The mechanical properties of CoNiCr medium-entropy alloys are outstanding, but their corrosion resistance, particularly resistance to pitting corrosion, requires further enhancement. This study employs a rotary accelerated shot peening (RASP) technology to perform surface self-nanostructuring on a CoNiCr alloy, successfully producing gradient nanostructures. The microstructural characteristics and corrosion resistance of the treated alloy are systematically investigated. The results indicate that nanocrystals and nanotwins are formed to produce a dual gradient nanostructure. The grains are refined from 43 μm to 50−1000 nm at the surface and then increase to 25 μm at 100 μm depth from the surface. However, extensive twin structures, manifesting as primary, intersecting, and multiple-level twins, are produced within a depth of 270 μm from the surface. Electrochemical tests reveal that both the open-circuit potential and self-corrosion potential of the RASP sample are higher than those of the untreated sample. Furthermore, the pitting corrosion resistance of the treated sample is improved by the inhibition of Ti oxidation. The passivation film formed on the surface of the RASP sample is dense and stable, as indicated by the fitted results of electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy (XPS), contributing to the improved corrosion resistance.
Two-dimensional MXenes like Ti3C2 are considered ideal materials to produce flexible energy storage devices due to their exceptional electrical conductivity and mechanical flexibility. Using the first-principles density functional theory (DFT) method, this study analyses the effect of oxygen (O), fluorine (F), and hydroxyl (OH) terminations on the surface of Ti3C2 MXenes with respect to their structural stability and mechanical flexibility in flexible energy storage devices. It is observed that oxygen functionalization leads to higher structural stiffness and stability due to the formation of strong Ti-O bonds, at the same time providing sufficient tensile strength for the electrodes. On the other hand, fluorination maintains a good balance between mechanical strength and surface properties, which may facilitate ion transport while maintaining mechanical flexibility. O incorporation is responsible for large structural changes and asymmetries, which result in better flexibility and fracture strains; consequently, Ti3C2O2 becomes the best choice for energy storage wearables. DFT simulations predict that the lattice constant decreases after oxygen and fluorine termination, whereas OH groups only cause minor lattice expansion and distortion. The thickness of layers changes from 4.63 Å in Ti3C2 without any functionalization to 6.78-7.22 Å for MXenes with different terminations. Mechanical calculations showed that Young's modulus varies from 87 N/m for Ti3C2(OH)2 to 478.4 N/m for Ti3C2O2, with corresponding fracture strains of 0.28 and 0.20, respectively, indicating the relationship between flexibility and mechanical strength. Energy-strain and stress-strain curves, together with analyses of coordination numbers, revealed that hydroxyl-terminated MXenes can change their shapes dramatically, without losing their electronic transport capability; on the other hand, oxygen and fluorine groups stabilize MXene and enhance its surface activity. This study illustrates that surface modification of Ti3C2 MXenes is a powerful tool for tuning their properties, which is a very important factor for the development of high-performance, multifunctional energy storage systems.
Friction-induced structural evolution in diamond abrasive grains and ta-C coatings affects the durability of diamond grinding tools, making atomistic investigation essential for linking interfacial bonding changes with macroscopic tribological performance. In this work, molecular dynamics simulations were performed to compare the tribological response of crystalline diamond and tetrahedral amorphous carbon (ta-C) with different sp3 contents during reciprocating sliding against a SiC tip. The evolution of coordination number, radial distribution function, bonding configuration, interfacial force, and stress response was analyzed, and friction experiments and Raman spectroscopy provided complementary experimental observations. The simulations show that sliding disrupts the ordered sp3 lattice of diamond, leading to C–C bond breaking, three-coordinated carbon formation, and sp2-related defective structures in the contact region. In contrast, ta-C accommodates interfacial shear through localized rearrangement of its amorphous sp2/sp3 network, while exhibiting lower friction and normal reaction forces under the same prescribed indentation displacement. Low-sp3 ta-C favors shear accommodation and friction reduction, whereas high-sp3 ta-C provides better structural stability and load-bearing capacity. Raman results show increased D-to-G intensity ratios after sliding, consistent with changes in sp2-related carbon structures. These findings provide atomistic insight into the tribological behavior of ta-C coatings.
The study discusses a thorough experimental analysis on RF-sputtered ZnTe thin films prepared with different substrate temperatures in the range of room temperature up to 300 °C at a constant pressure of 5 mTorr and RF power of 30 W. Substrate temperature was established as a thermal design variable controlling the transition of the deposited thin film from Te-rich amorphous to polycrystalline ZnTe film. All films were maintained at a thickness of approximately 85-90 nm. Raman spectroscopy of the 300 °C film confirmed four characteristic vibrational peaks at 121, 142, 210, and 420 cm−1, with a Zn/Te ratio of 45:55, close to the ideal stoichiometry. Increasing substrate temperature progressively improved crystallinity, enhanced p-type electrical conductivity with a bulk carrier concentration of 2.49 × 1015 cm−3, and tuned the direct optical bandgap from 3.04 eV (RT) to 3.39 eV (300 °C), accompanied by a reduction in Urbach energy to 0.58 eV and peak carrier mobility of 2.31×103 cm2V−1s−1. The film at 300 °C was determined to be the optimized thermal design point and was used as an interface layer in a CdTe solar cell architecture. Device characterization under illumination revealed that the ZnTe interlayer improved the Voc from 0.538 V to 0.546 V, fill factor from 30.47% to 33.20% and power conversion efficiency from 4.74% to 5.98% over an active area of 0.203 cm2. These results demonstrate that thermally engineered ZnTe is a viable undoped interface material for improving the performance of CdTe-based photovoltaics.
The continuous discharge of synthetic dye residues into aquatic environments poses serious ecological and public health concerns. In this study, a multifunctional magnetic Polyaniline/g-C 3 N 4 /Fe 3 O 4 /Ag (P-CNFA) nanocomposite was rationally designed and synthesized via in situ oxidative polymerization and chemical reduction methods for efficient dye reduction and antibiotic degradation. The engineered hybrid structure integrates graphitic carbon nitride (g-C 3 N 4 ) as a semiconductor scaffold, Fe 3 O 4 nanoparticles for magnetic recovery, polyaniline (PANI) as a conductive network, and plasmonic Ag nanoparticles as the main catalytic active sites. The P-CNFA nanocomposite exhibited outstanding catalytic performance toward the reduction of methylene blue (MB) and methyl orange (MO) under ambient light in the presence of NaBH4, with pseudo-first-order rate constants of 0.99 min −1 (MB) and 1.61 min −1 (MO), achieving 98% MB removal within 20 min and 97% MO removal within 40 min. The catalyst retained over 80% of its initial activity after five successive cycles, demonstrating excellent magnetic recoverability and structural stability. Comprehensive structural and compositional characterizations using XRD, FTIR, Raman spectroscopy, SEM–EDX, TEM, and ICP-OES confirmed the formation of the target nanocomposite, with an XRD-derived Fe 3 O 4 crystallite size of ≈11.0 nm and a TEM-derived median particle diameter of 15.1 nm across the composite. The superior catalytic kinetics, low catalyst dosage, and efficient magnetic recyclability highlight the strong potential of the P-CNFA nanocomposite as a versatile platform for the simultaneous remediation of dye contaminants in wastewater.
