ABSTRACT
Developing high-efficiency, durable, and low-cost catalysts based on earth-abundant elements for the oxygen evolution reaction (OER) is essential for renewable energy conversion and energy storage devices. In this study, we report a highly active nanostructured electrode, NanoCOT, which contains carbon, oxygen, and titanium, for efficient OER in alkaline solution. The NanoCOT electrode is synthesized from carbon transformation of TiO2 in an atmosphere of methane, hydrogen, and nitrogen at a high temperature. The NanoCOT exhibits enhanced OER catalytic activity in alkaline solution, providing a current density of 1.33 mA/cm(2) at an overpotential of 0.42 V. This OER current density of a NanoCOT electrode is about 4 times higher than an oxidized Ir electrode and 15 times higher than a Pt electrode because of its nanostructured high surface area and favorable OER kinetics. The enhanced catalytic activity of NanoCOT is attributed to the presence of a continuous energy band of the titanium oxide electrode with predominantly reduced defect states of Ti (e.g., Ti(1+), Ti(2+), and Ti(3+)) formed by chemical reduction with hydrogen and carbon. The OER performance of NanoCOT can also be further enhanced by decreasing its overpotential by 150 mV at a current density of 1.0 mA/cm(2) after coating its surface electrophoretically with 2.0 nm IrOx nanoparticles.
ABSTRACT
Degussa P-25 TiO2 encapsulated in a SBA-15 mesoporous thin film silica matrix prepared using a block copolymer templating method. The film structure was characterized using small angle X-ray diffraction (XRD), variable angle spectroscopic ellipsometry (VASE), and polarized light microscopy. The photoactivity of the films was assessed using HPLC and UV-vis spectroscopy to study the photodegradation of 2,4-dichlorophenol, an industrial pollutant, in water under 350 nm irradiation. The unoptimized film was found to be approximately half as photoactive as an equivalent dispersion of TiO2.
