Pd supported on different anatase TiO₂ nanocrystals predominantly exposing either {1 0 0}, {1 0 1}, or {0 0 1} facets were tested for CO₂ hydrogenation into formate. Remarkable morphology-dependent catalysis was observed. Compared to 2%Pd/TiO₂{1 0 1} and 2%Pd/TiO₂{0 0 1} catalysts, 2%Pd/TiO₂{1 0 0} is highly active and stable, affording an unprecedented turnover frequency of ca. 1369 h⁻¹ and keeping stable after 6 cycles at 313 K. This can be associated with, on the one hand, higher density of moderate basic site and relatively more Pd(0) species over 2%Pd/TiO₂{1 0 0} contribute to the activations of CO₂ and H₂, respectively, favorable for the activity; On the other hand, higher oxygen vacancy concentrations in the TiO₂{1 0 0} promote the Pd-TiO₂ interactions and result in the formation and stability of flat Pd particles over 2%Pd/TiO₂{1 0 0}, beneficial to the stability. These results highlight the importance of oxide morphology in formate formation and open up possibilities of oxide morphology engineering for developing efficient Pd-based catalysts for CO₂ hydrogenation.

测试负载在主要暴露{1 0 0}、{1 0 1}或{0 0 1}面的不同锐钛矿TiO ₂纳米晶体上的Pd用于CO ₂氢化成甲酸盐。观察到显着的形态依赖性催化。与 2%Pd/TiO ₂ {1 0 1} 和 2%Pd/TiO ₂ {0 0 1} 催化剂相比，2%Pd/TiO ₂ {1 0 0} 具有高活性和稳定性，提供前所未有的周转频率约 1369 小时^-1            并且在 313 K 下经过 6 次循环后保持稳定。一方面，这可能与中等碱性位点的密度较高和 2%Pd/TiO ₂ {1  0  0}以上的 Pd(0) 种类相对较多有关CO ₂和H _{2 的}活化分别有利于活性；另一方面，TiO ₂ {1  0  0} 中较高的氧空位浓度促进了 Pd-TiO ₂相互作用并导致扁平 Pd 颗粒的形成和稳定性超过 2%Pd/TiO ₂ {1  0 0}，有利于稳定性。这些结果突出了氧化物形态在甲酸盐形成中的重要性，并开辟了氧化物形态工程开发用于 CO ₂加氢的高效 Pd 基催化剂的可能性。