Exposed {001} facet of anatase TiO2 nanocrystals in Ag/TiO2 catalysts for boosting catalytic soot combustion: The facet-dependent activity

[Display omitted] •The ratios of exposed {001} facets in anatase TiO2 nanocrystals can be elaborately adjusted.•Ag/TiO2-n% catalysts exhibited excellent catalytic activity during soot combustion.•The catalytic activity is strongly dependent on the exposed {001} facet ratios of TiO2.•The active sites locate at the interface between Ag and {001} facet of TiO2 nanocrystal.•Synergy effect of coordinatively unsaturated Ti5c and adjacent Ag atoms boosts O2 activation. Herein, the nanocatalysts of Ag nanoparticles (NPs) coated on anatase TiO2-n% nanocrystals with co-exposed {101} and {001} facets were elaborately constructed by the urea-induced hydrothermal method. The ratios (n%) of exposed {001} facet in TiO2 nanocrystals are adjusted in the range of 8–79%. Ag/TiO2-n% catalysts exhibited excellent the exposed {001} facet-dependent catalytic activity during soot combustion. Ag/TiO2-79% catalyst shows the highest catalytic activity (T50 = 364 °C, TOF = 0.174 h−1 at 310 °C) and the lowest apparent activation energy (84 kJ mol−1). Combination in-situ Raman spectra and density functional theory (DFT) calculations, the catalytic mechanism is proposed: the active sites locate at the interface between Ag and {001} facet of TiO2-n% nanocrystal, and the synergy effect of coordinatively unsaturated Ti5c and adjacent Ag atoms boosts the key step of O2 activation. It highlights an effective strategy to develop high-efficient catalysts by the crystal facet engineering of metal oxides during oxidation reaction.