Porous ZnO Nanoplates Supported Noble Metal For Gas Sensing Detection Of Total Volatile Organic Compounds And Chlorobenzenes

With the accelerating process of industrialization, people enjoy more conveniences as well as suffer more pollutions. The World Health Organization reported that air pollution causes about millions of premature deaths each year. Although most of the contaminants exist outdoors, the indoor air environment is deteriorated and dangerous for human beings especially because people spend more than 80% of their time indoors.Gas sensor, which is inexpensive, on-site, and convenient for wide application, has been an expected sensor with excellent performances in detecting air pollutions. Metal-oxide semiconductors, as conventional gas sensitive materials, have been used to monitor series of harmful gases widely. However, many problems concerning its sensitivity and examination area remain to be solved, and doping is one of the effective ways to promote the gas-sensitive properties of metal-oxide semiconductors. In this work, various noble-metal deposited semiconductor materials via photoreduction and impregnation-H2 reduction method free from additives in the products, showing excellent sensor performance for detecting VOCs and CBs.1. Au-deposited porous single-crystalline ZnO nanoplates for gas sensing detection of total volatile organic compoundsThe most pernicious of the indoor air pollutants are volatile organic compounds (VOCs), which can be classified into oxy hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, terpenes, esters and aldehydes. However, the common gas sensor usaually show a high selectivity for one or a kind of specific gases. Thus, it is imperative to explore a kind of gas sensors which can detect all the kinds of VOCs. In this report, high dispersed Au nanoparticles were deposited on porous ZnO single-crystalline nanoplates via photoreduction free from additives in the products, showing excellent sensor performance for detecting seven groups of volatile organic compounds. The contribution ratios of each group in the VOCs gas tests were explored and the gas-sensing properties of the Au@ ZnO sensor were studied systematically.2. High-dispersed Pd nanoparticles decorated ZnO nanoplates for sensing chlorobenzenes.Chlorobenzenes (CBs) have been widely used in industrial solvent, degreasing agents, and intermediates of plastics, resins and pharmaceuticals. Chlorobenzenes, as common persistent organic pollutant, have carcinogenicity, teratogenicity and mutagenicity, displaying high toxicity, lipotropy, bioaccumulation and persistence, which makes them easy to be transported over long distances and difficult to expel from human body. Therefore, developing a simple and portable chlorobenzenes gas sensor is extremely urgent. In this work, the ZnO nanoplates were fabricated via hydrothermal method, and high-dispersed Pd nanoparticles were decorated on ZnO nanoplates via impregnation followed by H2 reduction free from additives for the gas sensing detection of chlorobenzenes. The Pd nanoparticles-functionalized ZnO nanoplates displayed prominent response with high selectivity, fast response/recovery time and stable repeatability in the gas sensing tests. The influence of relative humidity was also considered.