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Hypothesis: The properties of the oxidized surface for common materials, such as silicon and titanium, are known to be markedly different from the reduced surface. We hypothesize that surface-oxidized aluminum gallium nitride ((oxidized-AlGaN)/GaN) surface charge behavior is different to unoxidized AlGaN (with ultrathin native oxide only), which can be validated via surfactant adsorption. Understanding these differences will explain why (oxidized-AlGaN)/GaN-based sensors are better performing than AlGaN ones, which has been previously demonstrated but not understood. Experiments: The surface of an AlGaN/GaN structure was oxidized with hot piranha solution and oxygen plasma. AFM force measurements and imaging were performed to probe the charge properties of the surface in aqueous solutions of varying pH containing only an acid or base, or with an added ionic surfactant: cationic cetyltrimethylammonium bromide (CTAB) or anionic sodium dodecylsulfate (SDS). Findings: The (oxidized-AlGaN)/GaN surface is positively charged at pH 4 and pH 5.5, although pH 5.5 should be close to the isoelectric point of the surface. The surface is negatively charged at pH 10 and pH 12, and sufficiently charged to attract cooperative adsorption of CTAB aggregates at pH 12. At pH 2, the evidence is inconclusive, but the surface is most likely positively charged. Compared to unoxidized AlGaN, the (oxidized-AlGaN)/GaN surface shows a wider range of surface charge magnitude over pH values between 2 and 12. This suggests that the (oxidized-AlGaN)/GaN surface has a higher surface hydroxyl group density than unoxidized AlGaN, which explains the higher sensitivity for pH sensors based on (oxidized-AlGaN)/GaN structures.

Bacterial adhesion and colonization on stainless steel (SSL) based surgical instruments, hospital equipment, orthopedic implants, water purification and food processing units are a major problem. Imparting rechargeable antibacterial properties to SSL offers the prospect of a reusable and clean surface. In this study, the SSL surface was functionalized with a hydantoin-based antibacterial polymer that prevents bacterial adhesion and colonization. A new hydantoin monomer with three halogen binding sites, (Z)-N-((4-(2,5-dioxoimidazolidin-4-ylidene)methyl)phenyl)methacrylamide (DMPM), was synthesized, characterized and copolymerized with a commercially available 3-(methacryloyloxy)propyltrimethoxysilane monomer to develop the antibacterial polymer. The SSL surface was treated with piranha solution and the copolymer was covalently immobilized on the surface. The modified surface was examined for its antibacterial and anti-biofilm activity. The modified surface exhibited total kill (6 log reduction) of bacteria such as S. aureus and E. coli in 10 and 12 min respectively. The anti-biofilm activity of the modified surface was evaluated using a combination of fluorescence-based metabolic activity and scanning electron microscopy imaging suggested the comprehensive damage of S. aureus and E. coli biofilm architecture.

In the present work we introduce a simple approach to produce porous PtPdAg alloy nanoparticles on TiO2 nanotubes by a simple combined sputtering-dewetting-dealloying process. In a first step, three individual metals (Pt, Pd and Ag) were sequentially sputter-deposited on spaced TiO2 nanotubes, followed by a thermal dewetting treatment in Ar to convert these metal layers into ternary PtPdAg alloyed particles. Dealloying was carried out by a selective chemical dissolution of Ag in piranha solution that finally generated porous alloyed nanoparticles located on the TiO2 nanotube walls. The porous PtPdAg-decorated TiO2 nanotubes show enhanced photocatalytic H2 generation in comparison with porous Pt (67% increase) or any monometallic decoration (>120% increase). The photocatalytic enhancement is not only due to the increased number of active sites (larger surface area) of the porous particles but also due to the synergistic effects of the different alloying elements.

The usability of nanomaterials in various research endeavour has been on the front. burner in the past few decades. This is due to its high aspect ratio and steep electrical, molecular defined structure, mechanical and physical properties. This present study reports the synthesis of carbon nanomaterials (CNM) from Eucalyptus globulus leaves. Fresh green leaves of Eucalyptus globulus were collected and dried under the sun. The dried brown leaves were later incinerated completely under atmospheric oxygen. Obtained ashes were treated with acid piranha solution in other to modify the peripheral of the ashes with carboxyl groups (CNM-COOH). Scanning electron microscopy image divulges the presence of carbon nanorods in the ash. CNM-COOH materials in percentages were then incorporated within the polyurethane polymer matrix of which Castor seed oil (Ricinus communis) and trimethylopropane (TMP) provided the hydroxyl base for urethanation. Infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis was used to confirm material modification. Synthesized urethane composites of CNM-COOH material shows improved thermal, mechanical, hydrophobicity and anticorrosion properties when compared with that of pristine polyurethane (PU).

We report controllable adjustment of the flow dynamics of polystyrene films supported by oxide-covered silicon by using a combination of ultraviolet ozone (UVO) treatment of the polymer and variable treatments of the substrate that adjust the contents of Si–OH and Si–H groups on the surface. The latter were achieved by submerging the substrates in a piranha solution and then in deionized water (leading to enrichment of Si–OH) or an aqueous hydrogen fluoride solution (leading to enrichment of Si–H) or both (leading to intermediate surface chemistry). X-ray photoelectron spectroscopic chemical analyses showed that the UVO treatment produced oxygenated functional groups in the polymer. Alongside, effective viscosity (ηeff) of the films became enhanced. However, the degree of enhancement increases (decreases) with the content of Si–OH (Si–H) groups on the substrate surface, ascribable to the resulting increases in the attractive interactions between the UVO-induced oxygenated groups in the polymer and Si–OH o...

Compared with polymer microfluidic devices, glass microfluidic devices have advantages for diverse lab-on-a-chip applications due to their rigidity, optical transparency, thermal stability, and chemical/biological inertness. However, the bonding process to construct glass microfluidic devices usually involves treatment(s) like high temperature over 400 °C, oxygen plasma or piranha solution. Such processes require special skill, apparatus or harsh chemicals, and destroy molecules or cells in microchannels. Here, we present a simple method for glass-glass bonding to easily form microchannels. This method consists of two steps: placing water droplets on a glass substrate cleaned by neutral detergent, followed by fixing a cover glass plate on the glass substrate by binding clips for a few hours at room temperature. Surface analyses showed that the glass surface cleaned by neutral detergent had a higher ratio of SiOH over SiO than glass surfaces prepared by other cleaning steps. Thus, the suggested method could achieve stronger glass-glass bonding via dehydration condensation due to the higher density of SiOH. The pressure endurance reached over 600 kPa within 6 h of bonding, which is sufficient for practical microfluidic applications. Moreover, by exploiting the reversibility of this bonding method, cell recoveries after cultivating cells in a microchannel were demonstrated. This new bonding method can significantly improve both the productivity and the usability of glass microfluidic devices and extend the possibility of glass microfluidic applications in future.

