Solid State Phenomena Vol. 317

Abstract: Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using gamma radiation technique in aqueous system at ambient temperature without using reducing agent. Cetyl trimethylammonium bromide was used to prevent oxidation during radiolysis process and help to shape the nickel nanoparticles into spheroid. Synthesized nanoparticles were characterized using X-ray diffraction, tunnelling electron microscopy and vibrating sample magnetometer. The particles formed are crystallized with fcc phase without any oxidation state. The particle size ranging from 20 – 50 nm which consists of unique morphology of paired spheroid. Vibrating sample magnetometer analysis shows that sample has ferromagnetic properties with value of magnetic remanence smaller that bulk due to its size.

Abstract: Graphene has drawn a lot of attention as a promising material for a conductive ink due to its high electrical conductivity and abundant source. Selection of solvent for ink formulation is crucial to obtain the desired result. In this work, microcrystal cellulose solution is investigated as alternative solvent for conductive ink formulation. Although the viability of the microcrystal cellulose solution was already presented in other works, further thorough and systematic study is highly required. Cellulose solution was prepared using microcrystalline cellulose and sodium hydroxide aqueous solution. Dispersions with different graphite-to-cellulose ratio were prepared. The exfoliation process was for sonication times of 8, 16, 24 and 32 hours. For Raman spectroscopy and 4-point probe measurement, graphene thin film was formed by drop-casting 20μl dispersion on glossy paper. Sample with low graphite-to-cellulose ratio exhibited more significant reduction in unexfoliated graphite content over the sonication time. The sufficient amount of cellulose in the dispersion leads to more effective exfoliation process. According to analysis on the Raman spectra, the exfoliated graphite could be classified as few-layer graphene with low defect content. The drop-casted thin film from dispersion with ratio of 20:1 showed sheet resistance lesser than 100 Ω/sq. The obtained results confirmed the effectiveness of microcrystal cellulose as the agent for exfoliation process.

Abstract: This paper reports on the synthesis of copper selenide (CuSe) and tin selenide (SnSe) powders by high energy planetary ball milling, starting from elemental powders. Synthesis time and milling speed have been optimized to produce single phase CuSe and SnSe materials. The structural, compositional, morphological and optical properties of the synthesized samples have been analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and UV-Vis. The low-temperature phase selection of the binary compound in this system is seen as a direct consequence of the thermodynamic facilitation, coupled with the capability of mechano-chemical synthesis to aid in overcoming kinetic constraints.

Abstract: In this work, silver (Ag) nanoparticles were synthesized using plasma-assisted hot-filament evaporation, both with and without plasma deposition environments. This technique was used for the deposition of the nanoparticles in high-density, with controlling the size and interparticle separation. The size and interparticle separation acted as the primary factors of the variation of the localized surface plasmon resonance characteristics of the nanoparticles. The Ag nanoparticles reflected an additional layer in a typical organic light-emitting diode (OLED). The OLED with the Ag nanoparticles layer resulted in a low operating voltage, with a high luminance that reached 62.9 % under the hydrogen plasma environment, as compared to the reference device (OLED without the Ag nanoparticles layer). The effects of the Ag nanoparticles synthesis layer, both with and without plasma deposition on the OLED luminance, were also discussed.

Abstract: Platinum-multiwall carbon nanotubes (Pt-MWCNTs) was prepared through a chemical reduction and was characterized by using UV–Vis Spectrophotometer, Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FESEM/EDX) and Raman Spectroscopy. Through this chemical reduction, Pt ions were reduced by the addition of sodium dodecyl sulfate (SDS) and Pt was in-situ deposited on the exterior walls of MWCNTs. TEM and FESEM/EDX analyses have confirmed the presence of Pt on the surface of MWCNTs. From Raman Spectroscopy, the ID/IG of MWCNT is 0.66 while ID/IG of Pt-MWCNT is 0.71, showing that not much defects were resulted by the functionalization of Pt on the surface of MWCNT, while from UV-Vis spectra, Pt-MWCNT is found to absorb at about 265 nm due to the presence of Pt nanoparticles that caused a weak surface plasmon resonance (SPR) absorption in the UV region which will contribute to the NLR measurement. The resulted Pt-MWCNTs was then investigated its third-order nonlinearity response as suspension in water using continuous wave laser and z-scan measurement at 532 nm. Pt-MWCNT displays good transmittance profile and self-defocusing effect with excitation intensity is in order of 10^-9 cm²/W. The presence of Pt on the surface of MWCNT has contributed to intrinsic properties and resulted in nonlinear refractive (NLR) effect. Thus, Pt-MWCNT is considered to possess significant third-order nonlinear responses considering its low Pt content and has potential in the development of photonics devices.

