Au-modified three-dimensionally ordered macroporous ZnO:In for high-performance ethanol sensors

In this paper, Au-modified three-dimensionally ordered macroporous ZnO:In (3DOM Au-ZnO:In) was synthesized by a one-pot method using a PMMA colloidal crystal template. The 3DOM ZnO:In with uniformly dispersed Au had large specific surface areas and highly ordered pore structures. The ethanol-sensing properties of 3DOM Au-ZnO:In were investigated and the sensor based on the 0.050 mol% Au-loaded 3DOM ZnO:In exhibited the highest sensitivity (similar to 240) to 100 ppm ethanol at the optimum operating temperature of 250 degrees C. Moreover, the fabricated sensor exhibited excellent selectivity and good stability. Therefore, the Au-modified 3DOM ZnO:In is a promising material for a novel ethanol sensor. The reason for the improvement of the sensitivity was investigated. The large surface area of the 3DOM structure was beneficial for gas adsorption and transfer, and In-doping can increase the electron carrier concentration. Moreover, Au modification enhanced the content of adsorbed oxygen, and thus resulted in a thick depletion layer and high sensitivity.