Hollow cavity engineering of MOFs-derived hierarchical MnOx structure for highly efficient photothermal degradation of ethyl acetate under light irradiation

The designed synthesis of hollow-structure catalysts is central for enhancing the absorption and utilization of light irradiation, which is the core process of improved photothermal catalytic activity of VOCs. Herein, we introduced a viable cavity engineering for the fabrication of hollow MnOx-m architectures with a well-defined central space by in situ polyvinylpyrrolidone (PVP)-assisted Mn-BTC self-aggregation. The optimized MnOx-100 catalyst with hollow cavity environment exhibited approximately 96% ethyl acetate degradation toward CO2, stability and moisture resistance under light irradiation, which was much better than the traditional Mn-based MOFs derivatives (MOF-74-O and MIL-100-O). Combined experiment and DFT calculations, the more exposed Mn4+ sites in the MnOx-100 catalyst through a hollow cavity engineering could provide abundant adsorption sites, lower temperature reducibility and narrower band gap, and its hollow structure endowed with significant advantages for the separation efficiency of photogenerated carriers and light absorption capacity. Moreover, coexistence of photocatalysis, thermocatalysis and photoactivation in this catalyst system synergistically participated in the light-driven photothermal catalytic ethyl acetate oxidation. Finally, in situ DRIFTS results revealed that the introduction of light could change the possible reaction pathway of ethyl acetate degradation over the MnOx-100 catalyst, and aldehyde and ethylene were generated as by-products or non-critical intermediates under light irradiation. The main degradation pathway of ethyl acetate degradation occurred through ethyl acetate → aldehyde, ethanol and acetic acid → methanol and formic acid → CO2 and H2O.