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oe1(光电查) - 科学论文

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  • Synthesis and formation mechanism of amorphous silica particles via sol–gel process with tetraethylorthosilicate

    摘要： Silica microspheres with narrow particle size distribution and average diameter of 80-200 nm were prepared by hydrolysis and condensation of tetraethylorthosilicate (TEOS) in ethanol solution. Effects of TEOS, ammonia, water concentration, and temperature on particle size and morphology were investigated by laser particle size analysis and field emission scanning electron microscopy (FESEM), in conjunction with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) spectroscopy. Monomer addition model was employed to analyze the stability of intermediate, as well as the direction in which the reaction of silica particles proceeds. The analysis was carried out by Materials Studio. Results demonstrated that particle size of Nano-silica increases with increasing concentrations of H2O, NH3.H2O, and TEOS in ethanol, whereas the size decreases with increasing temperature. In addition, when proper amount of H2O was added into NH3.H2O at suitable temperature, silicic acid can act as a nucleus for amorphous Nano-silica particles, forming microspheres with round and smooth surfaces. By contrast, when TEOS was used, resultant nanoparticles have poor surfaces. During nucleation process of Nano-silica, silicic acid can also acts as nucleating agent providing a platform for the growth of nanoparticles with symmetric structure. Findings further indicated that the reaction proceeds by first silicic acid participates in the reaction, and the dimer and trimer molecules then react with the surface of silicic acid molecules; the same products could be produced by different reactions.

    关键词： Amorphous,St?ber Method,TEOS,Nano-silica,Monomer addition mode

    更新于2025-09-23 15:23:52

  • Preparation of Spherical Silica with Controllable Size

    摘要： The spherical silica particles were prepared by sol-gel method with TEOS as precursor, ethanol as solvent in the presence of ammonia. The effects of reaction temperature and the amount of ammonia and TEOS on the size and morphology of silica particles were investigated. The hydrolysis temperature , alkali and TEOS content does not affect the morphology of silica, the silica particles were spherical; With the increase of hydrolysis temperature, particle size of silica showed first increased and then decreased, when the hydrolysis temperature is 30 oC, the silica particle size up to 0.6 μm, when the hydrolysis temperature is 60 oC, the silica particle size is 0.15 μm; With the increase of the content of alkali, silica particle size showed first increased and then decreased, when the alkali content is 20 ml, the silica particle size up to 0.6 μm and when the alkali content is 10 ml, the silica particle size is 0.2 μm; With the increase of TEOS dosage, the amount of spherical silica increased and the particle size of silica spherical particles first increased and then decreased.

    关键词： spherical,TEOS,silica

    更新于2025-09-23 15:23:52

  • Dumbbell–Like Silica Coated Gold Nanorods and their Plasmonic Properties

    摘要： Silica coated gold nanorods with dumbbell-like morphology allowing dual functionalization in an individual nanostructure have attracted great attention for applications such as sensing and biological imaging. We report a detailed study on the feasibility of controlling the morphology of silica coating on gold nanorods. The morphology of the silica shell can be either cylindrical or dumbbell shaped. The morphology of the silica shell can be either cylindrical or dumbbell shaped. With constant GNR concentration, the ratio of CTAB and TEOS concentration is the key to determine the amount of available TEOS for silica deposition on GNR since the TEOS will diffuse towards the surface of GNRs. The effect of morphologies on surface-enhanced Raman scattering (SERS) performance was also investigated and we found that the dumbbell morphology of silica coated gold nanorods has the most significant SERS enhancement. Our study is significant in terms of the capability to control the dumbbell morphology of silica coated gold nanorods, which can eventually broaden the application of these plasmonic nanomaterials.

    关键词： SERS,TEOS,plasmonic properties,dumbbell-like morphology,CTAB,Silica coated gold nanorods

    更新于2025-09-12 10:27:22

  • Controlled synthesis of reduced graphene oxide supported magnetically separable Fe3O4@rGO@AgI ternary nanocomposite for enhanced photocatalytic degradation of phenol

    摘要： A ternary nanocomposite of Fe3O4@rGO@AgI was successfully synthesized by re?ux method for photodegradation of phenol. The prepared nanocomposite was characterized for the physicochemical properties through XRD, FESEM, TEM, TGA, FTIR, and PL spectroscopy techniques. Fe3O4@rGO@AgI exhibited higher photo-catalytic performance of 99% phenol degradation compared to 62, 75 and 78% using Fe3O4, Fe3O4@rGO and Fe3O4@AgI nanocomposites, respectively. The superior photocatalytic performance was mainly attributed to the rapid transportation of photogenerated electrons from GO nanosheets to AgI. The addition of H2O2 has further enhanced the phenol degradation and was the optimized loading amount of 0.4 g/350 mL achieved the highest degradation ef?ciency. The ?ndings revealed that basic conditions, initial phenol concentration and catalyst amounts have signi?cant in?uence on the photocatalyst performance. The 81% recyclability after ?ve continuous cycles implied the excellent stability of the photocatalyst for practical applications.

