Electrocatalysts for the generation of hydrogen, oxygen and synthesis gas

TLDR

Water electrolysis, powered by renewable sources, is a promising route to high‑purity hydrogen and oxygen, with applications ranging from fuel to chemical synthesis, and can be performed at low or high temperatures using various electrolysis technologies that demand high catalytic activity and stability. This article reviews how the nature and structure of catalyst–electrode materials influence electrolyzer performance. It surveys recent progress in developing efficient anode and cathode materials for large‑scale water electrolysis, and discusses current trends, limitations, and future directions for different electrolysis technologies, including CO₂/H₂O co‑electrolysis for synthesis gas. The review identifies key material design strategies, highlights performance gaps, and outlines prospects for advancing electrolyzer efficiency and enabling synthesis gas production via CO₂/H₂O co‑electrolysis.

Abstract

Water electrolysis is the most promising method for efficient production of high purity hydrogen (and oxygen), while the required power input for the electrolysis process can be provided by renewable sources (e.g. solar or wind). The thus produced hydrogen can be used either directly as a fuel or as a reducing agent in chemical processes, such as in Fischer–Tropsch synthesis. Water splitting can be realized both at low temperatures (typically below 100 °C) and at high temperatures (steam water electrolysis at 500–1000 °C), while different ionic agents can be electrochemically transferred during the electrolysis process (OH−, H+, O2−). Singular requirements apply in each of the electrolysis technologies (alkaline, polymer electrolyte membrane and solid oxide electrolysis) for ensuring high electrocatalytic activity and long-term stability. The aim of the present article is to provide a brief overview on the effect of the nature and structure of the catalyst–electrode materials on the electrolyzer's performance. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The current trends, limitations and perspectives for future developments are summarized for the diverse electrolysis technologies of water splitting, while the case of CO2/H2O co-electrolysis (for synthesis gas production) is also discussed.