| The energy crisis and environmental pollution are becoming more and more serious.As an ideal energy source,hydrogen energy has received great attention from many scholars because of its high energy density,easy storage and transportation,and no pollution.Hydrogen has therefore become an alternative The feasibility of green energy for traditional fossil fuels.The use of photocatalytic technology to decompose water to produce hydrogen is a sustainable way to produce hydrogen and has great social and economic value.Graphite-like carbon nitride(g-C3N4)as a new type of non-metallic material,due to its more suitable band gap width(about 2.7 eV)and energy band position,good chemical stability and easy preparation The current research focus of photocatalysis.For photocatalytic materials,the modification of the material itself is the core to improve its photocatalytic performance.In this paper,by using different solvents(hydrochloric acid and ethylene glycol)to treat melamine,carbon nitride materials with large specific surface area(denoted as CN-HCl and CN-EG)were prepared respectively,and used as the base material The performance of their combined hydrogen production with different semiconductors was studied.The specific research results are as follows:(1)Preparation of modified g-C3N4 material and its performance in photocatalytic hydrogen production.Firstly,hydrochloric acid(HCl)and ethylene glycol(EG)were used to pre-treat melamine,and then the catalyst materials CN-HCl and CN-EG were prepared by calcination at 550℃.It has good hydrogen production efficiency.The output of H2 after being irradiated with a 250 W high-pressure mercury lamp for 5 h is 29.39 μmol/g and 24.65 μmol/g,respectively.The hydrogen production of CN-HCl sample is pure g-C3N4(CN)3 times as much.The characterization results of FT-IR,XRD,and SEM show that the prepared samples all have good crystal forms and unique functional groups.Transient fluorescence and photocurrent response test results show that the sample has a good electron-hole separation efficiency,thus accelerating the reduction reaction rate in water and increasing H2 production.(2)Preparation of ZnIn2S4/CN-HCl composite material and its performance in photocatalytic hydrogen production.With CN-HCl as the matrix material,In(NO3)3,Zn(NO3)2 and thioacetamide as the raw materials for the synthesis of ZnIn2S4.By hydrothermal method(the optimal hydrothermal temperature is 160℃,hydrothermal time is 4 h),ZnIn2S4/CN-HCl composite photocatalyst was successfully prepared,and a special charge transport channel between ZnIn2S4 and CN-HCl was constructed,which was significant The hydrogen production efficiency of the catalyst is improved.After 5 h,the H2 production of ZnIn2S4/CN-HCl can reach 205.46 μmol/g,which is 7 times that of the CN-HCl matrix sample.From the analysis of XRD and FT-IR,the sample prepared by the experiment has a good crystal structure,and the photocurrent response test shows that the sample has better photoelectric performance.(3)Preparation of ZnO/CN-HCl composite material and its performance in photocatalytic hydrogen production.Based on the CN-HCl material,a one-step hydrothermal method(optimal hydrothermal temperature of 200℃,hydrothermal time of 16 h)was used to synthesize ZnO/CN-HCl composite catalyst,using triethanolamine as a sacrificial agent,at 250 W After 5 hours of photocatalytic hydrogen production experiment under high-pressure mercury lamp irradiation,H2 production can reach 97.76 μmol/g,which is about 3 times higher than that of CN-HCl(29.39 μmol/g).XRD characterization shows that the composite catalyst has good crystallinity,and SEM analysis results show that the composite catalyst forms a good morphology of ZnO nanorods coated with a layer of CN-HCl.Multiple active sites improve the hydrogen evolution output of the catalyst. |
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