Retraction: Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods.

Small 2018, 14, 1704464 The above article, published online on February 27, 2018 in Wiley Online Library (https://onlinelibrary.wiley.com), has been retracted by agreement between the corresponding authors, the journal Editor-in-Chief, José Oliveira, and Wiley-VCH Verlag GmbH & Co. KGaA. Although the authors stand by the scientific content of the paper, the retraction has been agreed upon due to material (Figures 1j and 1k) collected by the first author in an external lab being included in the publication without the consent of the third party. L. Wang, K. Marcus, X. Huang, Z. Shen, Y. Yang, Y. Bi, Small 2018, 14, 1704464; https://doi.org/10.1002/smll.201704464.

Nickel Sulfide Freestanding Holey Films as Air-Breathing Electrodes for Flexible Zn-Air Batteries.

In this work, a combination of bottom-up electrochemical deposition and top-down electrochemical etching strategies followed by a subsequent sulfuration treatment was employed to rationally synthesize a nickel sulfide (NiS x) freestanding holey film (FHF). Owing to the holey structure along with the optimal electrochemically active surface area and active sites, the as-prepared NiS x FHF showed an impressive bifunctional electrocatalytic performance toward both oxygen evolution and reduction reactions. The holey and freestanding features provide the NiS x FHF with promising characteristics to be used as an ideal air-breathing cathode in flexible Zn-air batteries (ZABs). As a proof-of-concept, the rationally designed NiS x FHF achieved remarkable rechargeability and flexibility in a ZAB configuration.

Integration of Au nanoparticles with a g-C3N4 based heterostructure: switching charge transfer from type-II to Z-scheme for enhanced visible light photocatalysis.

Here, we demonstrate that a type-II g-C3N4 nanosheet (CNNS)/W18O49 heterostructure composite can be switched to Z-scheme through the deposition of Au nanoparticles (NPs) on the surface of CNNS. As a direct result, the designed Au/CNNS/W18O49 heterostructure shows enhanced photocatalytic performance for Cr(vi) reduction than the CNNS/W18O49 heterostructure and single components (CNNS and W18O49) under visible light irradiation.

Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods.

An Ar atmospheric treatment is rationally used to etch and activate hematite nanoflakes (NFs) as photoanodes toward enhanced photoelectrochemical water oxidation. The formation of a highly ordered hematite nanorods (NRs) array containing a high density of oxygen vacancy is successfully prepared through in situ reduction of NFs in Ar atmosphere. Furthermore, a hematite (104) plane and an iron suboxide layer at the absorber/back-contact interface are formed. The material defects produced by a thermal oxidation method can be critical for the morphology transformation from 2D NFs to 1D NRs. The resulting hematite NR photoanodes show high efficiency toward solar water splitting with improved light harvesting capabilities, leading to an enhanced photoresponse due to the artificially formed oxygen vacancies.

Freestanding NiFe Oxyfluoride Holey Film with Ultrahigh Volumetric Capacitance for Flexible Asymmetric Supercapacitors.

In this work, a freestanding NiFe oxyfluoride (NiFeOF) holey film is prepared by electrochemical deposition and anodic treatments. With the combination of good electrical conductivity and holey structure, the NiFeOF holey film offers superior electrochemical performance with maximum specific capacitance of 670 F cm-3 (134 mF cm-2 ), due to the following reasons: (i) The residual metal alloy framework can be used as the current collector to improve electrode conductivity. Moreover, the as-prepared freestanding NiFeOF holey film can be used as a supercapacitor electrode without reliance on binders and other additives. The residual metal alloy framework and binder-free electrode effectively reduce electrode resistance, thus improving electron transport. (ii) The highly interconnected holey structure and hierarchical pore distribution provide a high specific surface area to improve electron transport, enhancing rapid ion transport, and mitigating diffusion limitations throughout the holey film. (iii) The excellent mechanical characteristics facilitate flexibility and cyclability related performance. Additionally, the NiFeOF holey film presents exceptional electrochemical performance, showing that it is a promising alternative for small/microsize electronic devices.

Easily fabricated and lightweight PPy/PDA/AgNW composites for excellent electromagnetic interference shielding.

