Preparation and Photoelectric Properties of Pr-Doped p-Cu2O Thin Films Photocatalyst Based on Energy Band Structure Regulation

Abstract

A Pr-doped p-Cu2O thin film was prepared on indium tin oxide conductive glass by electrochemical deposition; the effect of Pr doping on the structure, morphology, and physicochemical properties of p-Cu2O was investigated. The results show that with the increase in Pr doping amount, the particle size of p-Cu2O increases, the absorption boundary redshifts, and the band-gap width decreases. Pr doping increases the flat band potential and carrier concentration of p-Cu2O; when the doping amount is 1.2 mM, the carrier concentration reaches 1.14 × 1024 cm−3. Compared with pure p-Cu2O, the charge transfer resistance of Pr-doped p-Cu2O decreases and the photocurrent and open circuit voltage increase, indicating that the carrier transfer rate is accelerated, and the separation efficiency of photogenerated electrons and holes is effectively improved. The result of a norfloxacin photocatalytic degradation experiment showed that the degradation rate of norfloxacin increased from 52.3% to 76.2% and Pr doping effectively improved the photocatalytic performance of p-Cu2O. The main reasons for enhancing the photocatalytic performance are that the band gap of Pr-doped p-Cu2O decreases, the Fermi level of Cu2O is closer to the valence band position, the hole concentration near the valence band, and the oxidation capacity increases, and more h+ oxidize norfloxacin molecules. In addition, the Pr in Pr-Cu2O acts as a conductor to guide electrons on the guide band to the crystal surface, which increases the contact between photogenerated electrons and dissolved oxygen, which is conducive to the formation of the active species ·O2− and can effectively reduce the recombination of photogenerated carriers. In the process of photocatalytic degradation of norfloxacin, the main active species are ·O2−, ·OH, and h+, which play auxiliary roles. TOC tests show that the norfloxacin molecules can be effectively degraded into small molecule organic matter, CO2, and H2O in the presence of Pr-doped p-Cu2O.