An integrated approach combining severe plastic deformation (SPD), chemical etching (CE), and atomic layer deposition (ALD) was used to produce titanium implants with enhanced osseointegration. The relationship between morphology, topography, surface composition, and bioactivity of ultra-fine-grained (UFG) titanium modified by CE and ALD was studied in detail. The topography and morphology have been studied by means of atomic force microscopy, scanning electron microscopy, and the spectral ellipsometry. The composition and structure have been determined by X-ray fluorescence analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The wettability of the surfaces was examined by the contact angle measurement. The bioactivity and biocompatibility of the samples were studied in vitro and in vivo. CE of UFG titanium in basic (NH4OH/H2O2) or acidic (H2SO4/H2O2) piranha solution significantly enhances the surface roughness and leads to microstructures, nanostructures, and hierarchical micro-/nanostruc...

Implant-associated infections are the major concern for failure of arthroplasty operations. The functionalisation of implant surface can provide solutions to the problem by either inhibiting the adherence of the bacteria or introducing a contact-killing mechanism. This work is focused on Ti6Al7Nb biomedical alloy modification involving chemical and plasma surface activation, followed by the deposition of chitosan layers enhanced with metal nanoparticles. A benign method using chitosan as an efficient reducing and stabilizing agent was applied to produce Au and Ag nanoparticles in situ with the size of ca. 20 nm and 5 nm, respectively. Piranha solution and O2/NH3/Ar plasma were used as a surface activation method, while Au and Ag NPs provide antimicrobial properties, as a viable alternative to the antibiotic-based approach. The surface topography on submicrometre scale of deposited layers was evaluated. Chitosan and chitosan–Ag NPs composite layers showed excellent hydrophilicity, characterised by wetting angles below 13°. Modified alloy showed minimal toxicity towards MG-63 cell line in vitro, acceptable corrosion resistance and release of titanium, aluminium as well as niobium ions from the resulting modified alloys. The chitosan layers were proven to uphold satisfactory Au (over 2.8 mg/dm3) and Ag (over 5.1 mg/dm3) ion dosages up to 96h.

Irrigation water is a primary source of fresh produce contamination by bacteria during the preharvest, particularly in hydroponic systems where the control of pests and pathogens is a major challenge. In this work, we demonstrate the development of a Listeria biosensor using platinum interdigitated microelectrodes (Pt-IME). The sensor is incorporated into a particle/sediment trap for the real-time analysis of irrigation water in a hydroponic lettuce system. We demonstrate the application of this system using a smartphone-based potentiostat for rapid on-site analysis of water quality. A detailed characterization of the electrochemical behavior was conducted in the presence/absence of DNA and Listeria spp., which was followed by calibration in various solutions with and without flow. In flow conditions (100 mL samples), the aptasensor had a sensitivity of 3.37 &plusmn, 0.21 k log-CFU&minus, 1 mL, and the LOD was 48 &plusmn, 12 CFU mL&minus, 1 with a linear range of 102 to 104 CFU mL&minus, 1. In stagnant solution with no flow, the aptasensor performance was significantly improved in buffer, vegetable broth, and hydroponic media. Sensor hysteresis ranged from 2 to 16% after rinsing in a strong basic solution (direct reuse) and was insignificant after removing the aptamer via washing in Piranha solution (reuse after adsorption with fresh aptamer). This is the first demonstration of an aptasensor used to monitor microbial water quality for hydroponic lettuce in real time using a smartphone-based acquisition system for volumes that conform with the regulatory standards. The aptasensor demonstrated a recovery of 90% and may be reused a limited number of times with minor washing steps.

The mechanically mixed aluminum and cubic boron nitride (cBN) powder are important raw materials for preparing super-hard metal cutting tools. So aluminum shell-coated cBN may have significant economic potential. A Brownian motion based electrostatic self-assembly route in liquid salt of high temperature was developed using silica nanolayer bridge joint for the aluminum coating of cBN microparticles. In this approach, piranha solution method was first used to activate the surface of cBN cores, the silica nanolayer via sol-gel method served as the substrate for an outer aluminum coating of cBN cores. Coating of aluminum on cBN cores was accomplished by a self-assembly process from a liquid state solution of molten salt and aluminum powders. To distinguish small amounts of non-reacted aluminum powders which acted as aluminum source with the core - shell structure product, bromoform (CHBr3) was used to separate both of them due to the density differences. Samples were characterized by SEM, XRD, EDX and DSC. The contribution of our work lies in the creation of a novel strategy to fabricate a light metal element coating on the inert material particles in view of the versatility of sol-gel process and the controllability of the molten salt process.

Organic dye detection requires high sensitivity, low-cost equipment, simplified procedures, and real-time capabilities; thus, electrochemical methods are gradually emerging in this field instead of chromatography. However, much attention has been paid to toxic and complex metal or noble-metal hybrid materials for constructing electrochemical sensors, which is extremely limiting for practical applications. In this study, a metal-free electrocatalyst, MWNTs with carboxylic groups (MWNTs–COOH), was prepared through surface oxidation in a piranha solution and a simple hydrothermal treatment. The obtained MWNTs–COOH possessed superior hydrophilicity, increased conductivity and substantial active carbon or carboxylic group sites, as determined by characterization using Raman spectroscopy, contact angle measurements, electrochemical surface area analysis, and X-ray photoelectron spectroscopy. The above advantages enabled MWNTs–COOH to exhibit excellent electrochemical activities, with a satisfactory utilization for determining trace Rhodamine B (RhB), showing a lower calculated detection limitation of 2.66 nM and a wider linear range from 0.05 to 850 μM with outstanding specificity and reproducibility. Furthermore, it was found that the carboxyl group on the MWNTs would probably have triggered the electron redistribution and exposed more adjacent active carbon sites, which facilitate the electrocatalytic function to CN on the RhB directly.

