Rational design of the FeS2/NiS2 heterojunction interface structure to enhance the oxygen electrocatalytic performance for zinc-air batteries

Fine design of nanostructures of bifunctional electrocatalysts and developing low-cost, efficient and durable electrocatalytic materials are important directions for the development of sustainable energy storage and conversion devices such as electrolytic water and metal-air batteries. In this work, nickel-iron layered sulfide hollow double-shell nanorods were synthesized by a one-step hydrothermal self-templating process followed by a high-temperature sulfurization process. Benefiting from the large electrochemically active surface area of the layered nanosheets, the electronic regulation of the FeS2/NiS2 heterogeneous interface, and the mechanical support of the hollow core-shell structured nanorods, the synthesized FeS2/NiS2 hollow multi-shell nanorods with an open layered array structure (FeS2/NiS2 HDSNRs) show better electrocatalytic performance than the single component FeS2 and NiS2 electrocatalysts in alkaline electrolyte solution. In 1.0 M KOH solution for the oxygen reduction reaction, the FeS2/NiS2 HDSNRs electrocatalyst has a half-wave potential of 0.80 V vs. RHE and an overpotential of only 280 mV at a current density of 50 mA cm(-2) for oxygen evolution reaction and the Tafel slope is only 33 mV dec(-1). The FeS2/NiS2 HDSNRs electrocatalyst used as the cathode of a liquid zinc-air battery showed a peak power density of 130 mW cm(-2) and a charge-discharge cycle life of 480 h at a current density of 5 mA cm(-2), with a voltage gap of only 0.92 V. In addition, the assembled solid-state zinc-air battery also exhibits a charge-discharge cycle life of 11 h at a current density of 5 mA cm(-2), and two solid-state batteries connected in series can also drive LED lights. This study provides new insights for the rational design of nickel-iron sulfides with a layered nanosheet-core-shell structure for electrocatalysis and renewable energy applications.

Automated summary

This study presents the synthesis of nickel-iron layered sulfide hollow double-shell nanorods with outstanding electrocatalytic performance in alkaline electrolyte. The FeS2/NiS2 HDSNRs catalyst shows low overpotential and excellent current density performance in oxygen reduction and evolution reactions. Furthermore, the catalyst exhibits promising performance in both liquid and solid-state zinc-air batteries.