A nitrogen-doped NiCo2S4/CoO hollow multi-layered heterostructure microsphere for efficient oxygen evolution in Zn–air batteries
Bin He, Juanjuan Song, Xiaoyu Li, Chunyu Xu, Yibo Li, Yawen Tang, Qingli Hao, Hong‐Ke Liu, Zhi Su
Abstract
Exploring highly effective and low-cost non-noble metal-based electrocatalysts for oxygen evolution reaction (OER) is critical for renewable energy conversion and metal-air batteries. Herein, a novel and high-efficient OER catalyst was reported with nitrogen-doped oxide/sulfide heterostructures (named N-NiCo2S4/CoO microsphere). The N-NiCo2S4/CoO microsphere was synthesized by annealing NiCo-BTC MOF to a multi-layered hollow structure of NiCo2O4 microspheres, followed by the direct vulcanization in the presence of NH4HCO3, resulting in an oxide/sulfide heterojunction. Benefiting from the nitrogen doping, the abundant multi-layered hollow heterostructure and the interfaces between multiple components, the N-NiCo2S4/CoO microsphere exhibited excellent OER activity with a low overpotential of 227 mV at 10 mA cm-2. The Zn-air battery based on the N-NiCo2S4/CoO + Pt/C catalyst displayed excellent cycling stability after 900 cycles at a large current density of 5 mA cm-2, where the commercial RuO2 + Pt/C-based battery exhibited a big drop after only 30 cycles, suggesting its great application prospects as power source devices.