Plasma-Assisted Atomic Layer Deposition of IrO2 for Neuroelectronics

Abstract

In vitro and in vivo stimulation and recording of neuron action potential is currently achieved with microelectrode arrays, either in planar or 3D geometries, adopting different materials and strategies. IrO2 is a conductive oxide known for its excellent biocompatibility, good adhesion on different substrates, and charge injection capabilities higher than noble metals. Atomic layer deposition (ALD) allows excellent conformal growth, which can be exploited on 3D nanoelectrode arrays. In this work, we disclose the growth of nanocrystalline rutile IrO2 at T = 150 °C adopting a new plasma-assisted ALD (PA-ALD) process. The morphological, structural, physical, chemical, and electrochemical properties of the IrO2 thin films are reported. To the best of our knowledge, the electrochemical characterization of the electrode/electrolyte interface in terms of charge injection capacity, charge storage capacity, and double-layer capacitance for IrO2 grown by PA-ALD was not reported yet. IrO2 grown on PtSi reveals a double-layer capacitance (Cdl) above 300 µF∙cm−2, and a charge injection capacity of 0.22 ± 0.01 mC∙cm−2 for an electrode of 1.0 cm2, confirming IrO2 grown by PA-ALD as an excellent material for neuroelectronic applications.

Ternary tin-doped titanium dioxide/calcium oxide (Sn-TiO2/CaO) composite as a photocatalyst for efficient removal of toxic dyes

“…29–32 A promising method to achieve this is through doping with metal or non-metal ions, which serves to decrease the band gap and shift the absorption edge towards longer wavelengths (doping refers to the intentional introduction of foreign elements into the crystal structure of a semiconductor material). 33–35 This modification allows the photocatalyst to be active under visible light, minimizing charge recombination and achieving the ideal nanoscale size for photocatalytic applications. 36 An efficient method to increase the photocatalytic activity of TiO 2 is doping with metal or non-metal ions.…”

“…Coupling (the formation of a heterogeneous structure where two different semiconductor materials are combined) between TiO 2 and CaO leads to improved light absorption, better separation and transfer of charge carriers, and enhanced photocatalytic performance. 33,35 In addition, the incorporation of CaO into TiO 2 photocatalysts can improve their stability and reusability. 43 The presence of CaO helps to prevent the accumulation of TiO 2 nanoparticles and reduces the corrosion rate, thereby increasing the lifetime of the photocatalysts, and can also be synthesized from cheap sources such as limestone, eggshells, shell waste and calcium hydroxide.…”

Loss of Oxygen Atoms on Well-Oxidized Cobalt by Heterogeneous Surface Recombination

“…Precise oxidation of various materials has attracted the attention of numerous authors involved across multiple research fields, from atomic layer oxidation [1,2] to polymer activation [3][4][5], sterilization [6,7], and degreasing of inorganic materials [8,9]. Oxygen under ambient conditions is composed of two-atom molecules, which are not very chemically reactive at room temperature [10,11].…”