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Ultrasound assisted deposition of highly stable self-assembled Bi2MoO6 nanoplates with selective crystal facet engineering as photoanode
摘要： The use of crystal facets of photocatalysts is well known as a promising strategy for the design of new photocatalysts with interesting physicochemical features for energy production applications. In this work, Bi2MoO6 thin films were synthesized by two methods, electrodeposition and sonoelectrodeposition. Preferential growth orientation depended on synthesis method. Results suggested that sonoelectrodeposition led to dominate the crystal facet {1 0 0} growth with self-assembled nanoplate morphologies while growth orientation in the {0 1 0} facet was dominant in electrodeposition in the absence of ultrasonic waves. As a highlight result, the {1 0 0} facet shows a smaller band gap, higher photocatalytic water splitting than the {0 1 0} facet. Efficient separation of charge pairs and long life time of photogenerated electrons was observed to be intrinsic features of the {1 0 0} facets. The higher charge transfer was confirmed by a higher photocurrent from linear sweep voltammetry and a smaller Nyquist radius arc. Ultrasound plays a key role in growth orientation and led to a production of homogeneous films with nanoplates which self-assembled together to form a flower-like structure. While in the absence of ultrasound the film has coral-like structure. Highly stable sonoelectrodeposited films exhibited incident photon-to-electron conversion efficiency (IPCE) of 22.4% at the specific wavelength of 500 nm. The sonoelectrodeposition method could act as a promising method for forming new films with specific crystal facet selection and developing as highly efficient photoanodes for PEC water splitting.
关键词： Crystal facet engineering,Coral-like,Water splitting,Bismuth molybdate,Self-assembled nanoplates,Sonoelectrodeposition
更新于2025-09-23 15:21:01
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Low temperature platinum chemical vapor deposition on functionalized self-assembled monolayers
摘要： The reaction pathways of Pt CVD using (COD)PtMe2 – xClx (x = 0, 1, 2) have been investigated on functionalized self-assembled monolayers (SAMs) as models for organic substrates. Residual gas analysis for (COD)PtMe2 and (COD)PtMeCl is consistent with the loss of methyl radicals as the initial step in deposition, while for (COD)PtCl2, the first step is the loss of a chlorine radical. It is further shown using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry that the deposition process leads to chemical damage of the SAM layer and little Pt deposition. Using this understanding, it is demonstrated that the Pt CVD rate can be controlled using a radical trap. In the presence of 1,4-cyclohexadiene, a well-known alkyl radical trap, Pt deposition was increased by 5× to 10×, creating a room-temperature effective Pt CVD process.
关键词： time-of-flight secondary ion mass spectrometry,x-ray photoelectron spectroscopy,Pt CVD,chemical vapor deposition,self-assembled monolayers,radical trap
更新于2025-09-23 15:21:01
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Choline Chloride-modified SnO2 Achieving High Output Voltage in MAPbI3 Perovskite Solar Cells
摘要： Choline chloride as a photosynthesis promoter is important for increasing plant yield, and we have found that it has a similar effect in perovskite solar cells (PSCs). Here, we propose the innovation of using molecular self-assembly methods to produce a choline chloride monolayer on the surface of the SnO2; this monolayer works as a passivation layer that reduces the surface oxygen vacancies and improves the performance of CH3NH3PbI3 (MAPbI3) PSCs. The MAPbI3 PSC based on SnO2 modified by choline chloride (Chol-SnO2) electron transport layer (ETL) achieves an optimal power conversion efficiency (PCE) of 18.90% under one solar illumination. The PCE is increased by 10% ~ 25% compared to the device without modification, and hysteresis is significantly reduced by eliminating the charge accumulation between the interface of the perovskite and ETL. More importantly, the MAPbI3 PSC based on Chol-SnO2 ETL exhibits a higher open-circuit voltage (VOC) of 1.145 V compared to the control device (1.071 V). This work provides a very simple and effective way to improve PSC performance, which has long-term significance for the sustainable development of energy.
