Tweaking Photo CO2 Reduction by Altering Lewis Acidic Sites in Metalated‐Porous Organic Polymer for Adjustable H2/CO Ratio in Syngas Production

• Published in: Angewandte Chemie International Edition Vol. 62; no. 50; pp. e202311304 - n/a
• Main Authors: Paul, Ratul, Das, Risov, Das, Nitumani, Chakraborty, Subhajit, Pao, Chih‐Wen, Thang Trinh, Quang, Kalhara Gunasooriya, G. T. Kasun, Mondal, John, Peter, Sebastian C.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 11-12-2023
• Edition: International ed. in English
• Subjects: Ammonia; Carbon dioxide; Catalysts; Cobalt; Electron density; Lewis acid; Lewis Acidity; Metalated Porous Organic Polymer (M-POP); Photocatalysis; Polymers; Syngas; Synthesis gas; Water splitting; Zinc
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202311304

Herein, we have specifically designed two metalated porous organic polymers (Zn‐POP and Co‐POP) for syngas (CO+H2) production from gaseous CO2. The variable H2/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 CO2 reduction and water splitting with the help of the two catalysts, where CO (145.65 μmol g−1 h−1) and H2 (434.7 μmol g−1 h−1) 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 NH3‐TPD studies, which considerably improve CO2 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 CO2 reduction over Co‐POP while water splitting occurred preferentially over Zn‐POP.
Zn and Co based POP with different Lewis acidity has been developed for controlling water splitting and CO2 reduction under sunlight. Low‐cost option of syngas production with adjustable H2/CO ratio was demonstrated obtained by skipping the use of any sacrificial electron donors (SEDs), cocatalysts, or photo‐sensitizers.