Ultra-low doping 0.1(PtMnFeCoNi)/TiO2 catalysts: Modulating the electronic states of active metal sites to enhance CO oxidation through high entropy strategy

In iron and steel production, incomplete fuel combustion is the main cause of high CO emissions during sintering, accounting for over half of the industry's total emissions. Developing technologies for purifying high-concentration CO flue gas is urgent. The bottleneck in the industrialization of CO catalytic oxidation for sintering flue gas is developing catalysts with high activity, strong anti-poisoning ability and low cost. Conventional noble metal catalysts have high activity but are scarce and costly; they also tend to deactivate due to active site poisoning in flue gas with high H₂O/SO₂ concentrations. Non-noble metal high-entropy catalysts are low-cost but suffer from insufficient low-temperature activity and poor active site dispersion, failing to meet the industry's ultra-low emission requirements. Therefore, analyzing the mechanism of high-entropy catalysts in CO oxidation and clarifying the electronic local structure between active components and supports will facilitate the design of catalysts with high activity and low cost.

Recently, Research Associate Zhao Yongqi from the team led by Researcher Zhu Tingyu at the Institute of Process Engineering, Chinese Academy of Sciences, has designed a 0.1wt% ultra-low loading 0.1(PtMnFeCoNi)/TiO₂ high-entropy catalyst. This catalyst exhibits excellent catalytic performance in CO oxidation reactions, resists interference from H₂O and SO₂, and is an industrial catalytic material with broad application prospects. The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64770-X).

In this study, an ultra-low loading (0.1 wt%) 0.1(PtMnFeCoNi)/TiO₂ catalyst was designed. Transition metals (Mn, Fe, Co, Ni) and noble metal Pt were combined into a composite, which was anchored on the surface of anatase TiO₂ support, forming a strong metal-support interaction (SMSI) with TiO₂. Compared with 0.1Pt/TiO₂ and 0.1(Pt-M)/TiO₂ catalysts, 0.1(PtMnFeCoNi)/TiO₂ exhibits excellent catalytic performance in CO oxidation reactions, making it an industrial catalytic material with broad application prospects. Notably, the introduction of high-entropy components reduces the complete CO conversion temperature (T₁₀₀) from 270 ℃ to 230 ℃.

Experiments and DFT calculations show that the strong synergy between high-entropy components and TiO₂ significantly optimizes the electronic structure of different elements on the catalyst surface and promotes the adsorption of CO and O₂ molecules on the catalyst surface. In-situ DRIFTS and DFT calculation results further confirm that the introduction of high-entropy active components increases the local electron density on the TiO₂ surface and promotes electron dispersion on the catalyst surface, thereby facilitating the conversion of CO and O₂ molecules into CO* and O*. By filling metal interstitial electrons into the sub-interstitial states of TiO₂, the activation of lattice oxygen in TiO₂ is promoted, which enhances the SMSI between high-entropy components and TiO₂ support and further improves the adsorption efficiency of CO and O₂. This strategy of ultra-low loading high-entropy component catalysts will provide important references for the design and production of efficient and economical industrial flue gas CO catalysts.

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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