Seaweed-like Co-MOF/Cu(OH)2/CF composite as an advanced pre-catalyst for oxygen evolution reaction

Abstract

Directly applying metal-organic frameworks (MOFs) as electrocatalysts or pre-catalysts for the oxygen evolution reaction (OER) faces significant challenges, due to the lack of exposed active sites, low electronic conductivity, and poor structure stability. Herein, a novel alkaline leaching-solvothermal strategy is proposed to synthesize seaweed-like Co-MOF/Cu(OH)2 on copper foam (CF), which is applied as self-supporting pre-catalyst for OER. After electrochemical activation, Co-MOF/Cu(OH)2/CF only requires an overpotential of 279 mV at 50 mA cm-2 and operates steadily for 72 h with negligible activity deterioration. The high activity and stability mainly benefit from the unique structural arrangement, in which Cu(OH)2 nanoneedles serve as firm substrates to grow and stabilize Co-MOFs. The two-dimensional Co-MOFs with nanometer thickness and high accessible surfaces could expose sufficient metal coordination sites, which are ready for reconstruction and electrocatalysis. Additionally, CF framework helps to maintain the self-supporting structure and acts as current collector to enhance the charge/electron transfer efficiency during OER.