Mechanism of the substrate-dependent photocatalytic property of Cu₂O heterojunctions

Riza Ariyani Nur Khasanah^1*, Hui-Ching Lin¹, Hsiang-Yun Ho², Yen-Ping Peng², Tsong-Shin Lim¹, His-Lien Hsiao¹, Chang-Ren Wang¹, Min-Chieh Chuang³, Forest Shih-Sen Chien¹

¹Applied Physics, Tunghai University, Taichung, Taiwan
²Environmental Science, Tunghai University, Taichung, Taiwan
³Chemistry, Tunghai University, Taichung, Taiwan

* Presenter:Riza Ariyani Nur Khasanah, email:riza.ariyani.n@mail.ugm.ac.id

The electrodeposited Cu₂O on conductive Ti and FTO substrates behaves as a photocathode. To date, Cu₂O electrodeposited on an n-type semiconductor such as TiO₂ nanotube arrays (TNA), frequently used as a photoanode, demonstrates a better photocatalytic activity than that of TNA. The preference of Cu₂O to be a photoanode or a photocathode remains unclear because no systematic study was done. In this work, the photocatalytic properties of Cu₂O/TNA, Cu₂O/Ti, and Cu₂O/FTO were studied without bias. From the spectral response, Cu₂O/TNA, Cu₂O/Ti, and Cu₂O/FTO exhibited UV−visible photocurrent with the onset at 590 nm wavelength, consistent with their absorption edge and Cu₂O/TNA photoanode demonstrated the spectral response outperformed Cu₂O/Ti and Cu₂O/FTO photocathodes. The photoanodic/photocathodic properties of those junctions were depicted by their energy diagrams. From time-resolved photoluminescence, no effect of charge separation occurred at Cu₂O/TNA junction. The improved photocatalytic properties of Cu₂O/TNA were attributed to the UV−visible absorption of Cu₂O.

Keywords: photocatalysis, spectral response, Cu₂O, TiO₂ nanotube array