Single-step Hydrothermal Synthesis Research Articles

Synergistic Effect of Simultaneous Doping of Ceria Nanorods with Cu and Cr on CO Oxidation and NO Reduction.

Ceria particles play a key role in catalytic applications such as automotive three‐way catalytic systems in which toxic CO and NO are oxidized and reduced to safe CO2 and N2, respectively. In this work, we explore the incorporation of Cu and Cr metals as dopants in the crystal structure of ceria nanorods prepared by a single‐step hydrothermal synthesis. XRD, Raman and XPS confirm the incorporation of Cu and Cr in the ceria crystal lattices, offering ceria nanorods with a higher concentration of oxygen vacancies. XPS also confirms the presence of Cr and Cu surface species. H2‐TPR and XPS analysis show that the simultaneous Cu and Cr co‐doping results in a catalyst with a higher surface Cu concentration and a much‐enhanced surface reducibility, in comparison with either undoped or singly doped (Cu or Cr) ceria nanorods. While single Cu doping enhances catalytic CO oxidation and Cr doping improves catalytic NO reduction, co‐doping with both Cu and Cr enhances the benefits of both dopants in a synergistic manner employing roughly a quarter of dopant weight.

Biconcave Bi2WO6 Nanoparticles for UV Light-Activated Detection of Nicotine in Human Sweat and Cigarette Samples

We report a single-step hydrothermal synthesis of morphologically engineered biomimetic three-dimensional (3D) biconcave-shaped Bi2WO6-nanostructures for photo-enhanced ultrasensitive determination of nicotine in human sweat and cigarette samples. Detailed characterization reveals the formation of orthorhombic, red blood cell-mimicking Bi2WO6 nanoparticles. The average diameter of the biconcave Bi2WO6 nanoparticles ranged from 50 to 100 nm. The fabricated sensor displayed a sensitivity of 56.97 ± 2 μM-1 in the wide linear range of 50 nM-100 μM, with a limit of detection (LOD) of 13 nM (3σ) when exposed to nicotine. An enhanced sensitivity of 83.23 ± 1 μM-1 and a reduced LOD of 0.9 nM in the presence of UV light can be attributed to the outstanding sensing response of nicotine in the presence of UV light due to the synergistic-catalytic and photo-responsive properties of large-surface-area Bi2WO6 nanostructures. The photoinduced oxygen ions react with the adsorbed oxygen atoms assisting in the formation of O2- ions, which further contributes to the enhanced interaction with nicotine. The sensor displayed excellent selectivity toward nicotine in the presence of interferences and was robust to bending conditions, thus bolstering its practical applicability. Further, the sensor was employed in determining the unknown concentrations of nicotine in sweat and commercially available cigarettes. The strategy employed here expands the scope of photo-activated flexible nanoelectronic devices to develop affordable platforms for sensing various bioanalytes.

Hydrothermally grown nano-WO3 electrochromic film: structural and Raman spectroscopic study

ABSTRACT Tungsten oxide (WO3) thin films have practical implications in a variety of technological fields including electrochromic devices thus a good quality film must be deposited using an appropriate method. This drives the research on fabricating uniform, nano-particle sized WO3 film for application-oriented work. Synthesis of well distributed, porous and uniform nano- WO3 film using single-step hydrothermal synthesis method has been reported here followed by investigation of its electrochromic properties. Structural and spectroscopic studies have been carried out using SEM, XRD and Raman spectroscopy. The SEM results reveal uniform deposition of WO3 nanoparticles all over the substrate. Raman and XRD spectroscopy have been further used to investigate its structural composition. Excellent properties possessed by WO3 film make it standing apart in inorganic materials’ realm and open the door for its varied device-oriented applications especially in the field of electrochromism.

Reduced graphene oxide supported nickel tungstate nano-composite electrocatalyst for anodic urea oxidation reaction in direct urea fuel cell

