Assembly,Interfacial Photogenerated Electron Transfer And Photocatalytic Hydrogen Production Of Heterogeneous Cuprous Oxide

In recent years,energy shortages and environmental pollution have made it urgent to develop clean and renewable energy.Clean chemical energy?hydrogen energy?can be obtained by converting renewable solar energy by means of photocatalytic decomposition of water.It is an effective way for human beings to solve the two problems and achieve sustainable economic and social development.Highly active photocatalysts are essential to improve conversion efficiency.As one of classic photocatalytic materials,Cu2 O is widely used in solar cells,gas sensors,lithium-ion batteries and photocatalysis because of its advantages such as photocatalytic activity,diverse morphology,low price,low toxicity and various preparation methods.Potential applications have been the target of widespread concern by domestic and foreign researchers.However,Cu2 O shows short hole diffusion length,poor stability due to photocorrosion,which limits its application in photocatalysis.Therefore,it is of great practical significance to modify Cu2 O and to obtain Cu₂O-based photocatalysts with excellent performance.The construction of Cu₂O-based heterostructures can greatly improve the photocatalytic performance of Cu2 O semiconductors.In this paper,a series of heterostructured Cu₂O-based photocatalysts were successfully prepared mainly by in-situ growth.The photogenerated electron transfer and photocatalytic performance of the obtained materials were studied in detail.The research contents are as follows:An excellent photoactive molecule,tetracarboxyporphyrin?TCPP?,was introduced and attached to the antenna-like Cu₂O/Ni O heterojunction.Subsequently,a series of Cu₂O/Ni O/TCPP nanocomposites were obtained.Furthermore,Assembly mechanism of the nanocomposites was investigated in detail.The results showed that,by coordination interaction and hydrogen bond,TCPP molecules can be strongly assembled onto the Ni O-riveted Cu2 O.Because of strong interaction among Cu2 O,Ni O and TCPP,and the enhanced light absorption,the photoelectric conversion efficiency of the composite is significantly improved compared to other contrasts?Cu₂O/Ni O/Ni TCPP,Cu₂O/Ni O,Cu2 O et al.?and the nanocomposite material shows higher photocatalytic hydrogen production activity.This is due to the efficient separation of charges in the system,increased light absorption,matched band-edge structures,and special heterogeneous interface.Induced by graphene oxide?GO?,a high-crystalline nano-flower-like Cu₂O/CuF₂ heterojunction was constructed in-situ on Cu2 O.The structure,morphology and assembly mechanism of the obtained target material?Cu₂O/GO/CuF₂?were studied in detail by means of XRD,SEM,TEM,solid UV-visible diffuse reflectance spectrum and XPS.The results showed,by the introduction of GO,on the one hand,the heterogeneous phase with lower hydrogen production was reduced,the proportion and crystallinity of CuF₂ were increased,and nano flower-like Cu₂O/CuF₂ heterojunctions was promoted.On the other hand,by the construction of the heterojunction,the light absorption and photo-generated electron-hole transfer of Cu2 O were improved,thereby its catalytic activity was effectively increased.Furthermore,the target material?Cu₂O/GO/CuF₂?showed a 292?4?higher photocatalytic activity than that of pure Cu2 O.However,under the same conditions,only163.7% higher activity was obtained over the composite prepared by simply-mixed.It shows the superiority of Cu₂O/GO/CuF₂ nanocomposites prepared by in-situ growth method by means of the inducion of GO.A series of novel Cu₂O/SiO₂/MIF?M = Cd,Zn,Cu,Mn,Ni,Co?nanocomposites were obtained by packaging Cu₂O/SiO₂ heterostructure with metal organic framework.The structure,morphology and assembly of the composites were studied in detail using XRD,SEM,TEM,UV-vis spectroscopy,XPS,et al.It was found that the migration of photogenerated charges can be effectively promoted,and the photocorrosion of Cu2 O can be reduced by the special SiO₂ layer,thus the composite showed a stable photocatalytic performance.Moreover,by means of the ordered framework structure of MIF,the interfacial resistance of the system was reduced,separation and transfer of photogenerated charges were promoted,and light absorption range of the composite was expanded.Therefore,Cu₂O/SiO₂/Cd IF showed higher photocatalytic hydrogen production activity.The above research will provide new ideas for preparing and assembling other semiconductor photocatalysts with special morphology and excellent performance.It also provides some experimental basis and theoretical guidance for photogenerated charge transfer and photocatalytic mechanisms in other photocatalyst systems.