Unlocking Pathway-Selective OER in a Self-Adaptive MOF-on-MOF Heterostructure toward Industrial-Level Alkaline Water Electrolysis
Tengjia Ni, Dewei Zhang, Kaiyu Ji, Xianbiao Hou, Jian Zhou, Canhui Zhang, Lei Chu, Huanlei Wang, Shenghong Ju, Heqing Jiang, Minghua Huang
Abstract
Understanding the intricate relationship between dynamic active site evolution and the pathway-selective oxygen evolution reaction (OER) is essential, yet it remains elusive. Herein, molecular-level integration of Ni-BDC (BDC = 1,4-benzenedicarboxylic acid) and Co-BPDC (BPDC = 4,4′-biphenyldicarboxylic acid) on Ni foam (NF) affords a self-adaptive bimetallic metal–organic framework (MOF)-on-MOF platform that enables dynamically responsive reconstruction into OER-active NiCoOOH/NF via real-time modulation of the coordination geometry at Ni–Co dual sites. Theoretical calculations and in situ spectroscopy uncover densely packed Ni–Co dual sites with shortened interatomic spacing in reconstructed NiCoOOH/NF, which facilitates the switching of the OER pathway from the adsorbate evolution mechanism (AEM) to the oxide pathway mechanism (OPM), thereby enabling spin-aligned O* intermediate formation and direct O–O* coupling for accelerated reaction kinetics. The resulting NiCoOOH/NF catalyst delivers an ultralow overpotential of 301 mV at 1 A cm –2 and maintains continuous operation beyond 1000 h. Upon integration into anion exchange membrane water electrolyzers (AEMWEs), it sustains a cell voltage of 1.77 V at 1 A cm –2 for durations exceeding 240 h. This work highlights a distinctive perspective on the fundamental mechanistic understanding of reconstructed catalysts.