Continuous-Flow Synthesis of BiVO₄ Nanoparticles: From Laboratory Scale to Practical Systems

Cost-effective and efficient photoelectrochemical (PEC) water splitting stands out as one of the most promising strategies to address sustainable energy supply in the form of green H₂. Large-area photoelectrodes featuring precise chemical and morphological control are key components for a practical solar-to-hydrogen conversion. Herein, we report the continuous flow synthesis of BiVO₄ nanoparticles (NPs) by using a simple microreactor configuration. The solution containing the as-prepared NPs enables the deposition of BiVO₄ photoanodes with areas up to 52 cm² through a simple and scalable chemical bath deposition method. On the other hand, surface protection by an ultrathin Al₂O₃ overlayer grown by atomic layer deposition (ALD) increases the performance of the 1 cm² BiVO₄ photoanodes ~30 %, exhibiting a photocurrent density of ~2.0 mA⋅cm^-2 at 1.23 V vs. the Reversible Hydrogen Electrode in the presence of a sacrificial hole scavenger. The optimized continuous flow synthesis provides an affordable methodology for the fabrication of cost-effective, large-scale photoanodes, which could potentially be applied for different photoelectrochemical reactions.