(광)전기화학 반응에서의 전극개질에 따른 활성 향상 연구

Abstract

Hypochlorous acid (HOCl), formed through the chlorine evolution reaction (ClER) in a chlor-alkali plant, is a high-value product essential for various chemical industries such as wastewater treatment and disinfection. Over the past 40 years, dimensionally stable anodes (DSA) electrodes, composed of precious metal oxides, have been used as efficient electrocatalysts for the chlorine evolution reaction. However, there has been a demand for the development of cost-effective catalysts for ClER. Antimony-doped tin oxide (ATO) has been studied as an electrode material for ClER. The excess electrons from Sb5+ play the role of charge carriers, enhancing electrical conductivity without any distortion. Additionally, it effectively suppresses the oxygen evolution reaction. In this study, the optimal doping ratio of Sb with minimal content of interlayer IrTaOx was investigated to achieve high selectivity for HOCl. In the case of the 3-layered 5% ATO/IrTaOx/Ti, a Faradaic efficiency of 94.4% was observed. This corresponds to an approximately 17.1% improvement compared to the IrTaOx/Ti electrode without the ATO catalyst.|Bismuth vanadate (BiVO4) has emerged as a highly promising photoanode for water splitting reaction due to its suitable band gap (~2.4 eV), valence band position for water oxidation, and cost-effectiveness. The preparation of a BiVO4 photoanode typically involves a thermochemical process following the electrodeposition of BiOI. As-prepared BiVO4 has a high surface area and nanoporous morphology, but the structural characteristics and photoelectrochemical performance can vary depending on the conditions employed during the BiOI electrodeposition. When BiOI was deposited using potentiostatic stimuli (-0.1 V vs. Ag/AgCl) or galvanostatic stimuli (-1 mA cm-2), the nucleation and growth rates of BiOI on FTO were changed according to the controlled parameters. These differences in nucleation and growth rates influence various factors, including particle size, uniformity, and exposed crystal facets. Consequently, these variances affect the structural characteristics in the resulting BiVO4, impacting its performance in photoelectrochemical sulfite oxidation. In particular, the photocurrent density of BiVO4 prepared under potentiostatic conditions reaches approximately 3.5 mA cm-2 at 1.1 V vs. RHE for sulfite oxidation. This performance exceeds that of BiVO4 prepared under galvanostatic conditions by nearly 24.5%.