A recent history of ligand modification for hydrogen evolution catalysts

Hydrogen evolution using first-row transition metal complexes has gained growing attention as a promising route to clean energy generation. This review focuses on recent progress in the molecular design of catalysts based on abundant metals such as iron, cobalt, and nickel, with emphasis given to electrocatalytic systems. We explore how ligand modification strategies have enhanced catalytic performance by influencing key properties such as electron and proton transfer, and active site reactivity. Drawing on major advances over the last decade, this review aims to guide future efforts in optimising ligand frameworks, improving electrochemical performance, and advancing molecular electrocatalysts toward real-world hydrogen production technologies.