Metal selenide photocatalysts for visible-light-driven Z-scheme pure water splitting

Abstract

Metal selenides with narrow bandgaps (480–750 nm) are shown to be applicable to stable photocatalytic Z-scheme pure water splitting.

Transition Metal Selenides for Electrocatalytic Hydrogen Evolution Reaction

“…Apart from application in electrocatalytic hydrogen production as excellent cathodic catalysts, TMSs are also utilized as catalysts of oxygen evolution reaction (OER), [139] oxygen reduction reaction (ORR). [140] Otherwise, attributed to TMSs' intriguing physicochemical properties, they have been applied in extensive fields, [141] e. g., photocatalysts, [142] electrochemical energy storage devices (ion batteries, supercapacitors), [143] dye-sensitized solar cells, [144] sensitivity glucose sensors, [145] photodetectors, [146] thermoelectric materials. [147]…”

Metal selenides for photocatalytic Z-scheme pure water splitting mediated by reduced graphene oxide

“…Therefore, this approach reduces the thermodynamic requirements and expands the choice of semiconductors, and in particular, allows the consideration of narrow bandgap materials [8]. To date, various types of visible-light-responsive photocatalysts have been applied in Z-scheme systems, including oxides, (oxy)nitrides, (oxy)sulfides, oxychlorides, and selenides [9][10][11][12][13][14]. However, considering that the driving force for the redox reactions decreases with decreasing bandgap, the development of narrow bandgap semiconductors for efficient Z-scheme overall water splitting is still significantly challenging [15].…”

“…This is because the VBMs of the former are typically associated with Se 4p orbitals and thus, are shallower than those associated with O 2p and S 3p orbitals. In particular, solid solutions of zinc selenide and copper gallium selenide (denoted as ZnSe:CGSe) can have tunable band structures and semiconductor characteristics, depending on the Zn/(Zn+Cu) and Ga/Cu molar ratios [13]. Recently, our group has used these metal selenides as hydrogen evolution photocatalysts (HEPs), in conjunction with CoOx/BiVO4 and Au as the oxygen evolution photocatalyst (OEP) and electron mediator, respectively, for the Z-scheme overall pure water splitting.…”

“…A previous work by our group demonstrated that selenide semiconductors can be used as HEPs for Z-scheme pure water splitting when they are assembled with CoOx-BiVO4 and Au as the OEP and electron mediator, respectively [13]. In such a case, the photocatalyst system was constructed in the form of a sheet, and the Au layer was prepared by vacuum evaporation.…”

“…Because the optimal Zn/(Zn+Cu) ratio for both sacrificial H2 evolution and sheet-based overall pure water splitting was determined to be 0.5 [13], (ZnSe)0.5(CGSe)0.5 was employed to assess the effect of the Ga/Cu ratio. As shown in Fig.…”