Synthesis Of Surface Modified Coprospinel And Their Application For Hydrogen Evolution

Surface modificatiion have been used in the photocatalytic hydrogen production to harvest the visible light to exhance the enficiency of the reaction.Cu NPs have been extensively studied on account of their potential to replace the rare noble-metal catalysts?Pt,Au,Ag?used in various chemical reactions.Being responsible to the visible light and a large specific surfce area,graphitic carbon nitride?g-C₃N₄?has been regard as hot topic in photocatalysis.Multiple facile ways to prepare Cu NPs onto the semiconductor have been widely applied to the catalysis design,such as photocatalysis,organic synthesis,and electrocatalysis,to make use of the extraordinary optical performance around the interface by introducing the electrons'collective oscillation around it.Therefore,many efforts devoted to preventing Cu NPs from being oxidized have been made.On the other hand,the spinel structure of CuFe₂O₄ where Cu-O in tetrahedral site and Fe-O in octahedral site was reported to have the potential in hydrogen evolution from water splitting,a great deal about the catalytic process still remained unclear.So it's of great necessity to explore the active site which was responsible for the catalytic process.Dyes have been used in the photocatalytic hydrogen production as a visible light harvesting molecules.And considering the small specific surface area due to the aggregation of the CuFe₂O₄,it is of great necessity to enlarge the specific surface area by introducing the g-C₃N₄.Herein,a closed system has been introduced,where Cu NPs synthesized on CuFe₂O₄ via photoreduction under vacuum and HER?hydrogen evolution reaction?followed,which avoided the formation of oxidized Cu species.More specially,a convenient way to detect the oxygen vacancy in CuFe₂O₄ for the catalytic process is also investigated.The analysis of Raman spectra indicated that tetrahedron of?-FeOOH was induced by the oxygen vacancy in octahedral site after HER?hydrogen evolution reaction?,which indicated that the phase change in octahedral site of CuFe₂O₄ was responsible for the HER.Furthermore,the results of DTG and the peak of Fe²⁺in XPS spectra after HER,which indicated that light activated Fe-O in octahedral site was responsible for the photocatalytic process.And enhancement of the catalytic QE?quantum efficiency?from 0.069%of blank CuFe₂O₄ to 0.34%of Cu/CuFe₂O₄.,showed that the LSPR?local surface plasmon resonance?of Cu NPs facilitated to the reaction activity of Fe-O in octahedral site.