Fe2 PO5 -Encapsulated Reverse Energetic ZnO/Fe2 O3 Heterojunction Nanowire for Enhanced Photoelectrochemical Oxidation of Water.

Zinc oxide is regarded as a promising candidate for application in photoelectrochemical water oxidation due to its higher electron mobility. However, its instability under alkaline conditions limits its application in a practical setting. Herein, we demonstrate an easily achieved wet-chemical route to chemically stabilize ZnO nanowires (NWs) by protecting them with a thin layer Fe2 O3 shell. This shell, in which the thickness can be tuned by varying reaction times, forms an intact interface with ZnO NWs, thus protecting ZnO from corrosion in a basic solution. The reverse energetic heterojunction nanowires are subsequently activated by introducing an amorphous iron phosphate, which substantially suppressed surface recombination as a passivation layer and improved photoelectrochemical performance as a potential catalyst. Compared with pure ZnO NWs (0.4 mA cm-2 ), a maximal photocurrent of 1.0 mA cm-2 is achieved with ZnO/Fe2 O3 core-shell NWs and 2.3 mA cm-2 was achieved for the PH3 -treated NWs at 1.23 V versus RHE. The PH3 low-temperature treatment creates a dual function, passivation and catalyst layer (Fe2 PO5 ), examined by X-ray photoelectron spectroscopy, TEM, photoelectrochemical characterization, and impedance measurements. Such a nano-composition design offers great promise to improve the overall performance of the photoanode material.

Assembly of g-C3N4-based type II and Z-scheme heterojunction anodes with improved charge separation for photoelectrojunction water oxidation.

Graphitic carbon nitride (g-C3N4) has been widely studied as a metal-free photocatalyst, leading to some excellent results; however, the rapid recombination of photogenerated charge carriers substantially limits its performance. Here, we establish two types of g-C3N4-based heterojunction (type II and nonmediator assisted Z-scheme) photoanodes on a transparent conducting substrate via coupling with rod-like and nanoparticulate WO3, respectively. In these composites, g-C3N4 film grown by electrophoretic deposition of exfoliated g-C3N4 serves as the host or guest material. The optimized type II WO3/g-C3N4 composite exhibits an enhanced photocurrent of 0.82 mA cm-2 at 1.23 V vs. RHE and an incident photo-to-current conversion efficiency (IPCE) of 33% as compared with pure WO3 nanorods (0.22 mA cm-2 for photocurrent and 15% for IPCE). Relative to pure g-C3N4 film (with a photocurrent of several microampere and an IPCE of 2%), a largely improved photocurrent of 0.22 mA cm-2 and an IPCE of 20% were acquired for the Z-scheme g-C3N4/WO3 composite. The enhancement can be attributed to accelerated charge separation in the heterointerface because of the suitably aligned band gap between WO3 and g-C3N4, as confirmed by optical spectroscopy and ultraviolet photoelectron spectroscopy (UPS) analysis. The photocatalytic process and mechanism of the g-C3N4-based heterojunctions are proposed herein, which potentially explain the origin of the enhanced photoelectrochemical performance. This achievement and the fundamental information supplied here indicate the importance of rationally designing heterojunction photoelectrodes to improve the performance of semiconductors. This is particularly important for materials such as pure g-C3N4 and WO3, as their photoactivities are strongly restricted by high recombination rates.

A new electrochemical sensor of nitro aromatic compound based on three-dimensional porous Pt-Pd nanoparticles supported by graphene-multiwalled carbon nanotube composite.

In this study, an electrochemical sensor of nitro aromatic compound based on three-dimensional porous Pt-Pd nanoparticles (Pt-Pd NPs) supported by reduced graphene oxide (rGO) nanosheets-multiwalled carbon nanotube (CNTs) nanocomposite (marked as Pt-Pd NPs/CNTs-rGO) was investigated for the first time. This hybrid nanocomposite has been prepared via a facile and versatile hydrothermal synthetic strategy while its structure and property are evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). The result shows that 3D porous Pt-Pd NPs/CNTs-rGO nanocomposite has a large specific surface area of 326.6m(2)g(-1) and exhibited ultrahigh rate capability and good cycling properties at high rates. Electrochemical studies have been performed for the nitro aromatic compounds detection by using different pulse voltammetry (DPV) techniques. The proposed nanocomposite exhibited much enhanced elctrocatalytic activity and high sensitivity toward the detection of nitro aromatic compounds which compared with Pt-Pd NPs dispersed on functionalized rGO, Pt-Pd NPs dispersed on functionalized CNTs, rGO-CNTs and bare glass carbon electrode (GCE). On the basis of the above synergetic electrochemical sensing and synthesis procedure, the hybrid material can be recommended as a robust material for sensor-related applications. Moreover, the proposed sensor exhibits high reproducibility, long-time storage stability and satisfactory anti-interference ability.