Lanthanum-doped α-Ni(OH)2 1D-2D-3D hierarchical nanostructures for robust bifunctional electro-oxidation

Abstract The development of advanced electrocatalysts for electro-oxidation reactions has attracted much attention because of the critical role of such electrocatalysts in improving the overall efficiency of coupled hydrogen production. We have developed an efficient lanthanum-doped α-Ni(OH)2 bifunctional catalyst with a 1D-2D-3D hierarchical nanostructure. It shows superior activity and stability in the anodic oxygen evolution reaction (OER) and urea oxidation reaction (UOR). Enrichment of the edge sites and conducting La doping in α-Ni(OH)2 phase enable formation and stabilization of abundant local Ni3+ ions. This guarantees ultralow onset potentials in electro-oxidation reactions. The 1D-2D-3D hierarchical nanostructure significantly boosts the in situ generation of high-valence active species, which results in efficient and stable OER and UOR performances, and the synergistic merit of doping-induced facile reaction kinetics. Because of the structural benefits of a large surface area, charge-transfer promotion, good structural stability, and bifunctionality, a 1% La-doped α-Ni(OH)2 hierarchical nanostructure gives superior OER and UOR performances with low overpotentials, large catalytic current densities, and excellent operational stability. It is therefore a promising catalyst for use in simultaneous alkaline wastewater treatment and hydrogen production.