Methane activation and utilization are among the major challenges of modern science. Methane is potentially an important feedstock for manufacturing value-added fuels and chemicals. However, most of known processes require excessive operating temperatures and exhibit insufficient selectivity. Here, we demonstrate a photochemical looping strategy for highly selective stoichiometric conversion of methane to ethane at ambient temperature over silverheteropolyacid-titania nanocomposites. The process involves stoichiometric reaction of methane with highly-dispersed cationic silver under illumination, which results in the formation of methyl radicals. Recombination of the generated methyl radicals leads to selective, and almost quantitative, formation of ethane. Cationic silver species are simultaneously reduced to metallic silver. The silver-heteropolyacid-titania nanocomposites can be reversibly regenerated in air under illumination at ambient temperature. The photochemical looping process achieves methane coupling selectivity over 90%, quantitative yield of ethane over 9%, high quantum efficiency (3.5% at 362 nm) and excellent stability.

Selective synthesis of ethers from biomassderived carbonyl compounds is an important academic and industrial challenge. The existing processes based on strong acid or metallic catalysts cannot provide high selectivity to ethers due to the occurrence of side reactions. Hereby we propose a Pd-I bifunctional heterogeneous catalyst for the selective reductive etherification of aldehydes with alcohols. Extensive catalyst characterizations uncovered the presence of iodine species on the surface of Pd nanoparticles. Heterolytic dissociation of hydrogen on the I-Pd surface sites leads to the "in situ" generation of a Brønsted acid, which promotes the reaction toward the corresponding ethers with extremely high selectivity under very mild reaction conditions.