Research On The Preparation And Catalytic Property Of NiS Loaded CdS/WO₃ Direct Z-Scheme Photocatalyst

It is of great significance to develop environmentally friendly semiconductor photocatalyst for efficient utilization of clean energy.In this paper,based on the design idea of artificial photosynthesis,the chemical in-situ growth and physical electrostatic adsorption were skillfully combined,and the photocatalytic composite NiS-CdS/WO₃supported by non-noble metal cocatalyst was constructed by using narrowband semiconductor with different morphologies of dimensions,to study the photogenic electron migration behavior in the material system.The photocatalytic reduction properties of the materials were studied under visible light（radiation wavelength>420nm）,and the catalytic reaction mechanism was discussed.In this paper,CdS nanorods and WO₃ nanosheets decorated with NiS quantum dots were first prepared by hydrothermal synthesis,and then they were electrostatically adsorbed in an aqueous environment（p H=3.5）between the isoelectric points of CdS and WO₃ materials,and anneal at 380℃for 2 hours in nitrogen protected atmosphere to increase the binding properties of the composites,NiS-CdS/WO₃ composites were prepared.By X-ray diffraction analysis,scanning electron microscope,transmission electron microscopy and X-ray photoelectron spectroscopy characterization methods of research and analysis of composite phase structure,microstructure,heterogeneous interface bonding,surface chemical composition and element valence,found that using the composite material synthesis route of heterogeneous interface to both the maximum effective quantity and quality,It provides valuable reference for the high quality preparation of multicomponent materials.Meanwhile,the band structure and interfacial electron transport dynamics of the material were studied by UV-vis diffuse reflection and absorption spectroscopy,photoluminescence spectroscopy,and the direct Z-scheme mechanism of photoelectron transport in the material system was described.Finally,the photocatalytic activity evaluation system was used to test the photocatalytic reduction properties of the materials.Using 30 m L potassium dichromate solution with a concentration of 40 mg/L as a pollutant indicator of Cr（Ⅵ）,it was found that CNW10 sample had the strongest photocatalytic degradation activity,with a degradation rate of 33.3μmol·min^-1·g^-1_cat,which was 4.2 times that of pure CdS sample.Moreover,the degradation rate of the sample is above 93%in 5 cycles,which shows excellent performance and stability.In the hydrogen production reaction of photolytic water,lactic acid was used as a hole sacrificial agent,and CNW10 sample also had the best hydrogen production rate,which was 70.6 mmol·h^-1·g^-1_cat,more than7 times that of the reference CdS.In this paper,a novel composite material synthesis method was used to prepare CdS/WO₃ direct Z-scheme photocatalyst supported by non-noble metal NiS.The reaction mechanism was revealed and the experimental foundation was laid for the dual-function application of efficient photochemical energy conversion materials in green and clean energy preparation and water environment treatment.