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Different mechanisms have been proposed for Fischer-Tropsch synthesis, the conversion of CO and H 2 to long-chain alkanes. Density functional theory calculations indicate that CO activation has a barrier of 220 kJ/mol on Co(0001), and hence the concentration of surface C or CH 2 species is likely too low to explain the high chain growth probability. Hydrogenation lowers the C-O dissociation barrier to 90 kJ/mol for HCO and to 68 kJ/mol for H 2 CO; however, CO hydrogenation has a high energy barrier of 146 kJ/mol and is +117 kJ/mol endothermic. We propose an alternative propagation cycle starting with CO insertion into surface RCH groups. The barrier for this step is 80 kJ/mol. RCHCO is subsequently hydrogenated to RCH 2 CHO, which undergoes C-O dissociation with a barrier of 50 kJ/mol. The hydrogenation barriers are 120 and 48 kJ/mol along the dominant reaction path. The calculated CO turnover frequency for the proposed CO insertion mechanism is 1 to 2 orders of magnitude faster the hydrogen-assisted CO activation mechanism and 4 orders of magnitude faster than direct CO activation on a model Co(0001) surface.

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To construct photocatalytically active MOFs, various strategies have recently been developed. We have synthesized and characterized a new metal-organic framework (MOF-253-Pt) material through immobilizing a platinum complex in 2,2 0 -bipyridine-based microporous MOF (MOF-253) using a post-synthesis modification strategy.The functionalized MOF-253-Pt serves both as a photosensitizer and a photocatalyst for hydrogen evolution under visible-light irradiation. The photocatalytic activity of MOF-253-Pt is approximately five times higher than that of the corresponding complex. The presence of the short Pt/Pt interactions in the framework was revealed with extended X-ray absorption fine structure (EXAFS) spectroscopy and low temperature luminescence. These interactions play an important role in improving the photocatalytic activity of the resulting MOF.