CN103381367B - A photocatalytic water splitting hydrogen production material CdS/Ba0.9Zn0.1TiO3 and its preparation method - Google Patents

Abstract

A photocatalytic water splitting hydrogen production material CdS/Ba _0.9 Zn _0.1 TiO ₃ is a catalyst with a heterogeneous structure formed by loading CdS onto Ba _0.9 Zn _0.1 TiO ₃ . The catalyst of the present invention is prepared by a hydrothermal sol method of. When the molar ratio of CdS to Ba _0.9 Zn _0.1 TiO ₃ is 1:5, the expression is 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ , and the catalytic effect of the material is the best. Under the irradiation of a 300W xenon lamp, Na ₂ S/Na ₂ SO ₃ was used as the sacrificial reagent. The advantages of the present invention are: 1. The catalyst of the present invention is directly synthesized by a hydrothermal melt adhesive method, which has simple operation, low production cost, high synthetic yield, high purity and good repeatability, and is suitable for enlarged production 2. The catalyst of the present invention has good stability and is easy to reuse; 3. The catalyst of the present invention has high photocatalytic hydrogen production efficiency.

Description

A photocatalytic water splitting hydrogen production material CdS/Ba0.9Zn0.1TiO3 and its preparation method

technical field

The invention relates to a material CdS/Ba _0.9 Zn _0.1 TiO ₃ for photocatalytically decomposing water to produce hydrogen and a preparation method thereof.

Background technique

Energy is the basis of human activities and the material premise of the development of human society. Compared with traditional fossil energy (such as coal and petroleum), hydrogen energy is a clean energy source. It can be obtained from water, and the product of complete combustion is water. It will not cause any pollution to the environment and is the cleanest energy in the world. Although the technology of using natural gas, oil, coal and other fossil energy to produce hydrogen through thermochemical method is relatively mature, it is neither economical nor environmentally friendly, and the method of electrolyzing water consumes a lot of energy. If we can use renewable energy (Such as solar energy) decomposes water to produce hydrogen, then hydrogen can be called a real "green energy". the

Since the late 1960s, Japanese scholars Fujishima A and Honda K have discovered the phenomenon that light n-type semiconductor TiO ₂ electrodes lead to the decomposition of water to produce hydrogen, revealing that the use of solar energy to split water to produce hydrogen—or to use solar energy directly Possibility of conversion into chemical energy. At present, among many photocatalysts, _TiO2 has become a hot spot in the field of heterogeneous photocatalysis due to its cheap and non-toxic properties, appropriate conduction band valence band potential, low photocorrosion, and no secondary pollution. It is currently the most promising green photocatalyst for development. However, TiO ₂ has the following problems: 1. The recombination rate of photo-induced holes and photo-generated electrons is fast, and the quantum efficiency is low; 2. TiO ₂ has poor adsorption to pollutants; 3. Wide band gap (Eg=3.2ev) . Therefore, it is necessary to explore and develop new photocatalysts.

Contents of the invention

The purpose of the present invention is to provide a novel photocatalytic water splitting hydrogen production material and a preparation method thereof, so as to provide new materials for solving current energy problems. The material preparation of the present invention adopts the hydrothermal melt glue method, which has the advantages of simple operation, low production cost, high synthesis yield, high purity and good repeatability, and is suitable for expanding production requirements. the

The present invention is realized in this way, and the characteristic is that the catalyst is a heterojunction catalyst formed by loading CdS on Ba _0.9 Zn _0.1 TiO ₃ . When the molar ratio of CdS to Ba _0.9 Zn _0.1 TiO ₃ is 1:5, the expression is 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ , and the catalytic effect of the material is the best. Under the irradiation of a 300-watt xenon lamp, using Na ₂ S/Na ₂ SO ₃ as a sacrificial reagent, the material 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ of the present invention can produce hydrogen by photocatalytically decomposing water without noble metal co-catalysis. 1473 .

The catalyst CdS/Ba _0.9 Zn _0.1 TiO ₃ of the present invention can obtain CdS/Ba _0.9 Zn _0.1 TiO ₃ heterojunction catalysts with different loading ratios by changing the molar ratio of CdS to Ba _0.9 Zn _0.1 TiO ₃ .

