Ultrafast stabilization of positive charges revealed in solar fuel catalyst
The simulations showed that hole polarons undergo stabilization of about 70 meV within just 50 femtoseconds, driven mainly by elongation of oxygen-tantalum bonds. This contrasts with electron polarons, which remained delocalized and displayed negligible stabilization. These results explain why holes play a dominant role in driving catalytic reactions in NaTaO3.
The team overcame experimental limits by employing Born-Oppenheimer molecular dynamics with an accelerated divide-and-conquer density-functional tight binding approach. This enabled atomistic, real-time visualization of carrier dynamics within a nanoscale model of NaTaO3 containing 256 formula units, tracked at 1 femtosecond resolution.
According to the researchers, the two-step stabilization pathway begins when a hole localizes near pre-elongated O-Ta bonds, which then stretch further during structural relaxation. The strong correlation between bond elongation and hole energy stabilization highlights O-Ta bonding as a critical design target.
The findings align with prior experimental evidence of trapped carriers and open the way for rational catalyst design. By focusing on the B-site chemistry of perovskites, future materials may be engineered to fine-tune O-Ta interactions, prolong hole lifetimes, and boost solar hydrogen production efficiency.
Research Report:Quantum-chemical molecular dynamics study of polaron formation in perovskite NaTaO3 as a water-splitting photocatalyst
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