Selenide/sulfide heterostructured NiCo2Se4/NiCoS4 for oxygen evolution reaction, hydrogen evolution reaction, water splitting and Zn-air batteries

Rational design and constructing multifunctional electrocatalysts featuring with low cost and high efficiency is critical for promoting the implement of sustainable energy devices such as water splitting and zinc air batteries. Herein, we report a facile means to prepare a selenide/sulfide hetero-structured NiCo2Se4/NiCoS4 catalyst for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), overall water splitting (OWS), and Zn-air batteries (ZABs). The NiCo2Se4/NiCoS4 heterostructure showed excellent OER and HER performance, evidenced by the small overpotential of 248 mV and 180 mV @ 10 mA cm−2 for OER and HER, and superior long-term stability to the benchmark IrO2 and Pt/C catalyst for OER and HER, respectively. It also exhibited a potential of 1.660 V @ 10 mA cm−2 in the practical OWS test, close to the Pt/C + IrO2 catalyst. Furthermore, when employed as air-cathode catalyst for ZABs, the NiCo2Se4/NiCoS4 modified battery exhibited the narrow charge-discharge voltage gap of 0.98 V @ 50 mA cm−2 and a maximal specific capacity of 693.17 mA h g−1, outperforming the IrO2 counterpart. Such excellent performance can be attributed to the advantageous structural merit of the NiCo2Se4 nanoflowers, and especially the heterostructure interfaces created in NiCo2Se4/NiCoS4, which significantly boosted the catalytic synergistic effects. This study can offer a new avenue to design and prepare abundant-element-based cost effective, efficient and durable electrocatalysts with multifunctionalities that hold great promises to be applied in electrochemical devices.