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 (H 2 ) economy via low‐cost electrocatalytic (EC) or photocatalytic (PC) H 2 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 (Δ G H* ) 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 H 2 evolution rate in alkaline electrolytes. For PC HER, MoC@NC couple with 2D graphitic carbon nitride (g‐C 3 N 4 ), which significantly reduces the PC HER energy barrier and enhances the separation efficiency of photogenerated carriers, and consequently, achieves an outstanding photocatalytic H 2 evolution rate of 1709 µmol h −1 g −1 , which is 213‐fold of that of pure g‐C 3 N 4 . This study paves a new avenue for developing sustainable non‐noble metal catalysts for both EC and PC HERs.