Double Perovskite Type (Nh4)3fexco1-Xf6 Electrocatalyst Synthesized Via Low-Temperature Reaction for Efficient Water Oxidation

Developing efficient nonprecious electrocatalysts to accelerate the sluggish oxygen evolution reaction (OER) is of great significance for boosting water splitting. Here, we propose that NH4F can serve as a structure-directing agent to replace the imidazole ligand in ZIF-67 so that Fe cations can be incorporated to form a double perovskite structured bimetallic fluoride [(NH4)3FexCo1-xF6, NFCF]. This NFCF electrocatalyst has an open framework structure with porous hollow, which guarantees lower charge transfer resistance, abundant active sites, and larger electrochemical surface area. DFT calculation verifies that the coexistence of Co and Fe can moderate the OH* adsorption and decrease the energy barrier from O* to OOH* of NFCF during OER catalysis. It requires low overpotentials of 243 and 360 mV to achieve current densities of 10 and 100 mA cm-2 in 1 M KOH, respectively. Moreover, it can work at a constant current of 100 mA cm-2 for up to 100 h.