Yolk–Shell\nα‑/β-Ni(OH)<sub>2</sub>/Carbon Nanostructure for\nan Efficient Oxygen Evolution Reaction

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