The preparation method of catalyst CdS/Ba _0.9 Zn _0.1 TiO ₃ of the present invention is: disperse 2 grams of Ba _0.9 Zn _0.1 TiO ₃ powder prepared by hydrothermal sol method in 30 milliliters of water, add corresponding amount of acetic acid after stirring Cadmium (add different amounts of cadmium acetate according to the molar ratio of CdS to Ba _0.9 Zn _0.1 TiO ₃ , the range of usage is: 0.2256~0.9024 g), ultrasonically disperse for 15 minutes, add corresponding amount of thiourea (according to CdS Add different amounts of thiourea according to the molar ratio of Ba _0.9 Zn _0.1 TiO ₃ , the usage range is: 0.0644~0.2574 g), ultrasonically disperse for 15 minutes, and put the resulting solution into 100 ml of polytetrafluoroethylene In the reaction kettle, put it into a muffle furnace at 150°C for hydrothermal reaction for 10 hours. The sample after the hydrothermal reaction is filtered, washed, dried and ground for many times to obtain the target catalyst.

Among them, Ba _0.9 Zn _0.1 TiO ₃ was prepared by hydrothermal melt adhesive method, and its preparation method was as follows: first, 9 mmol (2.4609 g) of barium acetate and 1 mmol (0.2195 g) of zinc acetate were dissolved in 10 mL of 36% (the volume ratio of acetic acid to the solution) of acetic acid solution, stirred for 30 minutes to obtain A solution. Then, 10 mmol of tetra-n-butyl titanate was dissolved in 5 ml of isopropanol, and 1.5 ml of glacial acetic acid was added and stirred to obtain B solution. Slowly add solution B to solution A, and stir for 30 minutes to obtain solution C. The C solution was charged into a 25 ml polytetrafluoroethylene reaction kettle, and put into a muffle furnace at 100° C. for hydrothermal reaction for 2 hours. The obtained xerogel was ground and calcined at 900° C. for 10 hours to obtain Ba _0.9 Zn _0.1 TiO ₃ powder.

The advantages of the present invention are: 1. The catalyst of the present invention is directly synthesized by hydrothermal melt adhesive, which has simple operation, low production cost, high synthetic yield, high purity and good repeatability, and is suitable for large-scale production. Requirements; 2. The catalyst of the present invention has good stability and is easy to reuse; 3. The catalyst of the present invention has a very high photocatalytic hydrogen production efficiency under simulated sunlight. the

Description of drawings

Figure 1 is the X-ray powder diffraction comparison diagram of the catalyst of the present invention and pure Ba _0.9 Zn _0.1 TiO ₃ , CdS and CdS/Ba _0.9 Zn _0.1 TiO ₃ heterojunction catalysts with different loading ratios (0% in the figure represents Ba _0.9 Zn _0.1 TiO ₃ , 10% represents 10%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 20% represents 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 30% represents 30%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 40% represents 40%CdS/Ba _0.9 Zn _0.1 TiO ₃ and CdS represent standard powder diffraction peaks of pure CdS).

Fig. 2 is the ultraviolet-visible diffuse reflection comparison diagram of the catalyst of the present invention and pure BaTiO ₃ , Ba _0.9 Zn _0.1 TiO ₃ , CdS and CdS/Ba _0.9 Zn _0.1 TiO ₃ heterojunction catalysts with different loading ratios (10 in the figure % stands for 10%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 20% stands for 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 30% stands for 30%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 40% stands for 40%CdS/Ba _0.9 Zn _0.1 TiO ₃ and CdS, BaTiO ₃ and Ba _0.9 Zn _0.1 TiO ₃ represent pure CdS, BaTiO ₃ and Ba _0.9 Zn _0.1 TiO ₃ , respectively).

Figure 3 is the catalyst of the present invention and Ba _0.4 Sr _0.6 TiO ₃ and CdS/Ba _0.4 Sr _0.6 TiO ₃ heterojunction catalysts with different loading ratios under the induction of simulated sunlight, using Na ₂ S/Na ₂ SO ₃ as a sacrifice Reagents, in the absence of noble metal co-catalysis, the comparison effect diagram of photocatalytic water decomposition for hydrogen production (0% in the figure represents Ba _0.9 Zn _0.1 TiO ₃ , 10% represents 10%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 20% represents 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 30% represents 30%CdS/Ba _0.9 Zn _0.1 TiO ₃ , 40% represents 40%CdS/Ba _0.9 Zn _0.1 TiO ₃ ).

