@article{Sajid2026, 
author = {Muhammad Sajid and Huan Pang and Saba Hazoor and Touqeer Ahmad and Jinghao Chen and Mohsin Ali and Aoun Raza and Yuancheng Feng and Jingwen Xu and Husam N. Alshareef and Wei Chen},
title = {Decoupled water splitting for hydrogen generation},
year = {2026},
journal = {Nano Research Energy},
volume = {5},
pages = {e9120201},
keywords = {decoupled water splitting (DWS), water electrolysis, redox mediators, HER/OER, hybrid water splitting, green hydrogen},
url = {https://www.sciopen.com/article/10.26599/NRE.2025.9120201},
doi = {10.26599/NRE.2025.9120201},
abstract = {Green hydrogen (H2) has the potential to displace fossil fuels because it has a high energy density, and its consumption yields solely water (H2O). Water electrolysis generates green H2, but it is expensive to operate. In conventional water splitting (CWS), hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are closely correlated, producing H2 and oxygen (O2) concurrently. Decoupled water splitting (DWS) may geographically and temporally isolate HER from OER. The costly membrane may no longer be necessary. Since 2013, utilizing an auxiliary electrode or redox mediator to separate the rate, time frame, or location of H2 and O2 generation during water splitting has been extensively studied. This review provides a comprehensive overview of the latest developments in decoupled water splitting, which offers various benefits over conventional water splitting, including improved safety, higher purity, reduced membrane degradation, and greater design flexibility. The development history, electrolyzer configuration design, improved decoupled water splitting techniques, as well as challenges and future perspectives, are extensively reviewed. We also discuss H2 generation mechanisms of different DWS technologies, i.e., electron-coupled proton buffers, proton-independent electron reservoirs, electrochemical-thermally activated chemical (E-TAC) water splitting, pseudocapacitors by using soluble molecular redox mediators, insoluble solid-state redox mediators, and hybrid water splitting by integrating oxidative biomass valorization in acidic, alkaline, and neutral environments. Overall, DWS offers promising applications for long-term, renewable energy-driven, viable hydrogen generation from water. Future hydrogen generation from renewable sources may be improved with the help of DWS due to its greater versatility and consistency.}
}