The light-driven CO<sub>2</sub> reduction to multi-carbon products is especially meaningful, while the low efficiency of multi-electron transfer and sluggish C-C coupling greatly hinder its development. Herein, we report a photocatalyst comprising of P and Cu dual sites anchored on graphitic carbon nitride (P/Cu SAs@CN), which achieves a high C<sub>2</sub> H<sub>6</sub> evolution rate of 616.6 μmol g<sup>-1</sup> h<sup>-1</sup> in reducing CO<sub>2</sub> to hydrocarbons. The detailed spectroscopic characterizations identify the formation of charge-enriched Cu sites, where the isolated P atoms serve as hole capture sites during photocatalysis. Theoretical simulations combined with in situ FTIR measurement reveal a kinetically feasible process for the formation of C-C coupling intermediate (*OC-COH) and confirm the favorable production of C<sub>2</sub> H<sub>6</sub> on the P/Cu SAs@CN photocatalyst. This work offers new insights into the photocatalyst design with atomic precision toward highly efficient photocatalytic CO<sub>2</sub> conversion to high value-added carbon products.