Enhanced alkaline hydrogen evolution reaction through a sponge-like structure: Synergistic impact of diverse active sites

Abstract

The electrochemical hydrogen evolution reaction (HER) stands as a pivotal strategy in the transition toward a sustainable energy future, however, the evolution of an efficient, non-precious metal-based electrocatalyst for HER in alkaline electrolysis remains a challenge. Herein, a functional HER electrocatalyst with sponge-like structure was successfully prepared, termed 5Co-NC. The removal of the polystyrene spheres and high-temperature calcination process facilitated the formation of a hierarchical porous structure including macropores, mesopores and micropores. Furthermore, X-ray absorption fine structure indicated the existence of Co single atom site and Co nanoclusters, while the synergistic effect can promote the decomposition of water and the production of hydrogen. Benefited from the dominant structure, the 5Co-NC electrocatalyst exhibited a remarkably low overpotential of 245 mV at 10 mA cm⁻², while a Tafel slope as low as 86.2 mV⋅dec⁻¹. It also showed catalytic activity exceeding 24 h and large double layer capacitance of 14.5 mF cm⁻². The study supplies insights into developing advanced electrocatalysts with precisely controlled morphology and outstanding performance, paving the way for future energy applications.