关键词： self-assembled monolayer,choline chloride,SnO2,electron transporting layer,perovskite solar cells
更新于2025-09-23 15:21:01
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Gallium arsenide waveguides as a platform for direct mid-infrared vibrational spectroscopy
摘要： During recent years, mid-infrared (MIR) spectroscopy has matured into a versatile and powerful sensing tool for a wide variety of analytical sensing tasks. Attenuated total reflection (ATR) techniques have gained increased interest due to their potential to perform non-destructive sensing tasks close to real time. In ATR, the essential component is the sampling interface, i.e., the ATR waveguide and its material properties interfacing the sample with the evanescent field ensuring efficient photon-molecule interaction. Gallium arsenide (GaAs) is a versatile alternative material vs. commonly used ATR waveguide materials including but not limited to silicon, zinc selenide, and diamond. GaAs-based internal reflection elements (IREs) are a new generation of semiconductor-based waveguides and are herein used for the first time in direct spectroscopic applications combined with conventional Fourier transform infrared (FT-IR) spectroscopy. Next to the characterization of the ATR waveguide, exemplary surface reactions were monitored, and trace-level analyte detection via signal amplification taking advantage of surface-enhanced infrared absorption (SEIRA) effects was demonstrated. As an example of real-world relevance, the mycotoxin aflatoxin B1 (AFB1) was used as a model analyte in food and feed safety analysis.
关键词： Mid-infrared chem/biosensor,Surface modification,Gallium arsenide,Self-assembled monolayers,Evanescent field absorption,Surface-enhanced infrared absorption
更新于2025-09-23 15:21:01
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Synthesis of Sphere-Like Silver Nanostructures Composed of Self-Assembled Nanosheets
摘要： Sphere-like silver nanostructures composed of self-assembled nanosheets were rapidly synthesized through adding ferrous sulfate into the mixture of silver nitrate and citric acid aqueous solution by magnetic stirring at room temperature for 20 min. The effects of the concentrations of the ferrous sulfate and citric acid on the morphology of the silver nanostructures were investigated in detail. The characterization of the sphere-like silver nanostructures composed of self-assembled nanosheets have been discussed by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and differential scanning calorimetry. Furthermore, the possible formation mechanism of sphere-like silver nanostructures composed of self-assembled nanosheets was explored. The experimental results show that the high concentration of citric acid and the low concentration of ferric sulfate are better for obtaining the sphere-like silver nanostructures composed of self-assembled nanosheets due to a low diffusion rate of silver atoms to the silver nucleus and a low growth rate of silver ?akes along the {111} facets. Such sphere-like silver nanostructures exhibit a strong surface-enhanced Raman scattering effect associated with their geometries, which is much stronger than that from nanosheets.
关键词： nanosheet,self-assembled,Sphere-like silver nanostructure,surface-enhanced Raman scattering effect
更新于2025-09-23 15:21:01
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Direct Patterning of Piezoelectric Thin Films by Inkjet Printing
摘要： Inkjet printing is currently gaining momentum as a low-cost and eco-friendly additive manufacturing technique for electronics. Patterning of functional metal oxide thin films on high surface energy substrates via inkjet printing remains a challenge and requires assistance from lithographic processes. This work unveils a novel process for lithography and etching-free patterning of lead zirconate titanate (PZT) films on pristine platinized silicon through the use of inkjet-printed alkanethiolate-based templates. The technique requires neither lithography nor etching, respectively, before and after PZT printing. The described process allows for feature sizes in the sub-100 μm range with control over the thickness of the final film. Inkjet-printed PZT displays typical ferroelectric and piezoelectric properties of solution-derived thin films, with remnant polarization 13 μC cm?2, coercive field 58 kV cm?1, permittivity 900, dielectric losses 0.07, and effective longitudinal piezoelectric coefficient 50 pm V?1.
关键词： piezoelectrics,lead zirconate titanate,inkjet printing,patterning,self-assembled monolayers
更新于2025-09-23 15:21:01
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A new SERS substrate of self-assembled monolayer film of gold nanoparticles on silicon wafer for the rapid detection of polycyclic aromatic hydrocarbons
摘要： A facile and rapid method for the SERS detection of polycyclic aromatic hydrocarbons (PAHs) was reported. The Au colloids assemble to form gold nanoparticles (Au NPs) monolayer film at the air/water interface through the modification of n-dodecanethiol (DT), and then the film was directly transferred by tilt-lifting onto the silicon wafer to fabricate uniformed SERS substrate. PAHs could be preconcentrated into DT layer on the surface of the SERS substrate through the hydrophobic interaction, and detected by SERS. The linear range of detection for Benzo[a]-pyrene (B[a]P) is from 10-8 to 10-5 mol/L with a linearity (R2) of 0.92 to 0.99. The recovery rates range from 89.5% to 103.7%. The detection limit can reach the ng/L level. Pyrene (Pyr) and Chrysene (Chr) were also detected by SERS. The substrate had good stability, uniformity, reproducibility and reusability, which demonstrated that the DT-functionalized Au NPs film prepared by the self-assembly method at the air/water interface could be used as a reliable SERS candidate for the rapid analysis of PAHs.
