Bifunctional Transition Metal Hydroxysulfides: Room‐Temperature Sulfurization and Their Applications in Zn–Air Batteries

• Published in: Advanced materials (Weinheim) Vol. 29; no. 35
• Main Authors: Wang, Hao‐Fan, Tang, Cheng, Wang, Bin, Li, Bo‐Quan, Zhang, Qiang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-09-2017
• Subjects: bifunctional air cathodes; CoFe hydroxysulfides; Electrical resistivity; Electrocatalysis; Electrocatalysts; Electrodes; Electronic structure; Hydrogen storage; Hydroxides; Iridium; layered double hydroxides; Materials science; Metal air batteries; oxygen evolution reaction; oxygen reduction reaction; Platinum; Rechargeable batteries; Room temperature; Sulfurization; Zinc-oxygen batteries; Zn–air batteries; oxygen evolution reaction; layered double hydroxides; CoFe hydroxysulfides; bifunctional air cathodes; oxygen reduction reaction; Zn-air batteries
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201702327

Bifunctional electrocatalysis for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) constitutes the bottleneck of various sustainable energy devices and systems like rechargeable metal–air batteries. Emerging catalyst materials are strongly requested toward superior electrocatalytic activities and practical applications. In this study, transition metal hydroxysulfides are presented as bifunctional OER/ORR electrocatalysts for Zn–air batteries. By simply immersing Co‐based hydroxide precursor into solution with high‐concentration S2−, transition metal hydroxides convert to hydroxysulfides with excellent morphology preservation at room temperature. The as‐obtained Co‐based metal hydroxysulfides are with high intrinsic reactivity and electrical conductivity. The electron structure of the active sites is adjusted by anion modulation. The potential for 10 mA cm−2 OER current density is 1.588 V versus reversible hydrogen electrode (RHE), and the ORR half‐wave potential is 0.721 V versus RHE, with a potential gap of 0.867 V for bifunctional oxygen electrocatalysis. The Co3FeS1.5(OH)6 hydroxysulfides are employed in the air electrode for a rechargeable Zn–air battery with a small overpotential of 0.86 V at 20.0 mA cm−2, a high specific capacity of 898 mAh g−1, and a long cycling life, which is much better than Pt and Ir‐based electrocatalyst in Zn–air batteries.
Transition metal hydroxysulfides are proposed as bifunctional electrocatalysts in working Zn–air batteries with high oxygen evolution reaction/oxygen reduction reaction reactivities, high power densities, large capacities, and extraordinary stabilities. These transition metal hydroxysulfides are fabricated through a novel room‐temperature sulfurization strategy, which opens new doors to materials innovation of transition metal (hydro/oxy)sulfides and their practical applications in hetero/electrocatalysis, energy storage, and healthcare applications.