Jinran Chen,Xiurui Ke,Zhou Zhou,Wenqi Ye,Hong Liu,Wei Zhang,Xiaohong Liu
We report the fabrication of a substrate with cavity-nanorods and decorated with Ag-nanoplates (C-NR@Ag). The cavities on the substrate are formed by metal assistant chemical etching, and the Ag-nanoplates in the cavities by galvanic cell deposition enhance the SERS performance effectively. Analytes in solution are adsorbed on Ag-nanoplates and located in hot spots, which enhance the SERS performance effectively. The enhancement factor of the Ag-nanoplates decorated on nanorod cavities is calculated to be 3.6 × 106, which is about 3 fold higher than that on the nanorods. The C-NR@Ag substrate is able to detect polychlorinated biphenyls (PCBs) with the lower limit of detection at 1.0 × 10−12 M. Additionally, due to the semi-volatile nature of PCB-77, the lower limit of detection of the C-NR@Ag substrate for PCB-77 was 1.0 × 10−11 M by the non-contact collection method. These results present a novel approach towards enhancing SERS performance and facilitating the rapid detection of PCB-77.
As a piezoelectric ceramic material, SeZnO3 has received increasing attention for pressure sensing. However, the poor conductivity and low dielectric constant of bare SeZnO3 severely limit its wide applications. Herein, to improve the pressure sensing properties of SeZnO3, SeZnO3 nanosheets composited with Ag nanoplates were synthesized via a dissolution coprecipitation method, which exhibited a higher sensitivity (54.8 kPa−1) to external pressure with an excellent repeatability than that of bare SeZnO3 nanosheets (12.3 kPa−1). The enhanced pressure sensing properties of Ag/SeZnO3 nanocomposites could be attributed to an increased dielectric constant and an enhanced charge output. Moreover, the nanocomposite-based pressure sensors showed an accelerated response/recovery rate (0.7 s/2.7 s) because of the effective charge transfer between SnZnO3 and Ag, which was confirmed by XPS results. This Ag/SeZnO3 composite nanosheet-based pressure sensor demonstrates a potential for practical monitoring of human movement.
Cu nanowire (Cu NW) and Ag nanosheet (Ag NS) bimetallic nanocomposites were fabricated on a flexible polyethylene terephthalate (PET) slice for non-enzymatic glucose sensing via a facile two-step approach, vacuum filtration, and galvanic displacement. Low-cost Cu NW-based conductive films were employed as the conductive substrates to substitute the traditional glassy carbon electrodes or indium tin oxide electrodes. The highly stable Ag NSs grow directly on the surface of Cu NWs without additional binders. The AgNO3 concentration and displacement time were adjusted to control the consumption of Cu NWs and the growth of Ag nanostructures. With the large load of Ag and the great connection of Cu NWs, a high sensitivity of 2033 μA mM−1cm−2, a fast amperometric response of 2 s, a wide linear range of 0.0015–4.02 mM, and a satisfactory result in human serum analysis were obtained by this novel Ag NS/Cu NW/PET sensor. Especially the sensitivity of the sensor was over four-fold higher than that of pure Cu NWs/PET, benefiting from the synergistic effect of bimetals. Furthermore, the Ag NS/Cu NW/PET sensor demonstrated a stable amperometric signal against mechanical bending. The material holds promise to use to fabricate flexible electrochemical devices.
The direct ethanol fuel cells (DEFCs) are considered as a kind of green and sustainable portable power source with high energy density, stable convert efficiency and zero/low emissions. In this study, the Pd x Ag 1-x nanosheet assemblies (NSAs) composed of a 2D sheet structure are synthesized by a facile one-step method. Alloyed Pd x Ag 1-x NSAs perform better catalytic activities and anti-toxicity than that of pure Pd NSA, closely related to their macroscopic morphological characteristics and microscopic electronic structure. Also, the mechanisms of the common four electrons pathway of ethanol oxidation reaction (EOR) on Pd x Ag 1-x NSAs are studied using the cyclic voltammetry method. Higher catalytic temperature and concentrations of both the KOH and ethanol have a positive effect on the overall reaction of the EOR, especially for the rate determination step in anodic scanning and the removal of the oxygen containing Pd-related intermediate species during cathodic scanning. However, excessive concentrations of KOH and ethanol should be avoided due to the formation of the oxide layer embedded at the surface of Pd at higher potentials and the decrease in conductivity, respectively. So, appropriate reaction temperature and medium conditions are favorable for the catalytic reaction.
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