In recent time direct urea fuel cell (DUFC) emerges as a potential candidate for sustainable urea reach wastewater treatment and power generation. The efficiency of DUFC mainly governed by the anodic urea oxidation reaction (UOR) kinetics. The design and development of efficient electrocatlysts for UOR remains a key factor for practical utilization of DUFC. In current study, we present a single step hydrothermal synthesis of NiWO4 NPs/rGO (h-NiWO4 NPs/rGO) composite for UOR catalysis in alkaline medium. The synthesized NiWO4 NPs/rGO composite offers a 218 mA/cm2 UOR catalytic current density. Moreover, the h-NiWO4 NPs/rGO composite retains its 94% UOR catalytic current after 1000 cyclic voltammetric cycles. Further, h-NiWO4 NPs/rGO composite shows superior UOR catalytic performance than physical mixture of NiWO4 NPs and rGO, NiWO4 NPs, NiO/WO3 physical mixture and only NiO with reference to catalytic current density, onset potential, and durability. The enhanced electrocatalytic activity of the h-NiWO4 NPs/rGO composite attributed to the synergetic coupling of physiochemical properties of NiWO4 NPs and rGO which improves the charge transfer generates larger electroactive surface and reduces catalyst poisoning. An air cathode DUFC with h-NiWO4 NPs/rGO composite modified anode and Pt/C cathode produces a maximum power density of 5.1 mW/cm2 and 927 mV open circuit potential.

Hydrothermal synthesis of zeolites from green container glass

Landfilling and stockpiling unrecycled colored container glass represents a considerable failure in sustainability with respect to the conservation of energy and mineral resources. In this study, the single-step hydrothermal synthesis of low-silica zeolites from a mixture of waste green container glass and aluminum foil (Al:Si = 1) in 4 M NaOH(aq) at 125 °C was followed at 1, 3, 7 and 14 days. The principal phases, sodalite and cancrinite, appeared within 1 day accompanied by minor quantities of hydrogarnet and tobermorite arising from a stoichiometric excess of calcium ions in the parent glass. Products of 63, 67, 71 and 72% crystallinity were obtained at 1, 3, 7 and 14 days, respectively, with partial successive conversion of sodalite to cancrinite over time. Ion-exchange and catalytic applications of sodalite and cancrinite arise from the high anionic charge of the 1:1 ratio of alternating SiO44- and AlO45- units within their aluminosilicate frameworks. In this respect, the uptake capacity of the 14-day zeolitic product for Cu2+ and Cd2+ ions (1.58 meq g-1 and 1.66 meq g-1, respectively) was within the expected range for zeolites and compared favorably with those reported for other inorganic sorbents derived from industrial and municipal wastes. The 14-day product was also found to be an effective basic heterogeneous catalyst for the Knoevenagel condensation reaction.

Tailoring morphology and structure of manganese oxide nanomaterials to enhance oxygen reduction in microbial fuel cells

In this study, 1D structures based on α-MnO2 nanowires and β-MnO2 nanorods were fabricated by a single-step hydrothermal synthesis and evaluated as cathode components for microbial fuel cells (MFCs). The role of crystallinity and morphology on electrocatalytic activity was investigated by combining X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy with an electrochemical analysis of oxygen reduction reaction at the surface of MnO2-based structures. Among the synthesized composites, β-MnO2 nanorods showed higher ORR activity thanks to the synergy between the rod-like morphology and the nitrogen presence in/on the carbon support which provides a more accessible surface for oxygen adsorption and consequent reduction. MFCs assembled with β-MnO2 nanorod cathode allowed achieving a maximum power density of 524 ± 3 mW m−2 and superior cycling stability as compared to α-MnO2 nanowires and control Pt/C.

Chalcopyrite based carbon composite electrodes for high performance symmetric supercapacitor

In the present work, we demonstrate a facile and single-step hydrothermal synthesis of chalcopyrite based carbon composite material (CuFeS2/carbon nanotubes) with the unique architecture in which the porous CuFeS2 (CFS) microflowers are encapsulated by the carbon nanotubes (CNT). The structural, morphological, compositional, chemical, vibrational and electrochemical properties of the fabricated CFS/CNT composite are analyzed in detail through comprehensive characterization techniques. When used as binder-free negative electrode material in the supercapacitor application, the CFS/CNT composite exhibits exceptional electrochemical performance than its pristine form (CFS). The electrochemical analysis clearly reveals the pseudocapacitive nature of composite electrode with improved electrical and charge-transport properties. In three-electrode configuration, the CFS/CNT composite electrode exhibits a high specific capacitance of 667F/g, a high columbic efficiency of 95% with 100% cyclic stability for 3000 cycles. The key factors influencing the supercapacitive performance of the electrodes are validated using extensive experimental results and are backed up with theoretical calculations of the relevant simulated models. The plausible storage sites of Na+ ions along with its valence charge transfer, electronic properties and binding characteristics on the composite electrode are identified through first-principles density functional theory (DFT) calculations. Furthermore, to evaluate its feasibility for practical application, a solid-state symmetric device (CFS/CNT//CFS/CNT) based on polymer gel electrolyte (PVA-Na2SO4) was fabricated. The symmetric device exhibited the highest specific capacitance of 128F/g, an energy density of 22 Wh/kg, a power density of 2083 W/kg and notable durability (94% cyclic stability for 10,000 cycles) reflecting its formidable candidature for future energy storage systems.

