Tweaking Photo CO Reduction by Altering Lewis Acidic Sites in Metalated-Porous Organic Polymer for Adjustable H /CO Ratio in Syngas Production.

Herein, we have specifically designed two metalated porous organic polymers (Zn-POP and Co-POP) for syngas (CO+H ) production from gaseous CO . The variable H /CO ratio of syngas with the highest efficiency was produced in water medium (without an organic hole scavenger and photosensitizer) by utilizing the basic principle of Lewis acid/base chemistry. Also, we observed the formation of entirely different major products during photocatalytic CO reduction and water splitting with the help of the two catalysts, where CO (145.65 μmol g  h ) and H (434.7 μmol g  h ) production were preferentially obtained over Co-POP & Zn-POP, respectively. The higher electron density/better Lewis basic nature of Co-POP was investigated further using XPS, XANES, and NH -TPD studies, which considerably improve CO activation capacity. Moreover, the structure-activity relationship was confirmed via in situ DRIFTS and DFT studies, which demonstrated the formation of COOH* intermediate along with the thermodynamic feasibility of CO reduction over Co-POP while water splitting occurred preferentially over Zn-POP.