Numerical Modeling of Degradation in Photoelectrochemical Water Splitting Devices

Abstract

One of the main challenges for advancing large-scale implementation of photoelectrochemical devices is performance loss, mainly due to photocorrosion [1]. Semiconductors with good photoabsorption behavior and interesting band alignments are inherently non-stable, and therefore photocorrode in few minutes to hours. Usually, photocorrosion is interpreted on the basis of energy schemes, comparing the quasi-Fermi levels of charge carriers to the corrosion potentials of the photoelectrode [2]. However, the competition between the pure redox process of water splitting and photoelectrode dissolution/passivation can be highly influenced by kinetic parameters [3]. We use a physics-based model to study photocorrosion phenomenon in monolithic photoelectrochemical devices. The studied device is composed of different catalyst covered semiconductors, immersed in a liquid electrolyte. Acidic and alkaline conditions are tested. The catalyst layer is considered a nanoporous media, the solid phase being composed of a supporting structure and catalyst particles. Accurate thermodynamic and kinetic measurements on different semiconductor/catalyst/electrolyte combinations support our study. These measurements include rotating ring-disc measurements, cyclic voltammetry and chronoamperometry. The simulation results show how irradiation intensity, kinetic parameters, and mass transport in the two-phase flow can impact the stability of the photoelectrode/electrolyte interface. [1] F. Nandjou and S. Haussener. Degradation in photoelectrochemical devices: Review with an illustrative case study. J. Phys. D: Appl. Phys. 50 (2017) 124002. [2] Gerischer H, et al. Report EUR 9531 EN (1984), Commission of the European Communities. [3] R. Memming. The Role of Energy Levels in Semiconductor ‐ Electrolyte Solar Cells. J. Electrochem. Soc. 125 (1978) 117.