Unravelling the Role of Hydrogen Evolution Reaction Co-Catalysts in Photocatalytic Water Splitting: Mechanistic Insights and Material Strategies

Abstract

The reliance on fossil fuels has led to a substantial increase in greenhouse gas emissions, presenting a critical environmental challenge. Addressing this issue necessitates the adoption of alternative renewable energy sources, with green hydrogen emerging as a promising candidate due to its high gravimetric energy density and absence of harmful emissions. Among the various hydrogen production techniques, photocatalytic technology has garnered significant attention for its dual potential to produce green hydrogen and degrade pollutants, thereby addressing both energy and climate crises. Efforts to scale photocatalytic technology for industrial applications have identified cocatalyst integration as a pivotal strategy, as it enhances reaction kinetics by lowering the activation energy and mitigating charge carrier recombination. This review comprehensively examines the hydrogen economy, the underlying principles of photocatalysis, recent technological advancements, key factors influencing photocatalytic reactions, the role of catalysts in hydrogen evolution reaction (HER) surface mechanisms, strategies for cocatalyst optimization, and future directions for the field.

Keywords

Photocatalysis / HER / CO-catalyst / Surface reactions / Charge recombination

Statement of the Use of Generative AI and AI-Assisted Technologies in the Writing Process

During the preparation of this manuscript, author Dr. Bhagatram Meena used ChatGPT to enhance English grammar, editing, and restructuring sentences. After using this tool, author Dr. Bhagatram Meena reviewed, checked, and edited the content as needed and takes full responsibility for the content of the published article.

Acknowledgments

The authors acknowledge University of Cincinnati for providing research infrastructure.

Author Contributions

B.M.: Original draft, Writing—review and editing. P.C.M.: Review and editing. P.G.S.: Supervision, review and editing.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data used in the review can be accessed through the cited publication within the manuscript.

Funding

This research received no external funding.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Dedication

This paper is dedicated to Professor David F. Ollis, who left us on 6 October 2023. Renowned internationally, Professor Ollis was a pioneer in chemical engineering and technology, making groundbreaking contributions that reshaped the field. His research was marked by remarkable depth and diversity. He played a key role in introducing Biochemical Engineering to most Chemical Engineering departments across the United States and many other countries. Beyond his exceptional research, he was a devoted teacher who deeply cared for his students and their education. As a dear friend and mentor to me (PGS), Professor Ollis will be greatly missed, but his legacy and work will endure.

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