CuO-ZnO Micro/Nanoporous Array-Film-Based Chemosensors: New Sensing Properties to H2S

CuO-ZnO micro/nanoporous array-films are synthesized by transferring a solution-dipped self-organized colloidal template onto a device substrate and sequent heat treatment. Their morphologies and structures are characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectrum analysis. Based on the sensing measurement, it is found that the CuO-ZnO films prepared with the composition of [Cu2+]/[Zn2+]=0.005, 0.01, and 0.05 all show a nice sensitivity to 10ppm H2S. Interestingly, three different zones exist in the patterns of gas responses versus H2S concentrations: a platform zone, a rapidly increasing zone, and a slowly increasing zone. Further experiments show that the hybrid CuO-ZnO porous film sensor exhibits shorter recovery time and better selectivity to H2S gas against other interfering gases at a concentration of 10ppm. These new sensing properties may be due to a depletion layer induced by p-n junction between p-type CuO and n-type ZnO and high chemical activity of CuO to H2S. This work will provide a new construction route of ZnO-based sensing materials, which can be used as H2S sensors with high performances.