Efficient Photocatalytic CO 2 Reduction to C 2+ Products with Pt 1‐ x Pd x Sn 4 Dirac Nodal Arc Semimetal

ABSTRACT The photochemical CO 2 reduction reaction (CRR) represents a zero‐carbon pathway for converting CO 2 into value‐added chemicals, yet its industrial implementation has been constrained by low selectivity and product diversity. Dirac nodal arc semimetals characterized by ultrahigh carrier mobility (>25 000 cm 2 ·V −1 ·s −1 ) offer a promising platform to search for efficient catalysts for CO 2 conversion. Herein, we demonstrate that strategic Pt incorporation into PdSn 4 optimizes the electronic structure and carrier dynamics of this Dirac semimetal. Experimental and theoretical analyses reveal that the resulting Pd─Sn─Pt local electronic structure redistributes charge density around Pd and Pt atoms, which facilitates C─C coupling via *OC─COH and *OC─CHOH intermediates and enhances carrier mobility by 40% versus the pristine PdSn 4 single crystal. The optimized Pd 0.4 Pt 0.6 Sn 4 single crystal achieves C 2 H 4 i) formation rate of 328 µmol∙g −1 ∙h −1 ; ii) product selectivity of 73.1%; iii) electron‐based selectivity of 89%. This work establishes electronic‐structure‐tunable Dirac semimetals as a new paradigm for multi‐carbon photochemical CO 2 reduction, providing a design strategy for next‐generation photocatalysts.