A Self-Templated Design Approach toward Multivariate Metal-Organic Frameworks for Enhanced Oxygen Evolution

Multivariate metal-organic framework (MOF) is an ideal electrocatalytic material due to the synergistic effect of multiple metal active sites. In this study, a series of ternary M-NiMOF (M = Co, Cu) through a simple self-templated strategy that the Co/Cu MOF isomorphically grows in situ on the surface of NiMOF is designed. Owing to the electron rearrange of adjacent metals, the ternary CoCu-NiMOFs demonstrate the improved intrinsic electrocatalytic activity. At optimized conditions, the ternary Co3Cu-Ni(2)MOFs nanosheets give the excellent oxygen evolution reaction (OER) performance of current density of 10 mA cm(-2) at low overpotential of 288 mV with a Tafel slope of 87 mV dec(-1), which is superior to that of bimetallic nanosheet and ternary microflowers. The low free energy change of potential-determining step identifies that the OER process is favorable at Cu-Co concerted sites along with strong synergistic effect of Ni nodes. Partially oxidized metal sites also reduce the electron density, thus accelerating the OER catalytic rate. The self-templated strategy provides a universal tool to design multivariate MOF electrocatalysts for highly efficient energy transduction.

Automated summary

In this study, ternary M-NiMOF (M = Co, Cu) materials were designed through a simple self-templated strategy, where Co/Cu MOF isomorphically grows in situ on the surface of NiMOF, forming a multivariate MOF. The ternary CoCu-NiMOFs demonstrate improved electrocatalytic activity due to the electron rearrangement of adjacent metals. Under optimized conditions, the ternary Co3Cu-Ni(2)MOFs nanosheets exhibit excellent oxygen evolution reaction performance, surpassing that of bimetallic nanosheets and ternary microflowers.