Epitaxial domain of PdO formed on Sr3Ti2O7 effective as an environmental catalyst

To strategically realize the epitaxial growth of heterogeneous catalysts, it is necessary to use highly crystalline ceramic materials, which is a major disadvantage of catalyst materials in terms of surface area. Therefore, it is difficult to intentionally apply epitaxial growth in the design of catalyst materials. Against this background, this study reveals that a distorted PdO is epitaxially bonded to the ab surface of Sr3Ti2O7, which is a ceramic material synthesized by calcination at 1273 K, by loading a very small amount of a Pd species on it. Density functional theory calculations suggest that the charge-transfer from Sr3Ti2O7 to PdO induces an epitaxial junction to produce a structural fluctuation of PdO. Pd/Sr3Ti2O7 catalyst with a unique heterojunction exhibits an excellent catalytic activity for the purification of automotive exhaust gases. In addition, the Pd/Sr3Ti2O7 catalyst is more active than the benchmark Pd/Al2O3 catalyst despite its extremely small surface area. This study demonstrates that ceramic materials can be used as catalyst materials by precisely designing their heterojunctions.