Fabrication of core–shell AuNP@UIO-66/Au nanoparticles for in situ SERS monitoring of the degradation process

Abstract

Core–shell structure AuNP@UIO-66/Au nanoparticles were fabricated, consisting of a 50 nm AuNP core, a UIO-66(Zr) shell, and a 4 nm AuNP layer on the shell. AuNP@UIO-66/Au offers highly sensitive and stable SERS performance for probing 4-aminothiophenol (4-ATP) because the ∼3 nm ultrathin shell guarantees both the adsorption of UIO-66 and sustains good SERS activity. Benefiting from the abundant carboxyl group of UIO-66, the 4 nm AuNPs were in situ grown on the shell surface. Two-dimensional finite-difference time-domain simulation was employed to investigate the electromagnetic field distribution of AuNP@UIO-66/Au. In addition, this new SERS substrate offers excellent catalyst activity due to the 4 nm AuNP layer. The AuNP@UIO-66/Au can thus offer in situ label-free monitoring of the chemical reaction process by SERS. As a proof of concept, this application was evaluated by SERS monitoring of the reductive degradation process of 4-nitrophenol (4-NP), as well as the oxidative degradation process of crystal violet (CV), without adding extra catalysts. The new nanoparticle structure has great potential to simultaneously catalyze and monitor other surface chemical reactions and is thus favourable to further investigate the reaction mechanism.