Stability and Reactivity of TiO 2 n $$ {\left({\mathrm{TiO}}_2\right)}_n $$ , n = 1-10, Clusters and Their...

Area of Science:

• Computational Chemistry
• Materials Science
• Catalysis

Background:

• Small titanium dioxide (TiO2) clusters are promising for CO2 conversion, but their stability and reactivity are not fully understood.
• Understanding size-dependent properties is crucial for designing efficient TiO2 photocatalysts.

Purpose of the Study:

• To identify stable and reactive titanium dioxide (TiO2) clusters for carbon dioxide (CO2) conversion.
• To establish design principles for TiO2 cluster catalysts by analyzing stability and reactivity relationships.

Main Methods:

• Density Functional Theory (DFT) calculations (M06/def2-TZVP) were employed to study TiO2 clusters (n=1-10).
• Global and local reactivity descriptors, including stability function (ε³), electrophilicity (Δω), Fukui functions, and fractional occupation number-weighted density (NFOD), were utilized.
• Non-covalent interaction (NCI) analysis was performed to understand CO2 binding.

Main Results:

• Magic number clusters with high stability were identified at n=2, 4, and 8.
• Electrophilicity varied with size, with n=6 showing high electrophilicity and localized 'hot' electron sites.
• CO2 interaction energies inversely correlated with cluster stability, with unstable clusters binding CO2 more strongly than stable magic numbers.

Conclusions:

• The study provides key insights into the stability and reactivity of small TiO2 clusters for CO2 conversion.
• Magic numbers (n=2, 4, 8) represent stable platforms, while other sizes offer tailored reactivity for CO2 activation.
• Design principles balancing stability and reactivity are established for developing advanced TiO2 photocatalysts.