ZnO is an important n-type semiconductor
sensing material. Currently, much attention has been attracted to
finding an effective method to prepare ZnO nanomaterials with high
sensing sensitivity and excellent selectivity. A three-dimensionally
ordered macroporous (3DOM) ZnO nanostructure with a large surface
area is beneficial to gas and electron transfer, which can enhance
the gas sensitivity of ZnO. Indium (In) doping is an effective way
to improve the sensing properties of ZnO. In this paper, In-doped
3DOM ZnO with enhanced sensitivity and selectivity has been synthesized
by using a colloidal crystal templating method. The 3DOM ZnO with
5 at. % of In-doping exhibits the highest sensitivity (∼88)
to 100 ppm ethanol at 250 °C, which is approximately 3 times
higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity
to ethanol was attributed to the increase in the surface area and
the electron carrier concentration. The doping by In introduces more
electrons into the matrix, which is helpful for increasing the amount
of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM
ZnO is a promising material for a new type of ethanol sensor
