Researchers reveal interfacial confinement on open space of oxide–oxide catalysts

Confined catalysis has been regarded as an important strategy to modulate chemical reactions and enhance catalytic performance. Previous studies have demonstrated that the applications of the confinement effect in catalysis are in enclosed nanospace. However, whether an open space also has this effect is still unclear.

Recently, a research group led by Prof. Bao Xinhe and Prof. Fu Qiang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) revealed the interface confinement effect on open space in an In₂O₃-TiO₂ catalyst during a reverse water gas shift (RWGS) reaction. The study is published in Journal of the American Chemical Society.

The researchers physically mixed In₂O₃ and TiO₂ to obtain an In₂O₃-TiO₂ catalyst for the RWGS reaction. They verified that the open surface of TiO₂ could create a confined environment for In₂O₃, which drove the spontaneous transformation of free In₂O₃ nanoparticles into In oxide nanolayers (InO_x) covering onto the TiO₂ surface during RWGS.

Additionally, the researchers found that the formed InO_x nanolayers were easy to create in surface oxygen vacancies but were against over-reduction to metallic In in the H₂-rich atmospheres, resulting in enhanced activity and stability compared with the pure In₂O₃ catalyst. They identified that the formation of interfacial In–O–Ti bonding drove the In₂O₃ dispersion and stabilized the metastable InOx layer.

Therefore, the researchers demonstrated that the InO_x overlayers with distinct chemistry from their free counterparts could be confined on various oxide surfaces, demonstrating the important confinement effect at oxide–oxide interfaces.

"The interface confinement effect plays an important role in many oxide–oxide catalysts, which can be used to enhance the catalytic performance," said Prof. Fu.