Here, we report a non-aggressive method to obtain nanocellulose (NC) from the parenchyma of Agave salmiana leaves. This is accomplished by using a low concentration of a “piranha solution” to achieve solubilization and remove non-cellulosic components, isolating the NC in a single hydrolysis step. X-ray diffraction analysis has shown an increase in the crystallinity index of cellulose from 35 to 60 a result of the hydrolysis, and analysis by Fourier-transform infrared spectroscopy and Raman spectroscopy demonstrated that the cellulose had been purified. To test the thermal, mechanical, and optical properties of the NC, it was used to produce a paper. Analysis by scanning electron microscopy showed that the paper was formed from cellulose nanoplatelets (CNPs) stacked on top of each other.

We fabricated the first solid, mechanically robust inverse opal photonic crystals that diffract in the deep ultraviolet (UV) spectral region. These photonic crystals are fabricated by self-assembling

In this article, we used modified woven carbon fiber mat (wCF-COOH), as one of the contact-electrification Triboelectric Nanogenerator (TENG) friction layer to generate high open circuit voltage (Voc) and short circuit current (Isc). We designed the contact-separation mode TENG which is functional using spring structure. The oxidation of wCF into wCF-COOH by Piranha solution followed by coupling of aniline through electrostatic interactions and in-situ oxidative polymerization to get woven carbon fiber-polyaniline emeraldine salt (wCF.PANI.ES) composite is a novel approach. The wCF-PANI.ES composite displays the surface resistivity of 0.324 Ω m and serves as a friction layer to generate charges by harvesting energy through vertical contact-separation mode TENG against PVDF membrane. The dynamic interactions of novel wCF-PANI.ES and PVDF membrane produced high Voc of 95 V, and Isc of 180 μA, respectively. In particular, wCF-PANI.ES-TENG has shown an enhancement of 498% of Voc with respect to wCF-COOH-TENG due to availability of PANI layer. In addition, it was observed that the proposed wCF-PANI.ES-TENG has shown the output power of 12.4 mW at 5 Hz, and the rectified current upto 180 μA. The novel wCF-PANI.ES is the potential candidate for fulfilling the need of optimized energy harvesting device as an alternate material option for contact-separation mode TENGs.

Failures of biomedical implants due to implant-related infections and implant loosening remains a major concern in orthopaedic fixations. The current work aims to address the issues by examining the effect of dual interaction i.e surface modification and surface coatings on orthopaedic implant materials, i.e. commercially pure titanium (cpTi). The cpTi surface was initially modified with piranha solution (H 2 SO 4 + H 2 O 2 ) to create an antibacterial surface. Further, the biological properties similar to bone tissue were improved by electrospun coating on the piranha treated substrate with poly(e-caprolactone)(PCL)/hydroxyapatite (HA) composite nanofibers. The PCL/HA composite nanofibers have been characterized using SEM, XRD, EDS contact angle measurements, and FTIR spectroscopy. The coating adhesion of PCL/HA on cpTi was evaluated by cross-cut tape test (ASTM D3359-09). The newly fabricated substrates showed favourable properties and higher wettability. The antibacterial tests on piranha treated nanostructured substrates also confirmed a substantial reduction in bacterial growth over large areas. Cellular interactive responses such as adhesive and proliferation of osteosarcoma MG-63 cell lines has also demonstrated that presence of PCL/HA electrospun coating on the modified surface have improved the biological properties. The currently developed piranha treated and PCL/HA nanocomposite coated cpTi substrates seems to be a promising method to obtain both antibacterial and bioactive titanium surfaces.

Cell adhesion is essential for a cell to maintain its functions, and biomaterials acting as the extracellular matrix (ECM) play a vital role. However, conventional methods for evaluating the functions of biomaterials become insufficient and sometimes incorrect when we give a deeper insight into single-cell research. In this work, we reported a novel methodology for the measurement of cell-matrix adhesion at single-cell resolution that could precisely evaluate the functions of biomaterials for adherent cell culture. A microfludic device, a live single-cell extractor (LSCE), was used for cell extraction. We applied this method to evaluate various modified biomaterials. The results indicated that poly(l-polylysine) (PLL)-coated glass and fibronection (FN)-coated glass slides showed the best biocompatibility for adherent cell culture following by the (3-aminopropyl)triethoxysilane (APTES)-coated glass, while piranha solution treated glass slide and octadecyltrichlorosilane (OTS)-coated glass showed weak biocompatibilities. Furthermore, APTES, PLL, and FN modifications enhanced the cell heterogeneity, while the OTS modification weakened the cell heterogeneity compare to the initial piranha solution treated glass. The method not only clarified the cell-matrix adhesion strength at single-cell resolution but also revealed the influences of biomaterials on cell-matrix adhesion and heterogeneity of cell-matrix adhesion for adherent cell culture. It might be a general strategy for precise evaluation of biomaterials.

The surface of polystyrene foil (PS) was chemically modified. Firstly, the surface was pre-treated with Piranha solution. The activated surface was grafted by selected amino-compounds (cysteamine, ethylenediamine or chitosan) and/or subsequently grafted with five members of inorganic metallaboranes. Selected surface properties were studied by using various methods in order to indicate significant changes before and after individual modification steps of polymer foil. Elemental composition of surface was conducted by using X-ray photoelectron spectroscopy, chemistry and polarity by infrared spectroscopy and by electrokinetic analysis, wettability by goniometry, surface morphology by atomic force microscopy. Antimicrobial tests were performed on individual samples in order to confirm antimicrobial impact. Our results show slight antibacterial activity of PS modified with SK5 for Escherichia coli in comparison with the rest of the tested borane. On the other hand molecules of all tested metallaboranes could easier pierce through bacterial cell of Staphylococcus epidermidis due to absence of outer membrane (phospholipid bilayer). Some borane grafted on PS surface embodies the strong activity for Staphylococcus epidermidis and also for Desmodesmus quadricauda growth inhibition.

Two alumina samples, a high surface powder γ-alumina and a sintered α-alumina have been studied as substrates for apatite growth. In the first case, the initial stage was the calcium adsorption in an alkaline solution, followed by phosphate uptake. On the other hand, the α-alumina was firstly subjected to an acid piranha treatment at 80 °C for four hours, before alternate immersions on calcium and phosphate solutions. Next, the alumina samples were immersed repeatedly in a glycine buffer, pH 10.2, and then in tris buffer solutions, pH 7.4 at 32 °C. The resultant solids were studied by means of XRD, TEM or SEM. Calcium phosphate growth was observed in both cases. An almost uniform and continuous layer was formed on the sintered α-alumina. The results suggest that pretreatment with piranha solution seems to be a fast and efficient alternative to bioactivate the α-alumina surface.

