Windle Christopher D, Pastor Ernest, Reynal Anna, Whitwood Adrian C, Vaynzof Yana, Durrant James R, Perutz Robin N, Reisner Erwin
Christian Doppler Laboratory for Sustainable SynGas Chemistry, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (U.K.); Department of Chemistry, University of York, Heslington, York YO10 5DD (U.K.).
Chemistry. 2015 Feb 23;21(9):3746-54. doi: 10.1002/chem.201405041. Epub 2015 Jan 29.
The photocatalytic activity of phosphonated Re complexes, [Re(2,2'-bipyridine-4,4'-bisphosphonic acid) (CO)3(L)] (ReP; L = 3-picoline or bromide) immobilised on TiO2 nanoparticles is reported. The heterogenised Re catalyst on the semiconductor, ReP-TiO2 hybrid, displays an improvement in CO2 reduction photocatalysis. A high turnover number (TON) of 48 molCO molRe(-1) is observed in DMF with the electron donor triethanolamine at λ>420 nm. ReP-TiO2 compares favourably to previously reported homogeneous systems and is the highest TON reported to date for a CO2-reducing Re photocatalyst under visible light irradiation. Photocatalytic CO2 reduction is even observed with ReP-TiO2 at wavelengths of λ>495 nm. Infrared and X-ray photoelectron spectroscopies confirm that an intact ReP catalyst is present on the TiO2 surface before and during catalysis. Transient absorption spectroscopy suggests that the high activity upon heterogenisation is due to an increase in the lifetime of the immobilised anionic Re intermediate (t50% >1 s for ReP-TiO2 compared with t50% = 60 ms for ReP in solution) and immobilisation might also reduce the formation of inactive Re dimers. This study demonstrates that the activity of a homogeneous photocatalyst can be improved through immobilisation on a metal oxide surface by favourably modifying its photochemical kinetics.
报道了固定在TiO₂纳米颗粒上的膦酸化铼配合物[Re(2,2'-联吡啶-4,4'-二膦酸)(CO)₃(L)]（ReP；L = 3-甲基吡啶或溴化物）的光催化活性。半导体上的多相化铼催化剂ReP-TiO₂杂化物在CO₂还原光催化方面表现出改进。在二甲基甲酰胺中，使用电子供体三乙醇胺，在λ>420 nm时观察到高达48 molCO molRe⁻¹的高周转数（TON）。ReP-TiO₂与先前报道的均相体系相比具有优势，并且是迄今为止报道的在可见光照射下用于CO₂还原的铼光催化剂的最高TON。甚至在λ>495 nm波长下用ReP-TiO₂也观察到了光催化CO₂还原。红外和X射线光电子能谱证实，在催化之前和催化过程中，TiO₂表面存在完整的ReP催化剂。瞬态吸收光谱表明，多相化后的高活性是由于固定化的阴离子铼中间体的寿命增加（ReP-TiO₂的t₅₀%>1 s，而溶液中ReP的t₅₀% = 60 ms），并且固定化还可能减少无活性铼二聚体的形成。这项研究表明，通过有利地改变其光化学动力学，将均相光催化剂固定在金属氧化物表面上可以提高其活性。