Detailed ways

1. Synthesis of compound Ba _0.9 Zn _0.1 TiO ₃

Dissolve 9 mmol (2.4609 g) of barium acetate and 1 mmol (0.2195 g) of zinc acetate in 10 ml of acetic acid solution with a concentration of 36% (acetic acid accounts for the volume ratio of the solution), and stir for 30 minutes to obtain solution A . Then, 10 mmol of tetra-n-butyl titanate was dissolved in 5 ml of isopropanol, and 1.5 ml of glacial acetic acid was added and stirred to obtain B solution. The B solution was slowly added dropwise to the A solution, and after stirring for 30 minutes, the C solution was obtained. The C solution was charged into a 25 ml polytetrafluoroethylene reaction kettle, and put into a muffle furnace at 100° C. for hydrothermal reaction for 2 hours. The obtained xerogel was ground and calcined at 900° C. for 10 hours to obtain Ba _0.9 Zn _0.1 TiO ₃ powder.

2. Synthesis of catalyst 10%CdS/Ba _0.9 Zn _0.1 TiO ₃

Weigh 2 grams of the prepared _{Ba0.9Zn0.1TiO3} powder and disperse it in 30 milliliters of water. After stirring evenly, add dropwise _a solution made _of 0.2256 gram of cadmium acetate, ultrasonically disperse for 15 minutes, and dropwise add a solution made of 0.0644 gram of thiourea. Ultrasonic dispersion was carried out for 15 minutes, and the obtained solution was charged into a 100 ml polytetrafluoroethylene reaction kettle, and put into a muffle furnace at 150° C. for hydrothermal reaction for 10 hours. The sample after the hydrothermal reaction is filtered, washed, dried and ground for many times to obtain the target catalyst.

3. Synthesis of catalyst 20%CdS/Ba _0.9 Zn _0.1 TiO ₃

Weigh 2 grams of the prepared _{Ba0.9Zn0.1TiO3} powder and disperse it in 30 milliliters of water. After stirring evenly, add a solution made _of 0.4514 grams of cadmium acetate _dropwise , ultrasonically disperse for 15 minutes, and add dropwise a solution made of 0.1286 grams of thiourea. Ultrasonic dispersion was carried out for 15 minutes, and the obtained solution was charged into a 100 ml polytetrafluoroethylene reaction kettle, and put into a muffle furnace at 150° C. for hydrothermal reaction for 10 hours. The sample after the hydrothermal reaction is filtered, washed, dried and ground for many times to obtain the target catalyst.

4. Synthesis of catalyst 30%CdS/Ba _0.9 Zn _0.1 TiO ₃

Weigh 2 grams _of prepared _{Ba0.9Zn0.1TiO3} powder and disperse it in 30 milliliters of water, stir evenly, add dropwise a solution made of 0.6769 _gram of cadmium acetate, ultrasonically disperse for 15 minutes, add dropwise a solution made of 0.1933 gram of thiourea, Ultrasonic dispersion was carried out for 15 minutes, and the obtained solution was charged into a 100 ml polytetrafluoroethylene reaction kettle, and put into a muffle furnace at 150° C. for hydrothermal reaction for 10 hours. The sample after the hydrothermal reaction is filtered, washed, dried and ground for many times to obtain the target catalyst.

5. Synthesis of Catalyst 40%CdS/Ba _0.9 Zn _0.1 TiO ₃

Weigh 2 grams of the prepared Ba _0.9 Zn _0.1 TiO ₃ powder and disperse it in 30ml of water. After stirring evenly, add dropwise a solution made of 0.9024 g of cadmium acetate, ultrasonically disperse for 15 minutes, add dropwise a solution made of 0.2574 g of thiourea, and ultrasonically After dispersing for 15 minutes, the obtained solution was charged into a 100 ml polytetrafluoroethylene reactor, and put into a muffle furnace at 150° C. for hydrothermal reaction for 10 hours. The sample after the hydrothermal reaction is filtered, washed, dried and ground for many times to obtain the target catalyst.

