Wenbo Cheng

Preparation of silver nanoparticles/graphene nanosheets as a catalyst for electrochemical oxidation of methanol

In this report, silver nanoparticles (AgNPs) decorated graphene nanosheets have been prepared based on the reduction of Ag ions by hydroquinone, and their catalytic performance towards the electrochemical oxidation of methanol is investigated. The synthesis of the nano-composite is confirmed by transmission electron microscope measurements and UV-vis absorption spectra. Excellent electrocatalytic performance of the material is demonstrated by cyclic voltammograms. This material also contributes to the low peak potential of methanol oxidation compared with most of the other materials.

Effect of thermal annealing on optical emission properties of low‐temperature grown AlGaAs/GaAs multiple quantum wells

We have investigated the effect of thermal annealing on optical emission properties of low‐temperature (LT) grown AlGaAs/GaAs multiple quantum wells (MQWs) by using photoluminescence (PL) spectroscopy. For comparison, the results on normal‐temperature (NT) grown MQWs implanted with protons are also presented. The LT sample was grown by molecular beam epitaxy at 310 °C. The as‐grown LT‐MQWs show moderately strong PL. Upon annealing at 600 °C, the PL intensity of the LT‐MQWs is dramatically quenched, in sharp contrast to the large increase in PL intensity of the implanted NT‐MQWs. The quenching of PL intensity in the LT‐MQWs is attributed to the formation of arsenic clusters that fast trap photoexcited carriers. In addition, an enhancement in the interface intermixing and roughening induced by thermal annealing has also been observed in the LT‐MQWs.

Preparation of a Peptide-Modified Electrode for Capture and Voltammetric Determination of Endotoxin

Endotoxin is the major structural constituent of the outer membrane of Gram-negative bacteria, which is a great threat to human health. Herein, a sensitive electrochemical biosensor for the detection of endotoxin is established by recording the voltammetric responses of the peptide-modified electrode. The utilized peptide has a high affinity for the target endotoxin, which ensures the high selectivity of this method. After the capture of endotoxin on the electrode surface, a negatively charged layer is formed, and the electron-transfer process is significantly hindered because of the increased steric hindrance and the electrostatic repulsion. The declined electrochemical signal could be used to indicate the concentration of endotoxin. This method is simple but effective, which requires limited reagents. Another highlight of this method is its user-friendly operation. Moreover, its applicability in human blood plasma promises its great potential utility in the near future.

Color Space Transformation-Based Smartphone Algorithm for Colorimetric Urinalysis

Urine strips are widely applied for rapid analysis of various indexes of urine for clinical examinations. The tests mainly rely on the application of a urine analyzer, which suffers several drawbacks and cannot meet the requirements of point-of-care testing (POCT). The integration of a smartphone with a biosensor has recently attracted great attention. We herein propose a human vision-based smartphone algorithm for colorimetric analysis of various urine indexes. A CIEDE2000 formula in CIELab color space is applied for the evaluation of color difference, which may greatly improve the analytical performances of urine strips. The proposed algorithm also possesses merits such as good accuracy, quantitative analysis, and limited calculation task, which is suitable for the application with smartphone platform. Experimental results demonstrate that the proposed method shows excellent reliability compared with the urine analyzer and some other algorithms. In addition, human real samples are successfully analyzed with excellent accuracy. Therefore, this work provides a convenient colorimetric tool for POCT urine analysis.