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

The photochemical CO2 reduction reaction (CRR) represents a zero-carbon pathway for converting CO2 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 cm2·V-1·s-1) offer a promising platform to search for efficient catalysts for CO2 conversion. Herein, we demonstrate that strategic Pt incorporation into PdSn4 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 PdSn4 single crystal. The optimized Pd0.4Pt0.6Sn4 single crystal achieves C2H4 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 CO2 reduction, providing a design strategy for next-generation photocatalysts.