Comparative Study on the Electrocatalytic Activity of Transition Metal-Doped Ni(OH)2 Microflowers for Oxygen Evolution Reaction

Abstract

Green hydrogen production by water splitting holds great potential as a clean and renewable source of energy for sustainable energy solutions. However, the efficiency of this process is hampered by the sluggish oxygen evolution reaction (OER). Overcoming these kinetic hurdles requires the development of highly efficient electrocatalysts. This study explores the effect of transition metal doping on the electrocatalytic properties of Ni(OH)₂ microflowers towards alkaline OER. Transition metal-doped Ni(OH)₂ microflowers, with highly porous structures due to interconnected nanosheets, are synthesized by a facile, cheap, and scalable chemical bath deposition (CBD), and combined with graphene paper (GP) substrates to fabricate electrodes. Through a systematic exploration of the relationship between the transition metal dopant element type (Mn, Fe, Co, Zn) or concentration and the consequent electrochemical properties, Co-doping demonstrates improvement in the overpotential at a current density of 10 mA cm⁻² (329 mV), Tafel slope (45 mV dec⁻¹), and other key performance indicators of Ni(OH)₂ microflowers for OER. These results are attributed to the high number of active sites and their enhanced electrocatalytic activity benefiting from the presence of the transition metal dopant. The proposed strategy paves the way for the development of cost-effective and highly efficient electrocatalysts for water splitting technologies.