Infrared solar cells that utilize low-bandgap colloidal quantum dots (QDs) are promising devices to enhance the utilization of solar energy by expanding the harvested photons of common photovoltaics into the infrared region. However, the present synthesis of PbS QDs cannot produce highly efficient infrared solar cells. Here, a general synthesis is developed for low-bandgap PbS QDs (0.65–1 eV) via cation exchange from ZnS nanorods (NRs). First, ZnS NRs are converted to superlattices with segregated PbS domains within each rod. Then, sulfur precursors are released via the dissolution of the ZnS NRs during the cation exchange, which promotes size focusing of PbS QDs. PbS QDs synthesized through this new method have the advantages of high monodispersity, ease-of-size control, in situ passivation of chloride, high stability, and a “clean” surface. Infrared solar cells based on these PbS QDs with different bandgaps are fabricated, using conventional ligand exchange and device structure. All of the devices produced in this manner show excellent performance, showcasing the high quality of the PbS QDs. The highest performance of infrared solar cells is achieved using ≈0.95 eV PbS QDs, exhibiting an efficiency of 10.0% under AM 1.5 solar illumination, a perovskite-filtered efficiency of 4.2%, and a silicon-filtered efficiency of 1.1%.
Qiming Luo,Huiliang Cao,Lanyu Wang,Xiaohan Ma,Xuanyong Liu
Cell-selective toxic titanium is highly desired in clinical dental practice. Herein, based on the in situ conversion of ZnO to ZnO@ZnS, nanorod-array structured coatings with a controllable release features of zinc (Zn), has been successfully fabricated by a two-step hydrothermal method to endow titanium surface with cell-selectivity, i.e. boosting the functions (attachment and migration) of human gingival fibroblasts (HGnFs) while acting against the invasion of pathogenic bacteria. The improved functions of HGnFs over the ZnO@ZnS nanorod-array were attributed to the material’s optimized zinc release, which was decreased from an order of 3.5 mg L −1 to about 0.3 mg L −1 (within the first week). But more importantly, this concentration still had a high antibacterial efficacy up to 100% (against both the S. aureus and E. coli , 10 7 CFU mL −1 ). This study demonstrated that a ZnO@ZnS nanorod-array coating could be a promising strategy to endow titanium dental implants with improved soft tissue sealing and effectively reduce peri-implantitis.
Bo Ji,Jixiang Zhang,Cheng Zhang,Nian Li,Tingting Zhao,Fa Chen,Lihe Hu,Shudong Zhang,Zhenyang Wang
The photocatalytic degradation for environmentally hazardous substances has been widely explored with the use of various photocatalysts and techniques. It still remains a challenge to achieve efficient degradation and removal of residual antibiotics in the water environment. Here, we report an improved photocatalytic activity chip for degradation of antibiotic tetracycline hydrochloride by perpendicular ZnS-coated ZnO nanorod arrays (ZnO@ZnS NAs). The enhanced photocatalytic activity contributed to the polycrystalline ZnS shell’s effective inhibition of the recombination of photogenerated electron–hole pairs. Meanwhile, vertically aligned ZnO@ZnS nanorod arrays can increase the light harvesting ability by enhancing scattering of light among ZnO@ZnS NAs. On the basis of these findings, an improved photocatalytic activity ZnO@ZnS NA chip has been fabricated by growth of ZnO NAs on a piece of silicon wafer and further sulfurization. More importantly, ZnO@ZnS NA chips have been utilized to construct a ladderlike device, purifying antibiotics wastewater in one step, to effectively degrade tetracycline hydrochloride with enhanced photocatalytic efficiency in flowing contaminated water. In addition, the ZnO@ZnS NA device exhibited excellent recyclability in multiple repeated cycles. The ZnO@ZnS NA chip provided a convenient and fast strategy for removal of antibiotics and pharmaceutical residues in wastewater.
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