In this communication, we report the surface plasmon induced reduction of metal salts wherein the ‘hot holes’ generated during the surface plasmon resonance of gold nanoparticles are indirectly used to reduce metal ions by a citrate oxidation step. Here we show the reduction process of two metals, namely silver and copper by exciting the gold nanoparticles with 589 and 658 nm light source at room temperature, thus highlighting the possibility of reducing metal salts by plasmon-mediated technique.Highlights► A new surface plasmon induced reduction technique is demonstrated. ► Reduction of silver and copper ions were succesfully demonstrated by exciting the gold nanoparticles with laser. ► UV–visible spectroscopy and TEM analysis confirmed the reduction process.

Crystal growth occurs in nature in the form of snow flakes, igneous rocks, stalactites, stalagmites, etc., which sometimes arrest the growth pattern. The crystal growth in the lab or industry during a deposition process is generally evaluated by in situ microscopy techniques or by arresting the reaction at various time intervals. However, capturing the total growth process from the formation of nuclei to macrostructure is not easy. Here, we show a spontaneous formation of an unusual patterned growth during galvanic displacement of both gold and silver on silicon, wherein systematic concentric rings of 50–100 μm in diameter were formed at discrete places. The most striking pattern arrested the complete growth process from nuclei that formed the innermost concentric circle, to the formation of various network structures and dendrites, each forming separate circular patterns. The pattern formation was attributed to the bubble growth during the galvanic displacement reaction. We also compared the growth pattern formed in the concentric rings to the actual crystal growth process during the galvanic displacement reaction by arresting the reaction at various time intervals and found that spontaneously formed concentric rings provided greater detailed crystal growth phenomena. Thus, we could say that by controlling the growth of the bubble, it is possible to visualize the complete crystal growth process in one step.

Different alkylamine-capped Au nanoparticles (NPs) and nanowires (NWs) have been successfully prepared through a facile one-pot solution growth method. Alkylamines serve as reducing agents and stabilizers in the synthetic process. As the chain length of alkylamines has an effect on the diffusion rate of monomers, the sizes of NPs and the diameters of NWs can be adjusted by adding different alkylamines in the synthetic process. Surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G (Rh 6G) are obtained on the Au NPs and NWs modified substrates, indicating that the as-synthesized Au nanostructures have great potential for high sensitive optical detection application.Graphical abstractThe sizes of Au nanoparticles and the diameters of Au nanowires can be controlled by using different alkylamines as reducing agents and stabilizers in the synthetic process.Highlights► Au nanoparticles were synthesized by using alkylamines as reducing agents and stabilizers. ► Au nanowires were synthesized by reducing HAuCl4·4H2O in a micellar structure formed by alkylamines and oleic acid. ► The sizes of Au nanoparticles and nanowires could be adjusted by changing the chain length of alkylamines in the synthetic process. ► The synthetic strategy was simple and the as-synthesized Au nanoparticles and nanowires could be used as substrates for SERS detection.

1-Hexadecylamine (HDA)-capped Au and Ag nanoparticles (NPs) have been successfully prepared by a one-pot solution growth method. The HDA is used as both reducing agent and stabilizer in the synthetic process is favorable for investigating the capping mechanism of Au and Ag NPs’ surface. The growth process and characterization of Au and Ag NPs are determined by Ultraviolet–visible (UV–vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). Experimental results demonstrate that the HDA-capped Au and Ag NPs are highly crystalline and have good optical properties. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 2-thionaphthol are obtained on the Au and Ag NPs modified glass surface, respectively, indicating that the as-synthesized noble metal NPs have potentially high sensitive optical detection application.