Leaf-like Co-ZIF-L derivatives embedded on Co2AlO4/Ni foam from hydrotalcites as monolithic catalysts for toluene abatement

Abstract

Herein, a series of distinctively monolithic catalysts were first synthesized by decorating leaf-like Co-ZIF-L derivatives on Co₂AlO₄ coral-like microspheres from CoAl layered double hydroxides (LDHs), which were coated on three-dimensional porous Ni foam. As a proof of concept application, toluene was chosen as a probe molecule to evaluate their catalytic performances over the as-synthesized catalysts. As a result, the L-12 sample derived from Co₂AlO₄@Co-Co LDHs displayed an excellent catalytic performance, cycling stability and long-term stability for toluene oxidation (T₉₉ = 272 °C, 33 °C lower than that of Co₂AlO₄ sample), where leaf-like Co-ZIF-L served as a sacrificial template to synthesize Co-Co LDHs. The improved catalytic performance was attributed to its distinctive structure, in which leaf-like Co-ZIF-L derivatives on Co₂AlO₄ resulted in its higher specific surface area, lower-temperature reducibility, rich surface oxygen vacancy and high valence Co³⁺ species. This work thus demonstrates a feasible strategy for the design and fabrication of hybrid LDHs/ZIFs-derived composite architectures, which is expected to construct other novel monolithic catalysts with hierarchical structures for other potential applications.

Keywords: Co-ZIF-L; Layered double hydroxides; Monolithic catalysts; Ni foam; Toluene oxidation.