Key Laboratory of Resources Chemicals and Materials of SYUCT and Institute of Process Engineering of Chinese Academy of Sciences published a joint article in Nature Communications

Carbon monoxide (CO) is widely found in the exhaust of incomplete combustion of fossil fuels, such as automobile exhaust and sintering flue gas in the iron and steel industry, which can easily cause air pollution. Currently, platinum (Pt)-based catalysts are mainly used in industry to eliminate CO through catalytic oxidation, but still have problems, such as the loading is too high and the low-temperature activity is not good enough, etc. In order to meet stricter emission laws and regulations in the future, there is an urgent need to develop inexpensive low-temperature CO oxidation catalysts.

Recently, new progress in the cooperative research on CO oxidation has been made by the Key Laboratory of Resource Chemical and Materials of Education Department of our university and the Institute of Process Engineering of the Chinese Academy of Sciences and other organizations.

There are two reaction mechanisms for the catalytic oxidation of CO over Pt-based catalysts: the Mars-van Krevelen (MvK) mechanism and the Langmuir-Hinshelwood (L-H) mechanism. Typically, the MvK mechanism occurs on the reducible metal oxide carrier via activation of surface lattice oxygen species, and the L-H mechanism occurs on the catalyst surface via co-adsorbed CO and molecular O₂. However, the activation of oxygen (O₂) becomes difficult due to the strong absorption of CO on the Pt surface, which makes the activation of O₂ a critical step that constrains the occurrence of the L-H mechanism. Introducing a second reducible metal or increasing the oxygen vacancy (Ov) content are effective ways to promote O₂ activation, but it may lead to catalyst deactivation. To overcome these challenges, the researchers co-anchored Pt single atoms and Pt nanoparticles on H2-reduced TiO₂ (TiO₂-R) such that the Pt single atoms were surrounded by Ti, exhibiting a unique structure with a Pt-Ti intermetallic single-atom alloy (ISAA) with an overall Pt loading of only 0.15 wt%. The CO oxidation activity of this catalyst was substantially improved compared with similar Pt-based catalysts that have been reported. Through experiments combined with theoretical calculations, it was found that the synergistic effect between Pt nanoparticles and isolated Pt atoms could effectively weaken the competing absorption of CO and O₂, which could activate molecular oxygen and surface lattice oxygen at the same time, allowing two reaction mechanisms to occur simultaneously on a single Pt metal. This work is of great significance for the design and development of efficient and inexpensive Pt catalysts for low-temperature exhaust gas purification. The research work was published in Nature Communications (2024, 15, 6827. https://www.nature.com/articles/s41467-024-50790-3). Zhang Tengfei, PhD student from Institute of Process Engineering of Chinese Academy of Sciences, and Dr. Zheng Peng from Key Laboratory of Resource Chemical and Materials of Education Department of our university, were the co-first authors of the paper, with Institute of Process Engineering of Chinese Academy of Sciences as the first completion unit, Shenyang University of Chemical Technology as the second completion unit, and Su Fabing, researcher from Institute of Process Engineering of Chinese Academy of Sciences, as the responsible corresponding author.

Figure 1. Schematic diagram of catalyst structure and reaction mechanism (left) and comparison of CO catalytic oxidation performance (right)