Two-Dimensional Restructuring of Cu(2)O Can Improve the Performance of Nanosized n-TiO(2)/p-Cu(2)O Photoelectrodes under UV–Visible Light

[Image: see text] p-Cu(2)O/n-TiO(2) photoanodes were produced by electrodeposition of octahedral p-type Cu(2)O nanoparticles over n-type TiO(2) nanotubes. The photoresponse of the composite p–n photoanodes was evaluated in photoelectrochemical cells operating at “zero-bias” conditions under either visible or UV–vis irradiation. In both operating conditions, the produced electrodes invariably followed the p–n-based photoanode operations but exhibited lower photoelectrochemical performance as compared to the bare n-TiO(2) photoanode under UV–vis light. The reported experimental analysis evidenced that such decreased photoactivity is mainly induced by the scarce efficiency of the nanosized p–n interfaces upon irradiation. To overcome such limitation, a restructuring of the originally electrodeposited p-Cu(2)O was promoted, following a photoelectrochemical post-treatment strategy. p-Cu(2)O, restructured in a 2D leaf-like morphology, allowed reaching an improved photoelectrochemical performance for the p–n-based photoanode under UV–vis light. As compared to the bare n-TiO(2) behavior, such improvement consisted of photoanodic currents up to three times larger. An analysis of the mechanisms driving the transition from compact (∼100 nm) octahedral p-Cu(2)O to wider (∼1 μm) 2D leaf-like structures was performed, which highlighted the pivotal role played by the irradiated n-TiO(2) NTs.