Hollow structured Zn0.76Co0.24S–Co9S8 composite with two-phase synergistic effect as bifunctional catalysts. (15th February 2022)

• Record Type: Journal Article
• Authors: Yang, Pengzhan; Kong, Fanrong; Sui, Xulei; Zhao, Lei; Qiu, Yue; Zhang, Hongda; Wang, Zhenbo
• Is Part Of: International journal of hydrogen energy. Volume 47:Number 14(2022)
• Page Start: 8811
• Page End: 8819
• Publication Date: 2022-02-15
• Subjects: Non-precious metal catalysts -- Bifunctional catalysts -- Synergistic interaction -- Oxygen evolution reaction -- Oxygen reduction reaction; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.12.238
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: It is of great significance to develop efficient and inexpensive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalysts for the current energy crisis. But this is still a long-term and formidable challenge. In this work, a two-phase synergistic effect between transition metal sulfides is applied in the design of ORR/OER bifunctional catalysts. Co-based zeolite imidazolate framework (MOF) is used as a precursor to prepare the hollow Co9 S8 through vulcanization and heat treatment. At the same time, the phase transformation occurs to form some Zn0.76 Co0.24 S on surface during the heat treatment due to the Zn-polydopamine coating. The hollow structure Zn0.76 Co0.24 S–Co9 S8 composite has been verified and promotes the diffusion of reactants and products, and the interaction between two phases greatly promotes the catalytic reactions. The coating of Zn-polydopamine forms uniform carbon layer on surface, enhancing the conductivity of Zn0.76 Co0.24 S–Co9 S8 composite. The Zn0.76 Co0.24 S–Co9 S8 composite shows much better performance of ORR and OER compared to any of them. The overpotential of OER at a current density of 10 mA/cm 2 is 330 mV, and the half-wave potential of ORR is 0.83 V. Additionally, the Zn0.76 Co0.24 S–Co9 S8 composite displays better cyclic stability. The synergistic effect of Zn0.76 Co0.24 S and Co9 S8 can be considered as the foremost factor for the improvement of catalyst performance, which provides new possibilities for the development of non-precious metal bifunctional catalysts. Graphical abstract: Image 1 Highlights: Hollow Zn0.76 Co0.24 S–Co9 S8 composite with carbon coating as bifunctional catalyst. The uniform carbon coating derived from Zn-polydopamine enhances the conductivity. The unique hollow structure provides abundant active sites and promotes the diffusion. The two-phase synergistic effect greatly enhances the ORR and OER performance.