A microfluidic device with integrated ZnO nanowires for photodegradation studies of methylene blue under different conditions

•Large-area and well-aligned ZnO nanowires were prepared on glass substrate by hydrothermal growth.•ZnO nanowires were integrated into a microfluidic device for photocatalysis of organic pollutant.•The performances of the devices pretreated using different methods were compared.•Cyclic photodegradation was evaluated to demonstrate the high efficiency of the device.

A microfluidic device with integrated ZnO nanowires (NWs) has been used for photodegradation studies of organic dye. By using conventional photolithography and hydrothermal growth techniques, high density and well-aligned ZnO NWs were grown on a patterned area over a glass substrate, allowing easy integration into a microfluidic reaction chamber for photodegradation under continuous-flow conditions. Cyclic photodegradation experiments are shown to demonstrate the variation of the photocatalytic efficiency during the first cycles. Accordingly, the device pretreatments such as ZnO NWs annealing and flushing with dye solution were performed in order to determine the optimal photocatalytic conditions. As expected, the microfluidics based approach exhibited a much improved photodegradation efficiency comparing to the conventional method using dispersed ZnO NWs.

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