Applied Surface Science Advances最新文献

The impact of humidity on the efficiency of gas sensors has become highlighted in the realm of gas detection. Due to the complex relationship between humidity and gas sensor performance, the development of gas sensors has recently focused on minimizing humidity-related interference. This research aims to address humidity-related challenges in zinc oxide (ZnO) gas sensors designed to detect triethylamine. The ZnO nanostructures (NSs) were synthesized using thermal decomposition methods at varying temperatures (380 °C, 480 °C, and 580 °C) and annealing times (3 h, 7 h, 12 h, and 21 h). X-ray diffraction (XRD) confirmed the formation of a wurtzite hexagonal close-packed structure in ZnO NSs. Scanning electron microscopy (SEM) images provided insights into the morphologies of ZnO NSs at different annealing temperatures, while energy dispersive spectroscopy (EDS) demonstrated the elemental distribution. Subsequently, gold (Au) nanoparticles were uniformly sputtered onto ZnO sensors with thickness variations (0.1 nm, 0.6 nm, 1 nm, 5 nm, and 10 nm). XPS was employed to analyse the elemental composition and oxygen vacancies of the synthesized sensing materials. The effectiveness of 0.6 nm-thick Au nanoparticles in mitigating humidity effects was observed in ZnO sensors synthesized at 380 °C. The results indicated that ZnO sensors coated with 0.6 nm-thick Au nanoparticles exhibited highly stable responses to ethanol and triethylamine at different humidity levels from 50 % to 90 %. Notably, these sensors demonstrated promising selectivity towards triethylamine (with a response of 17.57) compared to various gas targets at room temperature. The sensor exhibited rapid response and recovery times of 9.8 s and 4.4 s, respectively, toward triethylamine with excellent stability in variable humid environments. The sensor maintained a consistent response over 24 days, demonstrating good stability at high humidity.

This study delves into the corrosion resistance enhancement of stainless steel through laser processing, focusing on the interplay between surface chemistry, morphology, and electrochemical properties. Two sets of 3 × 3 full factorial design of experiment (DoE) designs were employed to explore the influence of laser process parameters, including power, scan speed, frequency, and hatching distance. The findings underscore the superiority of reduced areal energy in producing optimal corrosion resistance 10 times better then unprocessed stainless steel, demonstrating the best results under optimized conditions of a 15 µm hatching distance, 250 mm/s scan speed, 100 kHz frequency, and 80 % power. X-ray Photoelectron Spectroscopy (XPS) analysis reveals the predominant surface composition of iron and chromium oxides, with variations in the oxide combinations correlating closely with areal energy. Depth profiling revealed the transformation of oxide layers and highlights the importance of chromium-to-iron ratio in surface corrosion behaviour. Cyclic polarisation results demonstrate the formation of passive, transpassive, and pitting domains, with metastable pitting observed in some samples. The direct positive correlation recorded between corrosion current and Cr/Fe ratio underscores the significance of oxide composition in corrosion resistance. Electrochemical impedance spectroscopy (EIS) further confirmed the superior corrosion resistance of laser-processed samples to non-laser processed samples, with lower areal energy exhibiting higher resistance compared to higher areal energy. SEM morphology analysis revealed the removal of surface defects and the formation of a protective oxide layer in laser-processed samples, with lower areal energy samples exhibiting the lowest level of surface defects. The 3D optical profilometer measurements of corrosion pits corroborate these findings, with lower areal energy samples demonstrating the lowest pit depth and area, indicating superior corrosion resistance. Overall, this study provides comprehensive insights into optimizing laser processing parameters to enhance the corrosion resistance of stainless steel, offering valuable understanding and strategy for improving the metal surface corrosion resistance.

Many organic inhibitors have been proposed for corrosion protection of 304 stainless steel (SS), but its effectiveness in acidic and high temperature environment is challenged. We utilized Tithonia diversifolia (Hemsl) A. grey leaf extract (TDLE) as an eco-friendly organic inhibitor to protect 304 stainless steel (SS) in acidic environment (1 M HCl) at high temperature (65 °C). The performance of TDLE was studied electrochemically using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The surface of the metal was characterized using scanning electron microscopy (SEM). The theoretical calculation was also studied to understand the inhibition process. The corrosion inhibition efficiency increases reaching 98.48 % at 65 °C in the presence of 3.5 g/L TDLE. The inhibition of TDLE on 304 SS surface was adsorption spontaneously based in Langmuir's adsorption isotherm. The SEM images show significant improvement of the 304 SS surface with TDLE. A theoretical study indicates that methyl 3.5-dicaffeoyl quinate is the most active inhibitor in TDLE. The study revealed that TDLE had good performance for inhibiting in acidic and high temperature environment.

