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Optimizing the interaction between metal active centers and supports by tuning crystal facets is an effective strategy to improve the activity and stability of catalysts. Herein, α-MnO2 nanowires with different exposed crystal facets (respectively (310), (110) and (100)) were synthesized via a facile hydrothermal method to promote the activity of an Au/α-MnO2 catalyst for propane combustion. Results reveal that Au/α-MnO2-110 exhibits the highest catalytic activity, achieving 90% propane (2500 ppm) conversion at just 216 °C (apparent activation energy as low as 50.2 kJ mol−1). Compared with Au/α-MnO2-310 and Au/α-MnO2-100, Au/α-MnO2-110 with the largest quantity of oxygen vacancies, strong reducibility, and high surface oxygen mobility possesses the best capability for adsorbing and activating oxygen molecules. DFT results reveal that the (110) facet of α-MnO2 has the lowest formation energy of oxygen vacancies (Evo(110) = 0.6 eV), suggesting the presence of weak surface Mn–O bonds, facilitating the formation of Auδ+ species and therefore promoting C–H bond breaking in propane. This work highlights a new strategy for the design of efficient catalysts for stable light alkane low-temperature decomposition by surface exposed facet engineering.

MnOx oxides with different morphologies (nanowire (MnOx-W), nanocube (MnOx-C), nanorod (MnOx-R), and nanosphere (MnOx-S)) and exposed facets were synthesized via a solvothermal method. The catalytic performance of the synthesized MnOx materials for methyl ethyl ketone (MEK) destruction was investigated. Results show that the activity of MnOx-W with highly exposed {101} facets of Mn3O4 is superior to that of MnOx-C, MnOx-R, and MnOx-S exposing {321} facets of Mn2O3, {110} facets of MnO2, and {101} and {112} facets of Mn3O4, respectively. MEK can be completely mineralized into CO2 at 195 °C over MnOx-W under a relatively high gas hourly space velocity of 37 200 h−1, which is even better than some typical noble metal loaded catalysts. The lowest apparent activation energy of MnOx-W (27.7 kJ mol−1) for MEK destruction also confirms its excellent catalytic activity. Density functional theory (DFT) results reveal that the {101} facets of Mn3O4 have the highest MEK adsorption energy (0.79 eV), which indicates that MEK molecules have a high affinity to adsorb onto the MnOx-W surface, promoting the oxidation process of MEK. In situ DRIFTS and TPSR results indicate that the mineralization of MEK into CO2 over MnOx-W goes through an oxidation route with diacetyl as the primary intermediate. We found that the highly exposed {101} active facets, abundant oxygen vacancies, and excellent low-temperature reducibility are responsible for the superior oxidation performance of MnOx-W. This finding may bring new insights into the designing of highly effective catalysts and has implications for a wide range of reactions not limited to MEK oxidation.