CuO/PbTiO3: A new-fangled p–n junction designed for the efficient absorption of visible light with augmented interfacial charge transfer, photoelectrochemical and photocatalytic activities

Abstract

An innovative tactic is to architecture novel p–n junctions for the efficient separation of charge carriers at heterojunction interfaces and enhance the photocatalytic activity under visible light irradiation. In view of this, we have fabricated a novel CuO/PbTiO₃ p–n junction by a simple impregnation method and examined its photocatalytic activity towards the degradation of malachite green. First and foremost, the photoelectrochemical measurements confirmed the n-type and p-type semiconducting properties of PbTiO₃ and CuO, respectively. The measured asymmetric photocurrent in opposite directions and the rectifying behaviour of all the prepared heterojunctions confirmed the formation of a p–n junction between the CuO and PbTiO₃. The TEM results reveal that the p-type CuO nanoparticles were successfully assembled on the surface of the polyhedron-shaped n-type PbTiO₃ and a strong p–n junction interface was formed between them. A regular study is represented for the detailed characterization of the phases, surface chemical composition, surface morphology, and optical properties of the prepared heterojunctions. All the CuO/PbTiO₃ p–n junctions exhibited superior photocatalytic activity for the degradation of malachite green (MG) under visible light irradiation compared to neat PbTiO₃ and CuO. The superior photocatalytic activity of the p–n junction samples was due to the efficient separation of charge carriers at the junction interface. The efficient separation of charge carriers at the p–n junction interface was confirmed by EIS, steady state, and time-resolved PL analysis. The 33% CuO/PbTiO₃ p–n junction reveals a higher activity around 91% degradation of malachite green under visible light irradiation in comparison to the other p–n junctions. The kinetic analysis of the prepared photocatalysts for malachite green (MG) degradation showed that the process followed a pseudo-first-order kinetics model.