Exploring the Performance Improvement of the Oxygen Evolution Reaction in a Stable Bimetal–Organic Framework System

TLDR

The origin of the improved performance of bimetallic electrocatalysts in OER remains unclear despite their widespread use. The study proposes a model to guide the design of efficient bimetallic catalysts for energy storage and conversion by elucidating their OER mechanisms. The authors synthesized stable MOFs NNU‑21‑24 with trinuclear metal carboxylate clusters and tridentate ligands to probe the OER mechanism. NNU‑23 outperforms monometallic MOFs, and DFT and experimental results show that adding a second metal atom enhances the activity of the original metal.

Abstract

Despite wide applications of bimetallic electrocatalysis in oxygen evolution reaction (OER) owing to their superior performance, the origin of the improved performance remains elusive. The underlying mechanism was explored by designing and synthesizing a series of stable metal-organic frameworks (MOFs: NNU-21-24) based on trinuclear metal carboxylate clusters and tridentate carboxylate ligands. Among the examined stable MOFs, NNU-23 exhibits the best OER performance; particularly, compared with monometallic MOFs, all the bimetallic MOFs display improved OER activity. DFT calculations and experimental results demonstrate that introduction of the second metal atom can improve the activity of the original atom. The proposed model of bimetallic electrocatalysts affecting their OER performance can facilitate design of efficient bimetallic catalysts for energy storage and conversion, and investigation of the related catalytic mechanisms.