Sumaria V., Rawal T.B., Li Y.F., Sommer D., Vikoren J., Bondi R.J., Rupp M., Prasad A., Prasad D.
Journal of Physical Chemistry C, vol. 128, n° 34, pp. 14247-14258, 2024
The photoconversion of CO<sub>2</sub> to hydrocarbons is a sustainable route for its transformation into value-added compounds, which is crucial to mitigating energy and climate crises. CuPt nanoparticles on TiO<sub>2</sub> surfaces have been reported to show promising photoconversion efficiencies. For further progress, a mechanistic understanding of the catalytic properties of these CuPt/TiO<sub>2</sub> systems is vital. Here, we employ ab initio calculations, machine learning, and photocatalysis experiments to understand the photocatalytic reduction of CO<sub>2</sub> on CuPt/TiO<sub>2</sub>. We explore the configurational space of the CO<sub>2</sub>@CuPt/TiO<sub>2</sub> systems and examine their structures and energetics. We find that the CuPt/TiO<sub>2</sub> interface plays a key role in determining CO<sub>2</sub> activation and, thus, the conversion to hydrocarbons. The interface stabilizes *CO and other intermediates containing CH groups, thus facilitating a higher activity and selectivity for methane. A bias-corrected machine-learning interatomic potential trained on density functional theory data enables the efficient exploration of the potential energy surfaces of numerous CO<sub>2</sub>@CuPt/TiO<sub>2</sub> configurations using basin-hopping Monte Carlo simulations, greatly accelerating the study of these photocatalyst systems. Our simulations show that CO<sub>2</sub> preferentially adsorbs at the interface, with a C atom bonded to a Pt site and one O atom occupying an O-vacancy site. The interface also promotes the formation of *CH and *CH<sub>2</sub> intermediates. For confirmation, we synthesize CuPt/TiO<sub>2</sub> samples with various compositions, analyze their morphologies and compositions using scanning electron microscopy and energy-dispersive X-ray spectroscopy, and measure their photocatalytic activity. Our computational and experimental findings qualitatively agree and highlight the importance of the interface design for the selective conversion of CO<sub>2</sub> to hydrocarbons.
