Nanocages Coupling with Carbides Quantum Dots for Efficient Hydrogen Evolution

An innovative strategy for synthesizing nitrogen-doped carbon nanocages embedded with ultrafine Mo2C and W2C quantum dots (Mo2C/W2C@NCNs) has been proposed through transition metal-assisted catalysis metal–organic framework (MOF) decomposition. During pyrolysis, Mo and W species derived from Mo(CO)6 and W(CO)6 facilitate the controllable thermal decomposition of the MOFs, forming a clear hollow structure. Meanwhile, the Mo and W substances transform into ultrafine Mo2C and W2C quantum dots and disperse in N-doped carbon matrix uniformly, which is conductive to boosting the catalytic activity and stability for HER. The optimized Mo2C/W2C@NCNs exhibits excellent HER performance, achieving low over potentials of 53.7 mV and 67.5 mV at 10 mA cm–2 in acidic and alkaline media, respectively. The density functional theory calculations reveal that the Mo2C/W2C heterojunctions effectively modulate the d-band center position and optimize the Gibbs free energy for hydrogen adsorption, thereby enhancing the catalytic activity of the carbides.