Huiying Lu

Studies on oxidation of arene by superoxide ions electrocatalysed by metallo-porpbyrins

The superoxide ion, 02, is a potential toxic oxygenderived species for aerobic organisms, and it can react with various organic compounds, owing to its anionic, radical and redox nature. This makes it important in biochemistry [1, 2] but also it may find application as a new organic synthetic reagent [3-6]. Of particular concern are the redox reactions of 02 with organic compounds. The superoxide ion can be generated by oneelectron reduction of O2 in aprotic media. The electrochemical method of generating O~: is experimentally more convenient because the continuous generation of O~- is possible on the electrode and the solubility of O2, in the presence of the tetraethylammonium cation as supporting electrolyte, is sufficiently high [7]. However, the electrochemical method is often restricted by the reduction potential of the organic compounds. If the organic compound possesses less negative reduction potential than that of 02, it undergoes undesirable electroreduction before the generation of O~-. It has previously been reported that metalloporphyrins, FeTTP and MnTTP, possess higher electrocatalytic activity for the nucleophilic substitutions of haloarenes with O~- from electroreduction of 02 in DMF [8]. In this paper we report on the catalytic activity of metallo-porphyrins in the oxidation of nitrotoluene with O~ from the electroreduction of 02. Advantages of oxidation by electrogenerated superoxide ion in the presence of metallo-porphyrins are threefold. The oxidation can proceed under mild conditions, it does not require any oxidizing chemicals and it can be more widely used in organic synthesis. 2. Experimental details

High-response and low-temperature nitrogen dioxide gas sensor based on gold-loaded mesoporous indium trioxide

Nitrogen dioxide (NO2), as a typical threatening atmospheric pollutant, is hazardous to the environment and human health. Thus, the development of a gas sensor with high response and low detection limit for NO2 detection is highly important. The highly ordered mesoporous indium trioxide (In2O3) prepared by simple nanocasting method using mesoporous silica as template and decorated with Au nanoparticles was investigated for NO2 detection. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Characterization results showed that the samples exhibited ordered mesostructure and were successfully decorated with Au. The gas sensing performance of the sensors based on a series of Au-loaded mesoporous In2O3 were systematically investigated. The Au loading level strongly affected the sensing performance toward NO2. The optimal sensor, which was based on 0.5u202fwt% Au-loaded In2O3, displayed high sensor response and low detection limit of 10u202fppb at low operating temperature of 65u202f°C. The excellent sensing properties were mainly attributed to the ordered mesoporous structure and the catalytic performance of Au. We believe that the Au-loaded mesoporous In2O3 can provide a promising platform for NO2 gas sensors with excellent performance.

Novel Self-Assembly Route Assisted Ultra-Fast Trace Volatile Organic Compounds Gas Sensing Based on Three-Dimensional Opal Microspheres Composites for Diabetes Diagnosis

The development of ultra-fast response semiconductor gas sensors for high-accuracy detection of trace volatile organic compounds in human exhaled breath still remains a challenge. Herein, we propose a novel self-assembly synthesis concept for preparing intricate three-dimensional (3D) opal porous (OP) SnO2-ZnO hollow microspheres (HM), by employing sulfonated polystyrene (S-PS) spheres template-assisted ultrasonic spray pyrolysis. The high gas accessibility of the unique opal hollow structures resulted in the existence of 3D interconnection and bimodal (mesoscale and macroscale) pores, and the n-n heterojunction-induced change in oxygen adsorption. The 3D OP SnO2-ZnO HM sensor exhibited high response and ultra-fast dynamic process (response time ∼4 s and recovery time ∼17 s) to 1.8 ppm acetone under highly humid ambient condition (98% relative humidity), and it could rapidly identify the states of the exhaled breath of healthy people and simulated diabetics. In addition, the rational structure design of the 3D OP SnO2 HM enables the ultra-fast detection (within 1 s) of ethanol in simulation drunk driving testing. Our results obtained in this work provided not only a facile self-assembly approach to fabricate metal oxides with 3D OP HM structures but also a new methodology for achieving noninvasive real-time exhaled breath detection.