Electrodeposition of High-Surface-Area IrO2 Films on Ti Felt as an Efficient Catalyst for the Oxygen Evolution Reaction

Yu Jin Park,Jung Woo Lee,Juchan Yang,Yoo Sei Park,Jooyoung Lee,Myeong Je Jang,Jaehoon Jeong,Sung Mook Choi,Jung-Dae Kwon,Seunghoe Choe

doi:10.3389/fchem.2020.593272

Yu Jin Park, Jung Woo Lee + Show 8 more

Open Access

https://doi.org/10.3389/fchem.2020.593272

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Abstract

Under acidic conditions, IrO2 exhibits high catalytic activity with respect to the oxygen evolution reaction (OER). However, the practical application of Ir-based catalysts is significantly limited owing to their high cost in addition to the scarcity of the metal. Therefore, it is necessary to improve the efficiency of the utilization of such catalysts. In this study, IrO2-coated Ti felt (IrO2/Ti) electrodes were prepared as high-efficiency catalysts for the OER under acidic conditions. By controlling the surface roughness of the Ti substrate via wet etching, the optimum Ti substrate surface area for application in the IrO2/Ti electrode was determined. Additionally, the IrO2 film that was electrodeposited on the 30 min etched Ti felt had a large surface area and a uniform morphology. Furthermore, there were no micro-cracks and the electrode obtained (IrO2/Ti-30) exhibited superior catalytic performance with respect to the OER, with a mass activity of 362.3 A at a potential of 2.0 V (vs. RHE) despite the low Ir loading (0.2 mg cm−2). Therefore, this proposed strategy for the development of IrO2/Ti electrodes with substrate surface control via wet etching has potential for application in the improvement of the efficiency of catalyst utilization with respect to the OER.

Highlights

Hydrogen, which is a pollution-free energy resource with the convenience of long-term storage in small and large quantities without significant loss, has a number of distinct advantages as an alternative to fossil fuels (Bensaid et al, 2012; Nam et al, 2019)
To increase the surface area of the Ti felt before the electrodeposition, its surface roughness was increased via wet etching
After etching for 30 min, there was an increase in its surface roughness, and the amorphous IrO2 layer was uniformly deposited

Summary

Introduction

Hydrogen, which is a pollution-free energy resource with the convenience of long-term storage in small and large quantities without significant loss, has a number of distinct advantages as an alternative to fossil fuels (Bensaid et al, 2012; Nam et al, 2019). As a promising hydrogen production strategy, water electrolysis has emerged as a sustainable and eco-friendly technology (Brillet et al, 2012; Park et al, 2019b) Despite these benefits, one key reason it has not been utilized in practical applications is the slow associated rate of the oxygen evolution reaction (OER) (Zhou et al, 2020). The OER involves four electron-proton coupled reactions, and requires the use of a relatively higher amount of energy (higher overpotential) compared to the hydrogen evolution reaction (HER), which is a typical two electron-transfer reaction (Suen et al, 2017; Jang et al, 2020).

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