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 10 ppm 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 10 ppm. 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 H ₂S. This work will provide a new construction route of ZnO-based sensing materials, which can be used as H₂S sensors with high performances. Extra-sensitive films: The CuO-ZnO micro/nanoporous array-film-based chemosensor is fabricated by using a solution-dipping colloidal template. The obtained CuO-ZnO films exhibit a more homogeneous structure, higher H₂S sensitivity, shorter recovery time, and better selectivity than those of the pure ZnO thin film (see figure).