| With the rapid development of industry and the massive exploitation and use of fossil fuels,problems such as environmental pollution and energy shortage have become increasingly serious.How to avoid environmental pollution and find green and sustainable new energy has become an urgent problem for researchers to solve.In recent years,with the continuous development of photocatalytic technology,various high-efficiency semiconductor photocatalysts have been widely used in the research of degradation of organic pollutants and hydrogen production from water splitting.Titanium dioxide（Ti O2）,as one of the promising photocatalysts,has been widely used in photocatalytic hydrogen production due to its excellent stability,low cost,and nontoxicity.However,the wide band gap（Eg=3.2 e V）leads to the limited utilization of Ti O2 for visible light,and the fast electron-hole pair recombination leads to the low quantum efficiency of Ti O2,which limit the further application of Ti O2.In this paper,two different modification methods were used to improve the catalytic performance,and Ni-Ti O2/Cd S and Ti O2/g-C3N4/Ni O composite photocatalysts were prepared respectively.The composition and morphology of the composite photocatalyst were characterized by XRD,SEM,XPS and DRS.The photocatalytic performance of the composite photocatalyst was investigated by hydrogen production experiments with triethanolamine as a sacrificial reagent.Finally,the process of photocatalytic degradation of pharmaceutical wastewater with composite catalysts for synergistic hydrogen production was studied.1.Nickel-doped Ti O2（Ni-Ti O2）was prepared by a simple sol-gel method.To further improve the photocatalytic performance,Ni-Ti O2/Cd S composites were prepared by hydrothermally modifying Cd S onto Ni-Ti O2 composites.The hydrogen production effect of the composite catalyst under visible light was explored,and the effects of Ni doping amount,Cd S composite amount,catalyst amount,volume fraction of sacrificial reagent,and cycle times on the activity of Ni-Ti O2/Cd S photocatalyst were investigated.The experimental results show that the prepared Ni-Ti O2/Cd S photocatalyst has high photocatalytic performance,and the hydrogen production rate can reach 3796μmol·g-1·h-1.The main reason for the improvement of photocatalytic performance is that Ni doping can reduce the forbidden band width of Ti O2 and expand the photoresponse range.Secondly,the recombination of Cd S can effectively inhibit the recombination of photogenerated electrons and holes,and improve the photocatalytic performance.2.Ti O2 was prepared by sol-gel method,melamine was calcined at high temperature to obtain g-C3N4,Ti O2 was compounded with g-C3N4 by hydrothermal method to obtain Ti O2/g-C3N4,and Ni O was loaded into Ti O2/g-C3N4 compound by impregnation method The photocatalytic properties of the materials were further improved,and Ti O2/g-C3N4/Ni O composite photocatalysts were prepared.The hydrogen production effect of the composite catalyst under visible light was also studied.In addition,the effects of g-C3N4composite amount,Ni O loading,catalyst dosage,sacrificial reagent volume fraction,and cycle times on the activity of Ti O2/g-C3N4/Ni O photocatalyst were systematically studied.The experimental results show that the prepared Ti O2/g-C3N4/Ni O photocatalyst has a large surface area,shows high photocatalytic activity and stability,and the hydrogen production rate is as high as 4843μmol·g-1·h-1.The main reason for the improved photocatalytic performance is that the recombination of g-C3N4 and Ni O can form a heterojunction,increase the specific surface area,enhance the absorption of light,and significantly improve the separation efficiency of photogenerated electron-hole pairs.3.Select the optimal composite catalyst Ti O2/g-C3N4/Ni O to conduct photocatalytic degradation and synergistic hydrogen production experiments on pharmaceutical wastewater.Through single factor experiment and response surface methodology,it is concluded that the optimal process conditions for hydrogen production degradation of pharmaceutical wastewater are as follows:when the catalyst dosage is 0.05 g,the initial p H value of the solution is 7.96,and the dilution factor concentration is 3 times,the Ti O2/g-C3N4/Ni O The hydrogen production rate was 1364.16μmol·g-1·h-1,and the COD degradation rate was 47.52%. |
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