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TC4 titanium alloy has been widely used in the automotive field due to its exceptional properties. However, inherent defects such as low hardness and poor wear resistance for TC4 alloy limited its wider application. The microarc oxidation (MAO) technique was employed in this paper to prepare MAO coatings on TC4 titanium alloy. The microstructure, phase structure, mechanical properties, and tribological performance were systematically evaluated. The results show that the coating contains a large amount of rutile TiO2 hard phase after MAO treatment, which significantly improves the mechanical properties of the substrate. The hardness of the MAO coating can reach 581 HV.05. Furthermore, the synergistic lubrication effect of onion‐like carbon (OLC) nanoparticles and organic molybdenum dithiocarbamate (MoDTC) in PAO oil was observed for MAO‐treated TC4. Particularly, when.01 wt.% OLC is used with 1 wt.% MoDTC oil, the coefficient of friction (COF) decreases to.062, and the wear rate decreases to 4.3 × 10−7 mm3/Nm. Combined Raman and X‐ray photoelectron spectroscopy (XPS) analysis indicate that OLC is deposited on coating area to form a lubricating carbon film. Additionally, OLC can promote the decomposition of MoDTC during sliding to generate a tribofilm containing MoS2. [ABSTRACT FROM AUTHOR]

The development of high-performance and low-cost bifunctional electrocatalysts is crucial for industrial-scale hydrogen production through water electrolysis. In this study, bimetallic FexCo1−xP nanosheet array electrocatalyst was prepared successfully by a hydrothermal method on the three-dimensional porous nickel foam substrate, which not only retains the excellent HER performance of CoP, but also effectively reduces the activation energy barrier during the OER process by incorporating Fe. This composite structure adjusts the local electronic structure, thereby enhancing the adsorption capacity of reaction intermediates at the active sites. Consequently, the nanosheet-like FexCo1−xP electrocatalyst without noble metal doping exhibits outstanding catalytic performance. Specifically, at the current density of 20 mA·cm− 2 in 1.0 M KOH electrolyte, the overpotentials of Fe0.2Co0.8P nanosheet for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are significantly lower than those of most electrocatalysts, measuring 162 mV and 234 mV, respectively. The results demonstrate the synergistic effect among the Fe, Co, and P elements, which facilitate the electrocatalytic process. Moreover, the synthesized Fe0.2Co0.8P nanosheet array electrocatalyst possesses a large active surface area and good conductivity, effectively promoting the kinetics of the electrocatalytic reactions. This work provides an effective approach for synthesizing efficient and inexpensive bifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

Manipulating the catalyst body and surface photogenerated charge separation is significant in expanding research in the field of photoelectrochemical water splitting. This paper introduces a certain amount of Bi-vacancies at the BiVO4 photoanode by in-situ photoreduction and makes rational use of polarization field engineering to promote the separation of surface photogenerated carriers. Focusing on comparing the photoelectrochemistry (PEC) performance of BiVO4 with different concentrations of Bi-vacancies under piezoelectric polarization field. At 1.23 V vs. RHE, the photocurrent density of the best sample is 0.147 mA/cm2, which is 1.8 times higher than that of BiVO4. In addition, the photocurrent density reached 0.162 mA/cm2 under ultrasonic conditions. The presence of a moderate amount of Bi-vacancies provides a large number of active sites, which lowers the potential barrier for redox reactions thereby reducing the resistance to electron leaps, decreasing the forbidden bandwidth and increasing the light absorption range. The piezoelectric polarization field is triggered by ultrasonic conditions, and the cavitation bubbles are ruptured by ultrasonic vibrations, generating a large amount of charge involved in the water splitting reaction. The presence of surface vacancies makes the piezoelectric polarization easier to be triggered, and the enhanced built-in piezoelectric field acts as a driving force to improve the interfacial separation and transport efficiency of photogenerated carriers, which effectively improves the PEC performance. This work provides a new and scientifically sound idea for the combined use of vacancy defect engineering and piezoelectric effect in the field of PEC splitting water. [ABSTRACT FROM AUTHOR]