Photoelectrochemical water splitting in separate oxygen and hydrogen cells

TL;DR

This paper introduces a novel photoelectrochemical water splitting system with separate oxygen and hydrogen cells connected by wires, achieving high efficiency and cost competitiveness for sustainable hydrogen production.

Contribution

It presents a new architecture for PEC water splitting with separated cells and auxiliary electrodes, improving safety and efficiency over traditional co-produced systems.

Findings

Achieved 7.5% solar-to-hydrogen efficiency.

Demonstrated potential to surpass 10% efficiency with commercial components.

Showed cost competitiveness with conventional PEC systems.

Abstract

Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyzer architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical (PEC) water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional PEC systems, enabling safe and potentially affordable solar hydrogen production.