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Inter-Diffusion of Iridium, Platinum, Palladium and Rhodium with Germanium
摘要： The down-scaling of nanoelectronic devices to ever smaller dimensions and greater performance has pushed silicon-based devices to their physical limits. Much effort is currently being invested in research to examine the feasibility of replacing Si by a higher mobility semiconductor, such as germanium, in niche high-performance metal oxide semiconductor (MOS) devices. Before Ge can be adopted in industry, a suitable contact material for the active areas of a transistor must be identified. It is proposed that platinum group metal (pgm) germanides be used for this purpose, in a similar manner as metal silicides are used in Si technology. Implementation of Ge-based technology requires a thorough understanding of the solid-state interactions in metal/Ge systems in order to foresee and avoid problems that may be encountered during integration. We present a systematic study of the solid-state interactions in germanide systems of four of the pgms: iridium, platinum, palladium and rhodium. Our approach was essentially twofold. Firstly, conventional thin film couples were used to study the sequence of phase formation in the germanide systems. Conventional thin film couples were also used to identify and monitor the dominant diffusing species during the formation of some of the germanides as these can influence the thermal stability of a device. Secondly, we observed and analysed several aspects of the lateral diffusion reactions in these four systems, including activation energies and diffusion mechanisms. Lateral diffusion couples were prepared by the deposition of thick rectangular islands of one material on to thin films of another material. Rutherford backscattering spectrometry (RBS) and microprobe-Rutherford backscattering spectrometry (μRBS) were used to analyse several aspects of the thin film and lateral diffusion interactions respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were also employed.
关键词： nanoelectronic devices,solid-state interactions,germanium,platinum group metal germanides,lateral diffusion
更新于2025-09-10 09:29:36
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Microwave Assisted Synthesis, Modification With Platinum And Photocatalytical Properties of TiO2 Nanofibers
摘要： In the present work formation of active TiO2 nanoparticles in microwave synthesis and their modification with platinum were studied. Anatase nanopowder and 10 M KOH solution were used as raw materials. Microwave assisted synthesis method permited to obtain TiO2 nanofibres and nanowires with a diameter of 10 nm and a specific surface area in the range of 70 – 150 m2/g. In order to modify TiO2 nanofibers with platinum it was stirred in H2PtCl6 solution under UV irradiation. Photocatalytic activity was determined by degradation of the methylene blue (MB) solution under UV and visible light irradiation. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds as well as for hydrogen production by water splitting.
关键词： platinum,nanowires,titania nanofibers,anatase,photocatalysis
更新于2025-09-10 09:29:36
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Neutral heteroleptic cyclometallated Platinum(II) complexes featuring 2-phenylbenzimidazole ligand as bright emitters in solid state and in solution
摘要： A series of 8 neutral cyclometallated platinum(II) complexes featuring 2-phenylbenzimidazole chromophoric ligand and acetylacetonate as ancillary ligand has been synthesized and characterized. The introduction of a variety of substituent on the phenyl ring allows to finely tune the emission wavelength. The emission data reveal high quantum yield in deaerated solution and in bulk solid state (micro-crystalline powder), with values up to an impressive 51%. The emission for all of the complexes is attributed to a mixed 3LC-MLCT state. Both absorption and emission data have been correlated successfully with the redox potentials and the Hammett parameters.
关键词： photophysics,phosphorescence,platinum,organometallic,solid state emission
更新于2025-09-10 09:29:36
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Effects of platinum photodeposition time on the photoelectrochemical properties of Fe2O3 nanotube electrodes
摘要： A photo-assisted deposition method for the deposition of platinum nanoparticles on Fe2O3 nanotubes (Pt/Fe2O3), prepared by anodizing, has been developed. The chemicophysical properties and elemental composition of the synthetic Pt/Fe2O3 samples have also been determined. The investigation of the photoelectrochemical properties of the prepared Pt/Fe2O3 samples showed their greatly increased photocurrent density for photoelectrochemical (PEC) water splitting compared to bare Fe2O3. Therefore, the deposition of Pt is effective on the enhancement of the PEC response. In addition, the effect of the Pt photodeposition time on water splitting capability was studied. The current density produced by sample HPt3 was 220 lA/cm2 at +0.4 V vs. Ag/AgCl, which is 2 times higher than that of the bare Fe2O3 nanotube samples (105 lA/cm2, at +0.4 V vs. Ag/AgCl).
关键词： Platinum,Fe2O3 nanotube,Deposition,Thin films,Photoelectrochemical
更新于2025-09-10 09:29:36
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Synthesis, characterization, thermal and luminescent properties of thiophenol-functionalized platinum(II) bis(acetylide) complexes
摘要： Two thiophenol-functionalized trans-platinum(II) bis(acetylide) complexes, having one thiophenol moiety in each alkenyl backbone with general formula trans-[(PPh3)2Pt{C≡C–Ar–CH=CH(SC6H5)}2], (2a–2b), (Ar = phenylene or 2,5-dimethylphenylene), were synthesized in good yields and good regioselectivities. Compared to the absorption bands of the trans-platinum(II) bis(acetylide) complexes 1, the positions of the lowest energy absorption bands were redshifted by 17–18 nm, after functionalization with thiophenol. For both of the platinum(II) complexes 2, the lowest energy absorption bands in chloroform solution at room temperature were observed in the range 376–379 nm, and under excitation at the absorption maximum both complexes showed emission maxima in the range of 408–419 nm. All the new Pt complexes have been characterized by physico-chemical and spectroscopic methods.
