Selective synthesis of Au and graphitic carbon-encapsulated Au (Au@GC) nanoparticles by pulsed laser ablation in solvents: Catalytic Au and acid-resistant Au@GC nanoparticles

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Gold nanoparticles (Au NPs) are the most versatile nanomaterials reported to date owing to their unique physiochemical properties as well as promising various applications. Recently, many techniques have been used for the synthesis of Au NPs. In this study, various types of Au NPs were synthesized by pulsed laser ablation in liquid (PLAL) using the following four solvents: methanol, deionized (DI) water, hexane, and acetonitrile. Pulsed laser ablation in methanol and DI water is used for the synthesis of bare Au NPs, as photocatalysts. Au NPs showed an enhanced catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol. Interestingly, Au NPs prepared by PLAL using hexane and acetonitrile were encapsulated with graphitic carbon (GC) layers (Au@GC), where the solvent was used as a carbon source for the GC layers. In contrast to bare Au NPs, Au@GC NPs exhibited no catalytic activity due to the protective GC layers formed on Au NPs. On the other hand, Au@GC NPs demonstrated a high corrosion resistance against strong acids. The present study revealed that the PLA of Au plate in various liquid medium is a facile method for the synthesis of excellent catalytic or acid resistant Au NPs with a unique surface structure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bare Au nanoparticles (NPs) were prepared by PLA in methanol and DI water. </LI> <LI> Au@graphitic carbon (GC) NPs were prepared by PLA in hexane and acetonitrile. </LI> <LI> Catalytic activity was observed by only bare Au NPs, but no activity by Au@GC NPs. </LI> <LI> GC layers were formed only on small Au NPs (< ~50 nm) due to carbon solubility. </LI> <LI> Acid treatment is an easy and simple way for the preparation of small Au@GC NPs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>