Preparation And Visible Light Catalysis H₂O₂ Production Properties Of SnO₂ Composite Material

Semiconductor photocatalysis,a technology that uses sunlight for environmental purification and energy conversion,owns the advantages of green environmental protection,cost saving,high efficiency and stability.Tin dioxide(SnO2)is a kind of ntype direct band-gap semiconductor material,which has many excellent properties in optics,electricity,gas sensitivity,etc.However,the wide band gap(about 3.8 eV)makes it respond only in the ultraviolet range,and the solar energy conversion efficiency is low.In this work,SnO2 has been improved by means of semiconductor composite and Ni adsorption,so as to increase the yield of photocatalytic pure water to H2O2.This experiment was carried out in pure water under visible light(?>400 nm)without any sacrificial agent or oxygen,and the photocatalytic H2O2 production rate is higher than that reported in the literature.In this paper,SnO2 containing oxygen vacancies was prepared by solvothermal method with Sn Cl4·5H2O as raw material and ethylene glycol as solvent,and SnO2/gC3N4 composite materials with different mass ratios were prepared to investigate the yield of photocatalytic H2O2 production from deionized water under visible light irradiation.The SnO2:g-C3N4=5:1 composite shows the highest hydrogen peroxide generation rate of 151.50 ?mol·g-1h-1,which is 2.6 and 5.6 times of SnO2 and g-C3N4,respectively.The reaction followed the zero order kinetic equation,and the rate constant was 2.24 ?mol·L-1min-1.After three cycles and 9 hours of illumination,the amount of H2O2 produced by SnO2:g-C3N4 =5:1 composite material can still reach 83.30 % of the original,indicating that the catalyst has good cyclic stability.During the reaction,·O2-,·OH,·OOH radicals are produced,and ·OH is the main active substance.During the preparation of SnO2 materials containing oxygen vacancy,a series of Ni adsorbed SnO2 materials were synthesized by adding nickel nitrate.The effects of different Ni adsorbed amounts on the optical properties and visible catalytic activity of the SnO2 were investigated.The 9 % Ni/SnO2 has the best activity,the photocatalystic production H2O2 rate is 106.32 ?mol·g-1h-1,which is 1.8 times that of SnO2.The formation of H2O2 follows the zero-order reaction kinetics equation,and the rate constant is 1.58 ?mol·L-1min-1.The grain size of the Ni adsorbed SnO2 is 5-7 nm,lower than that of the SnO2.The adsorption of Ni reduces the band gap of SnO2,significantly improved the visible light absorption capacity of SnO2,and reduces the charge transfer resistance of the material,and has higher photogenerated carrier separation efficiency.The appearance of Ni promote the increase of aromatic carbon species,which exist in the form of carbon film,make the catalyst has good cycling stability.The active species involved in the reaction include ·O2-,·OH,·OOH,e-which plays an important role in the reaction process.