Modified photochemical strategy to support highly-purity, dense and monodisperse Au nanospheres on graphene oxide for optimizing SERS detection

The integration of highly-purity, dense and monodisperse plasmonic nanoparticles (NPs) on two-dimensional (2D) graphene-like support possesses great potential for optimizing surface-enhanced Raman spectroscopy (SERS). Based on ultraviolet (UV) laser-induced modified photochemical reaction , we report an ingenious and green strategy to support highly dispersed Au NPs with controllable distribution on graphene oxide (GO). Without using any stabilizing agents or other complex chemical additives , the GO with abundant oxygen-containing functional groups can be effectively excited by 375 nm laser irradiation in HAuCl 4 solution, resulting in controlled reduction of Au ions and then overgrowth of highly-purity Au NPs. Highly dense and monodisperse Au NPs with uniform diameter of ~20 nm formed on GO supports can be achieved by 30 min irradiation, which can offer maximized SERS activity in comparison with GO/Au NPs obtained by other irradiation times. The optimized GO/Au NPs give rise to ultralow SERS analyses of (10 −14  M) methylene blue (MB), (10 −13  M) rhodamine 6G (R6G) and (10 −13  M) malachite green (MG), respectively. More importantly, it can also simultaneously analyze these three aromatic dyes in a mixture condition at detection limits as low as nano-mole level (10 −9 –10 −11  M), achieving the urgent requirement of mutually independent SERS trace detection. Therefore, the obtained GO/Au NPs with extremely high SERS activity and superior spectroscopic identification will be a prominent candidate for widespread SERS applications in real-word scenarios.