Au nanoparticles decorated β-Bi2O3 as highly-sensitive SERS substrate for detection of methylene blue and methyl orange

Abstract

In this work, Au/Bi₂O₃ was synthesized by loading Au nanoparticles (NPs) onto β-Bi₂O₃ by a simple solution reduction method. β-Bi₂O₃ was synthesized by a precipitation-thermal decomposition procedure, which results in significantly improved SERS detection limits down to 10⁻⁹ M for methylene blue (MB) and 10⁻⁷ M for methyl orange (MO) as probe molecules, comparable to those reported for the best semiconductor SERS substrates. In particular, further deposition of Au NPs (5.20% wt%) onto β-Bi₂O₃ results in a two-order-of-magnitude enhancement in detection sensitivity, achieving a detection limit of 10⁻¹¹ M for MB and 10⁻⁹ M for MO. Under ultraviolet/visible irradiation, the Au/Bi₂O₃ hybrids substrate exhibits superior self-cleaning ability due to its photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. The advanced composite substrate simultaneously achieved ultra-low mass loading of Au NPs, outstanding detection performance, good reproducibility, high stability and self-cleaning ability. The development strategy of low load noble metal coupled high performance semiconductor β-Bi₂O₃ to obtain nano-hybrid materials provides a method to balance SERS sensitivity, cost effectiveness and operational stability, and can be synthesized in large quantities, which is a key step towards commercialization and has good reliability prospects.