CuO/PbTiO3: A new-fangled p-n junction designed for the efficient absorption of visible light with augmented interfacial charge transfer, photoelectrochemical and photocatalytic activitiesElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ta05206e

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/PbTiO 3 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 PbTiO 3 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 PbTiO 3 . The TEM results reveal that the p-type CuO nanoparticles were successfully assembled on the surface of the polyhedron-shaped n-type PbTiO 3 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/PbTiO 3 p-n junctions exhibited superior photocatalytic activity for the degradation of malachite green (MG) under visible light irradiation compared to neat PbTiO 3 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/PbTiO 3 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. The asymmetric photocurrent in opposite directions and the rectifying behaviour of all the CuO/PbTiO 3 samples reveal the formation of a p-n junction between them, this helps to augment the charge anti-recombination process at the interface and enhance the photocatalytic performance.