We demonstrated dual-surface modification of GaN/AlGaN/GaN high-electron mobility transistors using tetramethylammonium hydroxide (TMAH) and piranha solutions prior to gate metallization. The TMAH-treated device exhibits improved performances with lower I-V hysteresis, in off-state leakage current and gate leakage current. The device performances were further significantly improved with applies additional piranha solution treatment right after the TMAH treatment, especially in hysteresis and 1/f-noise characteristics. It is found that the Schottky barrier height is high and ideality factor is low measured from I-V characteristics for the TMAH and piranha solution treated device. Reasonable gate leakage mechanisms were also discussed using Poole-Frenkel and Schottky emissions. In addition, it is observed that the magnitude of interface state density for the TMAH treatment after the piranha solution treated device shows significantly low compared to other devices. These excellent device-performances are observed due to the reason of dual-surface treatment which effectively decreases the surface trap density with an appropriate etching and passivation of the device surface exposed prior to the gate metallization.

Polyethylene terephthalate (PET) foils were activated with piranha solution and grafted with selected amino compounds (cysteamine, ethylenediamine or chitosan) and then with borane compounds. Changes in their surface properties after particular modification steps were examined using electrokinetic analysis, X-ray photoelectron spectroscopy (XPS), goniometry and UV-vis spectroscopy. Several tests showed that the presence of some amino compounds and one borane cluster significantly improved the antimicrobial properties of the composites investigated. In particular, they exhibited strong antibacterial activity against Staphylococcus epidermidis but only weak activity against Escherichia coli. The samples modified with amino compounds and subsequently with borane clusters were luminescent under UV lamp irradiation. Therefore, the nanocomposites consisting of (cheap) polymer and (more expensive) borane could be used in luminophore development, medicine or environmental protection.

In this work, Acetylcholinesterase enzyme (AChE) was immobilized on porous silicon (PSi) surface using two strategies. In the first method, acid chains were covalently grafted on the hydrogenated PSi by hydrosilylation reaction. The obtained acid-terminated surface was activated by a reaction with N -hydroxysuccinimide (NHS) in the presence of a peptide-coupling agent N -ethyl- N ′-(3-dimethylaminopropyl)-carbodiimide (EDC), and then reacted with the amino linker of the lysine residues AChE to anchor the enzyme by a covalent amide bond. In the second procedure, the PSi surface was first hydroxylated in piranha solution, followed by a silanization reaction with 3-aminopropyltriethoxysilane (APTES) to form amine-terminated surface. Finally, AChE was attached to the terminal amine groups by an aminolysis reaction with carboxylic acid groups of AChE in the presence of NHS/EDC mixture. Fourier transform infrared spectroscopy (FTIR) confirmed the efficiency of the surface modifications. The enzymatic activity of immobilized AChE was determined by means of a colorimetric test and was discussed according to the enzyme orientation on the surface which was revealed by contact angle measurements.

Removal of hydrogen sulfide as one of the most dangerous pollutants in molten sulfur has been studied here. In fact, catalytic degassing of Claus-derived molten sulfur containing about 150–200 ppmw of dissolved hydrogen sulfide and hydrogen polysulfide was performed over silica and nanosilica catalytic extrudates to reduce the hydrogen sulfide content up to environmental standard levels. In this regard, small extrude cylinders of silica and nanosilica particles were placed in a basket (mesh size of 4 mm) inside a batch reactor. Outlet of the degassing system was monitored by a hydrogen sulfide analyzer and also analyzed by IBT method. The results showed that residual content of hydrogen sulfide in molten sulfur during 4 h of degassing at 150 °C was as low as 6, 20, 60 ppmw for degassing by nanosilica, bulk silica, and nitrogen, respectively. This revealed the positive effect of accessible surface area in the decomposition of polysulfide bonds in molten sulfur. Degassing catalysts were then subjected to characterization by analytical methods including Brunauer, Emmett, and Teller analysis, field-emission scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and mechanical strength test. The spent catalysts were also regenerated by using Piranha solution for increasing the density of the lost silanol groups, which decreased the residual hydrogen sulfide in molten sulfur until 12 ppmw. This reflected the effect of surface silanol groups in improvement of proton abstraction, as the main reason for decomposition of hydrogen polysulfide in system.

This paper reports an ultra-thin glass sheet diaphragm transducer for measuring pressure. In this paper, we demonstrated the air pressure (0–800 mBar) measurement at room temperature and at high temperature (>300 °C). The proposed pressure transducer is suited for applications requiring a small size ( 2 ), visibility of the measuring area and both chemical and physical stabilities. The prototype ultra-thin glass sheet (UTGS) integrated all-glass transducer was made by sandwiching a 4 or 6 μm thick UTGS between a glass slide with an orifice and a glass slide with a channel. When applying pressure on the inlet of the channel, the UTGS at the orifice was deflected, and the deflection was measured through a video captured by a CCD mounted level difference measurement microscope. The maximum UTGS deflection was approximately 10.53 μm, and the response was at least faster than 10 Hz at an air pressure condition of 800 mbar. A practical sensitivity in the range of 0.0029–0.04105 μm/mbar was achieved experimentally, and that makes this transducer suitable for highly sensitive, low-pressure measurement. The pressure measurement function of our transducer was confirmed at 301 °C, and after a chemical cleaning process using acetone and piranha solution, the transducer appeared to have no obvious damage. The proposed transducer offers a new method for on-chip air and liquid pressure measurement during direct observation of the measurement point.

