Nest-like δ-MnO2 nanobelts for catalytic decomposition of low concentration toluene: Efficiency and catalytic mechanism

[Display omitted] •Nest-like δ-MnO2 nanobelts with 3D network structure was synthesized.•Toluene was converted into CO2 at room temperature.•The 99 % one-through removal capacity for 1.2 ppm toluene reached 27.35 mg/g.•The decomposition of small molecule carboxylic acid was the rate-determining step.•The aromatic ring of toluene could be opened directly after hydroxylation. The elimination of low concentration volatile organic compounds (VOCs) in indoor air at low temperature is an ideal approach and a focal research area for tackling their environmental pollution. Herein, the nest-like δ-MnO2 nanobelts with three-dimensional (3D) network structure was successfully synthesized by a facile water-bath heating method, which owned a lot of oxygen vacancies and high specific surface area. The as-prepared nest-like δ-MnO2 nanobelts exhibited excellent catalytic performance, which could convert toluene into CO2 at room temperature. In addition, the 99 % one-through removal capacity at room temperature for 1.2 ppm toluene reached 27.35 mg/g, which was 3.59 times higher than that of single La atom-doped δ-MnO2, and it could be fully regenerated at 105 °C. In-situ DRIFTS and online MS results indicated that the decomposition of small molecule carboxylic acid, such as acetic acid and formic acid, by nest-like δ-MnO2 nanobelts was the rate-determining step of toluene oxidation. Combined with ATD-GC/MS results, the possible decomposition pathway of toluene was proposed, the aromatic ring could be opened directly after hydroxylation. This investigation contributes novel insights into the efficient decomposition and catalytic mechanism of low concentration VOCs in indoor air environment.