An in situ self-assembled core–shell precursor route to prepare ultrasmall copper nanoparticles on silica catalysts

Ultrasmall copper nanoparticles (1.6 nm) on silica catalysts were successfully prepared via an in situ self-assembled core–shell precursor route. XRD, SEM-EDS and chemisorption results showed that only fatty acids with carbon chain length > 2 carbon atoms could effectively promote the dispersion of copper on silica. XPS results showed that non-stoichiometric copper butyrate was formed when butyric acid was used as a capping agent, and this non-stoichiometric compound of copper butyrate self-assembles into a shell structure outside the core of copper nitrate species. The in situ self-assembled core–shell structure could effectively prevent the copper particles from agglomeration. The catalytic performances of as-prepared 10% Cu/SiO2 catalysts enhanced with fatty acids with carbon chain length > 2 carbon atoms exhibited good activities for water–gas shift reaction due to the high proportion of defect sites, highly dispersed Cu particles and/or isolated Cu atom sites.