Self-assembly of a highly stable and active Co3O4/H-TiO2 bulk heterojunction with high-energy interfacial structures for low temperature CO catalytic oxidation

Abstract

Development of transition metal oxide catalysts with a tunable structure is extremely important for energy, chemical and environmental processes. Herein, we report a new strategy for the synthesis of a highly stable and active Co₃O₄/H-TiO₂ bulk heterojunction with high-energy interfacial structures through two-step hydrothermal-crystallization for efficient low-temperature CO catalytic oxidation. By selectively etching, an anatase TiO₂ support exposing the high-index (112) facet was first created. The high-index (112) facet with high surface energy can endow the bulk TiO₂ support with unique physical and chemical properties so as to act as a foundation to construct a robust high-energy interfacial bulk heterojunction. Because of the presence of Ti–O–Co species at the high-energy interface, the prepared Co₃O₄/H-TiO₂ bulk heterojunction possessed much more catalytic active sites compared to Co₃O₄ nanoparticles supported on conventional TiO₂ supports and exhibited a turnover frequency (TOF) value of 3.56 × 10⁻³ s⁻¹ at 120 °C, which was very competitive compared to those of reported cobalt-based catalysts and 1000 times higher than that of commercial Co₃O₄. Importantly, due to the strong interactions between Co₃O₄ and the TiO₂ bulk support exposed high-index facet, more attractive water-resisting properties for low temperature CO oxidation can be achieved in the presence of steam (∼2%) compared to previously reported catalysts. The results show promising opportunities for tailoring catalytic behaviors beyond a facile and rational design with a controllable metal–support interface.