Establishing high-performance Au/cobalt oxide interfaces for low-temperature benzene combustion

Abstract

A comprehensive strategy based on the facet control and elemental doping of Co3O4 support plus precise Au assembly was employed to develop the Au/h-MxCo3-xO4 (1 1 2) (h = hexagonal plates; M = Fe, Mn; x = 0.09–0.36) interfaces for low-temperature benzene combustion. The current route in synthesis of Co3O4 hexagonal plates with the most active (1 1 2) exposed facet is free of any organic solvent, surfactant, or coordinator, close to the nominal material yield. Well-controlled Au assembly onto the (1 1 2) facet of h-M0.18Co2.82O4 results in very efficient Au/h-M0.18Co2.82O4 for the target reaction. The processes developed for both controllable support fabrication and governable Au assembly are applicable to other systems and utilizations. N2 sorption, X-ray diffraction, scanning electron microscopy/(high-resolution)transmission electron microscopy, selected-area electron diffraction, energy-dispersive X-ray mapping, inductively coupled plasma mass spectrometry, H2 temperature-programmed reduction, O2 temperature-programmed desorption, and X-ray photoelectron spectroscopy were performed to understand the physicochemical properties of various interfaces. Turnover frequency calculation and activation energy determination were used to reveal distinct catalytic behaviors. The factors significantly determining the interface activity are as follows: (1) the critical support orientation and element constitution [h-MxCo3-xO4 (1 1 2) (M = Fe, Mn, x = 0.09–0.18)]; (2) the surface reconstruction [from (1 1 2) to (1 1 1)] owing to increasing dopant content; (3) the evolution of reactive oxygen species (OI− vs. OII−) and the oxidation state of Au entities.