Synthesis of Three‐Dimensional Nitrogen and Sulfur Dual‐Doped Graphene Aerogels as an Efficient Metal‐Free Electrocatalyst for the Oxygen Reduction Reaction

Abstract

Three‐dimensional (3D) nitrogen and sulfur dual‐doped graphene aerogels (NSGAs) are successfully synthesized by using a rational hydrothermal self‐assembly process with ammonia and sulfur powder as nitrogen and sulfur sources, respectively. Structural characterization, including TEM, HAADF‐STEM, SEM, and XPS indicated that the NSGA catalyst exhibits an interconnected macroporous framework of graphene sheets and tunable contents of N and S. The as‐prepared NSGAs show an excellent electrocatalytic activity for the oxygen reduction reaction, including a highly positive onset potential, high kinetic limiting current density, and fuel tolerance. In particular, the NSGA catalyst reveals a much better long‐term stability than that of Pt/C in alkaline medium.

High-sulfur coal-derived nitrogen, sulfur dual-doped carbon as an economical metal-free electrocatalyst for oxygen reduction reaction

“…5b ) can be resolved into four components: the typical C–C (284.4 eV), C–S (285.0 eV), C–N (286.0 eV), and C–O (288.3 eV). 8,9,28 In a similar way, the high-resolution XPS spectrum of N 1s ( Fig. 5c ) can be resolved into three components: pyridinic-N (398.7 eV), pyrrolic-N (400.1 eV), and graphitic-N (401.9 eV) with their proportion being 36.47%, 34.09%, and 29.44%, respectively.…”

“…Concretely, the surface atomic percentage of C, N, S, and O in NSC800 were determined to be 73.7%, 1.06%, 2.24%, and 23.0%, respectively, demonstrating the successful heteroatom doping of N and S into the carbon framework, which is regarded as one of the contributors to the ORR electrocatalytic activity. 1,3,8,9 Specically, the high-resolution XPS spectrum of C 1s (Fig. 5b) can be resolved into four components: the typical C-C (284.4 eV), C-S (285.0 eV), C-N (286.0 eV), and C-O (288.3 eV).…”

“…In recent years, carbon materials doped with metal-free heteroatoms, such as nitrogen (N), 4,5 phosphorus (P), 6,7 sulfur (S), 8,9 boron (B), 10,11 and uorine (F), 12,13 were demonstrated to be one of the most promising substitutes to carbon-supported noble metal platinum and its alloy electrocatalysts for the ORR in an alkaline solution. Moreover, the carbon materials dual-doped with these heteroatoms displayed a better ORR electrocatalytic activity owing to the synergistic effects of these dopants.…”

“…Moreover, the carbon materials dual-doped with these heteroatoms displayed a better ORR electrocatalytic activity owing to the synergistic effects of these dopants. [6][7][8][9][11][12][13][14][15][16] Nevertheless, the large-scale application of these materials is presently impossible as most heteroatom-containing precursors are toxic and ammable along with their complicated and environmentally unfriendly synthesis routes. Hence, the search for heteroatom-containing precursors in abundant resource and at much low-cost is an important and urgent necessity for the actual application of clean and renewable energy conversion and storage systems.…”

Three-Dimensional Heteroatom-Doped Nanocarbon for Metal-Free Oxygen Reduction Electrocatalysis: A Review

“…3D N, B-doped graphene aerogels (N, B-GAs) prepared via a two-step method involves a hydrothermal reaction and a pyrolysis procedure were also demonstrated to exhibit an outstanding catalytic activity for the ORR [93]. Among the dual-doped 3D graphene materials for ORR catalysts, N, S co-doped 3D graphene is the most popular one and has been widely prepared by various methods including biomass pyrolysis [94], hydrothermal method [95,96], hydrothermal reaction-pyrolysis two-step method [97], and soft template-assisted method [98]. In addition to dual doping, co-doping 3D graphene catalysts with more than two different heteroatoms is also an effective strategy to enhance the ORR performance, as exemplified by N-P-O co-doped 3D graphene [99].…”