Chloride and iodide electrosorption on Ag(111)

Rapid detection of Pseudomonas syringae pv. actinidiae by electrochemical surface-enhanced Raman spectroscopy

Bacterial cancer caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to kiwifruit in the world, and there is still a lack of effective control measures. The field of bacterial detection needs a fast, easy-to-use and sensitive identification platform. The current bacterial identification methods are lack of time efficiency, which brings problems to many sectors of society. Surface-enhanced Raman spectroscopy (SERS) and electrochemistry (EC) have been studied as possible candidates for bacterial detection because of their high sensitivity for the detection of biomolecules. In this work, SERS, EC and electrochemical surface-enhanced Raman spectroscopy (EC-SERS) were used for the first time to study the adsorption and EC behavior of Psa on the surface of nanostructured silver electrodes. Two different Raman spectra of a single analyte were obtained, and this dual detection was realized. Silver nanoparticles with iodide and calcium ions (Ag@ICNPs) were synthesized as SERS substrates significantly enhanced the characteristic signal peaks of Psa, and the limit of detection (LOD) is as low as 1.0 × 102 cfu/mL. Chemical imaging results show that the application of negative voltage can significantly improve the spectrum quality, showing a higher signal at -0.8 V, indicating that Psa molecules may have potential-induced reorientation on the electrode surface. Therefore, EC-SERS has the ability to greatly improve the SERS performance of bacteria in terms of peak intensity and spectral richness.

High purity silver microcrystals recovered from silver wastes by eco-friendly process using hydrogen peroxide

A simple, rapid, and environmentally friendly process using hydrogen peroxide, was developed for recovering high purity silver directly from industry and laboratory wastes. Silver ammine complex, [Ag(NH₃)₂]⁺Cl^-, derived from AgCl were generated and then directly reduced using H₂O₂ to reliably turn into high purity microcrystalline silver (99.99%) examined by EDS and XRD. Morphology of the recovered silver microcrystals could be selectively tuned by an addition of poly(vinyl pyrrolidone). The main parameters in the recovering process including pH, concentration of Ag⁺ and the mole ratio of H₂O₂:Ag⁺ were carefully optimized though the central composite design (CCD). The optimized condition was employed for a trial recovery of 50 L silver ammine complex prepared from a collection of silver-wastes during 3-year research on industrial nanoparticle production. The recovered silver microcrystals >700 g could be recovered with 91.27%. The remaining solution after filtering of the recovered silver microcrystals can be used repeatedly (at least 8 cycles) without losing recovery efficiency. Matrix interferences including Pb²⁺ and Cl^- play a minimal role in our silver recovery process. Furthermore, the direct usage of the recovered silver microcrystals was demonstrated by using as a raw material of silver clay for creating a set of wearable silver jewelries.

Rapid fabrication of silver microplates under an oxidative etching environment consisting of O2/Cl−, NH4OH/H2O2, and H2O2

Chloride ions are essential for creating an etching environment capable of selective dissolution of singly and multiply twinned crystals, while leaving plate structures unaffected.