Nano-Sized NiO Immobilized on Au/CNT for Benzyl Alcohol Oxidation: Influences of Hybrid Structure and Interface

Abstract

Tiny gold nanoparticles were successfully anchored on carbon nanotubes (CNT) with NiO decoration by a two-step synthesis. Characterizations suggested that Ni species in an oxidative state preferred to be highly dispersed on CNT. During the synthesis, in situ reduction by NaBH4 and thermal treatment in oxidation atmosphere were consequently carried out, causing the formation of Au-Ni-Ox interfaces and bimetal hybrid structure depending on the Ni/Au atomic ratios. With an appropriate Ni/Au atomic ratio of 8:1, Ni atoms migrated into the sub-layers of Au particles and induced the lattice contraction of Au particles, whilst a higher Ni/Au atomic ratio led to the accumulation of NiO fractions surrounding Au particles. Both contributed to the well-defined Au-Ni-Ox interface and accelerated reaction rates. Nickel species acted as structure promoters with essential Au-Ni-Ox hybrid structure as well as the active oxygen supplier, accounting for the enhanced activity for benzyl alcohol oxidation. However, the over-layer of unsaturated gold sites easily occured under a high Ni/Au ratio, resulting in a lower reaction rate. With an Au/Ni atomic ratio of 8:1, the specific rate of AuNi8/CNT reached 185 μmol/g/s at only 50 °C in O2 at ordinary pressure.

Co Ion‐, NiS2‐ and CNT‐Co‐Doped Nanoflower/Hollow Spherical NiO Nanocomposites for Efficient Electrocatalytic Oxidation of Methanol

“…[44][45][46] Carbon materials, such as carbon black, carbon nanofibers, graphene and carbon nanotubes, can be good carriers to increase the conductivity of NiO. [47,48] Among these carbon materials, carbon nanotubes are regarded as the best supports [37,49] because of the high surface area, fast electron transfer dynamics and high stability.…”

“…In order to further improve their activity, highly conductive support materials are usually required to immobilize NiO nano‐catalysts and ensure good dispersion and conductivity of catalysts [44–46] . Carbon materials, such as carbon black, carbon nanofibers, graphene and carbon nanotubes, can be good carriers to increase the conductivity of NiO [47,48] . Among these carbon materials, carbon nanotubes are regarded as the best supports [37,49] because of the high surface area, fast electron transfer dynamics and high stability.…”