AUTHOR=Liu Xuan , Tian Qianhong , Li Yvpei , Zhou Zixiang , Wang Jinlian , Liu Shuling , Wang Chao 

TITLE=Electron transfer dynamics and electrocatalytic oxygen evolution activities of the Co3O4 nanoparticles attached to indium tin oxide by self-assembled monolayers

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.919192

DOI=10.3389/fchem.2022.919192

ISSN=2296-2646

ABSTRACT=<p>The Co<sub>3</sub>O<sub>4</sub> nanoparticle-modified indium tin oxide-coated glass slide (ITO) electrodes are successfully prepared using dicarboxylic acid as the self-assembled monolayer through a surface esterification reaction. The ITO-SAM-Co<sub>3</sub>O<sub>4</sub> (SAM = dicarboxylic acid) are active to electrochemically catalyze oxygen evolution reaction (OER) in acid. The most active assembly, with Co loading at 3.31 × 10<sup>−8</sup> mol cm<sup>−2</sup>, exhibits 374 mV onset overpotential and 497 mV overpotential to reach 1 mA cm<sup>−2</sup> OER current in 0.1 M HClO<sub>4</sub>. The electron transfer rate constant (<italic>k</italic>) is acquired using Laviron’s approach, and the results show that <italic>k</italic> is not affected by the carbon chain lengths of the SAM (up to 18 -CH<sub>2</sub> groups) and that an increase in the average diameter of Co<sub>3</sub>O<sub>4</sub> nanoparticles enhances the <italic>k</italic>. In addition, shorter carbon chains and smaller Co<sub>3</sub>O<sub>4</sub> nanoparticles can increase the turn-over frequency (TOF) of Co sites toward OER. The Co<sub>3</sub>O<sub>4</sub> nanoparticles tethered to the ITO surface show both a higher number of electrochemically active Co sites and a higher TOF of OER than the Co<sub>3</sub>O<sub>4</sub> nanoparticles bound to ITO using Nafion.</p>