| Due to its large specific surface area,excellent adsorption performance,high photocatalytic activity,stronger chemical stability and environmental protection properties,the ternary metal chalcogenide has a very attractive application prospect in the field of photocatalytic hydrogen production.At the same time,the development of efficient,stable and low-cost photocatalytic hydrogen production from formic acid is a daunting challenge and has attracted a lot of interest from researchers.In this paper,new composite photocatalysts?Ni2P/Zn3In2S6?ZIS6?,MoP/ZIS6and MoS2/ZIS6?were studied.The effects of preparation methods and synthesis conditions of ternary sulfides and cocatalyst-loaded novel photocatalysts on morphology,crystal form,band structure and photocatalytic properties were systematically investigated.The optimal preparation conditions of the catalyst were optimized,and the key factors of high-efficiency photocatalytic activity were revealed.The reaction mechanism of formic acid photocatalytic hydrogen production was proposed.The research mainly includes the following aspects:1.A series of ZIS6 samples with different sulfur sources and different sulfur sources were synthesized by simple hydrothermal method.The effects of different molar sources and di fferent sulfur sources on the formation and activity of ZIS6 were investigated systematically.ZIS6 was successfully synthesized at 160°C.A sample synthesized using thioacetamide and L-cysteine as a sulfur source,and the crystal form is a hexagonal phase,and the sample synthesized using thiourea as a sulfur source is a mixed crystal phase of ZIS6 and ZnIn2S4.When thioacetamide is used as a sulfur source among the three sulfur sources,the photocatalytic activity exhibited in the formic acid aqueous solution is the best when the molar amount of the sulfur source is 10 mmol.2.The ZIS6 precursor was synthesized by hydrothermal method using thioacetamide as the sulfur source,and a new composite photocatalyst?Ni2P/?ZIS6?and MoP/ZIS6?was synthesized by solvothermally supported phosphide promoter.Formic acid was irradiated under visible light.The photocatalytic performance of H2is generated,wherein Ni2P and MoP are used as cocatalysts to enhance photocatalytic hydrogen production by ZIS6.The photocatalytic performance and mechanism of the composite photocatalyst were studied in detail through a series of characterization techniques.By controlling different amounts of cocatalyst,the optimum content of phosphide promoter is screened.The photocatalytic hydrogen production rates of the optimized 1.5wt.%Ni2P/ZIS6(45.73?mol h-1)and 0.25wt.%MoP/ZIS6(92.69?mol h-1)were 3.5 times and 7.2 times that of pure ZIS6,respectively(respectively 12.88?mol h-1).The apparent quantum efficiencies of the wavelength?=400±10 nm were about 1.8%and 6.4%,respectively.It is noteworthy that it has been found that a significant increase in hydrogen production performance can be attributed to the introduction of a phosphide promoter which can be used as a charge separation center and an active site for photocatalytic hydrogen generation from the decomposition of formic acid.3.A one-step hydrothermal method was used to synthesize a novel composite photocatalyst with ternary sulfide ZIS6 supported MoS2 as a cocatalyst.The photocatalytic activity of the composites was evaluated in water solubilization of formic acid,and the photocatalytic properties and mechanism of the samples were studied by various characterization methods.After adjusting the loading amount,the optimal loading amount was obtained,and the photocatalytic hydrogen production activity with the loading amount of 0.5%MoS2/ZIS6(74.25?mol h-1)was obtained.At the same time,it was found that the separation of photogenerated carriers and the transfer and enrichment of photogenerated charges can be effectively realized after the introduction of the cocatalyst,thereby greatly promoting the improvement of hydrogen production activity in the formic acid solution. |
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