Boosting hydrogen evolution electrocatalysis through defect engineering: A strategy of heat and cool shock

Abstract Developing new strategy to further improve hydrogen evolution reaction (HER) performance of transition metal-based electrocatalysts is of high significance to accelerate commercial application of hydrogen energy. Here, HER activity is significantly enhanced through introducing crystal defects. The combined methods of heat and cool shock calcination, mask fiber templates as both reducing agent and carbon source were applied to synthesize microtube-like electrocatalysts composed of cross-linked carbon sheets and ultrafine Ni nanoparticles. The extensive active sites (edges, corners, steps, jaggies and strain) on the surface of Ni nanoparticles caused by grain surface, twin boundaries and stacking faults could synergically accelerate HER activity by optimizing adsorption capability of electrocatalysts and exposing atoms with high surface energy. Meanwhile, the defect-rich Ni nanoparticles wrapped by few-layer graphene are uniformly fixed on the conductive carbon network, which provides abundant diffusion channels for H2 and electrolyte, as well as effectively prevents Ni nanoparticles aggregation and avoids Ni grains being peeled off during long-term HER operation. As expected, the as-prepared electrocatalyst exhibits prominently improved electrocatalytic activity and admirable stability for HER. This work provides some innovatively technical insight in new-type catalysts development and defects engineering.