In this study, we implemented a functionalization process on the surface of silicon nanowires (SiNWs) which were fabricated by chemical vapour deposition (CVD) method in a low-pressure CVD (LPCVD) chamber. Surface functionalization was carried out in three stages: hydroxylation of the surface with piranha solution, silanization with a solution of 3-Aminopropyl triethoxysilane (APTES) in n-hexane, and finally functionalization with folic acid as a detection agent. Optical spectroscopy and electron microscopy techniques were used to experimentally characterize materials. Surface functionalization was evaluated using Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (FTIR-ATR), Field Emission Scanning Electron Miscoscopy (FESEM), and Transmission Electron Microscopy (TEM). Cell adhesion to functionalized and non-functionalized silicon nanowires was compared; a cell assay analysis on lung metastatic cells was conducted. Lung cancer metastatic QUDB cells were seeded on a SiNWs surface in RPMI1640 complete medium. To evaluate the adhesion of cancer cells to these surfaces FESEM imaging was used. The number of cancer cells trapped on the folic acid functionalized SiNWs was found to be approximately 3 times higher than that of the non-functionalized ones. This article is protected by copyright. All rights reserved

Photonic encoding magnetized silica microspheres were synthesized from a polydisperse system containing silica and Fe3O4 nanoparticles by using a microfluidic self-assembly device. The optical and structural properties of the magnetized microspheres were characterized by scanning electron microscopy and reflection spectra. The concentration of Fe3O4 nanoparticles in polydisperse system was found to strongly affect the characteristics of magnetized microspheres. They possess a Janus face, are porous, and possess structural color (red). The magnetic characteristic of the synthesized microspheres is not lost after they are immersed in piranha solution for 12 h. The magnetized microspheres were applied to aptamer-based enrichment of the food toxin Ochratoxin A (OTA). Methods for immobilization of OTA aptamer on the microsphere surfaces were investigated. The modified microspheres can extract up to 80% of OTA if the surface of the microspheres is loaded with 275 ng·cm−2 of aptamer and the number of microspheres is 200. The work provides a new pathway for aptamer-based enrichment of small molecules from complex matrixes.

Graphene oxide (GO), an emerging material ornamented with oxygen-containing functional groups, is becoming a promising alternative for various applications. The piranha solution treatment of GO can increase oxygen-containing functional groups and result in improved graphene oxide (IGO), as well as restore the functional groups lost because of the reaction. It is found that GO can oxidize the amine to the corresponding imine in the absence of oxygen and a catalyst, and the obtained IGO even shows higher activity. In addition, the piranha solution can partially restore the reactivity of GO after the reaction. The different roles of oxygen-containing functional groups in the oxidative coupling reaction are investigated. A possible reaction mechanism for the oxidation of benzylamine to N-benzylidene benzylamine is also proposed.

Interfacial engineering has been considered as an effective technique to improve the photovoltaic performance of perovskite solar cells (PSCs). Here, the interface between tin oxide (SnO2) film and fluorine-doped tin oxide (FTO) glass is dealt with a piranha solution, resulting in more hydroxyl groups on the surface of FTO glass. SnO2 film is fabricated by spin-coating SnCl2·2H2O precursor. Our results demonstrate that SnO2 film exhibits high electrical conductivity, low electron trap density, and suitable energy level. Furthermore, SnO2 film with low roughness is beneficial to fabricate high-quality perovskite film. Then, the PSCs with the structure of FTO/SnO2/Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3/Spiro-OMeTAD/Au are also fabricated. The highest power conversion efficiency (PCE) of PSCs increases from 18.28% to 19.51%, and the average PCE enhances from 17.82% to 18.89%. The optimized PSC shows the long-term stability and remains 97% of its initial PCE after 4000 h on-shelf lifetime test.

In this work, we introduce a reliable and direct method to activate fluoropolymers via integrating covalent labile ones for further modification. Basic piranha solution was used for the first time to functionalize polymeric surface with hydroxyl moieties. Subsequently, surfaces were modified with a varied molecular grafting. Materials were characterized and tested in several separation processes, including air-gap membrane distillation, osmotic membrane distillation, and microfiltration. This method deciphers surface architecture for various applications not only in membranes but also in variety of fields where functionalized fluoropolymers are employed. The work is also comparing membranes activated with acid and base piranha. The latter produced much more stable and resistant membranes with respect to the acid-treated ones. Systematic and material characterization on the molecular level, with the implementation of various spectroscopic, microscopic, and other techniques, was performed to prove and assess the generated, highly effective separation materials. The presented method opened the gate for fast and easy production of advanced functionalized fluoropolymers.

Piranha solution is a highly acidic mixture of sulfuric acid and hydrogen peroxide. The present study aimed at developing a dimensionally stable anode (DSA), made of titanium metal foil coated with Ruthenium Dioxide (RuO2), for the electrochemical oxidation of hydrogen peroxide in the presence of strong sulfuric acid under ambient conditions. Results showed that hydrogen peroxide in the piranha solution was fully degraded in 5 h under a constant current of 2 A (or current density of 0.32 A-cm-2). The oxidation kinetics of hydrogen peroxide followed the Langmuir-Hinshelwood model. The observed rate constant was a function of applied current. The initial current efficiency was 17.5% at 0.5 A (or 0.08 A-cm-2) and slightly decreased to about 13.5% at applied current between 1.3 and 1.5 A (or current density of 0.208 and 0.24 A-cm-2). Results showed the capability and feasibility of the electrochemical oxidation process for the recovery of sulfuric acid from the spent piranha solution in semiconductor industrial installations or general laboratories.

A mixture of H2SO4 and H2O2 (known as piranha solution) was used to remove organic structure-directing agents (OSDA) from multilamellar MFI zeolite (ML-MFI). An aqueous solution of MFI zeolite nanosheets was obtained via exfoliation of the OSDA-free ML-MFI zeolite through sonication in water followed by purification through sedimentation. The exfoliated MFI zeolite nanosheets were characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and porosimetry by cryogenic N2 adsorption-desorption, indicating that single-layer MFI nanosheets were obtained and the micropores were opened. MFI nanosheets/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) were prepared by the solution casting method using the open-pore MFI zeolite nanosheets as the filler and PDMS as the continuous phase. The obtained MMMs exhibited greatly improved butane isomer permeabilities and ideal selectivities for n-butane over i-butane compared to the pure PDMS membrane. An ideal selectivity of 15.7 for n-butane/i-butane was achieved on the MMM at 1 wt% loading of MFI nanosheets, with a n-butane permeability up to 15615 Barrer.

