Multiphysics Modeling of Photoelectrochemical Devices for Simultaneous Solar-Driven Biomass Reforming and Hydrogen Production

Biomass reforming, including glycerol and 5-hydroxymethylfurfural oxidation, converts renewable biomass-derived molecules into value-added chemicals and fuels. This process is crucial for sustainable energy and chemical production, offering a carbon-neutral alternative to fossil-based feedstocks. Integrating biomass oxidation with photoelectrochemistry enables solar-driven reactions, reducing external electrical input and improving energy efficiency. Photoelectrochemical cells selectively oxidize biomass-derived compounds at the photoanode while generating hydrogen or other reduction products at the cathode, creating a synergistic system for sustainable fuel and chemical production. Electrolyte transport properties significantly impact membraneless PEC device performance. This study systematically investigates flow behavior, crossover effects, and device operation using a 0.5 M glycerol solution as the anolyte. Despite its similar density and viscosity to water, the glycerol solution exhibits density-driven instabilities, leading to electrolyte mixing when paired with a pure water catholyte. Simulations reveal that using the same glycerol solution in both compartments prevents crossover and enhances stability. A single-bridge design optimized to minimize iR drop while maintaining separation reduced voltage losses by 47% compared to a double-bridge configuration. At flow rates ≥60 mL/min, product crossover remains negligible, supporting the feasibility of membraneless PEC designs for glycerol oxidation. These findings contribute to scaling up PEC systems for sustainable hydrogen and high-value-added chemical production, emphasizing the potential of modular, high-efficiency solar-driven biomass reforming.