Dynamic reconstruction defines true active states in the hydrogen evolution reaction

Abstract

The hydrogen evolution reaction (HER) plays a pivotal role in sustainable hydrogen production and the transition to a carbon-neutral energy future. Traditionally, HER catalyst design has focused on optimizing as-synthesized structures such as composition, morphology, and electronic states, under the assumption that these features remain static during operation. However, accumulating evidence reveals that HER catalysts undergo profound reconstruction, including phase transformation, compositional change, and atomic rearrangement, which fundamentally redefine the true active states. Neglecting this dynamic evolution risks misidentifying catalytic sites, misinterpreting mechanisms, and misguiding design strategies. In this Perspective, we advocate a reconstruction-centered framework for the HER. We outline key reconstruction modes, argue that reconstruction is thermodynamically driven and shaped by intrinsic and extrinsic factors, and emphasize that catalysts should be designed as precursors engineered to evolve in situ into their most active and durable forms. Finally, we advocate for stability assessments that capture steady-state reconstructed phases instead of transient initial states. Adopting this dynamic viewpoint establishes a coherent foundation for mechanistic understanding and rational catalyst design, paving the way toward predictive control of catalytic activity and long-term durability.