关键词： self-assembled monolayer (SAM),air/water interface,SERS,polycyclic aromatic hydrocarbons (PAHs),gold nanoparticles (Au NPs)
更新于2025-09-23 15:21:01
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[IEEE ESSDERC 2018 - 48th European Solid-State Device Research Conference (ESSDERC) - Dresden, Germany (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Gated Four-Probe Method to Evaluate the Impact of SAM Gate Dielectric on Mobility in MoS2 FET
摘要： This study reports the interfacial engineering by means of SAM (Self-assembled monolayer)-based gate dielectric on channel mobility in molybdenum disulfide (MoS2) field-effect transistors (FETs). A gated four-probe method was implemented to eliminate the effect of contact resistance on channel mobility. The formation of SAM significantly plays an important role in the improvement of channel mobility as high as 19 cm2/Vs in MoS2 FETs because the superior interfacial properties can be realized in MoS2/SAM structure. This study opens up interesting direction of interface engineering for research in the applications and developments of 2-dimensional materials-based thin film devices.
关键词： FETs,Interface properties,Channel mobility,Self-assembled monolayer,MoS2
更新于2025-09-23 15:21:01
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Evolution of microstructures on stainless steel induced by ultra-short pulsed laser ablation
摘要： Ultra-short pulsed laser ablation of stainless steel is accompanied by the evolution of different microstructures. Depending on the fluence, accumulated energy and number of laser passes cones from impurities, laser induced periodic surface structures, cone-like protrusion (CLP), and thermal bumps evolve at the surface. These often unwanted morphologies can be induced or inhibited by carefully choosing the strategy and laser parameters. The investigated range reveals a small processing window for defined 515 nm sub 1 ps ablation leading to low surface roughness using circular polarization. Hitherto, the origin and dependencies of CLP are still not well understood and for the first time a precursor ripple structure reported. These precursor ripples reveal supra-wavelength periodicity with about 2 μm spacing and evolve earliest after the second layer of ablation. Potentially, low spatial frequency laser-induced periodic surface structure generated with the first laser pass with pulse and hatch overlap are the root cause of CLP evolution. Moreover, the CLP growth is grain orientation and strongly polarization state dependent. Preferentially, CLP start to evolve at the {110} planes of the face-centered cubic crystals of the inspected austenitic stainless steel and linear polarized laser radiation revealing a 1:1 aspect ratio of 10 μm. A nanoindentation study at the interface near region on cross-sections reveals robust mechanical properties of this CLP structure.
关键词： Laser machining,Laser induced periodic surface structures,Ultra-short laser pulses,Orthogonal processing,Nanoindentation,Self-assembled structures,Cone-like protrusions
更新于2025-09-23 15:19:57
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Controlled Electroless Deposition of Noble Metals on Silicon Substrates Using Self-Assembled Monolayers as Molecular Resists to Generate Nanopatterned Surfaces for Electronics and Plasmonics
摘要： Electroless deposition of noble metals on silicon has applications in a wide range of fields including electronic circuitry, metal plating industry, lithography, and other fabrication techniques. In addition, studies using self-assembled monolayers (SAM) as resists for electroless deposition for controlled deposition have significant potential for aiding advancement in the fields of nano electronics, sensing applications, and fundamental studies. Herein, we discuss the development of appropriate plating solutions for controlled deposition of metallic gold and silver on Si(111) surfaces in the presence of an organic silane monolayer acting as a resist film for directed metal deposition to produce metal-monolayer hybrid surfaces while investigating microscopic plating trends. For this, plating solutions were optimized to deposit metal on bare silicon surfaces while avoiding deposition on the SAM protected areas. Trends in the electroless deposition of gold and silver on a Si(111) surface as a function of concentration of metal ions, NH4F, citric acid, sodium citrate, polyvinylpyrrolidone (PVP) and deposition time have been monitored under ambient conditions. The resulting surfaces were characterized using atomic force microscopy (AFM) and the stability of plating solutions was investigated by UV-Vis spectroscopy. For both gold and silver, we observed an increase in metal deposition when the concentration of NH4F, citric acid, and deposition time increased. The addition of PVP and the pH of the solution were also shown to have a significant effect on the metal deposition. The octadecyltrichlorosilane (OTS) SAM films act as effective nanoscale resists when the NH4F concentration is reduced from typical plating conditions. In particular, NH4F concentrations from 0.02-0.50 M and metal ions concentrations from 0.001-0.020 M were found to allow deposition of metal nanostructures on a bare Si surface while preserving OTS protected areas.
关键词： self-assembled monolayers,AFM,silver,controlled metal deposition,gold,Electroless deposition
更新于2025-09-23 15:19:57