BiFeO3/Reduced Graphene Oxide (BFO/RGO) composites have been fabricated by a simple hydrothermal method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, and X-ray photoelectron spectroscopy (XPS) analysis reveal that graphene oxide was reduced in hydrothermal process and BFO/RGO composites were successfully synthesized. UV-visible absorption and photoluminescence properties show that the introduction of RGO can effectively reduce the recombination of photogenerated electron and hole pairs. Compared to the pristine BFO, the photocatalytic performance of BiFeO3 Graphene Oxide (BGO) composites is enhanced for the degradation of Methylene blue (MB) solution under visible light irradiation, and the result shows that the optimal amount of Graphene Oxide (GO) in the composites is 60 mg (BGO60). The excellent photocatalytic performance is mainly ascribed to improved light absorption, increased reactive sites, and the low recombination rate of electron-hole pairs. This work can provide more insights into designing advanced photocatalysts for wastewater treatment and environmental protection.
Inspired by natural photosynthesis, artificial heterojunction photocatalysts have been extensively studied. Herein, a novel ternary graphitic carbon nitride/platinum/bismuth vanadate (g-C3N4/Pt/BiVO4) photocatalytic system was successfully synthesized, where Pt/BiVO4 nanosheet is anchored on the surface of layered g-C3N4, as evidenced by structural observations. Ultraviolet photoelectron spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy are carried out to identify the position of the conduction band and valence band. A Z-scheme is used to interpret the superior photocatalytic performance of g-C3N4/Pt/BiVO4 and further verified by the capture of free radicals and terephthalic acid photoluminescence experiments. Compared with the g-C3N4/BiVO4 binary system, the Z-scheme g-C3N4/Pt/BiVO4 photocatalyst not only possesses enhanced carrier separation efficiency but also maintains sufficient redox properties, thus inducing superior photocatalytic activity. More importantly, the novel Z-scheme photocatalyst exhibits excellent recycle stability, which could provide inspiration for the rational design of efficient and practical photocatalysts for environmental pollution treatment. The ternary photocatalyst also exhibits significantly enhanced visible-light photocatalytic hydrogen production performance.
Non-destructive testing techniques are widely applied in industry for the evaluation of quantities of interest without inflicting additional damage accumulation. Crack detection and monitoring is a prime example of where non-destructive testing is valuable. Among the variety of non-destructive testing techniques, the direct current and alternating current potential difference methods, which are based on the principle that an electrical potential field around a conductive specimen is disturbed by the presence of geometric irregularities (or "features"), have received a great deal of attention in the literature. This is mainly due to the high levels of accuracy associated with these techniques and good estimations of crack initiation and propagation having been achieved.A critical review of the evolution and applications of potential difference methods is presented in this paper. Potential difference methods are capable of providing accurate and continuous measurements with simple installation and exclude the requirement of visual access under harsh service conditions. Alternating current potential difference methods require lower current input than direct current equivalents and hence provide higher sensitivity and offer better noise rejection but are vulnerable to capacitance effects and are more expensive. Calibration curves can be determined analytically, numerically, or by direct or analogue experimental techniques with each method offering strengths and limitations. Application of these should be determined in accordance with the specific scenario. The performance of electric probes (of voltage measurements and current injection) on topand side-face of C(T) and SEN(B) specimens are reviewed in detail as case examples. Specific guidance in normalising measurements and eliminating errors from thermoelectric effects can be implemented in order to improve the accuracy of PD methods. Abundant results have been obtained by applying PD methods in monitoring cracks geometries under aggressive conditions such as corrosion, high temperature, creep and cycled loading.
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