Crystallization behavior-dependent electrocatalytic activity and stability of Ti/IrO2[sbnd]RuO2[sbnd]SiO2 anodes for oxygen evolution reaction

Abstract

IrO2RuO2SiO2 ternary oxide coatings were fabricated on Ti substrate using a sol-gel route. The impacts of calcination conditions (e.g., temperature and time) on the electrocatalytic activity and stability of the anodes were explored. It was found that the calcination temperature and time significantly impact the electrocatalytic properties of the anode for the oxygen evolution reaction (OER). This can result from the properties of the surface (e.g., defects, crystallinity and crystallite size) as well as the preferred orientation of the active components. The amount of the defects of the coatings decreases with the increase of the calcination temperature and time. Besides, the crystallinity and crystallite size increase with the increase of calcination temperature and time. The amorphous oxide coating can be observed from the sample calcined at 350 °C for 15 min, while this coating can be crystallized when the calcination time is 60 min. The coatings calcined in the temperature range between 350 and 450 °C show preferred (101) planes of IrO2 and RuO2 crystallites, whereas the coatings calcined at the temperatures higher than 450 °C show the (211) orientation. The increase of calcination time does not change the preferred orientation of IrO2 and RuO2. The calculated voltammetric charges suggest that the active surface area of the prepared coating is dominated by the “outer” active surface area over the entire calcination temperature and time ranges. Given the electrocatalytic activity and stability of all investigated anodes, the anode calcined at 450 °C for 15 min is considered the most suitable for applications.