Structure And Photocatalytic Performance Of P-n Heterojunction Cu₂O/TiO₂Nanomaterals

Nano-TiO2has a potential application prospect in environmental protection and renewableenergy because of its good photochemical stability and free-from secondary pollution.BecauseTiO2only absorb ultraviolet light,which greatly limites its photocatalysis application anddevelopment.In order to expand its photoresponse to visible light rang,we set the p-n Cu2O/TiO2heterojunction nanomaterals as the main research object, the thesis studied the photocatalyticperformance of Cu2O-loaded TiO2particles and titanate nanotubes respectively,especiallyfocused on the influence of Cu2O particle size on the properties of composite photocatalyticnanomaterials.It provides the basis for the development of new hight efficiency p-nheterojunction photocatalyst.Main comtent includes：P25was used as raw material to synthesized the titanate nanotubes(TNTS） withhydrothermal treatment,we obtained the Cu2O/TiO2and Cu2O/TNTS(method A) byimpregnation reduction method,then Cu2O/TiO2was used as the substrate to furtherhydrothermal synthesis Cu2O/TNTS(method B).XRD characterization indicates that Cu2O isclearly presented in the catalysts by the impregnation reduction method. TEM and SEMcharacterization show that the P25and TNTS are decorated by smaller Cu2O nanoparticles withparticle sizes of about2-3nm, TEM and SEM show that Cu2O/TNTS(method B)owns moreuniform tubes and Cu2O/TNTS(method A)tubes were mostly cracked. N2adsorption/desorptionshows that Cu2O/TNTS(method B)has larger specific surface area.DRS demonstrated the Cu2Ois chemical bonded to both TiO2particles and titanate nanotubes.The particle sizes of Cu2O nanoparticles on TiO2particles or titanate nanotubes can bechanged by controlling the reductant concentration, TEM shows that the particle sizes of Cu2Onanoparticles decrease with the increase of glucose concentration. Based on the photocatalyticdegradation of methylene blue test,it shows that the small Cu2O nanoparticles own betterphotocatalytic activity. DRS shows that the energy gap of Cu2O nanoparticles increase with thedecrease of Cu2O nanoparticles sizes due to quantum confinement effect, which enlarge theenergy gap between two conduction band in p-n heterojunction, favor in the effective transfer of photoproduction electron in p-n heterojunction barrier so as to improve the photocatalyticactivity.In the adsorption test,we explored the adsorption performance of the Cu2O/TNTS preparedby two different methods.We found that the adsorption performance of Cu2O/TNTS (method B)is superior to the single component TNTS and the adsorption performance of Cu2O/TNTS(method A) is weaker than the single component TNTS.In the study of adsoption isotherms, allof them conform to Langmuir single molecule layer isothermal adsorption model.However,Cu2O/TNTS (method B) conformed to the pseudo-first-order adsorption dynamic model, whilethe Cu2O/TNTS (method A) conformed to the pseudo-second-order model.In the photocatalytic test, we explored the photocatalytic performance of the Cu2O/TNTSprepared by two different methods. The results show that the Cu2O/TNTS (method B) have ahigher photocatalytic activity than Cu2O/TNTS (method A) under visible light irradiation.