Nowadays, titanium-based implants are widely used to replace damaged or missing body organs. Poor chemical bonding with the bone and infection caused by formation of biofilm on the implant surface are the most common problems with them. So, antibacterial properties and osteoblast adhesion improvement have been intended to address these issues. The aim of this research is cell adhesion improvement and prevention of bacterial infection using surface roughness and in-situ antibiotic drug release. Here, micromachining (nanoseconds) laser with a groove distance of 10, 30, and 50 µm, was used to surface modification. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), hardness, roughness, and wettability tests were used for physical and metallurgical characterization of surface-modified samples to find the optimum laser processing conditions. Roughness has increased as a result of laser surface modification and surface characteristics of alloy exhibit sensitivity to the groove distance. The lower groove distance indicated the higher roughness and wettability. Martensite phase, α phase, and, Ti₃Al were observed in the fusion zone. Also, the dissolution of the beta phase has occurred in the fusion and the heat-affected zones. No oxidation was observed. All these occurred without any change in bulk. Then optimized sample surfaces were coated by the vancomycin-loaded polyvinyl alcohol solution using electrospinning process, and toxicity, cell adhesion, and drug release rate were evaluated. The results showed laser surface modification and coating did not hurt cell viability. Modified samples demonstrated high cell adhesion and improvement in drug release compared to the unmodified samples. The drug release rate was extended from 4 h to 25 h for modified samples. So, the modified implants could indicate a sustained release of antibiotics as well.

Nanoconstructs of gold nanoparticles (AuNPs) conjugated with SARS-CoV-2 specific antisense oligonucleotides (ASO) have been utilized to develop sensitive electrochemical nucleic acid biosensor for the detection of SARS-CoV-2 RNA. AuNPs were prepared through a one-pot synthesis method by utilizing Poly-L-Lysine (PLL) biopolymer and as synthesised AuNP were characterized by various analytical techniques such as UV–Vis spectroscopy, X-ray Diffraction (XRD) analysis, Fourier Transform Infra-Red spectroscopy (FT-IR), zeta potential, and Transmission Electron Microscopy (TEM). Poly-L-Lysine functionalized AuNPs (PLL-AuNPs) nanoconstructs platform was employed for immobilization of SARS-CoV-2 specific antisense oligonucleotides (ASO-conjugated PLL-AuNPs) via electrostatic interactions. The PLL-AuNPs were drop casted on glassy carbon electrode (GCE) following immobilization of ASO for fabrication of electrochemical biosensor. The ASO-conjugated PLL-AuNPs nanoconstructs were characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The responsiveness of ASO-conjugated PLL-AuNPs nanoconstructs in presence SARS-CoV-2 RNA was monitored using the DPV, SWV and EIS technique, where methylene blue was employed as an electrochemical indicator for DNA-RNA hybridization detection. The biosensor exhibits a detection range for SARS-CoV-2 RNA infection ranging from 0 to 100 nM, with a limit of detection at 30.2 nM. The electrode, modified with ASO-conjugated PLL-AuNPs, was employed for the detection of SARS-CoV-2 RNA from clinical samples collected from COVID-19-positive individuals.

This paper investigates the impact of duplex plasma nitriding and diamond-like carbon (DLC) coatings on the pure fatigue and fretting fatigue properties of 16MnCr5 steel extracted from industrial piston pins used in combustion engines. Two different nitriding and DLC coating processes were performed: "DLC-A" and "DLC-B". The Raman spectrometry and microhardness tests were utilized to evaluate the formation of DLC coating on the sample. Subsequently, the pure and fretting fatigue tests (at 350 MPa and under 100 Hz of the frequency) were performed on as-cast and DLC-coated specimens to obtain the effect of coatings on the fatigue behaviors of the 16MnCr5 steel. Finally, the formation of the DLC layer and the fracture mechanisms were also briefly investigated using field-emission scanning electron microscopy. Then, the obtained results demonstrated that DLC coating ("DLC-B") increased the fatigue lifetime of 16MnCr5 steel by 47.7 % and 85.3 % in pure and fretting fatigue conditions, respectively. This layer can improve the surface properties of engineering materials and components, which can enhance the fatigue lifetime by increasing microhardness and compressive residual stress, reducing wear and friction, and improving adhesion between the substrate and coating. However, due to the white layer, the “DLC-A” improperly enhanced the material performance.