A hierarchical SnS@ZnIn2S4 marigold flower-like 2D nano-heterostructure as an efficient photocatalyst for sunlight-driven hydrogen generation.

Herein, we report the in situ single-step hydrothermal synthesis of hierarchical 2D SnS@ZnIn2S4 nano-heterostructures and the examination of their photocatalytic activity towards hydrogen generation from H2S and water under sunlight. The photoactive sulfides rationally integrate via strong electrostatic interactions between ZnIn2S4 and SnS with two-dimensional ultrathin subunits, i.e. nanopetals. The morphological study of nano-heterostructures revealed that the hierarchical marigold flower-like structure is self-assembled via the nanopetals of ZnIn2S4 with few layers of SnS nanopetals. Surprisingly, it also showed that the SnS nanopetals with a thickness of ∼25 nm couple in situ with the nanopetals of ZnIn2S4 with a thickness of ∼25 nm to form a marigold flower–like assembly with intimate contact. Considering the unique band gap (2.0–2.4 eV) of this SnS@ZnIn2S4, photocatalytic hydrogen generation from water and H2S was performed under sunlight. SnS@ZnIn2S4 exhibits enhanced hydrogen evolution, i.e. 650 μmol h−1 g−1 from water and 6429 μmol h−1 g−1 from H2S, which is much higher compared to that of pure ZnIn2S4 and SnS. More significantly, the enhancement in hydrogen generation is 1.6–2 times more for H2S splitting and 6 times more for water splitting. SnS@ZnIn2S4 forms type I band alignment, which accelerates charge separation during the surface reaction. Additionally, this has been provoked by the nanostructuring of the materials. Due to the nano-heterostructure with hierarchical morphology, the surface defects increased which ultimately suppresses the recombination of the electron–hole pair. The above-mentioned facts demonstrate a significant improvement in the interface electron transfer kinetics due to such a unique 2D nano-heterostructure semiconductor which is responsible for a higher photocatalytic activity.

Controlling the multicolor upconversion luminescence in CaF2 nanocrystals doped with Yb3+, Er3+ and Nd3+ ions under the excitation of a 808 nm laser

Nd3+-sensitized nanoparticles have attracted attention recently due to their large absorption cross section and lower water absorption coefficient at 808 nm, which can potentially solve the laser-induced heating problem and is essential for labelling and imaging applications in living organisms. Here, we report a single-step hydrothermal synthesis of CaF2:Yb3+/Er3+/Nd3+ upconversion nanoparticles (UCNPs). The size of the as-prepared UCNPs decreases from ∼138 to ∼30 nm as the Nd3+ doping concentration increases from 0 to 3 mol%. Under the excitation of a 808 nm continuous-wave (CW) laser, these UCNPs exhibit typical UC emissions at 539 nm (green) and 656 nm (red) for Er3+, and the luminescence is strongest when Nd3+ doping concentration is 0.75 mol%. Moreover, with the increase of doped Nd3+ ions, the suppressing of green and the enhancing of red UC emissions can be observed, which leads to the luminescence color tuning from green to red. Further investigations suggest that the resonant cross-relaxations (CRs) between Er3+ and Nd3+ ions contribute to the UC luminescence color changing and the remarkable red UC emission for the highly Nd3+-doped UCNPs. These advances make the UCNPs potentially to be applied in vivo labelling, bioimaging and phototherapy.

A ruthenium(IV) disulfide based non-enzymatic sensor for selective and sensitive amperometric determination of dopamine.

