Construction of ZIF-67/MIL-88(Fe, Ni) catalysts as a novel platform for efficient overall water splitting

Constructing bifunctional non-precious metal electrocatalysts is necessary for effective overall water splitting (OWS), but challenging. Herein, a novel hybrid nanostructure of ZIF-67/MIL-88(Fe, Ni), denoted as Co-M-Fe/Ni(x) (x represents the mass of ZIF-67), was suc-cessfully synthesized by hydrothermal and in-situ growth method, and showed a highly efficient and stable bifunctionality of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte. The Co-M-Fe/Ni(150) exhibited excellent OER performance with a low overpotential of 269 mV and 149 mV @ 10 mA cm-2 for OER and HER in 1 mol L-1 KOH, respectively. With Co-M-Fe/Ni(150) as cathode and anode, the integrated OWS device had achieved low potential of 1.52 V @ 10 mA cm-2, exhibiting its excellent performance of OWS. Based on the results of experiments, ZIF-67 and MIL-88(Fe, Ni), as metal-organic frameworks (MOFs), which have a large specific surface area, uniform distribution of porous structures facilitates charge transmission, promoting the penetra-tion of electrolytes, and improves electron transfer rate. The mechanism of the superior electrocatalytic performance of Co-M-Fe/Ni(150) may be attributed to the synergy of ZIF-67 and MIL-88(Fe, Ni). This work provides guidance for the rational design or optimization of non-noble composites for energy conversion. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.