Conductive polymer composites (CPCs) containing nanoscale conductive fillers have been widely studied for their potential use in various applications. In this paper, polypyrrole (PPy)/polydopamine (PDA)/silver nanowire (AgNW) composites with high electromagnetic interference (EMI) shielding performance, good adhesion ability and light weight are successfully fabricated via a simple in situ polymerization method followed by a mixture process. Benefiting from the intrinsic adhesion properties of PDA, the adhesion ability and mechanical properties of the PPy/PDA/AgNW composites are significantly improved. The incorporation of AgNWs endows the functionalized PPy with tunable electrical conductivity and enhanced EMI shielding effectiveness (SE). By adjusting the AgNW loading degree in the PPy/PDA/AgNW composites from 0 to 50 wt%, the electrical conductivity of the composites greatly increases from 0.01 to 1206.72 S cm-1, and the EMI SE of the composites changes from 6.5 to 48.4 dB accordingly (8.0-12.0 GHz, X-band). Moreover, due to the extremely low density of PPy, the PPy/PDA/AgNW (20 wt%) composites show a superior light weight of 0.28 g cm-3. In general, it can be concluded that the PPy/PDA/AgNW composites with tunable electrical conductivity, good adhesion properties and light weight can be used as excellent EMI shielding materials.

Periodically Patterned Au-TiO2 Heterostructures for Photoelectrochemical Sensor.

Periodically patterned Au nanorods in TiO2 nanocavities (Au NRs@TiO2) were fabricated via magnetron sputtering followed by a thermal dewetting process. This innovative Au NRs@TiO2 heterostructure was used as a plasmonic sensing platform for photoelectrochemical detection of glucose and lactose. This Au NRs@TiO2 patterned heterostructure possesses superior sensing properties to other Au nanoparticle-based sensors because (i) localized surface plasmon resonance (LSPR) generated at Au/TiO2 interfaces enhanced sensitivity of glucose (lactose) amperometric detection; (ii) periodic Au nanocrystals in TiO2 nanocavities accelerated charge separation and transfer rate, especially under monochromatic blue light irradiation; (iii) discrete planar architectures comprising Au NRs immobilized on TiO2 substrates significantly improved stability and reusability of the sensors. A low detection limit of 1 µM (10 µM) and a high sensitivity of 812 µA mM-1 cm-2 (270 µA mM-1 cm-2) were achieved on the Au NRs@TiO2 heterostructures for glucose (lactose) detection without the addition of enzymes. Good selectivity and superb stability over more than 8 weeks was also demonstrated using these Au NRs@TiO2 heterostructures for glucose (lactose) detection. Additionally, this cost-efficient technique can be easily extended to other photoelectrochemical sensing systems when considering the combination of sensing and visible or infrared light source enhancement.

Enhanced Photoelectrocatalytic Reduction of Oxygen Using Au@TiO2 Plasmonic Film.

Novel Au@TiO2 plasmonic films were fabricated by individually placing Au nanoparticles into TiO2 nanocavity arrays through a sputtering and dewetting process. These discrete Au nanoparticles in TiO2 nanocavities showed strong visible-light absorption due to the plasmonic resonance. Photoelectrochemical studies demonstrated that the developed Au@TiO2 plasmonic films exhibited significantly enhanced catalytic activities toward oxygen reduction reactions with an onset potential of 0.92 V (vs reversible hydrogen electrode), electron transfer number of 3.94, and limiting current density of 5.2 mA cm-2. A superior ORR activity of 310 mA mg-1 is achieved using low Au loading mass. The isolated Au nanoparticle size remarkably affected the catalytic activities of Au@TiO2, and TiO2 coated with 5 nm Au (Au5@TiO2) exhibited the best catalytic function to reduce oxygen. The plasmon-enhanced reductive activity is attributed to the surface plasmonic resonance of isolated Au nanoparticles in TiO2 nanocavities and suppressed electron recombination. This work provides comprehensive understanding of a novel plasmonic system using isolated noble metals into nanostructured semiconductor films as a potential alternative catalyst for oxygen reduction reaction.

Paper-Based Inkjet-Printed Flexible Electronic Circuits.

Printed flexible electronics have been widely studied for their potential use in various applications. In this paper, a simple, low-cost method of fabricating flexible electronic circuits with high conductivity of 4.0 × 107 S·m-1 (about 70% of the conductivity of bulk copper) is demonstrated. Teslin paper substrate is treated with stannous chloride (SnCl2) colloidal solution to reduce the high ink absorption rate, and then the catalyst ink is inkjet-printed on its surface, followed by electroless deposition of copper at low temperature. In spite of the decrease in conductance to some extent, electronic circuits fabricated by this method can maintain function even under various folding angles or after repeated folding. This developed technology has great potential in a variety of applications, such as three-dimensional devices and disposable RFID tags.