Alkaline hydrogen evolution reaction (HER) is fundamentally limited by sluggish water dissociation kinetics associated with the Volmer step. Conventional strategies focus on designing static catalyst structures to promote water activation; however, many transition metal compounds undergo significant surface reconstruction under operating conditions, dynamically altering the active interface. Despite increasing recognition of this phenomenon, reconstruction is typically uncontrolled, leading to a trade-off between activity and stability.
Here, we demonstrate that surface reconstruction in alkaline HER is strongly dependent on the applied potential rather than reaction time, enabling its active regulation. Using nickel sulfide and iron sulfide as model systems, we show that Ni-based sulfides exhibit high activity but undergo excessive reconstruction and structural degradation, whereas Fe-based sulfides remain stable but show limited catalytic performance. By integrating Fe into a Ni–S spinel framework, we achieve a moderated reconstruction behavior that balances activity and stability.
Building on this understanding, we develop a multi-step potential programming strategy to guide the reconstruction process across distinct potential regions. This approach enables gradual transformation of Ni–S into catalytically active Ni–OH species while preserving the Fe–S framework, forming a stable and efficient interfacial structure. Compared to single-step activation, the multi-step strategy leads to improved catalytic activity, reduced Tafel slope, and enhanced stability.
This work highlights that reconstruction is not merely a passive process but can be actively controlled, providing a new pathway to bridge the gap between catalytic activity and durability in alkaline HER.