Plasmon-Mediated Nitrobenzene Hydrogenation with Formate as the Hydrogen Donor Studied at a Single-Particle Level

Hydrogenation of nitroaromatics is typically performed under harsh reaction conditions, which would bring safety issues and energy waste. The key for the hydrogenation reaction is to finely control the product selectivity under mild conditions. Herein, the anisotropic Pd–Au nanorods (NRs) exhibited efficient plasmon-enhanced selective hydrogenation of nitrobenzene to aniline with formate as the hydrogen donor. Under visible-light irradiation, both conversion and selectivity for nitrobenzene hydrogenation can reach nearly 100%. Plasmon-induced interaction between formic acid (FA), nitrobenzene, and plasmonic nanostructures was explored by single-particle photoluminescence (PL) measurement in situ. The complete quenching phenomenon of localized surface plasmon resonance PL for single Pd–Au NR was observed when immersed in FA. In addition, light-induced adsorption enhancement of nitrobenzene was discovered, which is vital for the plasmon-enhanced catalysis. This work provides direct evidence for the carrier transfer from Au–Pd NRs to FA via single-particle PL measurement and will give guidance to the rational design of hybrid plasmonic catalysts to promote eco-friendly organic conversion.