Decoupled photoelectrochemical water splitting system for centralized hydrogen production

TL;DR

This paper presents a decoupled photoelectrochemical water splitting system designed for centralized hydrogen production, optimizing stability and scalability for large-scale solar-to-hydrogen energy conversion.

Contribution

It introduces a novel decoupled PEC system with separate hydrogen and oxygen cells, using hematite photoanodes and redox mediators, optimized for continuous operation.

Findings

Successful operation over ten 8.3-hour cycles under simulated sunlight

Achieved an average short-circuit current of 55.2 mA without additional bias

Demonstrated stable and scalable hydrogen production system

Abstract

Photoelectrochemical (PEC) water splitting offers an elegant approach for solar energy conversion into hydrogen fuel. Large-scale hydrogen production requires stable and efficient photoelectrodes and scalable PEC cells that are fitted for safe and cost-effective operation. One of the greatest challenges is the collection of hydrogen gas from millions of PEC cells distributed in the solar field. In this work, a separate-cell PEC system with decoupled hydrogen and oxygen cells was designed for centralized hydrogen production, using 100 cm2 hematite (a-Fe2O3) photoanodes and nickel hydroxide (Ni(OH)2) / oxyhydroxide (NiOOH) electrodes as redox mediators. The operating conditions of the system components and their configuration were optimized for daily cycles, and ten 8.3 h cycles were carried out under solar simulated illumination without additional bias at an average short-circuit current of 55.2 mA. These results demonstrate successful operation of a decoupled PEC water splitting system with separate hydrogen and oxygen cells.