Porous NiCo2S4/Co9S8 Microcubes Templated by Sacrificial ZnO Spheres as an Efficient Bifunctional Oxygen Electrocatalyst

Abstract

AbstractInnovative nano/microarchitectures, owing to their promising catalytic features, such as abundant active sites, high surface area, and enhanced ion transport, are ideal for oxygen electrocatalysis. Herein, an inventive approach is put forward to fabricate ternary metal sulfide hollow microcubes by a hydrothermal method between spherical porous ZnO with transition metal cations in the presence of urea followed by etching and sulfurization. The significant electrocatalytic activity toward oxygen evolution reaction (OER) with onset potential of 1.48 V (vs reversible hydrogen electrode (RHE)) is obsereved. The objective material shows an overpotential of 320 mV, to achieve a current density of 10 mA cm−2 for OER and excellent robustness with slight variation in potential after long‐term chronopotentiometry test for 12 h. As expected, the material also exhibits oxygen reduction reaction (ORR) activity with a half wave potential of 0.8 V (vs RHE) and limited current density of 5.1 mA cm−2. Meanwhile, further investigations confirm the near four‐electron transport pathways for ORR. Such up‐bottom etching followed by sulfurization method provide a new concept for engineering porous electrocatalysts.