文摘
Visible-light irradiation of a ternary hybrid catalyst prepared by grafting a dye, an H<sub>2sub> evolving Co<sup>IIIsup> catalyst and a CO-producing Re<sup>Isup> catalyst on TiO<sub>2sub> have been found to produce both H<sub>2sub> and CO (syngas) in CO<sub>2sub>-saturated N,N-dimethyl formamide (DMF)/water solution containing a 0.1 m sacrificial electron donor. The H<sub>2sub>/CO ratios are effectively controlled by changing either the water content of the solvent or the molar ratio of the Re<sup>Isup> and Co<sup>IIIsup> catalysts ranging from 1:2 to 15:1. The controlled syngas formation is discussed in terms of competitive electron flow from TiO<sub>2sub> to each of the CO<sub>2sub>-reduction and hydrogen-evolving sites depending on the efficiencies of the two catalytic reaction cycles under given reaction conditions.