Nanoporous cobalt-doped AlNi₃/NiO architecture for high performing hydrogen evolution at high current densities

Engineering platinum-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is essential for electrochemical hydrogen production. In this paper, we report the synthesis of cobalt-doped AlNi₃/NiO (Co-AlNi₃/NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi₃/NiO can accelerate water adsorption / dissociation and optimize adsorption-desorption energies of H* intermediates, thus improving the intrinsic HER activity. Both the introduction of Co and Al can efficiently ameliorate the electronic density around Ni sites of NiO and AlNi₃, which can effectively reduce the energy barrier towards Volmer-Heyrovsky reaction and thus synergistically promote the hydrogen evolution. Benefiting from the large electrochemical active surface area, high electrical conductivity and electronic effect, the nanoporous Co-AlNi₃/NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm^-2 in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi₃/NiO catalyst can operate continuously over 1000 h at high current densities with a robust stability. This work provides a new vision for the development of low-cost and efficient electrocatalysts for energy conversion applications.