Detection of H2S down to ppb levels at room temperature using sensors based on ZnO nanorods

ZnO sensors were fabricated from ZnO nanorods prepared by a hydrothermal method and their gas-sensing properties were investigated. It was found that the phase composition of the product and the gas-sensing properties were dependent on the preparation conditions (the presence of surfactant and the ratio of VZnAc2(0.50 M)/VNaOH(5.0 M)VZnAc2(0.50 M)/VNaOH(5.0 M)). The sensor prepared at a ratio of VZnAc2(0.50 M)/VNaOH(5.0 M)=1VZnAc2(0.50 M)/VNaOH(5.0 M)=1 without any surfactant exhibited the best performance, which was characterized by high response and good selectivity to low concentrations of H2S at room temperature. The sensor also had a high response, high selectivity and short response time to low concentrations of C2H5OH at 350 °C. These characteristics make the sensor to be a promising candidate for practical materials detecting low concentrations of H2S and C2H5OH. Especially, the response to 0.05 ppm H2S attained 1.7 at room temperature.