    关键词： APTES and TEOS,Graphene oxide,Re?ux method,Plasmon resonance effect,Fe3O4@rGO@AgI,Phenol

    更新于2025-09-12 10:27:22

  • A novel approach to coat silica on quantum dots: Forcing decomposition of tetraethyl orthosilicate in toluene at high temperature

    摘要： The coating of silica (SiO2) on quantum dots (QDs) has been widely studied, because SiO2 can protect QDs from the damages of moisture, radiation, and heat. Conventional SiO2 coating methods for QDs are usually performed in aqueous or emulsion solutions, which require the addition of water for the hydrolysis of SiO2 precursors and lead to the photoluminescence (PL) quenching of QDs. To address this issue, a novel SiO2 coating approach on single particle level was developed by the thermally forcing decomposition of tetraethyl orthosilicate in toluene. The CdSe/CdS/ZnS:Al@SiO2 nanoparticles (NPs) were prepared without decreasing the original PL quantum yield (QY), which exhibited much better photo and thermal stability in comparison with uncoated CdSe/CdS/ZnS:Al QDs. Furthermore, due to the natural formation of silanol groups on the SiO2 shell, CdSe/CdS/ZnS:Al@SiO2 NPs present not only good solubility but also excellent room temperature stability in phosphate buffer saline solution for several months.

    关键词： SiO2,TEOS,stability,core/shell quantum dots,water solubility

    更新于2025-09-11 14:15:04

  • Effect of dielectric and conductive targets on plasma jet behaviour and thin film properties

    摘要： A double layer DBD plasma jet driven by a pulsed generator is used for SiOx thin film deposition. The effects of dielectric and conductive targets on discharge behavior and film properties are analyzed. Different optical emission of the plasma jet at different positions are characterized. Film surface morphology, composition properties is studied. Results show that the relative optical emission intensities of Si, O, Ar and N2, as well as and thickness are measured for different targets. The excitation temperature (Texc), vibrational temperature (Tvib) fraction of N2 is added to the working gas (argon) to modulate film growth rate. The electrical property and Texc, Tvib and Trot are higher for the PMMA target between the high voltage electrode and the grounded electrode and rotational temperature (Trot) are calculated. The relationship between the discharge behavior and the film as optical transparency, sufficient insulation strength and scratch resistance1. The application of SiOx films is found in many fields, for example, microelectronics 2, biomedicine 3, food packaging 4 and high voltage insulation5. Plasma-enhanced chemical vapor deposition (PECVD) is one of the well-established methods for (referred to as the H-G region). However, Tvib and Trot appear to be higher on the surface of the copper (conductive) target. The morphology of SiOx film is different: nanoparticles are formed on the PMMA (dielectric) target while the synthesis of SiOx films. It typically involves a low pressure non-thermal plasma system. A low-pressure SiOx film is higher on the copper target. The presence of PMMA at the downstream of the plasma can be dense amorphous film is formed on the copper target. With the same depositing parameters, the thickness of the through the H-G region. Although the presence of a dielectric target enhances the discharge in the H-G region, considered as a small capacitor with a large resistance, which inhibits the current into the primary circuit passing the charge accumulation on the PMMA surface limits the film growth. These results may contribute to the development of next-generation plasma surface modification technologies for diverse applications in electronics, Siloxane (SiOx) films are of great interest because of their excellent physical and chemical properties such

    关键词： Target conductivity,Plasma jet,Film deposition,TEOS dissociation,Discharge behavior

    更新于2025-09-10 09:29:36

  • AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Study of self cleaning fabric modified by Cu doped TiO2 with the addition of tetraethyl orthosilicate (TEOS)

