High reduction temperature generally induces the agglomeration of supported noble metals. Howerve, we found that high temperature reduction did not induce Pd particles sintering but improved Pd dispersion. Multiple methods were further carried out to illuminate the abnormal phenomenon. The results indicated more surface oxygen defects and diffusion of Pd particles were simultaneously induced by high temperature reduction. During diffusion process of Pd particles, they were trapped by the oxygen defects because of the strong metal-support interaction, which led to improvement of Pd dispersion on the Pd/TiO₂-450R catalyst. In addition, more surface oxygen vacancies on the Pd/TiO₂-450R catalyst resulted in more active sites of H₂O activation to form abundant surface OH groups which further enhanced adsorbed O₂ activation and mobility, and then opening a more effective pathway for HCHO oxidation, which result in its high activity of Pd/TiO₂-450R for ambient HCHO oxidation.

高还原温度通常引起负载的贵金属的团聚。但是，我们发现高温还原不会引起Pd颗粒烧结，但可以改善Pd的分散性。进一步采取了多种方法来阐明异常现象。结果表明，高温还原同时引发了更多的表面氧缺陷和Pd颗粒的扩散。在Pd颗粒的扩散过程中，由于强的金属-载体相互作用，它们被氧缺陷捕获，从而改善了Pd / TiO ₂ -450R催化剂上Pd的分散性。此外，Pd / TiO ₂ -450R催化剂上更多的表面氧空位导致了H _2的更多活性位点O活化形成丰富的表面OH基团，进一步增强了吸附的O ₂活化和迁移性，然后开辟了一条更有效的HCHO氧化途径，这使其Pd / TiO ₂ -450R对环境HCHO的氧化活性很高。