Unique activity of a Keggin POM for efficient heterogeneous electrocatalytic OER

Chandani Singh; Dan Meyerstein; Zorik Shamish; Dror Shamir; Ariela Burg

doi:10.1016/j.isci.2024.109551

Unique activity of a Keggin POM for efficient heterogeneous electrocatalytic OER

iScience. 2024 Mar 22;27(4):109551. doi: 10.1016/j.isci.2024.109551. eCollection 2024 Apr 19.

Authors

Chandani Singh^{1

2}, Dan Meyerstein^{2

3}, Zorik Shamish⁴, Dror Shamir⁴, Ariela Burg¹

Affiliations

¹ Department of Chemical Engineering, Sami Shamoon College of Engineering, Beer-Sheva, Israel.
² Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
³ Chemical Sciences Department, Ariel University, Ariel, Israel.
⁴ Analytical Chemistry Department, Nuclear Research Center Negev, Beer-Sheva, Israel.

Abstract

Polyoxometalates (POMs) have been well studied and explored in electro/photochemical water oxidation catalysis for over a decade. The high solubility of POMs in water has limited its use in homogeneous conditions. Over the last decade, different approaches have been used for the heterogenization of POMs to exploit their catalytic properties. This study focused on a Keggin POM, K₆[CoW₁₂O₄₀], which was entrapped in a sol-gel matrix for heterogeneous electrochemical water oxidation. Its entrapment in the sol-gel matrix enables it to catalyze the oxygen evolution reaction at acidic pH, pH 2.0. Heterogenization of POMs using the sol-gel method aids in POM's recyclability and structural stability under electrochemical conditions. The prepared sol-gel electrode is robust and stable. It achieved electrochemical water oxidation at a current density of 2 mA/cm² at a low overpotential of 300 mV with a high turnover frequency (TOF) of 1.76 [mol O₂ (mol Co)^-1s^-1]. A plausible mechanism of the electrocatalytic process is presented.

Keywords: catalysis; energy materials; materials chemistry.