MoC Quantum Dots@N-Doped-Carbon for Low-Cost and Efficient Hydrogen Evolution Reaction: From Electrocatalysis to Photocatalysis

Abstract

Sustainable and highly efficient non-noble metal catalysts could facilitate the realization of closed-loop and carbon-neutral hydrogen (H2) economy via low-cost electrocatalytic (EC) or photocatalytic (PC) H2 evolution reaction (HER) from water. Herein, molybdenum carbide (MoC) quantum dots onto N-doped porous carbon are in situ synthesized and immobilized, resulting in a bifunctional catalyst MoC@NC. Density functional theory calculation suggests that the targeted catalyst has a suitable Gibbs free-energy (ΔGH*) for the adsorption of atomic hydrogen, which is beneficial to both EC and PC HERs. For EC HER, the as-prepared MoC@NC catalyst delivers a low overpotential of 160 mV at −10 mA cm−2 and a remarkable H2 evolution rate in alkaline electrolytes. For PC HER, MoC@NC couple with 2D graphitic carbon nitride (g-C3N4), which significantly reduces the PC HER energy barrier and enhances the separation efficiency of photogenerated carriers, and consequently, achieves an outstanding photocatalytic H2 evolution rate of 1709 µmol h−1 g−1, which is 213-fold of that of pure g-C3N4. This study paves a new avenue for developing sustainable non-noble metal catalysts for both EC and PC HERs.