Kamada Kenji, Jung Jieun, Yamada Chihiro, Wakabayashi Taku, Sekizawa Keita, Sato Shunsuke, Morikawa Takeshi, Fukuzumi Shunichi, Saito Susumu
Department of Chemistry, Graduate School of Science, Nagoya University, Furo, Chikusa, 464-8602, Nagoya, Japan.
Toyota Central Research and Development Laboratories, Inc., 480-1192, Nagakute, Japan.
Angew Chem Int Ed Engl. 2024 May 27;63(22):e202403886. doi: 10.1002/anie.202403886. Epub 2024 Apr 23.
The photocatalytic reduction of carbon dioxide (CO) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO photoreduction also proceeded under irradiation with blue (λ=405 nm), green (λ=525 nm), or red (λ=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.
二氧化碳（CO₂）的光催化还原是一种极具吸引力的太阳能存储方法，可用于生产可再生燃料和有价值的化学品。尽管一些锇（Os）光敏剂能吸收可见光区域的长波长光，但尚未开发出用于红光驱动CO₂还原的自敏化单核Os催化剂。在此，我们发现将Os金属引入PNNP型四齿配体可使其吸收更长波长（350 - 700 nm）的光，并且该配体可应用于全色自敏化催化剂，用于CO₂还原，在光辐照（λ≥400 nm）下主要生成一氧化碳（CO），总周转数（TON）为625。在蓝光（λ = 405 nm）、绿光（λ = 525 nm）或红光（λ = 630 nm）辐照下，CO₂光还原也能进行，生成CO的选择性大于90%。利用红光生成CO的量子效率测定为12%。基于使用包括瞬态吸收、电子顺磁共振和紫外/可见光谱等各种光谱技术对中间体的检测，提出了一种催化机理。