Abstract: Temperature-programmed reduction (TPR) was used to observe the chemical reduction behaviour of molybdenum trioxide (MoO₃) and zirconia (Zr)-doped MoO₃ catalyst by using carbon monoxide (CO) as the reductant. The characterisation of catalysts was performed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses. The reduction performance were examined up to 700°C and reduction was continued for 60 min at 700°C in a stream of 20 vol. % CO in nitrogen. The TPR profile showed that the doped MoO­₃ catalyst was slightly moved to a higher temperature (580°C) as compared to the undoped MoO₃ catalyst, which began at around 550°C. The interaction between zirconia and molybdenum ions in doped MoO₃ catalyst led to an increase in the reduction temperature. According to characterisation of the reduction products by using XRD, it revealed that the reduction behaviour of pure MoO₃ to MoO₂ by CO reductant involved two reduction stages with the formation of Mo₄O₁₁ as the intermediate product. Meanwhile, MoO₃ catalyst doped with zirconia caused a delay in the reduction process and was proven by the presence of Mo₄O₁₁ species at the end of reactions. Physical analysis by using BET showed a slight increase in surface area of 3% Zr-MoO₃ from 6.85 m²/g to 7.24 m²/g. As for TEM analysis, black tiny spots located around MoO₃ particles revealed that the zirconia was successfully intercalated into MoO₃ particles. This confirmed that formation of intermetallic between Zr-MoO₃ catalyst will give new chemical and physical properties which has a remarkable chemical effect by disturbing the reduction progression of MoO₃ catalyst.

Abstract: Current world events have made several countries as a target for terrorism. Chemical weapon such as nuclear weapon is commonly referred as a weapon of mass destruction. Organophosphorus (OP) compounds have long been used as pesticides and developed into warfare nerve agents such as tabun, soman, sarin, and VX. They are highly toxic and considered to be the most dangerous chemical weapons. Development on the protection material against OP compounds has gained interest among researcher. Nanocellulose has shown a great potential for high-performance filtration material due to its interesting characteristics such as high adsorption capacity, large surface area, high strength, renewable, chemical inertness, and versatile surface chemistry. Therefore, the evaluation of the chemical interaction between nanocellulose and organophosphorus is important. The analyses of fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis), and elemental analysis were carried out in this study. It was found that the nanocellulose is capable to adsorb OP compound by forming the hydrogen bonding. The adsorption rate was increased as the nanocellulose concentration increased. This is the initial step to discover the potential of nanocellulose to be used in military protection mask.

Abstract: Novel electronic nanomaterial, the carbon nanotube (CNT) has emerged in many sensor applications as such its state dispersion has considerable importance to ensure the sustainability of its electronic properties. In this paper, we reported a state of art conductivity mapping on nanostructure surface of single walled carbon nanotubes (SWCNT) and poly(3-hexylthiophene-2,5-diyl), (P3HT) as potential sensing film. This composite is proposed to give selective analyte anchoring across the film as well as improved carrier mobility. The easy solution processing method was chosen to produce non-covalently wrapped conducting polymer onto the surface of SWCNT. We successfully observed high resolution images of the SWCNT walls that indicated increase of the thickness due to polymer wrapping. The image obtained from conductivity atomic force microscopy (CAFM) show the film’s electrical distribution that correlated with the observed nanostructure of film. Supporting optical characteristics of the nanocomposite obtained from UV-Vis spectroscopy and Raman spectroscopy discussed the morphology of the polymer wrapping and the state of dispersion of the polymer and the nanotubes. It is hypothesized the filament structures made by P3HT/SWCNT can give better sensing performance due to modification of π-π electronic band of SWCNT.

Abstract: The functionalization of multi-walled carbon nanotubes (CNT) with amide group is reported as an alternative to enhance response time, recovery time and sensitivity of detecting acetone gas. We have fabricated an interdigitated transducer (IDT) deposited with amide-functionalized CNT. The elemental compositional analysis was characterized using Energy Dispersion X-ray spectroscopy and CHNOS elemental analyzer. The detection of acetone gas was performed in room temperature and digital multimeter was employed to record the changes of resistivity of IDT upon exposure of acetone. Results showed that amide functional group increases sensitivity, shortens the response time as well as recovery time of the sensor.

Abstract: The scientific investigation based on the molecular design of aromatic compounds for high-performance chemosensor is challenging. This is because their multiplex interactions at the molecular level should be precisely determined before the desired compounds can be successfully used as sensing materials. Herein, we report on the molecular design of chemosensors based on aromatic structures of benzene as the organic motif of benzene-1,3,5-tricarboxamides (BTA), as well as the benzene pyrazole complexes (BPz) side chain, respectively. In the case of BTA, the aromatic benzene acts as the centre to allow the formation of π–π stacking for one-dimensional materials having rod-like arrangements that are stabilized by threefold hydrogen bonding. We found that when nitrate was applied, the rod-like BTA spontaneously formed into a random aggregate due to the deformation of its hydrogen bonding to form inactive nitroso groups for non-optical sensing capability. For the optical chemosensor, the aromatic benzene is decorated as a side-chain of BPz to ensure that cage-shaped molecules make maximum use of their centre providing metal-metal interactions for fluorescence-based sensing materials. In particular, when exposed to benzene, Cu-BPz displayed a blue-shift of its original emission band from 616 to 572 nm (Δ = 44 nm) and emitted bright orange to green emission colours. We also observe a different mode of fluorescence-based sensing materials for Au-BPz, which shows a particular quenching mechanism resulting in 81% loss of its original intensity on benzene exposure to give less red-orange emission (λ = 612 nm). The BTA and BPz synthesized are promising high-performance supramolecular chemosensors based on the non-optical and optical sensing capability of a particular interest analyte.