Visible‐Light Driven Z‐Scheme Water Splitting over NiS/CdS/PtO x /WO 3 through Modulating Redox Mediator Environments

Visible‐light‐driven Z‐scheme photocatalytic systems are very appealing for achieving efficient overall water splitting. However, developing the Z‐scheme using long wavelength responsive sulfides as H 2 ‐evolving photocatalysts remains challenging. Herein, the construction of Z‐scheme photocatalytic systems for overall solar water splitting is described using CdS and WO 3 as H 2 ‐evolving and O 2 ‐evolving photocatalysts, respectively, in the presence of a shuttle redox mediator. The stoichiometric water splitting into H 2 and O 2 under the solar‐simulated irradiation was determined through optimization of cocatalyst, shuttle redox mediator, and pH conditions. The activity attenuation during the long‐term reaction was mainly attributed to the backward reaction which can be alleviated by filling the system with moderate argon. This work provides a new photocatalysts combination for the Z‐scheme overall water splitting, further reflecting the importance of modulation of redox mediator environments.