Multiple heteroatom-doped few-layer carbons for the electrochemical oxygen reduction reaction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 6; no. 44; pp. 22277 - 22286
• Main Authors: Huang, Baobing, Liu, Yuchuan, Huang, Xing, Xie, Zailai
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Carbon; Carbonization; Catalysis; Catalysts; Chemical reduction; Chemical vapor deposition; Direct conversion; Doping; Electrochemistry; Graphene; Guanine; Organic chemistry; Oxygen; Oxygen reduction reactions; Polymerization; Sulfuric acid; Surface activity
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C8TA06743K

Heteroatom-doped two-dimensional (2D) carbon materials have been recognized as promising metal-free catalysts for the oxygen reduction reaction (ORR) due to their impressive surface activity. Such materials are often achieved by conventional chemical vapour deposition (CVD) growth followed by post-treatment of heteroatom-doping or obtained by template-guided polymerization and carbonization of organic substances. In this contribution, we report a new strategy that allows a direct conversion of three-dimensional (3D) aggregates of guanine into naturally N/O-doped ultrathin few-layer carbon nanosheets without the use of any template or guiding agent. Moreover, by pre-ionizing guanine with H 2 SO 4 /H 3 PO 4 , a group of multiple heteroatom-doped (N/O/S, N/O/P, and N/O/S/P) 2D carbons can also be readily realized. Considering the low cost of precursors and the simplicity of the synthetic procedure, large-scale production of such heteroatom-doped 2D carbons is potentially available. The best catalytic performance is obtained from the N/O/S/P-doped carbons which show a half-wave potential ( E 1/2 ) of 0.84 V vs. RHE and a diffusion-limited current density ( j L ) of 5.40 mA cm −2 in 0.1 M KOH, better than those of most graphene-based catalysts and even the commercial Pt/C catalyst. Systematic studies indicate that the observed superior ORR performance arises from a combined effect of the multiple heteroatom-doping, high surface area and abundant structural defects of the electrocatalyst.