Preparation Of Crystalline Red Phosphorus Composite Catalyst And Study On Its Photocatalytic Hydrolysis Performanc

Photocatalytic overall water splitting is a green and sustainable hydrogen production technology.However,the high energy barrier and slow kinetics of the oxygen evolution reaction greatly limit the efficiency of overall water splitting.The construction of efficient photocatalysts for overall water splitting remains a major challenge in the field.Crystalline red phosphorus（RP）has received increasing attention and research in the field of photocatalytic water splitting due to its advantages such as broad visible light response,bandgap matching,and low preparation cost.In this study,aiming to improve the photocatalytic activity and stability of crystalline red phosphorus,a nano-belt-shaped crystalline red phosphorus（C-RP）and graphitic carbon nitride（g-C₃N₄）Z-scheme heterostructure were developed,and various metal-doped C-RP catalysts were prepared.The main factors affecting the photocatalytic activity and stability of C-RP were explored.Highly efficient photocatalytic overall water splitting for H₂/H₂O₂ production was achieved without sacrificial agents.The specific research contents are as follows:（1）Nano-strip crystalline red phosphorus（C-RP）was combined with g-C₃N₄nanosheets（M-CN）prepared by melamine as precursor by the ultrasonic-assisted liquid phase mixing method to form corresponding heterostructures.It was found that C-RP and M-CN formed a Z-Scheme-type heterostructure（MCN/C-RP）,and achieved high efficiency photocatalytic complete hydrolysis to produce H₂ and H₂O₂.Using urea and dicyandiamide as precursors,g-C₃N₄ nanosheets（U-CN,D-CN）were prepared with C-RP heterostructures.It was found that the photocatalytic overall water splitting activity and stability of the heterostructures composed of C-RP and g-C₃N₄ were highly dependent on the band structure and crystallinity of g-C₃N₄.Under simulated sunlight irradiation,the optimized C-RP/M-CN exhibited stable H₂ and H₂O₂ precipitation rates of about 600μmol g^-1·h^-1 during continuous 22 h photocatalytic overall water splitting test.（2）By doping different metals with C-RP and conducting photocatalytic hydrogen evolution test,it was found that Cu-doped C-RP（Cu/C-RP）showed good hydrogen evolution activity in pure water system without sacrificant,and the highest was up to1921.23μmol g^-1·h^-1.The hydrogen evolution capacity of Cu/C-RP is 130 times higher than that of fiber red phosphorus（FRP）and 32 times higher than that of C-RP.By calculating the band structure,it is found that the conduction band of Cu/C-RP is more negative and the band gap is narrower than that of C-RP,which not only improves the carrier migration rate,but also provides a good potential for photocatalytic hydrogen evolution.Meanwhile,metal doping can also effectively reduce the energy barrier of hydrogen intermediates and the activation energy of hydrolytic dissociation during C-RP photocatalytic hydrogen evolution,so as to improve the effect of photocatalytic hydrogen evolution.