Synergistic effect over photocatalytic active Cu2O thin films and their morphological and orientational transformation under visible light irradiation

•[200] oriented Cu2O thin films were prepared by chemical bath deposition.•H2O2 played a major role in methyl orange (MO) degradation over Cu2O thin films.•The mechanism for the enhanced photocatalytic activity was proposed.•Cu2O thin film photocatalysts were considerably stable and recyclable.•Morphological evolution of Cu2O quasi-cubic particles was found when recycled. Cuprous oxide (Cu2O) thin films were prepared via a one-step chemical bath deposition (CBD) approach. The prepared samples were preferentially orientated along the [200] direction, with a ∼52nm crystallite size. The photocatalytic activities of the Cu2O thin films were evaluated by the degradation of methyl orange (MO) under visible light irradiation and monitored using a UV–vis spectrophotometer. The results confirmed that the photodegradation efficiency was dependent on several parameters, such as the amount of H2O2 and the pH of the MO solution. The optimum amount of H2O2 and the pH of the MO solution were determined to be 113.75μl and 5, respectively. A kinetic study had been performed, and the degradation kinetics was observed to follow a pseudo-first order kinetics model. The mechanism responsible for the enhanced photocatalytic activity of the Cu2O thin films in the presence of H2O2 was explored in detail. In recyclability tests, the prepared Cu2O thin film photocatalysts exhibited high photocatalytic activity, along with the morphological and orientational transformation. Interestingly, the photodegradation efficiency of the subsequent cycles was higher than the first cycle, which was due to the large specific surface area of the morphology-transformed photocatalyst.