Interfacial Electronic Structure Modulation of Hierarchical Co(OH)F/CuCo2S4 Nanocatalyst for Enhanced Electrocatalysis and Zn-Air Batteries Performances.

The exploration of robust multifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a continuing challenge for the sustainable energy sources. However, as the key reactions in renewable metal-air batteries and fuel cells, the energy conversion efficiencies of ORR and OER are greatly affected by their reaction kinetics. In addition to designing excellent electrocatalysts, new methods to stabilize the electrolyte/electrode interfaces are urgently needed. Herein, a hierarchical Co(OH)F/CuCo2S4 hybrid was created as an efficient catalyst for OER and ORR in alkaline media. Combining spinel ferrite with the hydroxide can greatly boost their catalytic performance. The optimal Co(OH)F/CuCo2S4 hybrid exhibits superior OER performance and durable stability, as demonstrated by an ultralow overpotential of 230 mV at 10 mA·cm-2. The onset potential and the half-wave potential in 0.1 M KOH solution for ORR are 0.88 and 0.80 V, respectively. Furthermore, the Co(OH)F/CuCo2S4 hybrid served as a catalyst in Zn air batteries catalyst exhibits a low overpotential of 1.12 V at 50.0 mA·cm-2, large power density of 144 mW·cm-2, and a long electrochemical lifetime of 118 h (118 cycles), which is even better than those of the Pt/C and RuO2 catalysts. The rational integration of spinel and hydroxide at the interface can provide multifunctional electrocatalysis and possess a high reactivity for oxygen conversion. Synergistic coupling effect and interfacial electronic interaction between Co(OH)F and CuCo2S4 can significantly enhance the electron transfer rate, and these synergistic advantages enable the heterogeneous structure of the multifunctional electrocatalyst to produce excellent catalytic performance.