Current-voltage characteristics of coupled photodiode-electrocatalyst devices

Abstract

Analytical expressions for the illuminated current-voltage characteristics of coupled photodiode-electrocatalyst fuel forming devices are derived. The approach is based on combining solid-state diode behavior with metal electrochemistry via the diode equation and the Butler-Volmer equation (charge transfer coefficients: αA = αC = α) or the Tafel equation (|η|≥118mVne), respectively. The analytical expression for the current-voltage behavior of the coupled photodiode-electrocatalyst device (αA = αC = 0.5) and an isolated photodiode is plotted, compared, and augmented with band diagrams at equilibrium, open circuit, short circuit, and the maximum power point to illustrate the effect of coupling an electrocatalyst to a photodiode. The applicability of the derived equations is then demonstrated by comparing with a recently reported high efficiency, thin film InP/InOxPy/Rh photoelectrosynthetic hydrogen evolution device.

Amorphous TiO 2 coatings stabilize Si, GaAs, and GaP photoanodes for efficient water oxidation

“…The raster area was 125 μm × 125 μm, with a centered 12500 μm 2 gated area. Count rates of 30 Si, 48 Ti, Spectroscopic ellipsometry Complex refractive index (n, k) data for films of unannealed, as-grown TiO 2 on n + -Si were obtained using spectroscopic ellipsometry. The ellipsometric data were acquired using a J.A.…”

Semiconductor Surface Transformations for Photoelectrochemical Energy Conversion

“…The photocurrent-voltage behavior of such a catalyst covered photodiode, immersed into a solution, has recently been modeled 58 and the output characteristics could be reproduced with high accuracy; the potential-current relationship is given below for a diode: [15] Here, the first term describes the photoactivity of the solid state part of the device and the second term its electrochemical behavior; j L denotes the light-induced current, j the operating current, j 0,PV is the reverse saturation current and n d is the junction ideality factor. In the second term, j 0,cat is the exchange current density of the catalyst and n e the number of electrons transferred in the reaction.…”

Stable Solar-Driven Water Oxidation to O2(g) by Ni-Oxide-Coated Silicon Photoanodes

“…1 The FTO glass was removed from these samples as described previously 2 . Briefly, the FTO-coated np + -Si was immersed in a mixture of 0.5 M HCl, 0.4 M FeSO 4 , and 0.1 M FeCl 3 and then the mixture was agitated while ~3.5 g Zn was slowly poured into the mixture. The solution turned clear after ~2 min and the samples were then removed and rinsed with deionized water.…”