Highly Selective Photocatalytic CO<sub>2</sub> Reduction to C<sub>2</sub>H<sub>6</sub> via Nanocluster-Single Atom-Vacancy on Ceria: Synergistic Mechanism and Orbital Effects.

Duan, Yingnan; Zhao, Hexiang; Ji, Jixiang; Shen, Zhurui; Wang, Yi; Du, Yaping · Nano Lett · 2025

basic_science · Level V

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Abstract

The photocatalytic reduction of CO<sub>2</sub> to high-value C<sub>2</sub> products involves sluggish multiple proton-electron couplings, resulting in low efficiency and selectivity. This study demonstrates that palladium (Pd) single-atom (Pd<sub>SA</sub>)- and Pd nanocluster (Pd<sub>NCs</sub>)-loaded CeO<sub>2</sub> with abundant oxygen vacancies (O<sub>v</sub>) synergistically enhance photocatalytic CO<sub>2</sub>-to-ethane (C<sub>2</sub>H<sub>6</sub>) conversion effectively and selectively. The Pd<sub>SA+NCs</sub>/CeO<sub>2</sub> photocatalyst achieves 80.4% electron selectivity for C<sub>2</sub>H<sub>6</sub> production with an electron consumption rate of 206.3 μmol g<sub>cat</sub><sup>-1</sup> h<sup>-1</sup> in pure water, representing a 172.4-fold enhancement over pristine CeO<sub>2</sub>. Pd<sub>NCs</sub> interact with neighboring Pd<sub>SA</sub> and O<sub>v</sub> to form a Fermi level with the continuous characteristics of discrete energy levels, improving the charge distribution in local spatial electric fields. This enhancement favors electron migration from the π to σ orbital of COCO*, promoting C-C coupling. Our findings provide new insights to rationally design synergistic interactions between SA, NCs, and O<sub>v</sub> to achieve high selectivity toward C<sub>2</sub> products.