General design of self-supported Co-Ni/nitrogen-doped carbon nanotubes array for efficient oxygen evolution reaction

The development of earth-abundant oxygen evolution reaction (OER) electrocatalysts with high activity and durability is critical for replacing noble-metal-based catalysts in the applications of scalable water electrolysis. A freestanding electrode architecture offers significant advantages over conventional coated powder forms due to enhanced kinetics and stability. However, precise control over electrode composition and the construction of uniformly distributed active sites within these electrodes remain challenging. Herein, a general strategy is proposed to utilize metal-organic frameworks (MOFs)/nickel foil to controllable synthesize self-supported CoNi/nitrogen-doped carbon nanotubes array (CoNi-NCNT/NiF) as efficient electrocatalyst for OER. The results of the experiments and density functional theory (DFT) calculations show that the synergistic effect of Co nano- particles, heteroatomic doping, and the confinement effect of the NCNTs could enhance the electronic transmission and accelerate electrocatalytic kinetics. Furthermore, the porous structure and optimized composition of CoNi-NCNT/NiF will enhance mass and charge transfer as well as intermediate adsorption, all together lead to the catalyst with excellent electrocatalytic activity and stability. A low and stable OER overpotential of 268 mV is needed for CoNi-NCNT/NiF to reach a current density of 20 mA cm- 2 in an alkaline electrolyte, which ranks among the top of the non-precious metal catalyst reported to date. This work offers new guidance for the precise construction of self-supported electrocatalysts for sustainable clean energy.