Rapid synthesis of uniformly small nickel nanoparticles for the surface functionalization of epitaxial graphene

TL;DR

This paper presents a rapid aqueous synthesis method for small nickel nanoparticles, their detailed characterization, and surface functionalization of epitaxial graphene, demonstrating stability and substrate-dependent arrangement.

Contribution

The study introduces a quick, simple synthesis of uniform Ni nanoparticles and explores their surface behavior on graphene, advancing functionalization techniques.

Findings

Ni NPs have ~11 nm diameter with narrow size distribution.

Ni NPs are stable up to 550°C on surfaces.

Surface arrangement depends on substrate type.

Abstract

Nickel nanoparticles (Ni NPs), thanks to their peculiar properties, are interesting materials for many applications including catalysis, hydrogen storage, and sensors. In this work, Ni NPs are synthesized in aqueous solution by a simple and rapid procedure with cetyltrimethylammonium bromide (CTAB) as a capping agent, and are extensively characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). We investigated their shape, dimension, and their distribution on the surfaces of SiO2 and epitaxial graphene (EG) samples. Ni NPs have an average diameter of ~11 nm, with a narrow size dispersion, and their arrangement on the surface is strongly dependent on the substrate. EG samples functionalized with Ni NPs are further characterized by X-ray photoelectron spectroscopy (XPS), as made and after thermal annealing above 350{\deg}C to confirm the degradation of CTAB and the presence of metallic Ni(0). Moreover, high resolution scanning tunneling microscopy (STM) topographies reveal the structural stability of the NPs up to 550 {\deg}C.