Non-thermal plasma restructuring of electrocatalyst surfaces for efficient hydrogen and oxygen reactions.

Electrocatalysts for water electrolysis, fuel cells, and metal-air batteries are largely governed by processes occurring within the outermost few nanometres of their surface. Low-temperature plasmas provide an effective means to tailor this region, using energetic electrons and reactive species to enable rapid, surface-confined modification while preserving the underlying scaffold. In this Feature Article, we review plasma engineering strategies for HER, OER and ORR electrocatalysts, including examples from zinc-air batteries and direct methanol fuel cells. We classify plasma effects into five generic design modes: phase transformation and plasma-assisted derivation; defect and vacancy engineering; plasma-induced doping; plasma-enabled deposition and interface construction; and single-atom anchoring with strong metal-support interactions. We also propose simple design rules that connect controllable plasma parameters to targeted active sites and device-level performance.