关键词： thermal properties,thiophenol-functionalized,characterization,synthesis,platinum(II) bis(acetylide) complexes,luminescent properties
更新于2025-09-10 09:29:36
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In situ Raman spectroscopic evidence for oxygen reduction reaction intermediates at platinum single-crystal surfaces
摘要： Developing an understanding of structure–activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidence for ORR intermediates indicates that, under acidic conditions, the pathway of ORR at Pt(111) occurs through the formation of HO2*, whereas at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of the ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O2?. Notably, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces not normally amenable to study with Raman spectroscopy.
关键词： density functional theory,in situ Raman spectroscopy,electrochemical surface-enhanced Raman spectroscopy,oxygen reduction reaction,platinum single-crystal surfaces
更新于2025-09-10 09:29:36
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Progresses in Chemical Sensor || Air-Suspended Silicon Micro-Bridge Structures for Metal Oxide- Based Gas Sensing
摘要： Maintaining specific temperature is a key parameter for most of the gas sensing materials, particularly for metal oxide-based thin film layers, to operate them more efficiently to detect different gaseous (or vapor) species at ppm and ppb concentration levels. For field applications, battery-operated micro-gas-sensors, power dissipation and the required temperature stability are to be maintained with a close tolerance for better signal stability and also to analyze the generated data from the sensing element. This chapter mainly focuses on several metal oxide films to highlight the base temperature and its creation on silicon-based platforms. Air-suspended structures are highlighted, and a comparison is drawn between simple and MEMS-based structures from the power dissipation point of view. Ease of fabrication and operation limitations are explained with fabrication issues.
关键词： Platinum resistance thermometer,Gas sensing devices,Platinum micro-heater,Surface micromachining,MEMS,Metal oxide thin films
更新于2025-09-09 09:28:46
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An Ultrasensitive and Ultraselective Hydrogen Sensor Based on Defect-Dominated Electron Scattering in Pt Nanowire Arrays
摘要： The detection of hydrogen gas has attracted extensive attention due to its wide applications. Here, ultrathin Pt nanowires (3.5 nm) with abundant defects are fabricated by focused ion beam (FIB) for hydrogen detection. Different from the surface-dominated scattering in previous reports where the resistance of Pt decreases after hydrogenation, the Pt hydrogen sensor prepared by FIB is based on defect-dominated electron scattering owing to the abundant defects, i.e., the resistance is dominated by defect scattering, while H atoms will diffuse along the defects and thus enhance the electron scattering and resistance. Thanks to the small volume of H atoms (easy to diffuse along defects), the sensor is very sensitive and selective to hydrogen and exhibits fast response–recovery properties. Moreover, the sensitivity can be improved after the response–recovery loops, which may be ascribed to the generation of extra defects (further accelerating H atom diffusion). After response in pure H2 and recovery in air, the sensor has an ultralow limit of detection (for H2 in air) of 10 ppb. The results present a hydrogen sensor with superior sensitivity and selectivity, which would not only facilitate the development of metal hydrogen sensors, but also provide a feasible strategy for hydrogen detection.
关键词： platinum nanowires,hydrogen sensors,diffusion,defects,resistance
更新于2025-09-09 09:28:46
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Symmetry lowering by cage doping in spherical superatoms: Evaluation of electronic and optical properties of 18-electron W@Au <sub/>12</sub> Pt <sub/><i>n</i> </sub> ( <i>n</i> ?=?0-4) superatomic clusters from relativistic DFT calculations
摘要： Attempts to expand the versatility of well defined clusters are a relevant issue in the design of building blocks for functional nanostructures. Here, we investigate the plausible formation of related structures from the emblematic highly symmetrical 18-e [W@Au12] cluster. The calculated [W@Au12Ptn] series, with n = 0, 1, 2, 3, and 4, show cohesion energies, HOMO-LUMO gap, adiabatic electron affinities (AEAs) and adiabatic ionization potentials (AIPs), indicating a relative stability to the parent cluster [W@Au12] experimentally characterized, where clusters with n = 1 and n = 4 are suggested as the most stable with respect to oxidation. The resulting symmetry lowering away from the high icosahedral symmetry upon adding Pt atoms induces a sizable splitting of the frontiers shells, which in turn effectively modify the properties of the calculated clusters, as observed from calculated optical properties. The estimated absorption spectra show an interesting broadening effect of the absorption peaks, which appears as a useful approach for further design of broad black absorbers, which are able to absorb light in a wider range, with potential capabilities to enhance the efficiency of thin film solar cells and photocatalysis processes, among other applications.
关键词： gold,superatoms,endohedral,platinum,heteroatomic
更新于2025-09-09 09:28:46
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Low-temperature synthesis of hydride semiconductor YH3?δ using Pt capped Y films and its chemical thermodynamics analysis
摘要： To decrease the temperature at which metallic yttrium (Y) reacts with H2 to form the semiconductor trihydride phase, we employed Pt capping layers as catalysts, and compared the result with those obtained when employing Pd, Ni, or their co-capping layers. It was found that Pt capping with 5 nm thickness makes trihydride phase majority when hydrogenated at 27°C, and allows us to obtain the trihydride phase with approximately 100% molar concentration when hydrogenated at 150 – 200°C. Chemical thermodynamics analysis of the experimental results reveals that both the enthalpy and entropy differences between pure states of trihydride phase and dyhydride phase with hydrogen vapor show monotonic hydrogenation temperature dependencies with their sign inversions at approximately the same temperature around 150°C, suggesting a particular thermodynamic mechanism specific to the hydrogen – yttrium system.
关键词： Platinum,Electron beam evaporation,Yttrium dihydride,Enthalpy,Yttrium trihydride,Yttrium,Entropy,Gibbs free energy
更新于2025-09-09 09:28:46