A simple way to synthesize large-scale Cu2O/Ag nanoflowers for ultrasensitive surface-enhanced Raman scattering detection

Nanocomposites of Cu2O with plasmonic metals (Au, Ag): design, synthesis, and photocatalytic applications

Metal-semiconductor nanocomposites have been utilized in a multitude of applications in a wide array of fields, prompting substantial interest from different scientific sectors. Of particular interest are semiconductors paired with plasmonic metals due to the unique optical properties that arise from the individual interactions of these materials with light and the intercomponent movement of charge carriers in their heterostructure. This review focuses on the pairing of Cu2O semiconductor with strongly plasmonic metals, particularly Au and Ag. The design and synthesis of Au-Cu2O and Ag-Cu2O nanostructures, along with ternary nanostructures composed of the three components, are described, with in-depth discussion on the synthesis techniques and tunable parameters. The effects of compositing on the optical and electronic properties of the nanocomposites in the context of photocatalysis are discussed as well. Concluding remarks and potential areas for exploration are presented in the last section.

Construction of Multifunctional and Adjustable Langmuir-Blodgett Composite Films Containing Black Phosphorus with High Stability for Optically Electrical Applications

Fabrication of composite thin-film materials based on black phosphorus (BP) will greatly broaden the applications of BP in various areas. However, it is still a challenge to prepare a BP-based composite film with good stability and controllable structure. In this work, a series of BP-based composite Langmuir-Blodgett (LB) films are prepared by the self-assembly of polyethyleneimine (PEI)-modified BP nanosheets (BPNSs) (BPNS-PEI) and dye molecules. The presence of PEI greatly improves the stability of BPNSs. As for BPNS-PEI and dye molecules, the electrostatic interactions or π-π stacking interactions ensure the formation of stable composite LB films. Due to the protonation and deprotonation of amino groups, the synthesized BPNS-PEI/dye composite films show a sensitive response to acid and alkali gases, which shows wide application prospects as a highly sensitive gas sensor. Furthermore, surface-enhanced Raman scattering (SERS) proves that the prepared LB films exhibit good reproducibility and obvious Raman enhancement effect on rhodamine 6G molecules. In addition, due to the high carrier transfer rate of the obtained composite films, they possess enhanced photocurrent generation performance than pure BPNS-PEI and pure dye films. The current work demonstrates an effective method for preparing the ordered self-assembled BP-based composite LB films with good SERS and photoelectric conversion performance.

Self-Assembled Black Phosphorus-Based Composite Langmuir-Blodgett Films with an Enhanced Photocurrent Generation Capability and Surface-Enhanced Raman Scattering Properties

In this work, Langmuir-Blodgett (LB) composite thin films were successfully prepared using black phosphorus nanosheets (BPNS) and dye molecules. Black phosphorus (BP) was first exfoliated in isopropanol solution to form BPNS, and then, BPNS were modified with 4-azidobenzoic acid (Az-BPNS) to improve their stability. The characterization results showed that the synthesized Az-BPNS-dye LB films have a uniform and ordered structure. In addition, the synthesized Az-BPNS-dye LB films exhibit excellent photoelectrochemical performance, and Az-BPNS-methylene blue (MB) produces higher photocurrent compared to Az-BPNS-Neutral red (NR) films. The current work shows an effective way to prepare functionalized BP-based materials and provide evidence for their application in optoelectronic devices.

Self-Cleaning-Mediated SERS Chip Coupled Chemometric Algorithms for Detection and Photocatalytic Degradation of Pesticides in Food

Pesticide residues in food have been a grave concern to consumers. Herein, we have developed a dual-mode SERS chip using Cu₂O mesoporous spheres decorated with Ag nanoparticles (MCu₂O@Ag NPs) as both sensing and degradation/clearing unit for rapid detection of pymetrozine and thiram pesticides in tea samples. Three kinds of chemometric algorithms were comparatively applied to analyze the collected SERS spectra of pesticides. In comparison, random frog-partial least squares achieved the best performance with root mean square error of prediction and residual predictive deviation values of 0.9871, 6.17, and 0.9873, 6.64 for pymetrozine and thiram, respectively. Additionally, the prepared SERS chip showed great photocatalytic activity to degrade pesticides under visible light irradiation. Through a facile method, this work presented a novel dual-functional SERS chip for the rapid detection and degradation of low-concentration pesticides in both environmental and food samples.