Boosting syngas production in photoelectrochemical CO₂ reduction through organic molecule interaction with copper photoanodes

Photoelectrochemical syngas production using photoanode-driven systems from aqueous CO₂ is a promising technology. To address the challenge of poor selectivity caused by the wide band gap of photoelectrode, we introduce a novel photoanode, PDI/Cu₂O/Cu, where PDI is the perylene tetracarboxylic di-(propyl imidazole). Using Cu₂O as a substrate enhances charge transfer kinetics, while PDI modification mitigates photocorrosion and augments photoelectrochemical CO₂ reduction reaction (PEC CO₂RR) activity. This enhancement stems from PDI’s narrow band gap and efficient visible light absorption. The syngas production achieved a noteworthy 124.47 μmol/(cm²·h) at 1.57 V vs. RHE, making it an optimal feedstock gas for hydrocarbon synthesis. Detailed UV–vis spectra indicate that layered structure significantly improves the absorption edge of the photoanode, facilitating enhanced utilization of visible light. Additionally, the electron lifetime of the PDI/Cu₂O/Cu photoanode is substantially increased which is also one of the factors affecting the reactivity, as demonstrated by the Bode phase plot.