Ag@CeO2-Au Nanorod Plasmonic Nanohybrids for Enhanced Photocatalytic Conversion of Benzyl Alcohol to Benzaldehyde

Plasmonic nanohybrids composed of semiconductors and plasmonic metal nanoparticles (NPs) have been intensively investigated in heterogeneous photocatalysis. The surface plasmonic resonance (SPR) effect of metal NPs plays a critical role in increasing light absorption and excitation of energetic carriers for photocatalysis. Most efforts are devoted to increasing the intrinsic absorptivity of the photocatalyst; however, the possible SPR scattering contribution of the metal NPs to photocatalysis has been long overlooked. In this work, we demonstrate a proof of concept of plasmonic scattering-enhanced absorption for efficient photocatalytic organic conversion in the visible to near-infrared wavelength region. With a multistep wet-chemical deposition approach, Ag NPs are encapsulated into the CeO2-Au system as the scattering core to form a Ag@CeO2-Au core@shell-satellite structure with a metal content of similar to 30.6%. By varying the size (30-100 nm in diameter) and aggregation status (single NP or coupled NPs) of the Ag NP core, its scattering effect can be adjusted over a wide spectral range. This smart design results in scattered photon energy by the core composed of coupled 100 nm Ag NPs to greatly resonate with the SPR excitation of Au nanorods on the CeO2 surface over a wide spectral range from 400 to 900 nm, resulting in the confinement of the incident light in the optical path. The SPR scattering effect-induced light harvest and the near-field enhancement at the Au-CeO2 interface greatly boost the generation and separation of hot charge carriers for surface reaction, leading to a superior conversion efficiency of >90% in 3 h with a high selectively of similar to 100% for oxidizing aminobenzyl alcohol to aminobenzaldehyde. This work reveals the immediate role of plasmonic scattering for light harvesting in photocatalysts.

Automated summary

This study demonstrates the importance of plasmonic scattering-enhanced absorption for efficient photocatalytic organic conversion in the visible to near-infrared wavelength region. By adjusting the size and aggregation status of the core, the scattering effect can be tuned.