Interaction-Dependent Interfacial Charge-Transfer Behavior in Solar Water-Splitting Systems

Abstract

Dual-band-gap systems are promising for solar water splitting due to their excellent light-harvesting capability and high charge-separation efficiency. However, a fundamental understanding of interfacial charge-transfer behavior in the dual-band-gap configuration is still incomplete. Taking CdS/reduced graphene oxide (CdS/RGO) nanoheterojunctions as a model solar water splitting system, we attempt here to highlight the interaction-dependent interfacial charge-transfer behavior based on both experimental observations and theoretical calculations. Experimental evidence points to charge transfer at the CdS–RGO interface playing a dominant role in the photocatalytic hydrogen production activity. By tuning the degree of reduction of RGO, the interfacial interaction, and, thereby, the charge transfer can be controlled at the CdS–RGO interface. This observation is supported by theoretical analysis, where we find that the interfacial charge transfer is a balance between the effective single-electron- and hole-transfer probability and the surface free electron and hole concentration, both of which are related to the surface potential and tailored by interfacial interaction. This mechanism is applicable to all systems for solar water splitting, providing a useful guidance for the design and study of heterointerfaces for high-efficiency energy conversion.

Microscopic Mechanism on Giant Photoeffect in Proton Transport Through Graphene Membranes

“…Since there is no change in the activation energy of the reaction, the metal catalyst increases the rate of a reaction by increasing the number of successful collisions of reactants for this significant photoeffect. This deduction is corroborated by the claim that the ratedetermining factor in the photocatalytic system is the concentration of surface-reaching photocharges before it reaches the threshold, instead of the widely accepted speculation of high reaction barriers to be overcome 24,51 . In most practical photo(electro)catalytic systems, the rapid photogenerated charge recombination 52,53 and possible inhibit of mass transfer due to the complex electric double layer or ions in solution [54][55][56] cause inferior performances.…”

“…the surface electric field is taken as a constant and the free charge is supposed to have a smooth even distribution, resulting a surface space charge region in a semiconductor 19 . However, many first principle calculations [20][21][22][23][24] and theoretic models show that the free electrons in both the surface space charge region and the interface specific region (ISR) have modulated oscillatory density distributions rather than even distributions 25 . The interaction force between graphene and metal nanoparticles is electrostatic force.…”

Multi‐Metal Nanocluster Assisted Cu‐Ga‐Sn Tri‐Doping for Enhanced Photoelectrochemical Water Splitting of BiVO4 Film

“…However, the slope of BiVO 4 ‐CGS is apparently less than BiVO 4 , manifesting that doping increases the carrier concentration of the sample so that the PEC property is improved. [ 47 ] Moreover, there was a significant negative shift in the flat band potential, similar to the change in onset potential, representing the lower starting voltage of BiVO 4 ‐CGS.…”

Irradiation Direction‐Dependent Surface Charge Recombination in Hematite Thin‐Film Oxygen Evolution Photoanodes

“…Although the holes have to travel across the film before injection, the increased width of the depletion layer under high biases will hinder the diffusion of electrons to the SCLJ and hence suppress their recombination with holes at the SCLJ. Simultaneously, the increased surface band bending at high biases will increase the surface hole concentration, which is beneficial to interfacial charge transfer . Taken together, the injection efficiency under BI will increase remarkably when the bias voltage is high.…”