A Br-regulated transition metal active-site anchoring and exposure strategy in biomass-derived carbon nanosheets for obtaining robust ORR/HER electrocatalysts at all pH values. Issue 47 (22nd November 2019)

• Record Type: Journal Article
• Authors: Lv, Xuehui; Chen, Yanli; Wu, Yanling; Wang, Haoyuan; Wang, Xinlong; Wei, Chuangyu; Xiao, Zuoxu; Yang, Guangwu; Jiang, Jianzhuang
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 47(2019)
• Page Start: 27089
• Page End: 27098
• Publication Date: 2019-11-22
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9ta10880g
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : An outstanding pH-universal bifunctional electrocatalyst is developed using a novel TMAAE strategy with departure of Br-species attached to the Co–N4 macrocycle. Abstract : A novel Br-regulated "Transition Metal Active-site Anchoring and Exposure" (TMAAE) strategy is reported, for the first time, to fabricate a hierarchical porous Co/N-doped bio-carbon bifunctional electrocatalyst (CoTBrPP@bio-C) for an all-pH ORR and HER by using a simple one-pot co-pyrolysis over a mushroom (MR) template with adsorbed Br-substituted porphyrinato cobalt (CoTBrPP). Introduction of CoTBrPP onto the MR template not only leads to a larger specific area of 604 m 2 g −1 in CoTBrPP@bio-C relative to that of CoTPP@bio-C (CoTPP = Br-free CoTBrPP), 98 m 2 g −1, but more importantly also regulates the oriented distribution of pores precisely which promotes effective exposure of multiple active sites depending on the departure of Br-species attached to the Co–N4 macrocycle periphery. Impressively, CoTBrPP@bio-C with a Co loading down to 0.77 at% exhibits higher all-pH ORR and HER performance compared to CoTPP@bio-C with a Co loading of 3.5 at%. An efficient TMAAE makes CoTBrPP@bio-C possess higher onset and half-wave potentials of 0.93 and 0.85 V for the ORR, and a smaller Tafel slope of 80 mV dec −1 for the HER in an alkaline medium. CoTBrPP@bio-C also had a superior all-pH long-term stability and outstanding methanol tolerance, surpassing commercial Pt/C and most non-precious-metal catalysts reported to date. Furthermore, Zn–air batteries assembled with CoTBrPP@bio-C exhibited a higher peak power density of 100 mW cm −2 and excellent durability than Pt/C.