Limited by the sluggish four-electron transfer process, designing high-performance nonprecious electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is urgently desired for efficient rechargeable Zn-air batteries (ZABs). Herein, the successful synthesis of porous nitrogen-doped cobalt pyrite yolk-shell nanospheres (N-CoS 2 YSSs) is reported. Benefiting from the abundant porosity of the porous yolk-shell structure and unique electronic properties by nitrogen doping, the as-prepared N-CoS 2 YSSs possess more exposed active surface, thus giving rise to superior activity for reversible oxygen electrocatalysis and outstanding cycling stability (more than 165 h at 10 mA cm −2) in ZABs, exceeding the commercial Pt/C and RuO 2 hybrid catalysts. Moreover, the assembled ZABs, delivering a specific capacity of 640 mAh g Zn −1 , can be used for practical devices. This work provides a novel tactic to engineer sulfides as high efficiency and promising bifunctional oxygen electrocatalysts for advanced metal-air batteries. Oxygen electrocatalysis has received widespread attention due to its importance in fuel cells, water splitting, and metal-air batteries. [1-4] Among these sustainable energy storage and conversion technologies, Zn-air batteries (ZABs) have been recognized as a promising global portfolio storage technology due to their unique half-open systems, significant theoretical energy density (1086 Wh kg −1 , including oxygen), much flatter operating voltage (1.66 V), environmental benignity, and good safety. [3,5] However, the sluggish kinetics of oxygen evolution reaction (OER) for charging and oxygen reduction reaction (ORR)

The proposed powder exfoliated monolayer-rich MoS2 electrode exhibits remarkable specific capacities and stable cyclic performance.

No abstract

No abstract

The 1T-phase MoS2 has gained widespread attention because of its superhigh electronic conductivity. However, the comparatively complicated preparation and low-yielding production may hinder its potential applications in the energy storage field; hence, we developed a facile process to selectively prepare 1T- and 2H-phase MoS2 nanosheets with abundant monolayer structure with a large scale by controlling annealing temperature. With the further liquid phase exfoliation and freeze-drying procedure, the proposed nanosheets could maintain monolayer structure in the powder phase, and the existence of monolayers is believed to improve the electrochemical performance. The electrochemical performances of both the supercapacitor and lithium-ion batteries indicate that those prepared 1T-phase MoS2 nanosheets with abundant monolayer structure exhibit superior cycling stability. Specifically, the proposed 1T-phase MoS2 nanosheets could remain 170.4 F g–1 at 10 A g–1, and a capacity retention of 91% is achieved after 5000 cycles at 1 A g–1 in the symmetrical supercapacitor. It also delivers the excellent stability property of lithium ion insertion and extraction, which still maintain a charge capacity of 598 mAh g–1 after 1000 cycles at 1 A g–1 in the evaluation of lithium-ion batteries. The mechanism suggested that the high conductivity and unique electronic structure of 1T-phase MoS2 nanosheets may contribute to the enhancement of electrochemical properties.