Light-Driven Reduction of CO<sub>2</sub> to CO in Water with a Cobalt Molecular Catalyst and an Organic Sensitizer
Pui‐Yu Ho, Shun‐Cheung Cheng, Fei Yu, Yau Yuen Yeung, Wen‐Xiu Ni, Chi‐Chiu Ko, Chi‐Fai Leung, Tai‐Chu Lau, Marc Robert
Abstract
We report an efficient visible light-driven CO 2 reduction system that functions in water and without any noble metal nor rare materials. Using the cobalt complex [Co(qpy)(OH 2 ) 2 ] 2+ ( 1, qpy = 2,2′:6′,2″:6″,2‴-quaterpyridine) as a catalyst, an organic triazatriangulenium ( TATA + ) salt as the photosensitizer (PS), BIH + TEOA (BIH = 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[ d ]imidazole and TEOA = triethanolamine) as the sacrificial reductant (SD), CO and formate were first produced with a total TON >3700 upon irradiation in CO 2 -saturated CH 3 CN solution with visible light. Upon the addition of a weak Brönsted acid (water), catalysis was enhanced and directed toward CO production (19,000 TON, 93% selectivity). The photocatalytic system was further shown to function in pure water as a solvent. High metrics with a TON for CO of 2600 and 94% selectivity were obtained using TEA (triethylamine) as the SD.