Noble metal nanostructures are currently of great interest for their unique plasmonic property and potential applications in catalysis and surface-enhanced spectroscopy. However, the application of plasmonic nanostructures for quantitatively in situ SERS monitoring of the catalytic reaction has been a great challenge for investigators because combining plasmonics with catalysis requires the same kind of noble metal nanoparticles (NPs) in two very different size regimes. Herein, We have demonstrated a facile wet chemical method to synthesize Au-Ag alloy plasmonic NPs that could combine the desired plasmonic and catalytic properties with same NPs. The catalytic activity of Au-Ag alloy NPs using the reduction of 4-nitrothiophenol (4-NTP) by sodium borohydride (NaBH 4) is chosen as a model reaction. The signals of the reaction processes are detected and identified through in situ SERS spectroscopy with high sensitivity. The insights gained by current study may serve as a promising and powerful technique for better investigation in the heterogeneous catalysis. Moreover, the reduction of aromatic nitro compounds with prepared Au-Ag alloy NPs also provides potential application in sewage treatment.

Colloidal quantum dots (CQDs) provide wide spectral tunability and high absorption coefficients owing to quantum confinement and large oscillator strengths, which along with solution processability, allow a facile, low-cost, and roomtemperature deposition technique for the fabrication of photonic devices. However, many solution-processed CQD photodetector devices demonstrate low specific-detectivity and slow temporal response. To achieve improved photodetector characteristics, limiting carrier recombination and enhancing photogenerated carrier separation are crucial. In this study, we develop and present an alternate vertical-stack photodetector wherein we use a solution-processed quantum dot photoconversion layer coupled to an amorphous selenium (a-Se) wide-bandgap charge transport layer that is capable of exhibiting single-carrier hole impact ionization and is compatible with active-matrix readout circuitry. This a-Se chalcogenide transport layer enables the fabrication of highperformance and reliable solution-processed quantum dot photodetectors, with enhanced charge extraction capabilities, high specific detectivity (D* ∼ 0.5−5 × 10 12 Jones), fast 3 dB electrical bandwidth (3 dB BW ∼ 22 MHz), low dark current density (J D ∼ 5−10 pA/cm 2 ), low noise current (i n ∼ 20−25 fW/Hz 1/2 ), and high linear dynamic range (LDR ∼ 130−150 dB) across the measured visible electromagnetic spectrum (∼405−656 nm).

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