A novel photocatalyst, PbBi2Nb2O9 has been discovered that shows high activities for degradation of organic pollutants, generation of photocurrent, and water decomposition into O2 or H2, all under visible right irradiation (λ ≥ 420 nm). This is the first example of an undoped, single-phase oxide photocatalyst that shows such reactivity. Its quantum yields are much higher than those for most of the previously reported materials, especially in water decomposition to generate oxygen (29%). Since it is an oxide, there is much less concern for stability under light irradiation.

The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO(2). The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO(2).

A series of highly crystalline, porous, zirconium-based metal-organic frameworks (Zr-MOFs) with different ligand functionality and porosity were applied for catalytic transfer hydrogenation of ethyl levulinate (EL) to form γ-valerolactone (GVL), using isopropanol as a hydrogen donor. The role of ligand functionality and the metal center of the Zr-MOFs were identified and reaction parameters were optimized, for selective production of GVL. Maximum yield of GVL (up to 92.7%) was achieved in 2 h at 200 o C with UiO-66(Zr). Interestingly, zirconium trimesate (MOF-808) emerged as the most suitable candidate, with the highest GVL formation rate (94.4 μmol/g/min) among the catalysts tested at 130 o C. It was also found effective in conversion of EL to GVL in an open system using the solvent refluxing method. Both the catalysts (UiO-66(Zr) and MOF-808) were recycled at least five times under their specified reaction conditions without notable change in catalytic activity and product selectivity. Fresh and recycled catalysts were characterized in detail using X-ray diffraction (XRD), N2 adsorption-desorption, thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) in order to understand the stability and structural changes that occurred in the catalysts. Finally, a plausible reaction mechanism was presented on the basis of active sites present in catalysts confirmed by characterization results.

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