The distribution of oxygen and aluminum vacancies across the hemispherical barrier oxide layer (BOL) of nanoporous anodic alumina (NAA) relies intrinsically on the electric field-driven flow of electrolytic species and the incorporation of electrolyte impurities during the growth of anodic oxide through anodization. This phenomenon provides new opportunities to engineer BOL's inherited ionic current rectification (ICR) fingerprints. NAA's characteristic ICR signals are associated with the space charge density gradient across BOL and electric field-induced ion migration through hopping from vacancy to vacancy. In this study, we engineer the intrinsic space charge density gradient of the BOL of NAA under a range of anodizing potentials in hard and mild anodization regimes. Real-time characterization of the ICR fingerprints of NAA during selective etching of the BOL makes it possible to unravel the distribution pattern of vacancies through rectification signals as a function of etching direction and time. Our analysis demonstrates that the space charge density gradient varies across the BOL of NAA, where the magnitude and distribution of the space charge density gradient are revealed to be critically determined by anodizing the electrolyte, regime, and potential. This study provides a comprehensive understanding of the engineering of ion transport behavior across blind-hole NAA membranes by tuning the distribution of defects across BOL through anodization conditions. This method has the potential to be harnessed for developing nanofluidic devices with tailored ionic rectification properties for energy generation and storage and sensing applications.
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http://dx.doi.org/10.1021/acsami.3c08745 | DOI Listing |
Phys Rev Lett
December 2024
Laboratory of Plasma Physics (LPP), CNRS, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris, Palaiseau, France.
Energy conservation dictates that an electron with elementary charge e traversing a vacuum gap formed by electrodes maintained at potential difference U volts acquires maximum energy of eU. In many experiments electrons with energies as high as 3eU have been observed. The experimental discovery of this effect was made over 50 years ago and is still a subject of significant controversy in applications related to x-ray generation from high voltage discharges.
View Article and Find Full Text PDFJ Mater Chem A Mater
December 2024
Department of Materials Engineering, Ben-Gurion University of the Negev Beer Sheva 8410500 Israel
Zinc ferrite (ZnFeO, ZFO) has gained attention as a candidate material for photoelectrochemical water oxidation. However, champion devices have achieved photocurrents far below that predicted by its bandgap energy. Herein, strong optical interference is employed in compact ultrathin film (8-14 nm) Ti-doped ZFO films deposited on specular back reflectors to boost photoanode performance through enhanced light trapping, resulting in a roughly fourfold improvement in absorption as compared to films deposited on transparent substrates.
View Article and Find Full Text PDFTalanta
December 2024
Department of Vascular Surgery, Zhongshan Xiamen Hospital, Fudan University, Xiamen, 361015, China. Electronic address:
Filling the microchannel with negatively charged hydrogel can exhibit microsacle ion current rectification (ICR) behavior, which is attributed to the space negative charge and structural asymmetry of hydrogel. In this study, this character had been applied to develop a trypsin sensor for the first time. A hydrogel synthesized with bovine serum albumin (BSA) and glyoxal (BSAG hydrogel) was filled at the tip of microchannel firstly.
View Article and Find Full Text PDFInt J Numer Method Biomed Eng
January 2025
Department of Biomedical Engineering, Inonu University, Malatya, Türkiye.
Spinal cord stimulation (SCS) represents a therapeutic approach for chronic pain management in patients refractory to conventional treatments. By implanting electrodes in the epidural space, SCS aims to mitigate pain transmission to the brain through electrical stimulation, often resulting in sensory perceptions such as paresthesia. This study investigates the influence of electrode configurations on electrical parameters, including current density and electric potential, within the spinal cord environment.
View Article and Find Full Text PDFACS Appl Mater Interfaces
December 2024
State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Medium-wide-bandgap (MWBG) organic photovoltaic (OPV) cells have emerged as a promising category with distinctive application possibilities, especially in environments characterized by specific light conditions, such as indoor spaces. However, there are few high-efficiency MWBG acceptors, and most of them are constructed through high-cost fused central units, which limits the industrialization of MWBG OPV cells. Here, two completely nonfused MWBG acceptors, TBT-38 and TBT-43 with different alkoxy substituent positions on the thiophene rings, are synthesized.
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