MO) in 10 minutes by about 75%, which shows that the sample has better capability of degrading MO by photocatalysis.
FIG. 8 is the electron paramagnetic resonance spectroscopy (ESR) test CDs @ (BiO)2CO3Whether the sample produced hydroxyl radical activity indicates that the sample produced hydroxyl radicals in aqueous solution only in the presence of light and not in the absence of light.
FIG. 9 is a test of ESR for CDs @ (BiO)2CO3Whether the sample produced superoxide radical actives indicates that superoxide radicals were generated in the sample in aqueous solution only when illuminated and not when not illuminated.
FIG. 10 is CDs @ (BiO)2CO3The photocurrent test of the sample shows that the photo-generated electron-hole pair can be well separated and can realize high-efficiency migration, which is beneficial to promoting surface catalytic reaction.
FIG. 11 is CDs @ (BiO)2CO3The repeatability test of the sample photocatalytic degradation RhB shows that the activity of the sample photocatalytic degradation RhB is not reduced after the sample photocatalytic degradation RhB is repeatedly used for four times under visible light, which indicates that the sample has high photocatalytic stability.
FIG. 12 is CDs @ (BiO) under different light intensities2CO3The sample photocatalytically degrades RhB, and it can be seen that the rate of photocatalytically degrading RhB of the sample is increased along with the increase of the illumination intensity, which shows that the performance of photocatalytically degrading organic matters can be improved by increasing the number of input photons.