Interface Engineering of Co‐LDH@MOF Heterojunction in Highly Stable and Efficient Oxygen Evolution Reaction

TLDR

Electrochemical water splitting is a promising clean energy route, but the oxygen evolution reaction remains inefficient, limiting overall performance. The study aims to design interface‑engineered heterojunctions between ZIF‑67 and Co‑LDH to boost OER catalytic activity and Co‑LDH stability. The heterojunction is formed by bonding the oxygen of Co‑LDH to the nitrogen of ZIF‑67’s 2‑methylimidazole ligand, thereby tuning the local electronic structure of the active site. Density functional theory and electrochemical tests demonstrate that the Co‑LDH@ZIF‑67 interface strengthens the Co‑Oout bond, lowers the free‑energy barrier of the rate‑determining step, and delivers a low overpotential of 187 mV at 10 mA cm⁻² with stability exceeding 50 h.

Abstract

The electrochemical splitting of water into hydrogen and oxygen is considered one of the most promising approaches to generate clean and sustainable energy. However, the low efficiency of the oxygen evolution reaction (OER) acts as a bottleneck in the water splitting process. Herein, interface engineering heterojunctions between ZIF-67 and layered double hydroxide (LDH) are designed to enhance the catalytic activity of the OER and the stability of Co-LDH. The interface is built by the oxygen (O) of Co-LDH and nitrogen (N) of the 2-methylimidazole ligand in ZIF-67, which modulates the local electronic structure of the catalytic active site. Density functional theory calculations demonstrate that the interfacial interaction can enhance the strength of the Co-Oout bond in Co-LDH, which makes it easier to break the H-Oout bond and results in a lower free energy change in the potential-determining step at the heterointerface in the OER process. Therefore, the Co-LDH@ZIF-67 exhibits superior OER activity with a low overpotential of 187 mV at a current density of 10 mA cm-2 and long-term electrochemical stability for more than 50 h. This finding provides a design direction for improving the catalytic activity of OER.