Tailoring active sites in trimetallic conductive metal–organic frameworks for highly efficient water splitting

Abstract

The construction of highly efficient conductive metal–organic frameworks (cMOFs) for water splitting remains a significant challenge. Herein, a hexagonal prismatic trimetallic cMOF grown on carbon cloth (NiFeCo–HHTP/CC) is prepared through a facile solvothermal method. The introduction of Co into NiFe–HHTP/CC not only significantly enhances the electrical conductivity but also modulates the electronic structure of NiFeCo–HHTP/CC, thereby endowing the catalyst with remarkable activities for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1.0 M KOH. X-ray absorption spectroscopy combined with in situ Raman spectroscopy demonstrates that Co incorporation effectively promotes the formation of NiFeCoOOH which serves as the active species during the OER. Meanwhile, the Co-induced electron redistribution leads to electron accumulation at Ni and Fe sites, facilitating water adsorption and dissociation, thus greatly improving the HER. NiFeCo–HHTP/CC achieves a current density of 10 mA cm⁻² at ultralow overpotentials of 214 mV for the OER and 75 mV for the HER, respectively. Furthermore, the assembled NiFeCo–HHTP/CC‖NiFeCo–HHTP/CC electrolyzer requires a remarkably low voltage of 1.53 V to reach 10 mA cm⁻² for water splitting and remains stable for 200 h, outperforming commercial RuO₂/CC‖Pt/C/CC and most reported MOF-related electrocatalysts. This work presents a promising pathway for designing high-efficiency electrocatalysts for energy conversion.