Limiting photocurrent analysis of a wide channel photoelectrochemical flow reactor

Abstract

The development of efficient and scalable photoelectrochemical (PEC) reactors is of great importance for the eventual commercialization of solar fuels technology. In this study, we systematically explore the influence of convective mass transport and light intensity on the performance of a 3D-printed PEC flow cell reactor based on a wide channel, parallel plate geometry. Using this design, the limiting current density generated from the hydrogen evolution reaction at a p-Si metal-insulator-semiconductor (MIS) photocathode was investigated under varied reactant concentration, fluid velocity, and light intensity. Additionally, a simple model is introduced to predict the range of operating conditions (reactant concentration, light intensity, fluid velocity) for which the photocurrent generated in a parallel plate PEC flow cell is limited by light absorption or mass transport. This model can serve as a useful guide for the design and operation of wide-channel PEC flow reactors. The results of this study have important implications for PEC reactors operating in electrolytes with dilute reactant concentrations and/or under high light intensities where high fluid velocities are required in order to avoid operation in the mass transport-limited regime.

Scalable Triple Cation Mixed Halide Perovskite–BiVO4 Tandems for Bias‐Free Water Splitting

“…A 3D-printed cell was developed for the larger electrodes and all back-to-back tandems, to maintain a constant sample position and ensure a certain separation between the cathodic and anodic compartments. In comparison to other recent models which have employed 3D-printing for electrodes, [94][95][96] electrochemical flow reactors [97][98][99][100] or biased photoelectrodes, [101] this represents the first reported 3Dprinted PEC cell design for bias-free tandems.…”

Rational design of photoelectrochemical cells towards bias-free water splitting: Thermodynamic and kinetic insights

“…This strategy is valid only if PECs show linear photocurrent increasement with light intensity, which maintains the ABPE at an unchanged value. However, the favorable proportional photocurrent response only lies in low light concentration region (normally less than 3 suns) [23,24], while a power function was observed in the highly concentrated region (up to more than 50 suns) [25], which, on the contrary, reduces the ABPE. The existing explanation attributes this undesirable photocurrent behavior to the higher recombination induced by increased intensity [25].…”

Optical Losses at Gas Evolving Photoelectrodes: Implications for Photoelectrochemical Water Splitting

“…1 sun of irradiance, which renders the extrapolation of existing models difficult. PEC systems under concentrated illumination (2–4 suns) have achieved photocurrent densities on the order of 10 1 A m –2 . , Recently, developments on high flux solar concentrators could prospectively increase photocurrent densities on the order of 10 3 A m –2 ; however, experimental studies under such conditions are still not available. A parameter consistently used in these models is the fractional surface coverage of electroactive area, normally Θ > 0.1 for current densities <10 1 A m –2 .…”