Biosensor is a rapid technique to determine the analyte based on the incorporation of bioactive materials with physio-chemical transducing element. In this work, multi-walled carbon nanotube (MWCNT) was functionalized with carboxylic groups and mixed with chitosan (CS) prior to drop casting on screen-printed carbon electrode (SPCE). The acid treatment of multi-walled carbon nanotube by using mixture of H2SO4 and HNO3 in 3:2 ratio was better compared to treatment by piranha solution, in terms of carboxylic group attachment and capacitance effect on the current response. The functionalized carbon nanotubes were characterized by using fourier transform infrared spectroscopy, field emission scanning electron microscopy and cyclic voltammetry analysis. Few modification parameters have been optimized to maximize the performance of working electrode including ratio of MWCNT:CS, coating volume and drying method. The addition of MWCNT/CS matrix on the screen-printed carbon electrode greatly enhanced the electron transfer rate and increased the electrode active surface area for further immobilization of bioactive components.

In this paper, we report a flame deposition method to prepare carbon nanoparticles (CNPs) from coconut oil. The CNPs were further modified with a piranha solution to obtain surface-carboxylated carbon nanoparticles (c-CNPs). When used as an anode for sodium-ion batteries, the CNPs and c-CNPs respectively delivered discharge capacities of 277 and 278 mA h g−1 in the second cycle at a current density of 100 mA g−1. At the 20th cycle, the capacities of CNP and c-CNPs were 217 and 206 mA h g−1 respectively. The results suggest that modification of the CNPs with the piranha solution improved neither the charge storage capacity nor the stability against cycling in a sodium-ion battery. When the CNP and c-CNP were used an anode in a lithium-ion battery, 2nd-cycle discharge capacities of 741 and 742 mA h g−1 respectively at a current density of 100 mA g−1 were obtained. After 20 cycles the capacities of CNP and c-CNP became 464 and 577 mA h g−1 respectively, showing the cycling stability of the CNPs was improved after modification. The excellent cycling performance, high capacity and good rate capability make the present material as highly promising anodes for both sodium-ion and lithium-ion batteries.

Beta-phase alloys like Ti-40Nb with outstanding elastic properties are promising new materials for implant applications. For the generation of bioactive surface states electrodeposition of hydroxyapatite (Hap) was conducted on alloy substrates in a water-based electrolyte with 6.1 × 10 − 4 M Ca(NO 3 ) 2 and 3.6 × 10 − 4 M NH 4 H 2 PO 4 and results were compared with those obtained for cp2-Ti. The impact of electrolyte temperature and of different chemical pre-treatments of the alloy surface, i.e. etching in piranha solution and alkali treatment, on the cyclic polarization behavior and on the potentiostaticly generated deposit characteristics were assessed. At all adjusted surface states the high Nb content of the beta-phase alloy alters passivity by incorporation of oxidized Nb species in the Ti oxide film, but this has no significant impact on the cathodic reduction steps of the complex deposition process. On Ti-40Nb single-phase microcrystalline Ca 10 (PO 4 ) 6 OH 2 (Hap) with preferred {002} orientation grows. Increasing the electrolyte temperature from 333 K to 353 K yields accelerated Hap growth rates and a morphology change from plate-like to needle-like. At 353 K on mechanically ground Ti-40Nb, adhesive layers with a mean thickness of 1–2 μm precipitate. Chemical pre-treatments of the alloy surface yield small variations of the Hap coating morphology.

Graphene oxide (GO) has been widely used as a fluorescence quencher, but its luminescent properties, especially tailor-made controlling emission colors, have been seldom reported due to its heterogeneous structures. Herein, we demonstrated a novel chemical oxidative strategy to tune GO emissions from brown to cyan without changing excitation wavelength. The precise tuning is simply achieved by varying reaction times of GO nanosheets in piranha solution, but there is no need for complex chromatography separation procedures. With increasing reaction times, oxygen content on the lattice of GO nanosheets increased, accompanied by the diminution of their sizes and sp(2) conjugation system, resulting in an increase of emissive carbon cluster-like states. Thereby, the luminescent colors of GO were tuned from brown to yellow, green, and cyan, and its fluorescent quantum yields were enhanced. The obtained multicolored fluorescent GO nanosheets would open plenty of novel applications in cellular imaging and multiplex encoding analysis.

In this study, a sensitive biosensor was developed based on aptamer functionalized polydimethylsiloxane (PDMS) film for the detection of Staphylococcus aureus (S. aureus) using surface-enhanced Raman scattering (SERS) technology. Initially, the surface of PDMS film was chemically modified by piranha solution and 3-Aminopropyltriethoxysilane (APTES), and then AuNPs-PDMS film was prepared by coating gold nanoparticles (AuNPs) through electrostatic interaction. Next, the aptamers were immobilized on the AuNPs-PDMS membrane via gold-sulfur bond to form the capture substrate. Meanwhile, gold-silver core-shell nanoflowers (Au@Ag NFs) modified with mercaptobenzoic acid (4-MBA) and aptamers were applied as a signal probe. In the presence of the target, the signal molecular probe and the capturing substrate specifically combined with the target and resulted in a sandwich structure “capture substrate-target-signal molecular probe”. Under the optimized experimental condition, the signal of 4-MBA at 1085 cm-1 was linearly related to the S. aureus concentration in the range of 4.3 × 10 cfu mL−1-4.3 × 107 cfu mL−1 (y = 326.91x-117.62, R2 = 0.9932) with a detection limit of 13 cfu mL−1. The method was successfully applied to spiked actual samples and a 92.5–110% recovery rate was achieved.

All-fiber modulators and switches have drawn great interest in the photonics domain, and they are applied in viable photonic and optoelectronic devices. In this work, with the assistance of an agarose membrane, aspherical gold nanoparticles are embedded on the surface of the microfiber treated with the piranha solution. An all-fiber Mach–Zehnder interferometer was used to realize a low-cost, low-loss, and conveniently prepared all-fiber phase modulator. By taking advantage of the local surface plasmon resonance effect of gold nanoparticles embedded in the agarose membrane, under the excitation of near-infrared region light, the gold nanoparticles were excited to change the effective refractive index of one arm of the Mach–Zehnder interferometer. A maximum phase shift of ∼ 6 π at 1550 nm was obtained from the device. In addition, an all-optical switch was achieved with a rising edge time of 47 ms and falling edge time of 14 ms. The proposed all-fiber modulator and switch based on the local surface plasmon resonance effect of gold nanoparticles embedded in agarose membrane will provide great potential in all-optical fiber systems.

