Boosting Electrochemical Activity of Porous Transparent Conductive Oxides Electrodes Prepared by Sequential Infiltration Synthesis

Abstract

The decoration of the TCO electrode surface with chemical species serving as a charge transfer mediator, electrochemical tag, or electrocatalyst is a widely employed strategy to realize desirable electrochemical properties in electrodes. [11][12][13] Recent progress in the fabrication of porous TCO electrodes has rendered the surface modification scheme more successful by maximizing the loading of the functional redox species onto the porous electrodes with a high surface area. [14,15] Given that the mass transport of the electrolyte species to the electrode is not restricted, surfacemodified porous electrodes will enable more efficient electron transfer, thereby increasing the efficiency of electrochemical and bioelectrochemical devices. [11][12][13] In addition, the high surface area of porous electrodes is anticipated to facilitate the miniaturization of devices owing to their increased implantable capability. [16,17] Numerous approaches have been proposed for the fabrication of porous transparent electrodes, including nanoparticle casting, [18,19] salt precursor deposition, [20,21] etching, [19,22] and electrospinning. [23] Casting a nanoparticle via dip coating or spin coating is a low-cost, simple method to prepare porous TCOs. However, it cannot easily achieve precise control over the pore morphology, such as the pore size and size distribution. [10] TCOs of organized structures with a controlled morphology can be realized via template deposition methods, which exploit the self-assembly of soft templates, such as molecular cationic surfactant templates [24,25] or block copolymers, [20,26] with a solution of soft templates containing precursor salts for oxide formation. In this study, we employed sequential infiltration synthesis (SIS) as a new approach to fabricate porous TCO electrodes. SIS has recently emerged as a novel and attractive approach for the fabrication of inorganic-organic hybrid films and porous templated films.SIS is similar to template deposition methods in that both methods require polymer films spun on a substrate. However, the growth mechanisms of SIS differ from those of soft template deposition methods. The key mechanisms involved in SIS are as follows: 1) Infiltration of gas-phase precursor molecules into the polymer matrix, 2) coordination of the precursor molecules with a specific functional group of the polymer, and 3) a chemical reaction between the infiltrated precursor molecules Sequential infiltration synthesis (SIS) is an emerging technique for producinginorganic-organic hybrid materials and templated inorganic nanomaterials. The application space for SIS is expanding rapidly in areas such as litho graphy, filtration, photovoltaics, antireflection, and triboelectricity, but not in the field of electrochemistry. This study performs SIS for the fabrication of porous, transparent, and electrically conductive films of indium zinc oxide (IZO) to evaluate their potential as an electrode for electrochemistry. The elec trochemical activity of IZOcoated electrodes is evaluated when th...

Thin-Film-Based Multifunctional System for Optical Detection and Thermal Treatment of Biological Samples

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Nanostructured Black Silicon as a Stable and Surface-Sensitive Platform for Time-Resolved In Situ Electrochemical Infrared Absorption Spectroscopy

“…In particular, achieving efficient surface enhancements requires a nanostructured morphology, the porosity of which can easily leave the TCO exposed and vulnerable to degradation if the conditions extend beyond the stability window of the oxide . Considering the chemical susceptibilities of the most commonly used TCOs, which include indium tin oxide (ITO), indium zinc oxide (IZO), and fluorine-doped tin oxide (FTO), − this can severely limit the accessible range of surface potentials and pH values during in situ electrochemical FTIR experiments. To overcome these stability limitations, an alternative method based on boron-doped diamond (BDD) thin films to replace the TCO layer was recently reported and shows exceptional stability over a broad range of electrochemical potentials .…”

Transparent Porous Conductive Substrates for Gas‐Phase Photoelectrochemical Hydrogen Production

“…Developing systems for the efficient and economical conversion of solar irradiation into chemical energy for the long-term storage of this intermittent renewable source and for generating reported via polymer templating, [21,22] oblique angle deposition, [23] sequential infiltration, [24] nanoparticle self-assembly, [25][26][27] in situ deposition-etching, [28] and atomic layer deposition on porous non-conducting scaffolds, [29] however the resulting pores are typically too small for the subsequent coating of a semiconducting layer while allowing for gas diffusion (which requires macropores [30] ). Moreover, these porous films have relatively poor conductivity while the deposition procedures rely on non-porous solid support substrates (e.g., standard FTO/glass) so they cannot be used as GDEs.…”

“…In general, while transparent conducting materials have gained widespread application [ 19,20 ] in the development of optoelectronic devices (such as photovoltaic cells, light‐emitting diodes, electrochromic panels, sensors, and PEC systems), the preparation of free‐standing highly porous transparent conducting substrates remains a significant challenge. Preparation routes for porous transparent conducting oxides have been reported via polymer templating, [ 21,22 ] oblique angle deposition, [ 23 ] sequential infiltration, [ 24 ] nanoparticle self‐assembly, [ 25–27 ] in situ deposition–etching, [ 28 ] and atomic layer deposition on porous non‐conducting scaffolds, [ 29 ] however the resulting pores are typically too small for the subsequent coating of a semiconducting layer while allowing for gas diffusion (which requires macropores [ 30 ] ). Moreover, these porous films have relatively poor conductivity while the deposition procedures rely on non‐porous solid support substrates (e.g., standard FTO/glass) so they cannot be used as GDEs.…”