Enhanced surface area, high Zn interstitial defects and band gap reduction in N-doped ZnO nanosheets coupled with BiVO4 leads to improved photocatalytic performance

Publication date: 31 July 2017
Source:Applied Surface Science, Volume 411
Author(s): Sonal Singh, Rishabh Sharma, Bodh Raj Mehta
For the first time, a series of Nitrogen-doped-ZnO nanosheet coupled with BiVO4 (N-ZnO/BiVO4) heterojunctioned photocatalysts have been synthesized. The new N-ZnO/BiVO4 material has been prepared via a simple and effective method of precipitation followed by high temperature annealing process. The photocatalytic activities of the N-ZnO/BiVO4 composites were evaluated for the degradation of methylene blue (MB) a common organic pollutant under visible-light irradiation. The results revealed that photocatalytic activity of the coupled system was directly influenced by the percentage amount of BiVO4 in N-ZnO which affected the available exposed surface area for photoreactions. 30% N-ZnO/BiVO4 system exhibited remarkable performance than 10%N-ZnO/BiVO4, 50%N-ZnO/BiVO4, and also to their pristine counterparts. The composite demonstrated the degradation efficiency of 90% in 90min which is 1.76 times the efficiency of pure ZnO for same time duration. This pronounced photocatalytic effect is ascribed to the reduced band gap and lowered recombination rate of ZnO due to nitrogen doping and enhanced low energy charge carrier transitions between zinc interstitial defect bands, formed by the addition of BiVO4 in N-ZnO, to the conduction band of N-ZnO at the interface. Based on the experimental results, a proposed Z-scheme mechanism for the Nitrogen-doped ZnO/BiVO4 photocatalyst was discussed.



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