Issue 10, 2024

Highly coordinative molecular cobalt–phthalocyanine electrocatalyst on an oxidized single-walled carbon nanotube for efficient hydrogen peroxide production

Abstract

H2O2 production via the two-electron oxygen reduction reaction (2e ORR) offers a potential alternative to the current anthraquinone method owing to its efficiency and environmental friendliness. However, it is necessary to determine the structures of electrocatalysts with cost-effectiveness and high efficiency for future industrialization demand. Herein, a supramolecular catalyst composed of cobalt–phthalocyanine on a near-monodispersed and oxidized single-walled carbon nanotube (CoPc/o-SWCNT) was synthesized via a solution self-assembly method for catalyzing the 2e ORR for H2O2 electrosynthesis. Benefiting from the enhanced intermolecular interaction by introducing oxygen functional groups on o-SWCNTs, the oxidation states of single-atom Co sites were tuned via the formation of two extra Co–O bonds. Coupled with structural characterizations, density-functional theory (DFT) calculations reveal that the depressed d-band center of the Co site regulated by two axially-bridged O atoms gives rise to a suitable binding strength of oxygen intermediates (*OOH) to favor the 2e ORR. Thus, the CoPc-6wt%/o-SWCNT-2 catalyst with optimized synthetic parameters delivers competitive 2e ORR performance for H2O2 electrosynthesis in a neutral electrolyte (pH = 7), including enhanced H2O2 generation, satisfactory molar selectivity of ∼83–95% and long-period stability (75 h) in H-cell measurement. Moreover, it could also be boosted to show a high current of 45 mA cm−2, recorded turnover frequency of 25.3 ± 0.5 s−1 and maximum H2O2 production rate of 5.85 mol g−1 h−1 with a continuous H2O2 accumulation of 1.2 wt% in a flow-cell device, which outperformed most of the reported neutral-selective nonprecious metal single-atom catalysts.

Graphical abstract: Highly coordinative molecular cobalt–phthalocyanine electrocatalyst on an oxidized single-walled carbon nanotube for efficient hydrogen peroxide production

Supplementary files

Article information

Article type
Communication
Submitted
13 Dec 2023
Accepted
04 Mar 2024
First published
05 Mar 2024

Mater. Horiz., 2024,11, 2517-2527

Highly coordinative molecular cobalt–phthalocyanine electrocatalyst on an oxidized single-walled carbon nanotube for efficient hydrogen peroxide production

Y. Li, H. Cheng, M. Wang, J. Xu and L. Guan, Mater. Horiz., 2024, 11, 2517 DOI: 10.1039/D3MH02142D

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