Plasmonically enhanced electromotive force of narrow bandgap PbS QD-based photovoltaics

Combined Effects of Emitter-Emitter and Emitter-Plasmonic Surface Separations Dictate Photoluminescence Enhancement in Plasmonic Field

The brightness of an emitter can be enhanced by metal-enhanced fluorescence, wherein the excitonic dipole couples with the electromagnetic field of the surface plasmon. Herein, we experimentally map the landscape...

The Preparation of CuInS2-ZnS-Glutathione Quantum Dots and Their Application on the Sensitive Determination of Cytochrome c and Imaging of HeLa Cells

Cytochrome c (Cyt c), one of the most significant proteins acting as an electron transporter, plays an important role during the transferring process of the energy in cells. Apoptosis, one of the major forms of cell death, has been associated with various physiological regularity and pathological mechanisms. It was found that Cyt c can be released from mitochondria to cytosol under different pathological conditions, triggering subsequent cell apoptosis. Herein, we developed a fluorescence nanoprobe based on negatively charged CuInS₂-ZnS-GSH quantum dots (QDs) for the sensitive determination of Cyt c. CuInS₂-ZnS-GSH QDs with high photochemical stability and favorable hydrophilicity were prepared by a simple hot reflux method and emit a bright orange-red light. The electron-deficient heme group in Cyt c is affiliated with the electron-rich CuInS₂-ZnS-GSH QDs through the photo-induced electron transfer process, resulting in a large decrease in fluorescence intensity of QDs. A good linearity for concentration of Cyt c in the range of 0.01-7 μmol L^-1 is obtained, and the detection limit of Cyt c is as low as 1.1 nM. The performance on the detection of Cyt c in spiked human serum and fetal bovine serum samples showed good recoveries from 85.5% to 95.0%. Furthermore, CuInS₂-ZnS-GSH QDs were applied for the intracellular imaging in HeLa cells showing an extremely lower toxicity and excellent biocompatibility.

Photoelectrochemical Formation of Polysulfide at PbS QD-Sensitized Plasmonic Electrodes

Effective electron-hole separation is a key to enhance photoenergy conversion of semiconductor quantum dot (QD)-sensitized plasmonic solar cells. However, in contrast to intense studies on electron transfer, hole transfer from QDs and consequent chemical reactions with donors in electrolytes remain unclear. Herein, in situ electrochemical surface-enhanced Raman scattering (SERS) measurement on a PbS QD-sensitized TiO₂/Au/TiO₂ photoelectrode indicated formation of cyclo-octasulfur (α-S₈) via tuning the electrochemical potential. A photocurrent density of 100 nA/cm² was recorded simultaneously even with an extremely low QD loading. Two-dimensional correlation analysis of the SERS revealed subsequent formation of S₈^- and S₄^2- at -1.1 to -0.1 V (vs Ag/AgCl), S₈ from -0.3 V, and S₅^2- and S₆^2- at ≥0.2 V via complex disproportionation reactions. The sensitive detection is attributed to the enhanced electromagnetic field of localized surface plasmon resonance, which provides a better understanding of charge separation processes in QD-sensitized solar cells.

Progress in the Utilization Efficiency Improvement of Hot Carriers in Plasmon-Mediated Heterostructure Photocatalysis

The effect of plasmon-induced hot carriers (HCs) enables the possibility of applying semiconductors with wide band gaps to visible light catalysis, which becomes an emerging research field in environmental protections. Continued efforts have been made for an efficient heterostructure photocatalytic process with controllable behaviors of HCs. Recently, it has been discovered that the improvement of the utilization of HCs by band engineering is a promising strategy for an enhanced catalytic process, and relevant works have emerged for such a purpose. In this review, we give an overview of the recent progress relating to optimized methods for designing efficient photocatalysts by considering the intrinsic essence of HCs. First, the basic mechanism of the heterostructure photocatalytic process is discussed, including the formation of the Schokkty barrier and the process of photocatalysis. Then, the latest studies for improving the utilization efficiency of HCs in two aspects, the generation and extraction of HCs, are introduced. Based on this, the applications of such heterostructure photocatalysts, such as water/air treatments and organic transformations, are briefly illustrated. Finally, we conclude by discussing the remaining bottlenecks and future directions in this field.