Tunable Metal-Free Imidazole-Benzimidazole Electrocatalysts for Oxygen Reduction in Aqueous Solutions
Author
Tanjedrew N. Thammanatpong K. Surawatanawong P. Chakthranont P. Chantarojsiri T. Unjarern T. Kiatisevi S.
Affiliations
Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC) Faculty of Science Mahidol University Bangkok 10400 Thailand; National Nanotechnology Center (NANOTEC) National Science and Technology Development Agency (NSTDA) 111 Thailand Science Park Pathum Thani 12120 Thailand
Type
Article
Source Title
Chemistry - A European Journal
ISSN
9476539
Year
2024
Volume
30
Issue
5
Open Access
All Open Access Hybrid Gold
Publisher
John Wiley and Sons Inc
DOI
10.1002/chem.202302854
Abstract
A series of metal-free imidazole-benzimidazole catalysts (ImBenz-H ImBenz-NO2 ImBenz-OCH3) for oxygen reduction reaction (ORR) were prepared. We demonstrate that the electrocatalytic O2 reduction by ImBenz-NO2 with the electron-withdrawing group showed high selectivity toward H2O with the number of electrons transferred (n=3.7) in a neutral aqueous solution. The highest ORR selectivity toward H2O2 was achieved using ImBenz-H (n=2.4) in an alkaline solution. Electrochemical studies of reaction kinetics disclosed that the highest turnover frequencies were obtained from ImBenz-H in both neutral and alkaline aqueous solutions. The results prove that the ORR selectivity is tunable by modulating the substituent of the ImBenz catalysts. Furthermore DFT calculations suggested that the ORR mechanism of ImBenz-H involves the electron transfer from imidazole-benzimidazole to O2 resulting in the formation of H2O2 which supports the redox active properties of the catalysts ImBenz. ? 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.
