Tunable multi-electron redox polyoxometalates for decoupled water splitting driven by sunlight

• Published in: Nature communications Vol. 16; no. 1; pp. 3674 - 12
• Main Authors: Cui, Li-Ping, Zhang, Shu, Zhao, Yue, Ge, Xin-Yue, Yang, Le, Li, Ke, Feng, Liu-Bin, Li, Ren-Gui, Chen, Jia-Jia
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.04.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 639/301/299/890; 639/4077/909/4101/4102; 639/638/224/909/4086/4087; 639/638/439/890; Buffers; Defects; Electrode potentials; Electrolysis; Electron transfer; Energy storage; Fuels; Humanities and Social Sciences; Hydrogen production; Molecular clusters; multidisciplinary; pH effects; Photocatalysis; Polyoxometallates; Protons; Redox potential; Redox properties; Relay systems; Science; Science (multidisciplinary); Solar energy; Splitting; Subsystems; Tungsten; Vanadium; Water splitting
• DOI: 10.1038/s41467-025-58622-8
• ISSN: 2041-1723

It remains a great challenge to explore redox mediators with multi-electron, suitable redox potential, and stable pH buffer ability to simulate the natural solar-to-fuel process. In this work, we present a defect engineering strategy to design soluble multi-electron redox polyoxometalates mediators to construct a photocatalysis-electrolysis relay system to decouple H 2 and O 2 evolution in solar-driven water splitting. The appropriate use of vanadium atoms to replace tungsten in the Dawson-type phosphotungstate successfully regulated the redox properties of the molecular clusters. Specifically, the single vanadium substitution structure ({P 2 W 17 V}) possesses 1-electron redox active and sequential proton-electron transfer behavior, while the tri-vanadium substituted cluster ({P 2 W 15 V 3 }) exhibits 3-electron redox active and cooperative proton electron transfer behavior. Based on the developed multi-electronic redox mediator with pH buffering capacity, suitable redox potential (0.6 V), and fast electron exchange rate, we build a photocatalysis-electrolysis relay water splitting system. This system allows for high capacity of solar energy storage through photocatalytic O 2 evolution using BiVO 4 photocatalyst and stable H 2 production with a high Faraday efficiency of over 98.5% in the electrolysis subsystem. Designing efficient redox mediators for solar-to-fuel conversion is a challenge, requiring multi-electron transfer, suitable redox potential, and stable pH buffering. Here, the authors report polyoxometalate-based mediators with defect engineering, enabling reliable solar-to-fuel conversion.