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Layer-by-layer self-assembly of polyaniline nanofibers/TiO2 nanotubes heterojunction thin film for ammonia detection at room temperature
摘要： In this paper, for the first time, polyaniline nanofibers/TiO2 nanotubes (PANI/TiO2) heterojunction thin film has been prepared on Pt interdigital electrodes by layer-by-layer self-assembly method and applied in room temperature NH3 detection. It is found that the optimal self-assembly layer number is three (PANI/TiO2-3) compared to one layer (PANI/TiO2-1) and five layers (PANI/TiO2-5). The PANI/TiO2-3 thin film sensor possesses superior response characteristics compared with our other PANI based sensors, including higher response value (336%@5 ppm NH3), acceptable response/recovery time (110 s/1086 s@5 ppm NH3), low detection limit (0.5 ppm), and remarkable selectivity. The enhanced gas sensing performances could be ascribed to the tremendous variation of the carrier concentration caused by the p-n junctions as well as the increased specific surface area and pore volume. This work not only offers a superb strategy to fabricate heterojunction thin film but also accelerates the development of room-temperature operable NH3 sensors.
关键词： Ammonia detection,Layer-by-layer self-assembly,Polyaniline/TiO2 heterojunction,Thin film,Room temperature operation
更新于2025-09-23 15:23:52
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Layer by Layer Self-Assembly of Hollow Nitrogen-Doped Carbon Quantum Dots on Cationized Textured Crystalline Silicon Solar Cells for Efficient Energy Down-Shift
摘要： Enhancing the efficiency of crystalline silicon solar cell (c-Si SC) by coating the energy shifting layer of quantum dots (QDs) is a recent approach to efficiently utilize the high energy spectrum of light. Carbon QDs are an attractive candidate for such applications, however, small Stokes shift and non-uniform coating due to high aggregation are the bottlenecks to fully utilize their potential. For the purpose, here we propose a layer by layer self-assembled uniform coating of ecofriendly red-emissive hollow nitrogen-doped carbon QDs (NR-CQDs), as an efficient energy-down shifting layer. A unique hollow and conjugated structure of NR-CQDs was designed to achieve a large Stokes shift (UV excited - red emission), with a quantum yield (QY) comparable to Cd/Pb QDs. Highly uniform coating of intrinsically negatively charged NR-CQDs on c-Si SCs was achieved by cationizing the c-Si SC by Bovine serum albumin (BSA), under mildly acidic conditions. By opposite charge assisted self-assembled over-layer, the short-circuit current density (Jsc) and power-conversion efficiency was increased by 5.8%, which is attributed to the large Stokes shift (255 nm) and high QY. Blue-emissive undoped-carbon QDs were synthesized for comparison with the proposed NR-CQDs, to elucidate the significance of the novel proposed structure.
关键词： energy-downshift,crystalline silicon solar cells,layer by layer self-assembly,Nitrogen-doped carbon quantum dots,cationization,photoluminescence
更新于2025-09-19 17:13:59
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Controllable Fabrication of Perylene Bisimide Self-assembled Film and Patterned All-solid-state Electrochromic Device
摘要： A water-soluble perylene bisimide derivative of N,N-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) was synthesized by introducing phosphoric acid units. PPDI self-assembled films were prepared controllably on hydroxylated ITO glass through a zirconium-phosphonate approach. There is a linear increase between the film thickness and the number of self-assembly layers. Electrochemical and spectroelectrochemical analysis reveal that the PPDI self-assembed films show excellent reversible redox behavior and cathodic electrochromic character which can be switched from a neutral orange-red color to deep purple color in the reduced state. In particular, the PPDI self-assembled film with 10 layers have good integrated performance in term of reasonable optical contrast (31%), fast switching time (0.75 s) and good cycle stability. A large-scale patterned all-solid-state electrochromic device (50 mm × 60 mm) was fabricated by utilizing PPDI self-assembled film as the electrochromic layer and the device shows obvious reversible electrochromism, which provides a new direction for the production of electrochromic device, like smart-window, sunglasses and electronic tags.
关键词： Perylene bisimide,Layer-by-layer self-assembly,Cathodic electrochromism,Patterned electrochromic device,Controllable fabrication
更新于2025-09-12 10:27:22