Thermal strain engineering in cobalt-coordinated Mo2N for efficient ampere-level current density alkaline fresh/seawater hydrogen evolution electrocatalysis

Lattice-strain engineering has demonstrated its capability to influence the electronic structure and catalytic performance of electrocatalysts. Herein, we present a facile method for inducing thermal strain in cobalt/molybdenum nitride rod-shaped structures (denoted Co/Mo 2 N) via ammonia-assisted reduction, which effectively modulating the HER performance. The optimized Co/Mo 2 N-500, characterized by 3% tensile lattice strain, demonstrates exceptional HER activity with lower overpotentials of 140 mV and 184 mV at high current density of 1000 mA cm −2 in alkaline freshwater and seawater electrolytes, respectively. Co/Mo 2 N also exhibits excellent long-term durability even at a high current density of 300 mA cm −2 , surpassing its counterparts and benchmark Pt/C catalyst. Density functional theory calculations validate that the tensile strain optimizes the d -band states, water dissociation, and hydrogen adsorption kinetics of the strained Mo 2 N in Co/Mo 2 N, thereby improving its catalytic efficacy. This work provides valuable insights into controlling lattice strain to develop highly efficient electrocatalysts towards advanced electrocatalytic applications.