As shown in Figure 1, the X-ray powder diffraction test shows that the catalyst of _the present invention is compared with pure _{Ba0.9Zn0.1TiO3} , and the position of the main peak in the X-ray powder diffraction pattern does not change, indicating _that the loaded cadmium sulfide does not destroy Ba _0.9 Zn _0.1 TiO ₃ structure, and as the loading of cadmium sulfide increases, the peak of cadmium sulfide gradually increases, indicating that cadmium sulfide is loaded into Ba _0.9 Zn _0.1 TiO ₃ instead of doped into the structure of Ba _0.9 Zn _0.1 TiO ₃ . In addition, it can be seen from Figure 2 that after BaTiO ₃ is doped with zinc, its absorption edge is red-shifted. After Ba _0.9 Zn _0.1 TiO ₃ is loaded with cadmium sulfide, the band gap width (Eg value) of the catalyst increases with the increase of cadmium sulfide content. show orderly changes. As shown in Figure 3, the catalyst 20%CdS/Ba _0.9 Zn _0.1 TiO ₃ of the present invention is induced by simulated sunlight, using Na ₂ S/Na ₂ SO ₃ as a sacrificial reagent, and without noble metal co-catalysis, The hydrogen production rate of photocatalytic water splitting reaches 1473 . Compared with single Ba _0.9 Zn _0.1 TiO ₃ and CdS/Ba _0.9 Zn _0.1 TiO ₃ heterojunction catalysts with other loading ratios, under the same experimental conditions, the catalyst of the present invention 20%CdS/Ba _0.4 Sr _0.6 TiO ₃ Photocatalytic splitting of water for hydrogen production has the best catalytic effect. In addition, the elemental analysis results show that the catalyst 20%CdS/Ba _0.4 Sr _0.6 TiO ₃ contains only six elements: Cd, S, Ba, Sr, Ti, and O, and the ratio between the elements is basically consistent with the ratio in the expression . The catalyst of the present invention is synthesized by a hydrothermal sol method, and has simple operation, low production cost, high synthetic yield, high purity and good repeatability, and is suitable for expanding production requirements; the catalyst of the present invention has good stability , easy to reuse; the catalyst of the present invention has a better photocatalytic hydrogen production effect under the irradiation of a 300-watt xenon lamp, and is an ideal photocatalytic water decomposition material for hydrogen production.

Claims (2)

1. a hydrogen material from photocatalytic water decomposition 20%CdS/ Ba _0.9zn _0.1tiO ₃, it is characterized in that by CdS and Ba _0.9zn _0.1tiO ₃and the hetero-junctions formed, CdS and Ba _0.9zn _0.1tiO ₃mol ratio be 1:5,300 watts xenon lamps irradiate under, with Na ₂s/Na ₂sO ₃for sacrificing reagent, described material is in the syncatalytic situation of non precious metal, and photochemical catalyzing hydrogen producing efficiency reaches 1473 μm of olh ^-1g ^-1.

2. a kind of hydrogen material from photocatalytic water decomposition 20%CdS/ Ba as described in claim 1 _0.9zn _0.1tiO ₃, it is characterized in that:

A. Ba _0.9zn _0.1tiO ₃preparation method be: first the zinc acetate of 9 mMs of barium acetates and 1 mM being dissolved in 10 ml concns is in the acetic acid solution of 36%, stir 30 minutes, obtain A solution, then the tetra-n-butyl titanate of 10 mMs is dissolved in the isopropyl alcohol of 5 milliliters, and add 1.5 milliliters of glacial acetic acids and stir and obtain B solution, B solution is slowly added drop-wise in A solution, stir and obtain C solution after 30 minutes, C solution is loaded in the reactor of the polytetrafluoroethylene (PTFE) of 25 milliliters, put into the Muffle furnace hydro-thermal reaction 2 hours of 100 DEG C, by the xerogel grinding obtained, and in 900 DEG C of calcinings 10 hours, grinding obtains Ba _0.9zn _0.1tiO ₃powder,

B. 20%CdS/ Ba _0.9zn _0.1tiO ₃preparation method be: Ba prepared by 2 grams of above-mentioned hydro-thermal sol methods _0.9zn _0.1tiO ₃powder dispersion in 30 ml waters, the solution that the cadmium acetate adding 0.4514 gram after stirring is made into; Ultrasonic disperse 15 minutes, drip the solution that 0.1286 gram of thiocarbamide is made into, ultrasonic disperse 15 minutes, gained solution is loaded in the reactor of the polytetrafluoroethylene (PTFE) of 100 milliliters, put into the Muffle furnace hydro-thermal reaction 10 hours of 150 DEG C, sample after hydro-thermal reaction is carried out multiple times of filtration, washing, and after dry, grinding, obtains final catalyst.