An electrochemical dopamine (DA) sensor has been fabricated by modifying a glassy carbon electrode (GCE) with ruthenium disulfide (RuS2) nanoparticles (NPs). FESEM and TEM micrographs show the NPs to have an average size of ~45nm. XRD, Raman and EDS, in turn, confirm the successful formation of cubic phased RuS2 NPs. The modified GCE displays has attractive features of merit that include (a) an ultra-low detection limit (73.8nM), (b) fast response time (< 4s), (c) a low oxidation potential (0.25V vs. Ag|AgCl), (d) excellent reproducibility and stability, (e) an electrochemical sensitivity of 18.4μAμM-1cm-2 and 1.8μA.μM-1.cm-2 in the linear ranges from 0.1-10μM of DA (R2 = 0.97) and 10-80μM of DA (R2 = 0.99), respectively. The sensor exhibits excellent specificity over potential interferents like ascorbic acid, glucose and uric acid. The superior performance of the sensor is attributed to its high electrical conductivity, large electro-active surface, and large numbers of exposed catalytically active sites resulting from the presence of unreacted sulfur atoms. Graphical abstract A ruthenium disulfide modified electrochemical sensor material was obtained by single-step hydrothermal synthesis. Sensitive and highly selective detection of dopamine is demonstrated.

Hydrothermal synthesis of silver molybdate/reduced graphene oxide hybrid composite: An efficient electrode material for the electrochemical detection of tryptophan in food and biological samples

A simple and accurate electrochemical sensor for the detection of tryptophan (TRP) was developed by modifying the surface of glassy carbon electrode (GCE) with silver molybdate incorporated reduced graphene oxide (AgM/RGO) composite. The AgM/RGO composite was synthesized by single step hydrothermal synthesis. The as-prepared AgM/RGO composite was confirmed by the various analytical and spectroscopic techniques. The electrochemical properties of the AgM/RGO composite was investigated by cyclic voltammetry and amperometric method. The AgM/RGO modified GCE shows an excellent electrochemical detection towards of TRP. The combination of AgM and RGO are not only enhanced the electrochemical properties of the composite but also improved the electron transfer between the electrode and TRP. Under the optimal condition, the proposed sensor was showed a wide linear range from 0.02 to 146.96 μM with a low detection limit of 0.0057 μM. Besides, the electrode sensitivity was calculated to be 4.327 μA μM−1 cm2. Remarkably, the proposed sensor exhibited good selectivity, stability, reproducibility and repeatability. The AgM/RGO/GCE was successfully applied to TRP determination in food and biological samples.

A novel design and synthesis of ruthenium sulfide decorated activated graphite nanocomposite for the electrochemical determination of antipsychotic drug chlorpromazine

A novel electrochemical sensor based on ruthenium sulfide nanoparticles decorated activated graphite sheets (RuS2/AG) was designed and fabricated for the determination of antipsychotic drug chlorpromazine hydrochloride (CPZ). Activated graphite sheets (AG) were prepared by non-explosive, non-hazardous and simple chemical activation technique. Then, the AG sheets were used for the synthesis of RuS2/AG nanocomposite by single step hydrothermal synthesis method. The synthesized materials were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), Raman spectrometer, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The synergistic effect of the RuS2/AG nanocomposite was applied for the determination of CPZ by cyclic voltammetry (CV) and differential pulse voltammetric (DPV) techniques. Fascinatingly, the RuS2/AG nanocomposite exhibited the excellent electrocatalytic activity and detects the CPZ at very lowest oxidation potential about 0.60 V vs Ag/AgCl in pH-7 PB solution. Moreover, the lowest LOD 8 nM and wider linear ranges from 0.05 to 79.75 and 79.75–1249 μM was obtained towards the CPZ determination. Besides, the proposed sensor shows the good selectivity, satisfactory repeatability, reproducibility and stability. Furthermore, the real time application was evaluated in pharmaceutical tablets and human urine samples.

Highly stable and bio-compatible luminescent molybdenum disulfide quantum dots for imaging of alimentary canal in Drosophila

Investigations on inorganic luminescent nanomaterials have always gained enormous attention of the science community for their possible applications in the fields of bioimaging and biomedicine. In this succession, various 0D structures including CdSe, CdTe, ZnS, graphene quantum dots (GQDs), carbon nanodots (CNDs) etc. have been explored for their possible applications in the field of biology. Recently, molybdenum disulfide quantum dots (MoS2-QDs) have been explored as an alternative of graphene quantum dots (GQDs) for their possible applications in relevant fields. Herein we report a facile, eco-friendly and single step hydrothermal synthesis of in-situ functionalized molybdenum disulfide quantum dots (f-MoS2-QDs). During the synthesis, variation in the pH of the starting solution provided the controlling over particle size. These as synthesized f-MoS2-QDs have shown excitation dependent broad emission spectra, which could be fitted for a parabolic function. The broadening in the emission spectra might be attributed to the polydispersity of f-MoS2-QDs in colloidal suspension, which was further confirmed with time resolved photoluminescence (TRPL) measurement. Due to surface capping provided by various functional groups present in the colloidal suspension, f-MoS2-QDs have shown excellent stability in aqueous medium and only a 3% of decrement in PL intensity was recorded even after six months. These synthesized f-MoS2-QDs possessed a quantum yield (QY) of 2.3% in aqueous media. Due to their high photostability and biocompatibility, these f-MoS2-QDs have been revealed as a potential entrant for in vivo bioimaging in Drosophila.

