Size-dependent selectivity and activity of highly dispersed sub-nanometer Pt clusters integrated with P25 for CO2 photoreduction into methane fuel.

[Display omitted] • Sub-nanometer Pt NCs were obtained by tuning the amount of Pt integrated on P25. • Pt-NC/P25 exhibited prominent CO 2 reduction activity for selective CH 4 generation. • Activity and selectivity of Pt-NC/P25 for CO 2 photoreduction depend on Pt-NC size. • Pt-NC/P25 had high stability during multiple CO 2 photoreduction test runs. • High proportion of edge/corner sites of Pt-NC/P25 led to high CH 4 selectivity. Integration of sub-nanometer–sized Pt cocatalysts on semiconductor materials is a promising approach to improve the activity and selectivity of CO 2 photoreduction. However, the practical realization of such an integrated catalyst is a challenging task. We rationally integrated sub-nanometer Pt nanoclusters (Pt NCs) on the surface of commercial P25 catalyst by adjusting the amount of Pt loading. The lateral reduction in the size of Pt NCs resulted in high metal dispersion, increased active metal surface area, better CO 2 adsorption, and hindered photoexcited charge-carrier recombination. The sub-nanometer Pt NCs integrated with P25 with a weight percentage of 0.5% (Pt-NC/P25-0.5) exhibited exceptional CO 2 photoreduction activity for CH 4 production and excellent stability during successive test runs. This catalyst outperformed its counterparts with larger Pt NCs and several previously reported state-of-the-art photocatalysts in terms of CH 4 generation. Importantly, compared to its counterparts, Pt-NC/P25-0.5 had a higher proportion of edge and corner sites, which have a strong affinity for CO molecules, resulting in a high CH 4 selectivity of 95% against H 2. The size-dependent selectivity and activity of Pt NCs for CO 2 reduction demonstrated in this study offer insights into the development of sub-nanometer metal-based catalysts for photocatalytic energy applications. [ABSTRACT FROM AUTHOR]