Tridoped Reduced Graphene Oxide as a Metal‐Free Catalyst for Oxygen Reduction Reaction Demonstrated in Acidic and Alkaline Polymer Electrolyte Fuel Cells

Abstract

Recently, it has been demonstrated that doping of graphene by elements such as N, S, or F creates active sites for the oxygen reduction reaction (ORR). This results from bond polarization caused by the difference in electronegativity between heteroatom dopants and carbon, and/or the presence of defects within the graphene lattice. In this work, fluorine, nitrogen, and sulfur tridoped reduced graphene oxide (F,N,S‐rGO) is designed to combine these catalytically active sites. F,N,S‐rGO can be inexpensively synthesized by a facile and scalable route involving pyrolysis at 600 °C of sulfur‐doped rGO in the presence of Nafion and dimethyl formamide (DMF). The pyrolysis of Nafion and DMF provides F• and N• radicals which serve as doping agents. Rotating disk electrode investigations reveal the ORR catalytic activities of F,N,S‐rGO in both acidic and alkaline media, which are consistent with the real performances of the respective polymer electrolyte fuel cells (PEFCs). Maximum power densities of 14 and 46 mW cm−2 are obtained for the acidic and alkaline PEFCs, respectively, using F,N,S‐rGO as ORR catalysts. To the best of knowledge, this is the first report on the synthesis of F,N,S tridoped rGO and on its ORR activity in both acidic and alkaline PEFCs.

Defect and Doping Co-Engineered Non-Metal Nanocarbon ORR Electrocatalyst

“…As reported, the ORR performance of the carbon-based materials can be further improved by dual- and multi-doping of heteroatoms (e.g., N/B; N/S; N/P; O/N, P/O, N/S, B/S/N, and P/N/S) due to their synergistic effects [ 123 – 126 ]. In a similar way, the combination of various defects with dual- and multi-heteroatom doping also provides powerful means for the possible of maximum enhancement of various electrocatalytic performances for carbon nanomaterials.…”

Transition-Metal- and Nitrogen-Doped Carbide-Derived Carbon/Carbon Nanotube Composites as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells

“… 21 However, pure carbonaceous materials lack the necessary electrocatalytic activity 22 − 25 and, thus, they need to be modified using non-precious metals 26 − 32 or different heteroatoms, such as N, 33 − 36 S, 37 , 38 P, 39 , 40 or their combinations. 41 − 44 Among the possible PGM-free electrocatalysts, transition-metal–nitrogen–carbon (M-N-C) type materials are the most promising, since they have shown very good ORR activity as well as superior stability in the half cell in comparison to the platinum-based materials under alkaline conditions. 21 , 45 …”

Cathode Catalysts Based on Cobalt- and Nitrogen-Doped Nanocarbon Composites for Anion Exchange Membrane Fuel Cells

“…It should also be noted that the AEMs used were different. The usage of different AEMs in the literature makes it difficult to specifically compare the catalyst materials on the basis of the results given because the anion exchange membrane plays a huge role in the AEMFC performance. , When comparing the AEMFC performance observed in this study with the works published by using the same AEM, namely HMT-PMBI, then the results obtained with Co-N-CDC/CNT_mel are superior, even better than that of platinum-based cathode catalyst. ,, The Co-N-CDC/CNT_mel catalyst exhibits a relatively large mesoporous network in addition to the micropores, which is important for the AEMFC application …”

“…12,33 When comparing the AEMFC performance observed in this study with the works published by using the same AEM, namely HMT-PMBI, then the results obtained with Co-N-CDC/CNT_mel are superior, even better than that of platinum-based cathode catalyst. 45,67,68 The Co-N-CDC/CNT_mel catalyst exhibits a relatively large mesoporous network in addition to the micropores, which is important for the AEMFC application. 40 The HMT-PMBI membrane was selected for this study thanks to the exceptional ex situ and in situ properties of this AEM, including good mechanical strength, good stability, and high ionic conductivity.…”