First-row transition metal-based materials derived from bimetallic metal–organic frameworks as highly efficient electrocatalysts for electrochemical water splitting
Electrochemical water splitting is a mature technology for hydrogen generation. Numerous studies have focused on the development of highly efficient electrocatalysts to produce hydrogen and oxygen from water electrolysis through the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Up to now, the most effective electrocatalysts for electrochemical water splitting are still materials based on Pt, Ru and Ir. Although these materials exhibit very good performance, their massive utilization is limited due to the scarce resources. Therefore, the search for suitable, efficient, inexpensive, stable and abundant materials for electrochemical water splitting is imperative for the large-scale, worldwide, commercial implementation of electrolytic hydrogen generation. Abundant first-row transition metal-based electrocatalysts for water splitting are considered as promising alternatives to those based on noble metals. It has been found that materials combining two metals exhibit enhanced electrocatalytic activity. It is the focus of this review to show that efficient first-row bimetallic materials can be obtained from the corresponding metal–organic frameworks (MOFs) as precursors. The present review describes recent advances in bimetallic electrocatalysts derived from bimetallic MOFs containing first row transition metals, including bimetallic oxides, bimetallic chalcogenides, bimetallic nitrides and their composites. Challenges in this area and future research directions are highlighted.