Atomic layer deposited RuO2 with controlled crystallinity and thickness for oxygen evolution reaction catalysis

The effective production of hydrogen as an attractive alternative energy source requires efficient electrocatalysis of the oxygen evolution reaction (OER), the rate-determining step in water splitting. Ruthenium oxide has been investigated as a representative OER catalyst; however, additional research is required for practical applications because of its low stability and varied performance depending on the fabrication method. In this study, RuO2 was prepared via atomic layer deposition (ALD). The crystallinity of the film was controlled by adjusting the ALD growth temperature, and its influence on the OER performance was examined. In addition, ALD cycles were controlled to study the influence of film thickness on the OER performance, allowing for a comparative analysis. The RuO2 film was deposited onto carbon fiber paper (CFP) to enhance its active surface area for the OER. The as-obtained samples were analyzed using various techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the crystalline RuO2 grown at 400 °C performed better catalytic performance than amorphous RuO2 grown at 350 °C, and adjusting the film thickness enhanced the electrochemical performance and stability of the catalyst film.