The present work describes the preparation and characterization of chemically treated graphite by different strategies and its use for the construction of nickel-based electrochemical sensors for ethanol determination. Chemical treatment of graphite powder was carried out under three different conditions: with nitric acid, with piranha solution (98% sulfuric acid and 30% hydrogen peroxide in the ratio of 70:30) and by the Hummers method. Treated and untreated graphite samples were characterized by scanning electron microscopy techniques (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and thermogravimetry (TG). Surface chemical groups were estimated by Boehm titration. Carbon paste electrodes were constructed using untreated and treated graphite and evaluated for adsorption of nickel ions. After that, exploring the catalytic proprieties of redox pair Ni(II)/Ni(III) the device was applied towards ethanol oxidation. From all chemical treatments evaluated, samples of graphite treated by the Hummers method presented the best analytical performance. Using the best set of experimental conditions, it was observed a linear dynamic range (LDR) between 50 and 1000 μmol L−1 with a sensitivity of 42.1 μA L mmol−1 and limit of detection (LOD) and quantification (LOQ) of 15 and 50 μmol L−1, respectively. The electroanalytical application of the sensor was performed for ethanol quantification in four distilled beverage samples (vodka, cachaca, pisco and whiskey) using amperometry. The obtained results agree with a comparative method at a confidence level of 95%. Repeatability studies for five different electrodes showed an RSD of less than 10%.

Surface of ultra-high-molecular-weight polyethylene (UHMWPE) was modified by chemical methods. Surface was firstly activated by Piranha solution and then grafted with selected amino-compounds (cysteamine, ethylenediamine or chitosan). The next step was grafting of some borane cluster compounds, highly fluorescent borane hydride cluster anti-B18H22 or its thiolated derivative 4,4'-(HS)2-anti-B18H20. Polymer foils were studied using various methods to characterize surface chemistry (X-ray photoelectron spectroscopy), roughness and morphology (atomic force microscopy, scanning electron microscopy), chemistry and polarity (electrokinetic analysis), wettability (goniometry) and photophysical properties (UV-Vis spectroscopy) before and after modification steps. Subsequently some kinds of antimicrobial tests were performed. Immobilization of anti-B18H22 in small quantities onto UHMWPE surface leads to materials with a luminescence. Samples grafted with borane clusters showed significant inhibition of growth for gram-positive bacteria (S. epidermidis). These approaches can be used for (i) luminophores on the base of polymers nanocomposites development and/or (ii) preparation of materials with antimicrobial effects.

We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested, and the between-fiber reproducibility (n = 3) was 0-15%, generally 5-10%, for all analytes tested. The repeatabilities of our sputtered fibers and the commercial 7 μm PDMS fiber are essentially the same. Fibers could be used for at least 300 extractions without loss of performance. More than 50 compounds were identified in a gas chromatography-mass spectrometry headspace analysis of a real world botanical sample with the 2.0 μm fiber.

An indium gallium zinc oxide (IGZO) layer was patterned and thin-film transistors (TFTs) were fabricated by surface modified polydimethylsiloxane (PDMS) stamping and IGZO solution. The PDMS stamp was prepared by immersion in piranha solution and treatment with UV–ozone to make a hydrophilic surface. Patterned PDMS was inked by contact with the IGZO layer, and then stamped on the desired substrate. The process did not cause etching damage, so the stamped amorphous-IGZO TFTs showed low leakage current of ∼10−11 A, high on/off current ratio of ∼108, carrier mobility of 6 cm2 V−1 s−1, and narrow hysteresis of 0.2 V. UV irradiation on the IGZO layer caused a photochemical annealing effect that improved the electrical properties of IGZO TFTs. This method provides a simple and versatile process to fabricate transparent metal-oxide TFTs based on patterning the devices by reusable stamping methods.

The aim of this work was to improve mechanical properties such as flexural strength and interlaminar shear strength (ILSS) of polyetheretherketone (PEEK) thermoplastic polymer which has very high processing temperature due to its high melting temperature. Carbon fiber (CF) surface was modified by two different methods: oxidative and non-oxidative. Piranha solution and chromate solution were used for chemical treatment (oxidative treatment), and silicone based polymers were used for polymer coating (non-oxidative). The changes on the surface structure and surface chemistry were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR), respectively. FTIR results indicate that coating fibers decreases carbon element content, whereas increases the oxygen and silicone content as well as their functional groups on the surface. Flexural strength and ILSS properties of CF/PEEK composites were measured according to ASTM D-790 and ASTM D2344, respectively.

Hydrophobic mica particles were prepared by piranha solution activation, silanization, and copolymerization with acrylate monomers. Its surface morphology, hydrophilic properties, and thermogravimetric analysis changed differently in comparison with those of pristine mica. Scanning electron microscopy (SEM) showed that the modified (001) mica surface changed from flat to coarse. Thermogravimetric curves demonstrated that silane coupling agents and the grafted polymer were anchored on the modified-mica surface. The alternating surface polarity state was verified by different dispersion performances in the solvents. SEM images showed that the polypropylene (PP)/modified-mica composites had a better quality compatibility than the PP/untreated-mica composites. The PP/polymer-grafted-mica composites had improved mechanical properties, including stretching, tension, and impact properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44985.

In the present work we introduce the formation of highly ordered single-walled TiO2 nanotubes based on anodizing nanoimprinted titanium substrates. In a first step, anodization on nanoimprinted substrates leads to the formation of highly ordered TiO2 nanotubes. These as-formed TiO2 nanotubes have a double-walled nature. After an optimized chemical treatment in piranha solution, the inner wall is removed and an array of single-walled TiO2 nanotubes is obtained that has a high degree of hexagonal ordering. These single walled arrangements show an enhanced photocatalytic activity for H2 evolution in comparison with classic self-ordered TiO2 nanotubes. Keywords: Nanoimprinting, Anodization, Single walled TiO2 nanotube, Photocatalysis

Two-dimensional zeolite nanosheets that do not contain any organic structure-directing agents were prepared from a multilamellar MFI (ML-MFI) zeolite. ML-MFI was first exfoliated by melt compounding and then detemplated by treatment with a mixture of H2 SO4 and H2 O2 (piranha solution). The obtained OSDA-free MFI nanosheets disperse well in water and can be used for coating applications. Deposits made on porous polybenzimidazole (PBI) supports by simple filtration of these suspensions exhibit an n-butane/isobutane selectivity of 5.4, with an n-butane permeance of 3.5×10(-7) mol m(-2) s(-1) Pa(-1) (ca. 1000 GPU).

