Abstract
Au nanoparticles synthesized from colloidal techniques have the capability in many applications such as catalysis and sensing. Au nanoparticles function as both catalyst and highly sensitive SERS probe can be employed for sustainable and green catalytic process. However, capping ligands that are necessary to stabilize nanoparticles during synthesis are negative for catalytic activity. In this work, a simple effective mild thermal treatment to remove capping ligands meanwhile preserving the high SERS sensitivity of Au nanoparticles is reported. We show that under the optimal treatment conditions (250 °C for 2 h), 50 nm Au nanoparticles surfaces are free from any capping molecules. The catalytic activity of treated Au nanoparticles is studied through H2O2 decomposition, which proves that the treatment is favorable for catalytic performance improvement. A reaction intermediate during H2O2 decomposition is observed and identified.
Highlights
Au nanoparticles synthesized from colloidal techniques have the capability in many applications such as catalysis and sensing
We show that the catalytic activity of Au NPs under the optimal treatment conditions increased enormously compared with untreated counterparts
The study consists of a comprehensive exploration about effects from thermal temperature and treatment time on the Au NPs SERS sensitivity and resultant catalytic activity
Summary
Au nanoparticles synthesized from colloidal techniques have the capability in many applications such as catalysis and sensing. Colloidal Au NPs are usually capped with specific surfactant or ligands, which enable particle size, shape and stability control during synthesis While these capping ligands are born with nanoparticle synthesis, they are detrimental for catalytic application since they block the binding sites where the reaction o ccurs[17]. Since the Au NPs size need be above 10 nm to be effective as SERS probes, thermal treatment at mild conditions by control the temperature and time can potentially work as an efficient means to remove ligands and preserving SERS sensitivity without changing the morphology of particles due to the melting-point depression[24,25]. We studied extensively the effect of treatment temperature and time on the morphology and SERS sensitivity of colloidal synthesized 50 nm Au NPs. We show that the catalytic activity of Au NPs under the optimal treatment conditions increased enormously compared with untreated counterparts. In situ studies were performed on the treated Au NPs to study the intermediates during particle-catalyzed H 2O2 decomposition
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