Probing Bidirectional Plasmon-Plasmon Coupling-Induced Hot Charge Carriers in Dual Plasmonic Au/CuS Nanocrystals

Full-spectrum plasmonic semiconductors for photocatalysis

Localized surface plasmon resonance (LSPR) of noble metal nanoparticles can focus surrounding light onto the particle surface to boost photochemical reactions and solar energy utilization. However, the rarity and high cost of noble metals limit their applications in plasmonic photocatalysis, forcing researchers to seek low-cost alternatives. Recently, some heavily doped semiconductors with high free carrier density have garnered attention due to their metal-like LSPR properties. However, plasmonic semiconductors have complex surface structures characterized by the presence of a depletion layer, which poses challenges for active site exposure and hot carrier transfer, resulting in low photocatalytic activity. In this review, we introduce the essential characteristics and types, synthesis methods, and characterization techniques of full-spectrum plasmonic semiconductors, elucidate the mechanism of full-spectrum nonmetallic plasmonic photocatalysis, including the local electromagnetic field, hot carrier generation and transfer, the photothermal effect, and the solutions for the surface depletion layer, and summarize the applications of plasmonic semiconductors in photocatalytic environmental remediation, CO2 reduction, H2 generation, and organic transformations. Finally, we provide a perspective on full-spectrum plasmonic photocatalysis, aiming to guide the design and development of plasmonic photocatalysts.

Dual-mode detection for the total antioxidant capability of skincare products based on porous CuS@CdS@Au nanoshells

The antioxidants in skincare products play a crucial role in delaying the aging process of the skin. With the growing variety of cosmetic products, it is essential to develop effective methods for measuring their total antioxidant capability (TAC). This study introduces a novel nanoenyzme, CuS@CdS@Au nanoshells (NSs), characterized by porous morphologies and composite materials, which demonstrate remarkable localized surface plasmon resonance (LSPR) effects, thereby enhancing their photocatalytic and photothermal properties. Under 808 nm laser irradiation, these nano-enzymes exhibited superior catalytic ability for TMB oxidation and temperature increases compared to CuS or CuS @Au NSs. The TMB absorption response and temperature increase showed high sensitivity to antioxidants such as ascorbic acid, glutathione, and ferulic acid, enabling the development of a dual-mode detection strategy for quantifying the TAC in skincare products without the need for complex pretreatments. Furthermore, the temperature response-based detection results proved to be more accurate than those derived from absorption response in recovery experiments. This research not only improves the reliability of antioxidant assessments but also provides a valuable tool for quality control in the skincare industry.

Fatty Amine-Mediated Synthesis of Hierarchical Copper Sulfide Nanoflowers for Efficient NIR-II Photothermal Conversion and Antibacterial Performance

Non-noble metal photothermal materials have recently attracted increasing attention as unique alternatives to noble metal-based ones due to advantages like earth abundance, cost-effectiveness, and large-scale application capability. In this study, hierarchical copper sulfide (CuS) nanostructures with tunable flower-like morphologies and dimensional sizes are prepared via a fatty amine-mediated one-pot polyol synthesis. In particular, the addition of fatty amines induces a significant decrease in the overall particle size and lamellar thickness, and their morphologies and sizes could be tuned using different types of fatty amines. The dense stacking of nanosheets with limited sizes in the form of such a unique hierarchical architecture facilitates the interactions of the electromagnetic fields between adjacent nanoplates and enables the creation of abundant hot-spot regions, thus, benefiting the enhanced second near-infrared (NIR-II) light absorptions. The optimized CuS nanoflowers exhibit a photothermal conversion efficiency of 37.6%, realizing a temperature increase of nearly 50 °C within 10 min under 1064 nm laser irradiations at a power density of 1 W cm-2. They also exhibit broad-spectrum antibacterial activity, rendering them promising candidates for combating a spectrum of bacterial infections. The present study offers a feasible strategy to generate nanosheet-based hierarchical CuS nanostructures and validates their promising use in photothermal conversion, which could find important use in NIR-II photothermal therapy.