In Situ Growth of POMOFs and Derived Nitride on Cu Foam to Produce Hydrogen with Promoted Water Dissociation Kinetics
Dispersing active material on working electrode without any binder is always desirable for electrocatalytic process. Here we report a promising method to in situ grow polyoxometalate-based MOFs (POMOFs) on a copper foam (CF) substrate. Impressively, CF can serve as the metal nodes for the direct growth of MOFs on its 3D skeleton tightly. After ammoniating the POMOFs/CF precursor, the nitride-based composite (MoN-Cu-NPC/CF) is achieved with such unique structure that MoN and Cu nanoparticles are embedded in N, P-doped amorphous carbon and decorated on CF uniformly. We find that MoN-Cu-NPC/CF has an improved HER activity over a wide pH range. Especially in alkaline electrolyte, this composite shows a small onset overpotential of 60 mV, a Tafel slope of 152 mV dec‒1 and a preeminent long-term stability (over 20 h), outperforming most of the nitride-based HER electrocatalysts to date. Density functional theory (DFT) calculations reveal that the synergy between MoN and Cu can modify the electronic structure of the active Cu sites, which significantly improves H* binding and water dissociation kinetics. This work provides a facile strategy for in situ growth of MOFs on a metal substrate without any binder and holds substantial promise for efficient HER applicaitons.