Engineering triple O-Ti-O vacancy associates for efficient water-activation catalysis

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Defect engineering in catalysts tunes electronic and geometric structures.
• Precise control and identification of catalyst defects, especially clustered vacancies, remain challenging.
• The origin of vacancy configurations is largely unknown.

Purpose of the Study:

• To achieve controllable fabrication and quantitative identification of triple O-Ti-O vacancy associates (VOVTiVO) in nanosized Ni-doped TiO2.
• To elucidate the role of these specific vacancy associates in catalytic reactions.
• To understand the mechanism of defect formation and its impact on active sites.

Main Methods:

• Controllable fabrication of nanosized Ni-doped TiO2.
• Quantitative identification of vacancy configurations using experimental and theoretical analyses.
• In situ studies of hydroxyl adsorption and its role in defect formation.

Main Results:

• Successfully fabricated and identified triple O-Ti-O vacancy associates (VOVTiVO).
• Terminal hydroxyls adsorbed at unsaturated cationic sites are crucial for VOVTiVO formation.
• VOVTiVO enhances H2O dissociation and OH* deprotonation, improving catalytic site regeneration.
• Single VO sites are prone to saturation by hydroxyls, reducing active site availability.
• Ni-doped TiO2 with VOVTiVO showed comparable performance in hydrogen evolution and hydrodechlorination reactions.

Conclusions:

• Terminal hydroxyls play a key role in forming beneficial VOVTiVO defects.
• VOVTiVO defects are crucial for efficient H2O dissociation and catalyst regeneration.
• Engineering vacancy-associated active sites is vital for designing high-performance catalysts for H2O-involved reactions.