We report etching-free and iodine-free transfer of highly aligned array of armchair-edge graphene nanoribbons (ACGNRs) and their field-effect transistor (FET) characteristics. They were prepared by on-surface polymerization on Au(788) templates. The ACGNRs were mechanically delaminated and transferred onto insulating substrates with the aid of a nano-porous support layer composed of hydrogen silsesquioxane (HSQ). The key process in the mechanical delamination is the intercalation of octanethiol self-assembled monolayers (SAMs), which penetrate the HSQ layer and intercalate between the ACGNRs and Au(788). After the transfer, the octanethiol SAMs were removed with Piranha solution, enabling the reuse of the Au single crystals. The FETs fabricated with the transferred ACGNR array showed ambipolar behavior when the channel length was as long as 60 nm. Quasi-one-dimensional conductivity was observed, which implies a good alignment of GNRs after the transfer. In contrast, short-channel ACGNR FETs (channel length ∼20 nm) suffer from a geometry-dependent short-channel effect. This effect is more severe in the FETs with ACGNRs parallel to the channel, which is an ideal geometry, than in ones perpendicular to the channel. Since the ID-VD curve is well fitted by the power-law model, the short-channel effect likely stems from the space-charge limited current effect, while the wide charge-transfer region in the GNR channel can be another possible cause for the short-channel effect. These results provide us with important insights into the designing short-channel GNR-FETs with improved performance.

In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS). Significant difference in the etching behavior of UFG and CG titanium has been found. UFG titanium exhibits higher etching activity independently of the etching medium. Formed structures possess higher homogeneity. The variation of the etching medium and time leads to micro-, nano-, or hierarchical micro/nanostructures on the surface. Significant difference has been found between surface composition for UFG titanium etched in basic and acidic Piranha solution. Based on the experimental data, the possible reasons and mechanisms are considered for the formation of nano- and microstructures. The prospects of etched UFG titanium as the material for implants are discussed.

The structure and light-emitting properties of Si nanowires (SiNWs) fabricated by a single-step metal-assisted chemical etching (MACE) process on highly boron-doped Si were investigated after different chemical treatments. The Si nanowires that result from the etching of a highly doped p-type Si wafer by MACE are fully porous, and as a result, they show intense photoluminescence (PL) at room temperature, the characteristics of which depend on the surface passivation of the Si nanocrystals composing the nanowires. SiNWs with a hydrogen-terminated nanostructured surface resulting from a chemical treatment with a hydrofluoric acid (HF) solution show red PL, the maximum of which is blueshifted when the samples are further chemically oxidized in a piranha solution. This blueshift of PL is attributed to localized states at the Si/SiO2 interface at the shell of Si nanocrystals composing the porous SiNWs, which induce an important pinning of the electronic bandgap of the Si material and are involved in the recombination mechanism. After a sequence of HF/piranha/HF treatment, the SiNWs are almost fully dissolved in the chemical solution, which is indicative of their fully porous structure, verified also by transmission electron microscopy investigations. It was also found that a continuous porous Si layer is formed underneath the SiNWs during the MACE process, the thickness of which increases with the increase of etching time. This supports the idea that porous Si formation precedes nanowire formation. The origin of this effect is the increased etching rate at sites with high dopant concentration in the highly doped Si material.

Pseudo-one dimensional (pseudo-1D) materials are a new-class of materials where atoms are arranged in chain like structures in two-dimensions (2D). Examples include recently discovered black phosphorus, ReS2 and ReSe2 from transition metal dichalcogenides, TiS3 and ZrS3 from transition metal trichalcogenides and most recently GaTe. The presence of structural anisotropy impacts their physical properties and leads to direction dependent light-matter interactions, dichroic optical responses, high mobility channels, and anisotropic thermal conduction. Despite the numerous reports on the vapor phase growth of isotropic TMDCs and post transition metal chalcogenides such as MoS2 and GaSe, the synthesis of pseudo-1D materials is particularly difficult due to the anisotropy in interfacial energy, which stabilizes dendritic growth rather than single crystalline growth with well-defined orientation. The growth of monoclinic GaTe has been demonstrated on flexible mica substrates with superior photodetecting performance. In this work, we demonstrate that pseudo-1D monoclinic GaTe layers can be synthesized on a variety of other substrates including GaAs (111), Si (111) and c-cut sapphire by physical vapor transport techniques. High resolution transmission electron microscopy (HRTEM) measurements, together with angle resolved micro-PL and micro-Raman techniques, provide for the very first time atomic scale resolution experiments on pseudo-1D structures in monoclinic GaTe and anisotropic properties. Interestingly, GaTe nanomaterials grown on sapphire exhibit highly efficient and narrow localized emission peaks below the band gap energy, which are found to be related to select types of line and point defects as evidenced by PL and Raman mapping scans. It makes the samples grown on sapphire more prominent than those grown on GaAs and Si, which demonstrate more regular properties., 15 pages, 3 figures, supplement (submitted version)

A chemical treatment for preparing high purity selectively oxidised SWNTs while preserving optical/electronic properties of the material has been developed. Efficient removal of both metal and carbonaceous impurities has been demonstrated by AFM, TEM, Raman and absorption spectroscopy, while XPS confirmed quantitative conversion of oxidised defects to functionalisable carboxylic acid groups. Furthermore persistence of the characteristic optical properties was confirmed using absorption and NIR photoluminescence spectroscopy, thus indicating preservation of the electronic structure. This chemical treatment thus paves the way for the preparation of high purity, covalently functionalised SWNTs enhancing their potential for use in high-performance optical/electronic applications. A comparison with commonly used purification protocols that utilize nitric acid and sodium hydroxide followed by piranha solution treatments or simple solvent washing is made, highlighting the advantages of the reported method for the production of SWNT starting materials ideal for efficient chemical modifications.

A generic process has been developed to grow nearly defect free arrays of (heterostructured) InP and GaP nanowires. Soft nanoimprint lithography has been used to pattern gold particle arrays on full 2 inch substrates. After lift-off organic residues remain on the surface, which induce the growth of additional undesired nanowires. We show that cleaning of the samples before growth with piranha solution in combination with a thermal anneal at 550 C for InP and 700 C for GaP results in uniform nanowire arrays with 1% variation in nanowire length, and without undesired extra nanowires. Our chemical cleaning procedure is applicable to other lithographic techniques such as e-beam lithography, and therefore represents a generic process., 12 pages, 4 figures, 2 tables