N, K Co-activated biochar-derived molybdenum carbide as efficient electrocatalysts for hydrogen evolution

Abstract

Molybdenum carbide (Mo2C) has offered great promise to serve as a platinum substitute towards efficient hydrogen evolution reaction (HER). However, both the lack of exposed catalytic sites and strong Mo–H binding strength will strongly hinder the HER process for Mo2C-based electrocatalysts. Herein, a scalable strategy is proposed for the preparation of highly porous Mo2C/C electrocatalysts with a specific surface area up to 611 m2 g−1 as well as uniform nitrogen doping derived from N, K co-activated biochar (NKAB). And the porous architecture with a large specific surface area can afford abundant catalytic sites. Additionally, both the Mo2C and carbon matrix are doped with nitrogen effectively, which can optimize the hydrogen adsorption free energy of Mo2C/C electrocatalysts associated with a higher intrinsic activity. As a result, the active site density and intrinsic activity of Mo2C/NKAB have been promoted simultaneously on account of the high specific surface area and nitrogen doping. Furthermore, the interconnected N-rich carbon matrix provides efficient electron transfer pathways for superior HER kinetics. Ultimately, the overall HER performances of Mo2C/NKAB can be significantly enhanced.