    摘要： Study of self – cleaning fabric modified by Cu doped TiO2 with the addition of TEOS has been done to achieve high performance of self – cleaning fabric. TiO2 doped Cu were made by using Photo Assisted Deposition (PAD) method. After that, certain compositions of the water, TEOS and Cu – TiO2 catalyst with the TEOS variated are prepared to be padded by the fabric and then dryed in the oven at certain temperature. The addition of TEOS in fabric coating is to improved the catalyst performance in self – cleaning ability and photodegradation of methylen blue. After the fabric is made, then analyzed it by using FTIR. The photodegradation is tested by puting a small amount of fabric to a methylen blue solution for 2 hours to see its absorbance using UV – Vis Spectroscopy and the self – cleaning ability test is to put the fabric in a sludge dirt for several minutes then spray it with water. FTIR result showed that the addition of TEOS cause Ti – O – Si bond to be applied in the fabric. The fabric coated with doped TiO2 has better performance than the undoped on both MB photodegradation and self – cleaning ability. The MB photodegradation performance of fabric increased with the amount of TEOS up to 74.4% within 2 hours and the efficiency of sludge dirt self – cleaning of fabric increased with the amount of fabric up to 83% efficiency, which is the type of fabric cotton Cu – TiO2 1,2% Si was the best among the other type of fabrics.

    关键词： photodegradation,TEOS,methylene blue,self-cleaning fabric,Cu doped TiO2

    更新于2025-09-04 15:30:14

  • Monitoramento da hidrólise/condensa??o do tetraetoxisilano em solu??o com baixo teor alcoólico por análises de espectroscopia de infravermelho

    摘要： O objetivo desse trabalho foi monitorar a hidrólise/condensa??o do tetraetoxissilano (TEOS) em fun??o do tempo de dilui??o do silano, por meio da análise de espectroscopia de infravermelho (IR). Inicialmente foram avaliadas duas concentra??es de silano (1 e 10% em volume). No entanto, verificou-se que em concentra??es de 1% de TEOS n?o foi possível identificar as liga??es químicas de interesse ao monitoramento da hidrólise de maneira adequada em regi?es características do espectro de infravermelho. Definida a concentra??o adequada, o monitoramento da hidrólise/condensa??o foi realizado por meio dos espectros de infravermelho obtidos em solu??es hidrolisadas à temperatura ambiente e extraídas a cada 10 minutos. Verificou-se que as rea??es de hidrólise dos grupos alcóxi aceleraram em 40 minutos a partir da dilui??o do TEOS. Em paralelo, a condensa??o dos silanóis também acelerou, devido ao aumento na sua concentra??o na solu??o. Após 70 minutos, a hidrólise/condensa??o apresentou uma desacelera??o por meio da forma??o de siloxano e devido à hidrólise completa dos grupos alcóxi do TEOS. A hidrólise do TEOS em solu??es com baixo teor alcoólico (em torno de 50% em volume) n?o mostrou prejuízos para o monitoramento das rea??es de interesse do sistema, apresentando cinética de rea??o similar ao reportado na bibliografia, mostrando-se como alternativa aos sistemas com consumo excessivo de solventes organicos.

    关键词： espectroscopia de infravermelho,silano,hidrólise,TEOS

    更新于2025-09-04 15:30:14

  • Water-dispersed fluorescent silicon nanodots as probes for fluorometric determination of picric acid via energy transfer

    摘要： Water-dispersed fluorescent silicon nanodots (SiNDs) were synthesized by a one-pot hydrothermal method starting from tetraethyl orthosilicate (TEOS) as silicon source and trisodium citrate as reducing reagent. The method is simple and convenient. The SiNDs, with excitation/emission peaks at 347/440 nm and with fluorescence quantum yield of 18% are shown to be viable fluorescent probes for picric acid (PA). The SiNDs strongly bind PA, and their blue fluorescence is quenched. The distance between the donor and acceptor (R0 value) is calculated from fluorescence data to be 2.1 nm. A fluorometric method was worked out that has a linear response in the 8 nM to 50 μM PA concentration range and a 0.92 nM limit of detection. The method has a fast response (2 min) and is well selective over other nitroaromatic compounds and metal ions. The average recoveries from spiked lake water samples ranged between 98.4 and 100.8%.

    关键词： Nitroaromatic compounds,Picric acid (PA),Fluorometric determination,Tetraethyl orthosilicate (TEOS),Hydrothermal strategy

    更新于2025-09-04 15:30:14