The Fabrication Of Heavily-doped Semiconductor With Localized Surface Plasmon Resonance And The Application

Exploitation of nanostructures with localized surface plasmon resonance?LSPR? has been a hot topic in recent decades owing to their great promise in photocatalysis and biomedical applications. In terms of nanostructure design,more and more efforts have been devoted to improving direct utilization of sunlight in visible region or ultraviolet range spectra as energy source, which is only 46% percent of solar energy. Therefore, the development of heteronanostructures with broad-band absorption, low cost, high stability, and outstanding catalytic performance is still critical and highly desirable for efficient application. The copper chalcogenide nanocrystals demonstrating excellent broad-band plasmonic absorption especially in the NIR region are promising candidates for building plasmon enhanced catalysts. The research contents are shown as below:1. We demonstrate a new strategy to greatly enhance the photothermal conversion efficiency of Cu₇S₄ nanostructures by assembling the dispersed nanoparticles into nanosuperlattices. According to the simulation, the self-assembly of Cu₇S₄ nanocrystals would enhance the photothermal conversion efficiency ?PCE? because of the localized surface plasmon resonance ?LSPR? effects, which is highly desirable for photothermal therapy?PTT?. We here report a new strategy to synthesize Cu₇S₄ nanosuperlattices with greatly enhanced PCE up to 65.7% under irradiation of 808-nm near infrared ?NIR? light. By tuning the surface properties of Cu₇S₄ nanocrystals during the synthesis via thermolysis of a new single precursor, dispersed nanoparticles, rod-like alignments and nanosuperlattices are obtained,respectively. To explore their PTT applications, these hydrophobic nanostructures are transferred into water by coating with self-synthesized amphiphilic polymer while maintaining their original structures. Under identical conditions, the PCE are 48.62% and 56.32% for dispersed NPs and rod-like alignments, respectively. As expected, when the nanoparticles are self-assembled into nanosuperlattices, the PCE is greatly enhanced up to 65.7%. This strong PCE, along with their excellent photothermal stability and good biocompatibility, renders these nanosuperlattices good candidates as PTT agents. In vitro photothermal ablation performances have undoubtedly proved the excellent PCE of our Cu₇S₄ nanosuperlattices. This research offers a versatile and effective solution to get PTT agents with high photothermal efficiency.2. We report a highly efficient photocatalyst comprised of Cu₇S₄@Pd heteronanocrystals with broad band plasmonic absorption. Our results indicated the strong near infrared ?NIR?-range plasmonic absorption feature of Cu₇S₄@Pd greatly facilitates hot carrier generation, subesequently promotes the catalytic reactions on Pd metallic surface. We confirmed such enhancement mechanism could effectively boost the sunlight untilization in a wide range of photocatalytic reactions, including the Suzuki coupling reaction,hydrogenation of nitrobenzene, and oxidation of benzyl alcohol. Even under irradiation at 1500 nm with low power density ?0.45 W/cm²?, these heteronanocrystals demonstrate excellent catalytic activities: for instance, it is approximately 3.3-4.3 times more efficient than the conventional heating strategy for the aforementioned three reactions. Under solar illumination with power density as low as 40 mW/cm², nearly 80-100% of conversion was achieved within 2 hours for different types of organic reactions. Furthermore,recycling experiments showed the Cu₇S₄@Pd were stable and could retain their structures and high activity after five cycles. The reported synthetic proctocol can be easily extended to other Cu₇S₄@M ?M=Pt, Ag, Au? catalysts.In summary, our heteronanocrystals offer a low cost and highly effective solution to efficiently convert solar energy to chemical energy in an environmentally friendly manner.3. We have successfully developed the plasmon enhanced photoelectri- ca.l nanocatalysts ?NCs? by coating a monolayer MoS₂ on the Cu_1.75S-Au hetero-nanoparticle for hydrogen evolution reaction ?HER?. The plasmonic NCs dramatically improve the HER, leading to 29.5-fold increase of current under 650-nm excitation ?1.0 W/cm²?. These NCs generate an exceptionally high current density of 200 mA/cm² at overpotential of 182.8 mV with a Tafel slope of 39 mV/decade and excellent stability, which is better than or comparable to the Pt-free catalysts with carbon rod as counter electrode. The enhanced HER performance can be attributed to the significantly improved broad light absorption ?400-3000 nm?, more efficient charge separation and abundant active edge sites of monolayer MoS₂. Our studies may provide a facile strategy for the fabrication of efficient plasmon-enhanced photoelectrical NCs for HER.