In situ synthesis of palladium nanoparticles on multi-walled carbon nanotubes and their electroactivity for ethanol oxidation

Pd nanoparticles (Pd-NPs) were prepared and directly anchored on the surface of multi-walled carbon nanotubes (MWCNTs) in the absence of chemical reduction agent, where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs. Effect of various surfactants on the in situ deposition of Pd-NPs on MWCNTs was investigated. When MWCNTs were modified with a cationic surfactant (hexadecyl trimethyl ammonium bromide, CTAB), the amount of the Pd-NPs (Pd-NP/CTAB-MWCNT) generated by such an in situ deposition method gets a notable increase, and the size of the as-synthesized Pd-NPs becomes smaller, compared with those in the absence of any surfactant (Pd-NP/MWCNT) or in the presence of an anionic surfactant SDS (Pd-NP/SDS-MWCNT) and a neutral surfactant OP (Pd-NP/OP-MWCNT). Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd²⁺. Among the prepared catalysts, Pd-NP/CTAB-MWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.