The distribution and coordination states of surface oxygen and metal ions in pure-phase metal oxides are dominated by the exposed crystal facets, which directly affects its physicochemical properties. Herein, we have elaborately constructed three catalysts of single-crystalline α-MnO2 nanowires with predominantly exposed {310}, {110} and {100} facets, respectively. The α-MnO2 catalyst exhibits a strong facet-dependent catalytic activity for the three-phase reaction of catalytic soot oxidation. Compared with the low-index {110} and {100} facets, the α-MnO2 catalyst with exposed high-index {310} facet exhibits the highest catalytic activities (T50 = 333 °C, TOF = 1.127 h−1), the lowest apparent activation energy (68.4 KJ mol−1), and excellent catalytic stability during soot oxidation. Combining the results of characterizations and density functional theory (DFT) calculations, the intrinsic mechanism of crystal facet-dependent catalytic activity for soot oxidation is revealed: The selectively exposed α-MnO2{310} facets can induce the formation of coordinative unsaturated atoms and surface defect sites, enhancing the adsorption-activation ability for O2 and NO. In-depth understanding of the face-dependent catalytic activity of α-MnO2 catalyst is valuable for the acquisition of high-efficient non-precious metal catalysts during soot oxidation.

中文翻译：

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单晶 α-MnO2 催化剂，具有定制的外露晶体刻面，用于促进催化烟尘氧化：晶体刻面依赖性活性


纯相金属氧化物中表面氧和金属离子的分布和配位态由暴露的晶体刻面主导，直接影响其物理化学性质。在此，我们精心构建了三种单晶 α-MnO2 纳米线催化剂，分别具有主要暴露的 {310}、{110} 和 {100} 面。α-MnO2 催化剂对催化烟灰氧化的三相反应表现出很强的刻面依赖性催化活性。与低折射率 {110} 面和 {100} 面相比，暴露出高折射率 {310} 面的 α-MnO2 催化剂表现出最高的催化活性 （T50 = 333 °C， TOF = 1.127 h-1）、最低的表观活化能 （68.4 KJ mol-1） 和在烟尘氧化过程中优异的催化稳定性。结合表征和密度泛函理论 （DFT） 计算的结果，揭示了晶面依赖性催化活性对烟尘氧化的内在机制：选择性暴露的 α-MnO2{310} 面可以诱导配位不饱和原子和表面缺陷位点的形成，增强对 O2 和 NO 的吸附活化能力。深入了解 α-MnO2 催化剂的表面依赖性催化活性对于获得烟尘氧化过程中的高效非贵金属催化剂。