Constructing an oxide-fluoride heterojunction supported on carbon cloth as a highly active and stable catalyst for enhancing overall water-splitting

To realize large-scale production of hydrogen by water electrolysis, the development of inexpensive and highperformance catalysts is urgently needed. Herein, we developed an oxide-fluoride (Co3O4-CoF2) heterojunction catalyst with mooncake shape morphology supported on carbon cloth (CC) used as a bifunctional water electrolysis catalyst in 1 M KOH. The obtained Co3O4-CoF2 heterojunction exhibits a preferable kinetic process and more active sites than its mono components Co3O4 and CoF2, which only needs 46 mV for HER and 169 mV for OER at 10 mA cm-2 comparable to benchmark Pt/C and even super to benchmark IrO2. Meanwhile, it also demonstrates long-term stability, maintaining activity for 100 h for both HER and OER. Importantly, when assembled as a water electrolysis device, only a low cell voltage of 1.45 V is required to achieve the current density of 10 mA cm-2. Meanwhile, it can output continuous and stable current densities of 10, 100, and 10 mA cm-2 approaching 24 h under constant cell voltages of 1.47, 1.69, and 1.47 V, respectively. Therefore, the oxidefluoride heterojunction catalyst unambiguously is a type of ideal bifunctional water electrolysis catalyst in alkaline media.