Equivalent conversion of metal-free and metal-based (Co1-xS/Co9S8 nanohybrid) catalysts: Easy construction of a "highway" shaped porous carbon material as a dual-functional electrocatalyst for high-performance Zn-air batteries

• Key Words:N-DOPED GRAPHENE; OXYGEN REDUCTION; EFFICIENT ELECTROCATALYSTS; FACILE PREPARATION; NITROGEN; CO; SULFUR; EXFOLIATION; NANOSHEETS; FRAMEWORK
• Abstract:Metal-free and metal-based electrocatalysts are designed according to different principles, but there should be an intimate connection between them. In this work, a simple yet cost-effective strategy is proposed to etch and disperse graphene oxide (GO) and porous hollow carbon shell loaded with CoS2 (PHCS-CoS2) into a porous skeleton similar to "highway" to effectively "trap" graphene oxide quantum dots (GOQDs) via a one-step process. Due to interconnected networks and size effects, N-S codoped porous graphene carbon sheets along with GOQDs (N,S-PGCS(QDs)) have eminent properties for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, the metal-free system can be transformed to a metal-based electrocatalyst (N,S-PGCS(QDs)-Co1-xS/Co9S8) loaded with Co1-xS/Co9S8 nanohybrids, which demonstrates superior electrocatalytic characteristics than Pt/C + RuO2 in terms of half-wave potential (0.85 V), current density, methanol tolerance, the potential difference between E-ORR1/2 and EOER10 (0.68 V), and long-term stability. The Zn-air battery assembled with N,S-PGCS(QDs)-Co1-xS/Co9S8 shows a large peak power density of 168.2 mW cm(-2), a capacity performance up to 817.9 mAh g(-1), an ultra-high specific energy density of 973.3 Wh kg(Zn)(-1) and considerable durability. The findings above may provide a scalable synthetic guidance and a novel direction for the design of metal-free and metal-based electrocatalysts. (C) 2021 Elsevier Ltd. All rights reserved.
• Volume:388
• Issue:
• Translation or Not:no