Promoted oxygen reduction kinetics on nitrogen-doped hierarchically porous carbon by engineering proton-feeding centers. Issue 9 (20th July 2020)

• Record Type: Journal Article
• Authors: Chen, Guangbo; Wang, Tao; Liu, Pan; Liao, Zhongquan; Zhong, Haixia; Wang, Gang; Zhang, Panpan; Yu, Minghao; Zschech, Ehrenfried; Chen, Mingwei; Zhang, Jian; Feng, Xinliang
• Is Part Of: Energy & environmental science. Volume 13:Issue 9(2020)
• Page Start: 2849
• Page End: 2855
• Publication Date: 2020-07-20
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/d0ee01613f
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : We demonstrate the important role of the water dissociation process in proton-feeding and enhancing ORR kinetics under an alkaline environment. Abstract : Electrocatalytic oxygen reduction reaction (ORR) is the vital process for next-generation electrochemical energy storage and conversion technologies, e.g., metal–air batteries and fuel cells. During the ORR, the O2 * and O* intermediates principally combine with protons to form OOH* and OH* species, respectively, which are the proton-coupled electron transfer processes. Unfortunately, under alkaline conditions, the protons are essentially generated from the sluggish water dissociation process, which unavoidably limits the ORR kinetics. Herein, we design and synthesize a nitrogen-doped hierarchically porous carbon with homogeneously distributed ultrafine α-MoC nanoparticles (α-MoC/NHPC) as a model electrocatalyst. Theoretical investigations unveil that α-MoC on NHPC could efficiently reduce the energy barrier of the water dissociation process to generate protons, eventually promoting the proton-coupled ORR kinetics. In a 0.1 M KOH aqueous solution, α-MoC/NHPC exhibits excellent ORR performance with a high half-wave potential of 0.88 V ( vs. reversible hydrogen electrode), which outperforms those for NHPC and commercial Pt/C. Moreover, as the air electrode in a zinc-air battery, α-MoC/NHPC presents a large peak power density of 200.3 mW cm −2 and long-term stability. Thereby, our approach to engineering proton-feeding centers paves a new avenue towards the understanding of ORR kinetics and the development of high-performance ORR electrocatalysts.