Single-step hydrothermal synthesis of WO3-MnO2 composite as an active material for all-solid-state flexible asymmetric supercapacitor

In present study, new strategy is employed to build composite nanostructure and asymmetric configuration to enhance the capacitive performance of supercapacitor device. The WO3-MnO2 composite with mesoporous structure is prepared by single-step hydrothermal method and used to gain superior electrochemical performance in asymmetric configuration. A binder-free and additive-less WO3-MnO2 composite electrode exhibits high specific capacitance of 609 F g−1 at a scan rate of 5 mV s−1. The flexible asymmetric supercapacitor device with WO3-MnO2 as a positive electrode and WO3 as a negative electrode demonstrates stable operating potential window of 1.4 V with specific capacitance of 103 F g−1 at a scan rate of 5 mV s−1 and energy density of 24.13 Wh kg−1 at power density of 915 W kg−1. Furthermore, WO3-MnO2//WO3 device exhibits good cycle life with capacity retention of 95% after 2500 cycles and excellent mechanical flexibility. These results reveal the potential of WO3-MnO2 composite electrode for fabrication of high-performance supercapacitors.

Single-step hydrothermal synthesis of wrinkled graphene wrapped TiO2 nanotubes for photocatalytic hydrogen production and supercapacitor applications

Herein, we discuss the synthesis of reduced graphene oxide and TiO2 (rGO-TiO2) nanocomposites with varying ratios of rGO to TiO2 by hydrothermal method. Photocatalytic ability of the nanocomposites was assessed for H2 production under natural sunlight. At 5wt% GO loading, the rGO-TiO2 exhibited 24,880μmol/g/h H2, 12.9 times to commercial P25-TiO2 (1920μmol/g/h). The symmetric supercapacitor device fabricated using rGO-TiO2 demonstrated 160F/g specific capacitance with 99% retention. The efficient charge carrier separation and transportation between TiO2 nanotubes and rGO resulted high photocatalytic activity. The synergistic double layer pseudo capacitor behavior of rGO-TiO2 is the reason for improved specific capacitance.

Green Synthesis of Fe3O4/RGO Nanocomposite with Enhanced Photocatalytic Performance for Cr(VI) Reduction, Phenol Degradation, and Antibacterial Activity

Herein, we report a novel single-step hydrothermal synthesis of a photocatalytically stable and magnetically separable g-Fe3O4/RGO nanocomposite in the presence of Averrhoa carambola leaf extract as a natural surfactant for multipurpose water purification application. The Averrhoa carambola leaf extract played a major role in the modification of structural, optical, and electronic properties of the Fe3O4 nanoparticle. At room temperature, the g-Fe3O4/2RGO nanocomposite showed 97% and 76% of Cr(VI) reduction and phenol degradation, respectively. The higher activity of g-Fe3O4/2RGO was attributed to the in situ loading of RGO, and the synergism developed between RGO and the super magnetic Fe3O4 nanoparticle results in better separation of photoexcited charge carriers (e–/h+) which was concluded from photoluminescence and photocurrent measurements. Further, the g-Fe3O4/2RGO nanocomposite showed better antimicrobial activity against three bacterial pathogens such as Staphylococcus aureous (MTCC-737), Bacillus...

