<p>The efficiency of proton-coupled electron transfer (PCET) critically governs the reaction pathway selectivity and catalytic performance in photocatalytic CO₂ reduction. However, the slow PCET kinetics and high energy barriers of key intermediates hinder the achievement of high generation efficiency and selectivity of the product. Herein, the regulation of the surface oxygen vacancy (V_o) concentration was achieved by introducing graphene quantum dots (GQDs) into the SrTiO₃ catalytic system (GQDs/STO). More importantly, the formation of Ti–O–C bonds between STO and GQDs further promoted the PCET process during CO₂ reduction, thereby significantly enhancing the reaction kinetics. Therefore, 3%GQDs/STO achieves remarkable CO production rates of 9500 µmol g⁻¹ h⁻¹, which is 187 times higher than that of pure STO (51.2 µmol g⁻¹ h⁻¹). Moreover, CO selectivity and electron utilization efficiency reach 99.8% and 99.2%, respectively, outperforming most previous photocatalysts. Experimental and theoretical investigations confirm that the synergistic effects of V_o electron traps and Ti–O–C bonds not only modulate the speciation of critical intermediates but also significantly reduce the activation energy barrier of the rate-determining step (*COOH to *CO). This work offers novel insights and ideas for developing efficient catalysts with highly effective photocatalytic CO₂ reduction.</p>