Improving the Oxygen Evolution Activity and Stability of Nb-Doped TiO<sub>2</sub>-Supported RuO<sub>2</sub> by a SnO<sub>2</sub> Interlayer: A Model Catalyst Study on Single-Crystal Oxide Heterostructures
Naoto Todoroki, Ryutaro Kudo, Kenta Hayashi, Mizuho Yokoi, Naomi Naraki, Toshimasa Wadayama
Abstract
The introduction of a SnO 2 (110) interlayer remarkably enhances the oxygen evolution reaction (OER) activity and electrochemical stability of RuO 2 /Nb-doped TiO 2 (110) single-crystal oxide heterostructure. The SnO 2 interlayer reduces the OER overpotential of RuO 2 /Nb:TiO 2 (110) by 25 and 55 mV before and after a chronopotentiometry (CP) measurement of 0.5 mA cm –2 for 2 h, respectively. The addition of the SnO 2 interlayer significantly reduces the interfacial resistance between RuO 2 and TiO 2 in the as-pristine state and the resistance remained nearly unchanged even after the CP. Additionally, the SnO 2 interlayer stabilizes the interface between surface RuO 2 (110) and substrate TiO 2 (110) under OER, suppressing structural degradation such as nanovoid generation at the RuO 2 /TiO 2 interface. Hence, the SnO 2 interlayer is correlated with the enhanced OER activity and stability of the RuO 2 /Nb:TiO 2 (110) model catalysts because it mitigates both electrical and structural mismatches of the surface RuO 2 layer and the TiO 2 substrate.