New synthesis routes to tailor graphene properties by controlling the concentration and chemical configuration of dopants show great promise. Herein we report the direct reproducible synthesis of 2-3% nitrogen-doped 'few-layer' graphene from a solid state nitrogen carbide a-C:N source synthesized by femtosecond pulsed laser ablation. Analytical investigations, including synchrotron facilities, made it possible to identify the configuration and chemistry of the nitrogen-doped graphene films. Auger mapping successfully quantified the 2D distribution of the number of graphene layers over the surface, and hence offers a new original way to probe the architecture of graphene sheets. The films mainly consist in a Bernal ABA stacking three-layer architecture, with a layer number distribution ranging from 2 to 6. Nitrogen doping affects the charge carrier distribution but has no significant effects on the number of lattice defects or disorders, compared to undoped graphene synthetized in similar conditions. Pyridinic, quaternary and pyrrolic nitrogen are the dominant chemical configurations, pyridinic N being preponderant at the scale of the film architecture. This work opens highly promising perspectives for the development of self-organized nitrogen-doped graphene materials, as synthetized from solid carbon nitride, with various functionalities, and for the characterization of 2D materials using a significant new methodology.
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http://dx.doi.org/10.1038/s41598-018-21639-9 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, Barcelona 08028, Spain.
The oxygen reduction reaction (ORR) stands as a pivotal process in electrochemistry, finding applications in various energy conversion technologies such as fuel cells, metal-air batteries, and chlor-alkali electrolyzers. Hereby, a comprehensive density functional theory (DFT) investigation is presented into the proposed conventional and unconventional ORR mechanisms using single-atom catalysts (SACs) supported on nitrogen-doped graphene (NG) as model systems. Several reaction intermediates have been identified that appear to be more stable than the ones postulated in the conventional mechanism, which follows the *OOH, *O, and *OH intermediates.
View Article and Find Full Text PDFSmall
January 2025
College of Material Science and Engineering, Hunan University, Changsha, Hunan, 410082, China.
Single-atom catalysts (SACs) with high activity and efficient atom utilization for oxygen reduction reactions (ORRs) are imperative for rechargeable Zinc-air batteries (ZABs). However, it is still a prominent challenge to construct a noble-metal-free SAC with low cost but high efficiency. Herein, a novel nitrogen-doped graphene (NrGO) based SAC, immobilized with atomically dispersed single cobalt (Co) atoms (Co-NrGO-SAC), is reported for ORRs.
View Article and Find Full Text PDFLangmuir
January 2025
Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
The mechanisms of NO reduction by CO over nitrogen-doped graphene (N-graphene)-supported single-atom Ni catalysts in the presence of O, HO, CO, and SO have been studied via density functional theory (DFT) modeling. The catalyst is represented by a single Ni atom bonded to four N atoms on N-graphene. Several alternative reaction pathways, including adsorption of NO on the Ni site, direct reduction of NO by CO, decomposition of NO to NO followed by reduction of NO to N, formation of active oxygen radical O*, and reduction of O* by CO, were hypothesized and the energy barrier corresponding to each of the reaction steps was calculated using DFT.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China.
Single-atom catalysts (SACs) have attracted widespread attention due to their potential to replace platinum-based catalysts in achieving efficient oxygen reduction reaction (ORR), yet the rational optimization of SACs remains challenging due to their elusive reaction mechanisms. Herein, by employing ab initio molecular dynamics simulations and a thermodynamic integration method, we have constructed the potential-dependent free energetics of ORR on a single iron atom catalyst dispersed on nitrogen-doped graphene (Fe-N/C) and further integrated these parameters into a microkinetic model. We demonstrate that the rate-determining step (RDS) of the ORR on SACs is potential-dependent rather than invariant within the operative potential range.
View Article and Find Full Text PDFTalanta
January 2025
School of Agricultural Engineering, Key Laboratory of Modern Agricultural Equipment and Technology, Ministry of Education, Jiangsu University, Zhenjiang, Jiangsu, 212013, China; College of Agricultural Equipment Engineering, Henan University of Science and Technology, Luoyang, Henan, 471003, China. Electronic address:
Searching for new alternative to tripropylamine (TPrA) with low toxicity and high chemical stability for the tris(4,4'-dicarboxylic acid-2,2'-bipyridyl)ruthenium (II) (Ru(dcbpy)) based coreactant electrochemiluminescence (ECL) system is essential for widespread analytical applications. Here, nitrogen-doped graphene quantum dots (NGQDs) have been discovered to significantly amplify the ECL emission and increase the ECL efficiency of Ru(dcbpy) for the first time. However, the mechanism by which NGQDs act as coreactants is not well comprehended.
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