Extra electric field-enhanced lightning rod effect in pine needle-like Au microarrays for boosting direct plasmon-driven photoelectrochemical hydrogenation reactions via in-situ SERS monitoring

Based on plasmonic metallic nanomaterials (NMs) with unique local surface plasmon resonance (LSPR), the photo-excited hot carrier-driven hydrogenation reaction becomes a new family of photocatalytic transformations in recent years. However, the high work function and rapid hot-carrier recombination of plasmonic NMs create huge barriers for widespread practical application. Herein, we propose a fascinating reactor of up-regulated electrochemical LSPR (EC-LSPR) driven hydrogenation reaction via the construction of hierarchical Au pine needles (H-Au PNs) with enhanced lightning rod effect under appropriate extra electric field. The plentiful elongated Au branches with sharp corners and edges can be served as excellent electron-transport channels for facilitating photo-excited hot carrier transmission and accelerating hot electron collection at nano-tips after plasmon decay. Additionally, the extra electric field with the applied voltage of similar to 0.8 V further improves the surface charge density and the internal polarization of H-Au PNs, boosting the separation efficiency of hot carriers as well as reducing the photoelectrochemical (PEC) potential on H-Au PNs. It directly leads to an effective activation enthalpy reduction to reach above the energy threshold of water splitting, which can achieve the direct plasmon-driven PEC-hydrogenation conversion of 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4ATP) in aqueous solution, and the conversion rate constant is about 5 times higher than bare EC-driven conversion. The present work provides a new opportunity for the emerging direct plasmon-driven hydrogenation reaction.

Automated summary

The study introduces a novel reactor for up-regulated electrochemical LSPR-driven hydrogenation reaction by constructing hierarchical Au pine needles with enhanced lightning rod effect. This approach enhances the catalytic efficiency of plasmonic gold nanomaterials for hydrogenation reactions by introducing an appropriate extra electric field.