Superhydrophobic/Icephobic tin oxide honeycomb-like nanostructures were synthesized on copper surfaces via facile controlled hydrothermal method. Effects of two crucial fabrication parameters including etching treatment variables and presence the seed layer, on the morphology and wettability of the resulted coating were determined. The chemical composition, wettability characteristics, and topographical properties of the samples were characterized by FE-SEM, stylus profilometry, contact angle measurement, and ATR-FTIR analyses. The wettability evaluations confirmed that the tin oxide deposited on the copper oxide (seed layer) exhibited excellent superhydrophobic properties. The prepared hierarchical surfaces showed high water contact angles (CA) as well as 169. $5^{\circ }\pm 1^{\circ }$ with a contact angle hysteresis (CAH) of 5°± 1°. Moreover, the results confirmed that the etching treatment and the presence of the seed layer can promote the morphology to a uniform state. The ice adhesion strength of the obtained superhydrophobic surfaces reached to 30.4 kPa, showing an excellent ice-phobicity. The mechanical resistance and/or sustainability of the optimized sample was also passed successfully under 10 abrasion test cycles.

In this work, oxygen reduction reaction (ORR) catalysts were developed from a precursor of spent coffee ground-based biochar. Nitrogen doping was achieved via urea addition preceding a pyrolysis synthesis process, yielding nitrogen-doped biochar (NDB). Cobalt was deposited onto the NDB surface using a non-conventional ball-milling procedure. The microstructure of the synthesized samples was studied through Scanning Electron Microscopy (SEM), where a rather distorted surface, highlighted by prominent wrinkles (which doubled the surface area at 50.58 m²/g), was shown for nitrogen-doped samples. Moreover, the high energy ball-milling technique shows an almost perfect coverage of cobalt nanoparticles on the biochar surface through SEM/EDS and Raman results. Additionally, electrochemical testing was conducted using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry measurements conducted under nitrogen (inert) and oxygen-saturated alkaline solution (0.1 M KOH) conditions showed that nitrogen doping enhances the oxygen reduction reaction current (-1 vs -0.59 mA.cm⁻¹ at -0.3 V vs Hg/HgO) and slightly reduces the onset potential compared to pristine biochar. Depositing cobalt onto the NDB surface had a minor adverse effect on the onset potential, but significantly increased the oxygen reduction reaction current, reaching a value of -2.09 mA.cm⁻² at -0.3 V vs Hg/HgO. All catalysts were compared to a commercial carbon supported platinum catalyst (Pt10%C) to showcase the potential room of improvement for the developed catalysts.

In this study the heavy metals (Cu²⁺, Pb²⁺, Hg⁺²) were removed from waste water using two types of sorbents, namely, MoO₃ and MoO₃ doped with 12 %Y₂O₃ were synthesized by solgel method. The as-prepared oxides were characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). A combination of quantitative and qualitative analysis techqnieus, portable X-ray fluorescence (pXRF) and laser-induced breakdown spectroscopy (LIBS) were used to evaluate the removing efficency. Calibration curves were performed to elucidate the limit of detection (LOD) of the Laser-Induced Breakdown Spectroscopy (LIBS) technique for the removal process The LOD were 1.65, 2–21 and 0.98 ppm for Cu, Pb and Hg respectively. The results indicated that the Y₂O₃-doped α-MoO₃ has a consistently greater removal efficiency compared to MoO₃. The removal effecieny of Hg²⁺, Pb²⁺ and Cu²⁺ was 95 %, 33 % and 21 % respectively with MoO₃ while it was 98 % 63 % 35 % for MoO₃ doped Y₂O₃, The results proved also that MoO₃ and MoO₃ doped Y₂O₃ nanoparticles can be utilized as cost effective adsorbent material for heavy metal removal in wastewater. The study showed the potential of using Laser-Induced Breakdown Spectroscopy (LIBS) in environmental applications.

The study focuses on an innovative process for the use of a ZrN coating on Ti6Al4V alloy for orthopaedic bone implants. The preparation process combines the technology of physical vapour deposition (PVD) and micro-arc oxidation (MAO) to achieve hydrophobic properties, improved corrosion resistance and enhanced coating adhesion to Ti6Al4V alloy. An alkaline electrolyte and different microarc discharge intensities were used to prepare MAO coatings. The evaluation of the structure and topography of the coatings was performed using SEM with XRPD, EDX, and XPS analysis. The prepared oxide coatings Zr, ZrSiO₄, and ZrTiO₄ increase the corrosion potential depending on the applied source frequency and thus increase the corrosion resistance of the hybrid system. At the same time, the formation of oxide phases leads to changes in surface topography associated with increasing friction coefficient and better wear resistance.