Nitrogen vacancies rich C3N4 supported PdCo catalyst for selective photocatalytic CO2 reduction to C2H4

Abstract

Photocatalytic CO₂ reduction to high-value hydrocarbons has emerged as a cutting-edge technology in energy conversion. To address the challenges of insufficient photogenerated electron density and sluggish C–C coupling kinetics in multi-carbon synthesis, dual nitrogen vacancies (N₂C/N₃C) were precisely engineered in C₃N₄ through a secondary hydrogen-assisted exfoliation approach. This induces localized electron density accumulation of the π-conjugated system at defect sites, generating a robust built-in electric field that achieves highly efficient spatial charge separation. Meanwhile, the modification with PdCo alloys overcomes the limitations in multi-carbon coupling reactions: Co optimizes the adsorption and stabilization of C₁ intermediates (CO*/CHO*), while Pd acts as the active centre for C–C coupling by facilitating hydrogenation. The optimized system achieves an exceptional C₂H₄ production rate of 36.3 μmol g⁻¹ h⁻¹ with 81.5% electron selectivity. This work establishes a new paradigm for designing advanced CO₂ photoreduction systems.