Modulating photogenerated electron density of Pr single-atom sites by coordination environment engineering for boosting photoreduction of CO2 to CH3OH

The performance of photocatalytic reduction CO2 to CH3OH is intimately tied to the photogenerated electron density of the active center, because CH3OH formation involves a 6-electron transfer process. However, the random migration of photocarriers in the photocatalysts is severely not conducive to the directional delivery and enrichment of photogenerated electrons to active sites, leading to poor photocatalytic activity for CO2 to CH3OH. Herein, we reported a coordination environment engineered Pr single-atom catalyst for boosting the photogenerated electron density of the active sites, achieving the high-efficiency photoreduction of CO2 to CH3OH. The carbon nitride (CN) supported Pr single-atom with oxygen coordination was designed via a three-step pyrolysis process. Then, the engineered oxygen coordination configuration for the Pr single-atom (Pr1-N4O2) was successfully achieved. Importantly, this Pr1-N4O2 sites can induce photogenerated electrons more easily to accumulate on the Pr atom as compared to the reference catalyst of the Pr atom without oxygen coordination (Pr1-N6). Moreover, the formed atomically dispersed Pr1-N4O2 active centers with ultra-high Pr loading (21.05 wt%) can promote CO2 adsorption and activation, and provide a high density of active sites for CO2 photoreduction. As a result, the optimized Pr1-N4O2/CN exhibited a boosted photoreduction of CO2 to CH3OH activity (511.1 μmol g−1 h−1), which was up to 28.9 and 1.9 times higher than those of CN (17.7 μmol g−1 h−1) and Pr1-N6/CN (274.1 μmol g−1 h−1), and preferable to most reported work under similar catalytic conditions. Our findings can provide a fresh prospect for developing innovative SACs to enhance the photoreduction of CO2 to CH3OH activity.