Hydrothermally grown ZnO nanowires (NWs) have been successfully synthesized and surface modified by an ultrathin layer of CuO using dip coating technique to achieve a highly sensitive H₂S sensor. XRD analysis confirmed the hexagonal structure of ZnO without any Cu sub-oxide peaks. After CuO modification, the peak shift was observed in the electronic states of O and assigned to the defects and increase in adsorbed oxygen species. Similarly, a red shift was also observed in the band edge absorption after CuO modification arising due to defects. The sensor film showed an overall n-type character as confirmed using I(V) characteristics. Interestingly, sensor response kinetics towards H₂S were enhanced after CuO modification. The highest sensor response value of 298 was measured towards 10 ppm H₂S at 150^oC for CuO : ZnO NWs sample having 1.26 at.% of Cu. This improved sensor response has been attributed mainly to the formation of randomly distributed p-n nano-hetero-junctions between p-type CuO and n-type ZnO over the sensor surface. In particular, the p-n nano-hetero-junctions collapsed due to conversion of semiconducting CuO into metallic CuS after the unique interaction with H₂S. Keywords: ZnO nanowires, gas sensing, H₂S, surface modifications, p-n hetero-junctions.

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Дата начала обработки статистических данных - 27 января 2016 г.