Cubic Cu₂O nanoparticles decorated on TiO₂ nanofiber heterostructure as an excellent synergistic photocatalyst for H₂ production and sulfamethoxazole degradation

We report a simple strategy for providing a homogenous TiO₂ nanofibre host environment to stabilize Cu₂O nanoparticles with an average size of ∼60 nm and high dispersibility. We found that the small fraction of Cu₂O nanoparticles in direct contact/partially submerged with TiO₂ nanofibre arrays (diameter ∼300 nm and length ∼650 nm) showed excellent synergistic photocatalytic performance for H₂ production rate of 48 μmol g⁻¹ h^-1 with an apparent quantum efficiency of 3.6 %. The H₂ production rate was much higher (factor of ∼6.5 times) compared with unmodified TiO₂-NF. In addition, the synergistic Cu₂O/TiO₂-NF photocatalyst showed significant oxidative-degradation of sulfamethoxazole (7 × 10^-2 mmol g⁻¹ min^-1) and was highly stable during five cycles. The small fraction of Cu₂O nanoparticles are well dispersed and form heterojunction interfaces to promote charge transfer and provide active sites. This argument is verified by morphology characterisation, band alignment, energy-resolved distribution of electron traps, electrochemical transient photocurrent, and electrochemical impedance (EIS). In addition, a detailed discussion is provided regarding the surface and bulk elemental composition determined by X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), and X-ray absorption near edge structure (XANES).