Yolk–Shell α-/β-Ni(OH)₂/Carbon Nanostructure for an Efficient Oxygen Evolution Reaction

Replacing the state-of-the-art IrO2 catalyst with nonprecious metal electrocatalysts for the oxygen evolution reaction (OER) remains a significant challenge. We report a facile synthesis of a precious-metal-free OER electrocatalyst using a silica-templated metal–organic framework (MOF)-mediated approach, where the MOF@silica composite results in a yolk–shell α-/β-Ni(OH)2/carbon nanostructure, named as αβ-Ni(OH)2/NC. αβ-Ni(OH)2/NC consists of both α- and β-Ni(OH)2 ultrathin nanosheets, decorated homogeneously on the N-doped yolk–shell carbon structure. αβ-Ni(OH)2/NC achieved an OER current density of 10 mA·cm–2 at an overpotential of only 0.254 V (vs RHE) under alkaline conditions with a small Tafel slope value. The superior OER activity might be attributed to its unique porous nature, the presence of an interfacial interaction between α- and β-Ni(OH)2, and its synergistic coupling with porous N-doped carbon. Additionally, we developed a durable water electrolysis cell using αβ-Ni(OH)2/NC as the cathode, generating a current density of 100 mA cm–2 at a cell voltage of 1.72 V.