SBIC ECR Symposium & Poster Presentation 21st International Conference on Biological Inorganic Chemistry 2025

Photochemical H2 Evolution from Biologically Relevant Metal Hydrides: Striving for Enhanced Quantum Yield (#444)

Abhishek Das 1 , Alexander J. M. Miller 1
  1. University of North Carolina at Chapel Hill, Chapel Hill, NORTH CAROLINA, United States

To achieve a more sustainable future, a substantial increase in carbon-neutral energy will be needed to meet global energy demands.1 Using sunlight to generate fuels has attracted wide interest as a strategy for carbon-neutral energy technologies.1, 2 The bioinorganic metal cofactors involved in photosynthetic production of sugars have served as key inspirations for chemists developing synthetic catalysts. In biology and in leading solar fuel technology, the processes of light harvesting and fuel-formation are carried out by separate components.3, 4 Since these methods rely on multi-component systems, the photon-to-fuel efficiency can be compromised by slow interfacial electron transfer. An alternative approach that might avoid this drop in efficiency is molecular photoelectrocatalysis, where electrochemical hydride production is coupled with photochemical H2 release.3 The biological analogy would be if photoexcitation of a hydrogenase could lead to higher rates, lower overpotentials, or new mechanistic pathways. Until our recent report of a first-row transition metal hydride capable of single-component photoelectrocatalysis,5 other systems relied on 2nd and 3rd row transition metals.3, 6-8 Compared to other molecular photoelectrocatalysts, however, the nickel-based photohydride has a low quantum yield for photochemical H2 production.5 Towards more efficient conversion of photons into fuel, a systematic structure-efficiency study has been undertaken. Mechanistic investigations of a variety of transition metal hydride complexes will be discussed, including photophysical studies, photochemical efficiency analysis, and photoelectrocatalysis. These studies provide insights into the factors that influence the efficiency of solar fuel generation by first-row transition metal photohydrides.

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