Self-Organized Single-Atom Tungsten Supported on the N-Doped Carbon Matrix for Durable Oxygen Reduction

Bisen, OY and Yadav, AK and Nanda, KK (2020) Self-Organized Single-Atom Tungsten Supported on the N-Doped Carbon Matrix for Durable Oxygen Reduction. In: ACS Applied Materials and Interfaces, 12 (39). pp. 43586-43595.

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Abstract

Rational engineering of atomically scaled metal-nitrogen-carbon (M-N-C) moieties has been the topic of recent research interest because of their potential application as an electrochemical oxygen reduction reaction (ORR) catalyst. Despite numerous efforts on M-N-Cs, attaining both adequate activity and a satisfactory stability simultaneously is a principal issue. Herein, we demonstrated the synthesis of a single-atom tungsten catalyst supported on the N-doped carbon matrix (W-N-C) and its application as an ORR catalyst. W-N-C was synthesized using the economically viable, simple, one-step pyrolysis of dicyandiamide and tungsten(VI) chloride at moderate temperature (700 °C). The synthesis of W-N-C avoids any post acid treatment as it does not require any subsidiary sacrificial metal like Zn and, hence, does not induce any burden associated with chemical waste management. The atomic dispersion of W atoms stabilized by N-doped porous carbon and the formation of WN2C2 were confirmed by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy. Interestingly, as-synthesized WN2C2 exhibited unprecedented electrocatalytic activity with a half-wave potential of 764 mV vs reversible hydrogen electrode (RHE) as well as significantly enhanced stability (retaining >99% diffusion-limited current density and the loss in activity is 10.5% at 0.84 V after 10,000 potential cycles), which is much better than the stability limit set by the US Department of Energy in an alkaline medium. Overall, the activity of W-N-C surpasses that of Pt/C after 5000 cycles. The excellent stability is believed to be due to the symmetric coordination of the metal active site (W2N2C2).

Item Type:	Journal Article
Publication:	ACS Applied Materials and Interfaces
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Alkalinity; Atoms; Carbon; Catalysts; Chlorine compounds; Doping (additives); Electrolytic reduction; High resolution transmission electron microscopy; Oxygen; Oxygen reduction reaction; Platinum compounds; Porous materials; Scanning electron microscopy; Stability; Waste treatment; X ray absorption spectroscopy, Diffusion-limited current; Economically viable; Electrocatalytic activity; Electrochemical oxygen reduction; High-angle annular dark fields; Moderate temperature; Reversible hydrogen electrodes; US Department of Energy, Tungsten compounds
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	13 Feb 2023 10:32
Last Modified:	13 Feb 2023 10:32
URI:	https://eprints.iisc.ac.in/id/eprint/80217

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