Interface engineering of NiS2/CoS2 nanohybrids as bifunctional electrocatalysts for rechargeable solid state Zn-air battery

Abstract Developing active, stable and cost-effective bifunctional electrocatalysts is critical for energy storage and conversion application. Constructing heterogeneous structures can integrate distinct individual properties into one entity and can yield exceptional functionalities. Herein, we report heterogeneous NiS2/CoS2 nanohybrids that are synthesized by successive ion injection method. Benefiting from the synergistic effect, the weak lattice distortion and the electronic modulation, the NiS2/CoS2 electrode exhibits much more catalytic active sites and faster electronic transfer rate, thus leading to better oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performances in KOH solution than the individual NiS2 and CoS2. Moreover, the solid state Zn-air battery (SSZAB) with NiS2/CoS2 as the air electrode exhibits a peak power density of 101 mW cm−2 and a specific capacity of 734 mAh g−1. For practical application, the two-series-connected NiS2/CoS2-based SSZABs can power light-emitting diode (LED) screens and water splitting system efficiently. In addition, the electrocatalytic properties of NiS2/CoS2 in solid state electrolyte deserve further investigation. This work opens a new way for developing high efficient bifunctional electrocatalysts in KOH solution for electronic device utilization.