Nanoimprinted and Anodized Templates for Large-Scale and Low-Cost Nanopatterning

Nanopatterning to fabricate advanced nanostructured materials is a widely employed technology in a broad spectrum of applications going from spintronics and nanoelectronics to nanophotonics. This work reports on an easy route for nanopatterning making use of ordered porous templates with geometries ranging from straight lines to square, triangular or rhombohedral lattices, to be employed for the designed growth of sputtered materials with engineered properties. The procedure is based on large-scale nanoimprinting using patterned low-cost commercial disks, as 1-D grating stamps, followed by a single electrochemical process that allows one to obtain 1-D ordered porous anodic templates. Multiple imprinting steps at different angles enable more complex 2-D patterned templates. Subsequently, sputtering facilitates the growth of ferromagnetic antidot thin films (e.g., from 20 to 100 nm Co thick layers) with designed symmetries. This technique constitutes a non-expensive method for massive mold production and pattern generation avoiding standard lithographical techniques. In addition, it overcomes current challenges of the two-stage electrochemical porous anodic alumina templates: (i) allowing the patterning of large areas with high ordering and/or complex antidot geometries, and (ii) being less-time consuming.

Uniform arrays of gold nanoelectrodes with tuneable recess depth

Nanoelectrode arrays are much in demand in electroanalytical chemistry, electrocatalysis, and bioelectrochemistry. One of the promising approaches for the preparation of such systems is templated electrodeposition. In the present study, porous anodic alumina templates are used to prepare Au nanoelectrode arrays. Multistage electrodeposition is proposed for the formation of recessed electrodes with the ability to tune the distance between the surface of the porous template and the top surface of the nanoelectrodes. A set of complementary techniques, including chronoamperometry, coulometry, and scanning electron microscopy, are used to characterize the nanoelectrode arrays. The number of active nanoelectrodes is experimentally measured. The pathways to further improve the recessed nanoelectrode arrays based on anodic alumina templates are discussed.

Revisiting anodic alumina templates: from fabrication to applications

Anodic Porous Alumina -AAO- (also known as nanoporous alumina, Nanohole Alumina Arrays –NAA- or Nanoporous Anodized Alumina Platforms –NAAP-) has opened new opportunities in a wide range of fields, either...

Nanoporous water oxidation electrodes with a low loading of laser-deposited Ru/C exhibit enhanced corrosion stability

For the oxidation of water to dioxygen, oxide-covered ruthenium metal is known as the most efficient catalyst, however, with limited stability. Herein, we present a strategy for incorporating a Ru/C composite onto a novel nanoporous electrode surface with low noble metal loading and improved stability. The Ru/C is coated on the pore walls of anodic alumina templates in a one-step laser-induced deposition method from Ru3(CO)12 solutions. Scanning electron microscopy proves the presence of a continuous Ru/C layer along the inner pore walls. The amorphous material consists of metallic Ru incorporated in a carbonaceous C matrix as shown by X-ray diffraction combined with Raman and X-ray photoelectron spectroscopies. These porous electrodes reveal enhanced stability during water oxidation as compared to planar samples at pH 4. Finally, their electrocatalytic performance depends on the geometric parameters and is optimized with 13 μm pore length, which yields 2.6 mA cm−2, or 49 A g−1, at η = 0.20 V.

Electrostatic Supercapacitors by Atomic Layer Deposition on Nanoporous Anodic Alumina Templates for Environmentally Sustainable Energy Storage

In this work, the entire manufacturing process of electrostatic supercapacitors using the atomic layer deposition (ALD) technique combined with the employment of nanoporous anodic alumina templates as starting substrates is reported. The structure of a usual electrostatic capacitor, which comprises a top conductor electrode/the insulating dielectric layer/and bottom conductor electrode (C/D/C), has been reduced to nanoscale size by depositing layer by layer the required materials over patterned nanoporous anodic alumina membranes (NAAMs) by employing the ALD technique. A thin layer of aluminum-doped zinc oxide, with 3 nm in thickness, is used as both the top and bottom electrodes’ material. Two dielectric materials were tested; on the one hand, a triple-layer made by a successive combination of 3 nm each layers of silicon dioxide/titanium dioxide/silicon dioxide and on the other hand, a simple layer of alumina, both with 9 nm in total thickness. The electrical properties of these capacitors are studied, such as the impedance and capacitance dependences on the AC frequency regime (up to 10 MHz) or capacitance (180 nF/cm2) on the DC regime. High breakdown voltage values of 60 V along with low leakage currents (0.4 μA/cm2) are also measured from DC charge/discharge RC circuits to determine the main features of the capacitors behavior integrated in a real circuit.