Anchoring branched Ag nano-islands on Au@CuxO mesoporous nanospheres as dual plasmonic absorbers for efficient photothermal conversion

Abstract

Plasmonic semiconductor nanomaterials have been widely accepted as promising candidates for photothermal conversion, while the efficiency is yet to optimize. Herein, we report a facile synthesis of Au@CuxO mesoporous nanospheres anchored with branched Ag nano-islands on the surface and explore their applications as photothermal conversion agent. Due to the intimate hybridization of two materials, the Au@CuxO-Ag hybrid nanocomposites display a unique dual-plasmonic absorption that covers the visible-NIR range, benefiting the utilization efficiency of light energy. The synthesis is realized by reacting Au@CuxO with Ag+, the galvanic replacement reaction between them enables a preferential depletion of Cu phase, leaving Ag and Cu2O as dominate crystal phases. The resulting hybrid nanocomposites are featured with a core-shell structure but incomplete coverage, as well as the mesoporous interior and dendritic outer shell. In addition to the enhanced photothermal conversion efficiency, the current nano-hybrids show excellent structural stability and no decay in conversion after five successive rounds of measurement. The advantages in both morphological and electronic structure aspects are discussed. The present study validates the promising synergetic use of distinct hot charge carriers originating from metal and semiconductor that are photoexcited in the same hybrid nanoparticle for photothermal conversion, shedding light on rational design of photothermal materials based on metal-semiconductor hybrid nanocomposites.