Pd@BTL–Cd core–shell nanoparticles as plasmonic photocatalysts for the reductive amination of furfural in water

Abstract

This work reports the step-wise fabrication of a core–shell plasmonic nanocomposite Pd@BTL–Cd consisting of a BTL–Cd shell and a palladium nanoparticle core. BTL–Cd is the [Cd(BTL)·CdCl₂] complex where the heptadentate framework of the bis-compartmental ligand encapsulated two Cd(II) centres in separate pockets. Pd@BTL–Cd has been found to be highly efficient for the photocatalytic conversion of furfural (a biomass-derived aldehyde) to furfuryl amine via reductive amination in aqueous ammonia at room temperature. The improved photocatalytic performance of the nanocomposite and its functioning in visible regions in contrast to parental species are attributed to the synergistic functioning of the core and the shell. The inclusion of the Cd–BTL nanoshell lowers the overall band gap of the material while the Pd nanocore generates in situ hydrogen species during photocatalysis. The optimization of catalytic conditions revealed that 10 mg of the fabricated photocatalyst can offer 99% conversion and a high turnover number in 4 h. The efficacy of the catalyst can be retained for up to 5 cycles with high selectivity for the formation of furfuryl amine (98%) in the presence of visible light (λ = 445 nm). Pd@BTL–Cd is also catalytically effective for the reductive amination of other aldehydes.