Chuanbiao Bie Challenges for Photocatalytic Overall Water Splitting

Chuanbiao Bie  Challenges for Photocatalytic Overall Water Splitting

The hydrogen economy is a sunrise industry, which is considered the ultimate solution to power the future society. Photocatalytic overall water splitting is projected as a potential technology for H₂ production. However, its performance is still far from the criteria for large-scale production. Most research works do not achieve a solar-to-hydrogen efficiency of over 10%, a competitive benchmark efficiency in the hydrogen market. Therefore, whether photocatalytic overall water splitting is the best option for H₂ production remains questionable.

Recently, Dr. Chuanbiao Bie from the China University of Geosciences (Wuhan) discusses challenges for photocatalytic overall water splitting and argues that photocatalytic overall water splitting is theoretically and practically hard to achieve. Thermodynamically, photocatalytic overall water splitting is a highly endothermic uphill reaction, while the reaction of hydrogen and oxygen is an exothermic downhill reaction. This condition makes the backward reaction of photocatalytic overall water splitting much easier than the forward reaction. Kinetics, the slow oxygen evolution reaction consuming four electrons is the main factor affecting the efficiency of photocatalytic overall water splitting. In addition, dissolved oxygen competes for electrons with the hydrogen evolution reaction, resulting in reduced photocatalytic overall water splitting activity. Finally, four backward reactions between dissolved (adsorbed) oxygen and dissolved (adsorbed) hydrogen seriously hinder the photocatalytic overall water splitting.

Figure 1. Challenges for photocatalytic overall water splitting.

In summary, the unfavorable thermodynamics, sluggish kinetics, dissolved oxygen, and backward reactions of photocatalytic overall water splitting are discussed, which can help researchers to better understand photocatalytic overall water splitting. The article titled "Challenges for photocatalytic overall water splitting" is published in Chem.

This work is supported by the National Natural Science Foundation of China. Prof. Jiaguo Yu and Dr. Chuanbiao Bie from the China University of Geosciences (Wuhan) are the first author, respectively.

Article link: https://www.sciencedirect.com/science/article/pii/S245192942200211X