Bottom-up synthesis of MOF-derived hollow N-doped carbon materials for enhanced ORR performance. (May 2019)

• Record Type: Journal Article
• Authors: Chai, Lulu; Zhang, Linjie; Wang, Xian; Xu, Leqiong; Han, Cheng; Li, Ting-Ting; Hu, Yue; Qian, Jinjie; Huang, Shaoming
• Is Part Of: Carbon. Volume 146(2019)
• Page Start: 248
• Page End: 256
• Publication Date: 2019-05
• Subjects: Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2019.02.006
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: The search on low-cost, ultra-stable, and high-performance non-novel metal replacements to the Pt-based catalysts for oxygen reduction reaction (ORR) is of great urgency. Herein, a bottom-up method has been proposed to synthesize unique hollow N-doped carbon spheres (HNCSs) from an initial amorphous coordination polymer (CP) template-assisted route for the first time. HNCSs exhibit competitively comparable high electrocatalytic ORR activity, excellent reaction selectivity, and stronger long-term stability and negligible methanol crossover effect compared to the commercial Pt/C under the alkaline medium. Together with the other two reported carbonaceous ORR catalysts, including SCSs and NGPCs, our HNCSs possess the lowest Tafel slope of 65.7 mV dec −1 which is close to Pt/C (62.6 mV dec −1 ), and show much enhanced ORR activity (JL = 5.34 mA cm −2 ) and stability (Retention = 96.5%, Time = 10 h). This CP-templated route for hollow carbon materials will shed light on a new synthetic strategy to prepare high-performance carbon-based and/or metal-free ORR catalysts. Graphical abstract: Herein, using the initial precursors of Zn-BTC microspheres, we have synthesized the core-shell ZnO@ZIF-8 micro-particles, which can be employed as self-sacrifice templates to fabricate hollow N-doped carbon microspheres (HNCSs), whose unique hollow architecture and mesopores can facilitate rapid diffusion and easy access of electrolytes and gas molecules, whereas the micropores can provide large pore volumes and high surface areas to create abundant active sites for catalytic activity enhancement. The HNCSs pyrolyzed at 1000 °C display an earlier Eonset of 0.92 V, a higher half-wave potential of 0.82 V ( vs . RHE), and a larger current density of 5.34 mA cm −2 than those of NGPCs (0.83 V, 0.64 V, 3.29 mA cm −2 ) and SCSs (0.85 V, 0.72 V, 3.99 mA cm −2 ) at 0.6 V, which are close to the corresponding values of 20% Pt/C (0.97 V, 0.83 V, and 5.30 mA cm −2 ). To the best of our knowledge, the impressive performances of HNCSs in terms of onset potential, half-wave potential, and limited current density have rarely been achieved in the previously reported MOF-derived carbon materials. Image 1