Enhancing electrochemical and photoelectrochemical degradation of organic dyes under visible irradiation with a novel Cu2O/BaHPO4-based photoelectrode

Abstract

A highly active Cu2O/BaHPO4 photoanode was obtained using a simple two-step electrodeposition technique. The synthesised material was characterised by various methods, including X-ray diffraction (XRD), which revealed the orthorhombic phase of BaHPO4 and the cubic phase of Cu2O, while scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX) showed the platelet and prism morphology of BaHPO4 and Cu2O, respectively. The optical features of both compounds as well as their band gap energies were also evaluated and calculated using diffuse reflection spectroscopy (DRS). The vibrational properties of the photoanode were studied using Fourier transform infrared (FT-IR). The electrocatalytic activity (EC) of the samples were evaluated using a central composite design for surface response methodology (CCD-RSM) to determine the optimal conditions for Rhodamine B (RhB) degradation. The photoelectrocatalytic performance (PEC) of the Cu2O/BaHPO4 photoanode was about 98% in 5 min of reaction under visible irradiation, which was higher than BaHPO4 and Cu2O alone significating a quick separation of photoexcited carriers thanks to the excellent synergetic properties exhibited by the composite. This finding was corroborated by the results obtained from electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) analysis. Various cationic and anionic dyes could be efficiently degraded. In addition, after 8 cycles, a non-significant decrease in the degradation rate was observed confirming the high cyclability of the photoanode. Therefore, Cu2O/BaHPO4 can be considered as a promising candidate for the efficient degradation of organic pollutants.