Tuning the active sites in the cobalt-based nitrogen-doped carbon by zinc for enhancing hydrogen evolution reaction

Abstract

The cobalt-embedded nitrogen-doped carbon is an attractive alternative to platinum-based catalysts for hydrogen evolution reaction (HER) due to their abundant active sites and excellent durability. In the present paper, a leaf-like zinc and cobalt-based bimetallic metal-organic framework is used to prepare the nitrogen-doped porous carbon sheet (ZnCo-NC). The introduction of Zn in the metal organic framework precursors ensures the uniform and dense distribution of cobalt nanoparticles in the final carbon structure, which reserves the prime active sites, nitrogen-coordinated cobalt (Co-Nx) and active metallic cobalt species embedded in the N-doped carbon layers (Co@NC), in the catalysts. The Co-Nx and Co@NC sites are found to be enriched in the ZnCo-NC, and the larger surface area and abundant pores on it further accelerate the mass transfer process, which are beneficial for enhancing HER performance of catalysts in acidic and alkaline media.