Catalytic oxidation of formaldehyde (HCHO) to CO₂ and H₂O under ambient condition is highly desired for purifying indoor air quality. In this work, it was found for the first time that TiO₂ supported subnanometer Rh catalyst exhibited a remarkable activity with complete removal of HCHO at room temperature. The humidity under ambient condition can significantly improve the activity, stability and specific rates but result in lower activation energy for the oxidation of HCHO on this catalyst. A combination of characterizations, such as H₂ temperature programmed reduction, adsorption microcalorimetry and in situ diffuse reflectance infrared Fourier transform spectroscopy, demonstrated the importance of Rh species for the dissociative adsorption of O₂ and the key role of water on the oxidation of HCHO. The O atoms facilitated the transformation of HCHO adsorbed on TiO₂ into intermediate of formates, while the presence of water led to the production of hydroxyl probably from the reaction with the adsorbed O species, which promoted the decomposition of formates to CO₂. This study can provide an important implication into the design and fabrication of more economic Rh-based catalysts for ambient HCHO oxidation.

甲醛（HCHO）于CO的催化氧化₂和H ₂ o在环境条件非常需要用于净化室内空气质量。在这项工作中，首次发现TiO ₂负载的亚纳米Rh催化剂在室温下完全去除HCHO时表现出显着的活性。在环境条件下的湿度可以显着提高活性，稳定性和比率，但导致该催化剂上HCHO氧化的活化能降低。特征的组合，例如H ₂程序升温还原，吸附量热法和原位漫反射红外傅里叶变换光谱学证明了Rh物种对于O ₂的解离吸附的重要性以及水对HCHO氧化的关键作用。O原子促进了吸附在TiO ₂上的HCHO向甲酸酯的中间体的转化，而水的存在可能导致羟基与吸附的O物种反应生成羟基，从而促进了甲酸酯分解为CO ₂。这项研究可以为环境HCHO氧化更经济的Rh基催化剂的设计和制造提供重要的启示。