Nanoporous cobalt-doped AlNi/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 AlNi/NiO (Co-AlNi/NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi/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 AlNi, 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-AlNi/NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi/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.