Single step hydrothermal synthesis of carbon nanodot decorated V2O5 nanobelts as hybrid conducting material for supercapacitor application

Carbon nanodot (C-dot) decorated V2O5 (C-dot@V2O5) nanobelts are synthesized by single step, low cost hydrothermal route at low temperature by using V2O5 and glucose as precursors. We have not added any extra organic solvents or surfactants which are commonly used for the preparation of different nanostructures of V2O5. Electron microscopy analyses demonstrate that C-dot is entrapped inside V2O5 nanobelts which in turn enhance the conductivity and ion propagation property of this composite material. The C-dot@V2O5 nanobelts exhibit an excellent three electrode electrochemical performance in 1M Na2SO4 and which showed a specific capacitance of 270Fg−1 at 1Ag−1, which is ~ 4.5 times higher than the pristine V2O5 electrode. The electrochemical energy storage capacity of this hybrid is investigated towards solid state supercapacitor application also for the first time by employing electrophoretically deposited C-dot as the counter electrode and Li based gel as the electrolyte. The hybrid material delivers an energy density of 60Whkg−1 and a reasonably high power density of 4.1kWkg−1 at 5Ag−1 and good cycling stability and capacitance retention of about 87% was observed even after 5000 cycles. Above mentioned results clearly show that C-dot embedded hybrid, nanostructured transition metal oxides has great potential towards fabrication of electrodes for energy storage devices.

One-dimensional TiO2 nanostructured photoanode for dye-sensitized solar cells by hydrothermal synthesis

One-dimensional nanostructured photoanode in the dye-sensitized solar cell (DSSC) provides better electron transport and lifetime. One-dimension TiO2 nanostructures (1D-TNs) were prepared by single-step hydrothermal synthesis for 10 h using titanium(IV) isopropoxide (TTIP) and titanium(IV) chloride (TiCl4) as the precursor. Nano parallelepiped TiO2 film was uniformly grown on the substrate which was ball milled to increase the specific surface area to felicitate sufficient dye-loading for efficient DSSC. The synthesized nanostructures were characterized by scanning and transmission electron microscopy and X-ray diffraction. Photovoltaic properties of DSSC with prepared TiO2 1D-TNs as the active layer, N719 dye and Pt counter electrode was investigated. The power conversion efficiency of the prepared cells was measured by using solar simulator under standard test conditions (100 mW/cm2, AM 1.5). The cell performance can be maximized by optimizing the thickness of 1D-TNs photoanode. The promising power conversion efficiency of 5.77% was obtained with the photoanode of 5 μm thickness.

Single step hydrothermal synthesis of mixed valent V 6 O 13 nano-architectures: A case study of the possible applications in electrochemical energy conversion

Availability of several stable vanadium oxidation states offers numerous advantages in terms of applications but at the same time it poses great challenge to isolate them in single phase during their synthesis process. In this study, we developed a facile single step hydrothermal synthesis of V6O13 nano-architectures using environmental friendly citric acid as a reducing agent. By means of time dependant hydrothermal conditions study, we observed evolution of several stable vanadium oxide phases. The as-synthesized powder samples phase confirmation was thoroughly studied by powder X-ray diffraction and transmission electron microscopy. The morphology of the products formed was investigated at each hydrothermal reaction time. Finally, these V6O13 nano-architectures were employed as counter electrode (CE) in dye sensitized solar cells (DSSCs). The photovoltaic performance and the electrical impedance studies of the DSSC device made use of V6O13 nano-architectures are reported here. It is believed that with further optimization, this relatively inexpensive material can act as efficient CE for DSSCs, which thereby open up a new avenue for vanadium oxides as a new class of materials for clean energy generation.

Functionalized TiO2 nanoparticles by single-step hydrothermal synthesis: the role of the silane coupling agents.

A simple, robust and versatile hydrothermal synthesis route to in situ functionalized TiO2 nanoparticles was developed using titanium(IV) isopropoxide as Ti-precursor and selected silane coupling agents (3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPS), and n-decyltriethoxysilane (DTES)). Spherical nanoparticles (ca. 9 nm) with narrow size distribution were obtained by using DTES or by synthesis performed without silane coupling agents. Rod-like nanoparticles along with 9 nm spherical nanoparticles were formed using aminosilane coupling agents because of a combination of oriented attachment of nanoparticles and specific adsorption of the aminosilane on crystallographic faces of anatase nanoparticles. The nanoparticles were functionalized in situ and became hydrophobic as silanes reacted to form covalent bonds on the surface of TiO2. The versatility of the aqueous synthesis route was demonstrated, and by selecting the type of silane coupling agent the surface properties of the TiO2 nanoparticles could be tailored. This synthesis route has been further developed into a two-step synthesis to TiO2–SiO2 core–shell nanoparticles. Combustion of the silane coupling agents up to 700 °C leads to the formation of a nanometric amorphous SiO2 layer, preventing growth and phase transition of the in situ functionalized nanoparticles.