Controlled reconstruction of metal–organic frameworks via coordination environment tuning as oxygen evolution electrocatalysts

Abstract

During the oxygen evolution reaction (OER), metal–organic framework (MOF) catalysts undergo structural reorganization, a phenomenon that is still not fully comprehended. Additionally, designing MOFs that undergo structural reconstruction to produce highly active OER catalysts continues to pose significant challenges. Herein, a bimetallic MOF (CoNi-MOF) with carboxylate oxygen and pyridine nitrogen coordination has been synthesized and its reconstruction behavior has been analyzed. The CoNi-MOF electrocatalyst attains a current density of 10 mA cm⁻² with a minimal overpotential of just 250 mV, along with a Tafel slope of 91.57 mV dec⁻¹, which is relatively low. After undergoing CV cycling tests, changes were observed in its catalytic activity, as well as in the microstructure and electrochemically active surface area, which are related to its activity. Importantly, in situ Raman analysis indicates that during the electrocatalytic process, the MOFs undergo a transition to MOOH, signifying the occurrence of reconstruction. Notably, compared to monometallic MOFs, bimetallic MOFs undergo reconstruction at lower voltage and with a faster reconstruction rate. Further analysis has revealed that the electrochemical reconstruction rate of the Co–N/O coordination mode at the active center is higher than that of Ni–N/O, playing a crucial role in enhancing OER activity. This study underscores the significance of the reconstruction strategy in enhancing the activity of MOF catalysts, providing new insights for the development of high-activity materials.