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.