New Transparent Laser-Drilled Fluorine-doped Tin Oxide covered Quartz Electrodes for Photo-Electrochemical Water Splitting

Abstract

A new-designed transparent, conductive and porous electrode was developed for application in a compact laboratory-scale proton exchange membrane (PEM) photo-electrolyzer. The electrode is made of a thin transparent quartz sheet covered with fluorine-doped tin oxide (FTO), in which an array of holes is laser-drilled to allow water and gas permeation. The electrical, morphological, optical and electrochemical characterization of the drilled electrodes is presented in comparison with a non-drilled one. The drilled electrode exhibits, in the visible region, a good transmittance (average value of 62%), a noticeable reflectance due to the light scattering effect of the hole-drilled internal region, and a higher effective surface area than the non-drilled electrode. The proof-of-concept of the applicability of the drilled electrode was achieved by using it as a support for a traditional photocatalyst (i.e. commercial TiO2 nanoparticles). The latter, coupled with a polymeric electrolyte membrane (i.e.Nafion 117) and a Pt counter electrode, forms a transparent membrane electrode assembly (MEA), with a good conductivity, wettability and porosity. Electrochemical impedance spectroscopy (EIS) was used as a very powerful tool to gain information on the real active surface of the new drilled electrode and the main electrochemical parameters driving the charge transfer reactions on it. This new electrode architecture is demonstrated to be an ideal support for testing new anodic and cathodic photoactive materials working in tandem configuration for solar fuels production by water photo-electrolysis.

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

“…Nevertheless, under highly oxidizing conditions, or in the presence of concentrated (acid or basic) electrolytes, they can suffer from low corrosion stability; moreover, they can have a lower surface area than the nanostructured substrates. In order to overcome some of such issues, a new design of FTO-covered quartz laser drilled electrodes was recently proposed by Hernández et al [93,94]. As shown in Figure 7, this substrate combines several advantages: good transparency (~62% of transmittance), high diffuse reflectance (~37%), low electric resistance, (≤40 Ω/square), and easy adhesion of the photo-catalysts; in addition, this substrate allows In order for these materials to be used in a Polymeric Exchange Membrane (PEM)-type photo-electrolysis device, to make a membrane-electrode assembly (MEA), the presence of macroporosity is indispensable to allow the diffusion of the water, protons (H + ) and produced gases.…”

A model for electrode effects based on adsorption theory

“…(19) for r 0 = 1.5 ×m 2 , a = 12× 10 −3 ×m 2 /s and b = 4.5 × 10 −3 s −1 , typical of the system considered by us, as discussed in the following, and for r b = 2r 0 , r b = r 0 , r b = r 0 /5 and r b = 0, that corresponds to the case described by Eq. (22). As it is evident from Fig.…”

“…oxygen and hydrogen, mainly using solar energy. A compact home-designed case similar to the one reported in our previous works [21,22] was used for the experiments, in order to minimize the distance between the electrodes (about 6 mm) thus reducing the ohmic drop in the cell (see Fig. 3b).…”

“…Of course, the validity of Eq. (22) is limited to the case where the bulk resistance of the cell is negligible with respect to that of the naked interface layer.…”

Core-substituted naphthalenediimides anchored on BiVO4 for visible light-driven water splitting

“…6,53,54 For instance, at 1.23 VRHE the charge transfer resistance of the BiVO4 + dye 3 film (∼ 136 Ω) is less than a half of such of the bare BiVO4 (∼ 300 Ω).…”