In-situ modulation of α-MnO2 surface oxygen vacancies for photothermal catalytic oxidation of propane: Insights into activity and synergistic mechanism.

• In-situ regulation of oxygen vacancies controlled by the crystal planes. • Oxygen vacancies promoted the valid separation of photogenerated electrons and holes. • Oxygen vacancies enhanced the adsorption and activation of O 2 and propane. • A multi-pathway enhancement mechanism in PTSCO was proposed. Crystallographic effects in photothermal synergistic catalytic oxidation (PTSCO) system for VOCs removal are essential but still lack in-depth systematic studies. Therefore, key factors and synergistic mechanism of propane removal by MnO 2 with different crystal planes in PTSCO system were investigated. The results showed that 160-M−300 with the mainly exposed (1 1 0) crystal plane displayed the optimal activity (T 90 = 235℃, TOF = 4.90 × 10-7·s−1) and long-term stability (40 h) due to the abundant oxygen vacancies (OVs) controlled by the crystal planes, outstanding low temperature reduction ability and higher oxygen mobility. OVs substantially enhanced the adsorption and activation of propane and O 2 , and accelerated the efficient separation of photogenerated electrons and holes by capturing the electrons. Correspondingly, density functional theory (DFT) calculations confirmed that (1 1 0) crystal facet had the lowest OVs generation energy and work function, based on which, a multi-pathway enhancement mechanism of PTSCO was proposed. This study clarified the crystal-PTSCO activity dependence, provided theoretical support for the efficient and energy-saving removal of low-carbon alkanes. [ABSTRACT FROM AUTHOR]