Au-deposited porous single-crystalline ZnO nanoplates for gas sensing detection of total volatile organic compounds

The indoors volatile organic compounds (VOCs), which can be classified into seven groups as oxy hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, terpenes, esters and aldehydes, have been brought to the forefront because millions of people are suffering from indoor air pollution. In this study, well-dispersive Au nanoparticles were deposited on porous single-crystalline ZnO nanoplates (Au@ZnO) via photodeposition free from additives for the gas sensing detection of the seven-group VOCs. The structure and morphology of Au@ZnO nanoplates were characterized by TEM, HRTEM, mapping and XRD. Comparing to pure ZnO nanoplates, the Au@ZnO sensor has prominent enhanced performance at 360 degrees C with high sensitivity (about 2-9 times for each group of VOCs), fast response/recovery time (less than 30/14 s) and stable repeatability (relative standard deviation less than 0.039) in the gas sensing tests. The fluctuation range of relative humidity is less than 80% and the contribution ratios of oxy hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, terpenes, esters and aldehydes were 0.1678, 0.0989, 0.0826, 0.0739, 0.2396, 0.1887, 0.1495, respectively. Finally, the possible sensing mechanism was discussed based on these results.