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.

Selectivity control is a challenging goal in Fischer–Tropsch (FT) synthesis. Hydrogenolysis is known to occur during FT synthesis, but its impact on product selectivity has been overlooked. Demonstrated herein is that effective control of hydrogenolysis by using mesoporous zeolite Y‐supported cobalt nanoparticles can enhance the diesel fuel selectivity while keeping methane selectivity low. The sizes of the cobalt particles and mesopores are key factors which determine the selectivity both in FT synthesis and in hydrogenolysis of n‐hexadecane, a model compound of heavier hydrocarbons. The diesel fuel selectivity in FT synthesis can reach 60 % with a CH4 selectivity of 5 % over a Na‐type mesoporous Y‐supported cobalt catalyst with medium mean sizes of 8.4 nm (Co particles) and 15 nm (mesopores). These findings offer a new strategy to tune the product selectivity and possible interpretations of the effect of cobalt particle size and the effect of support pore size in FT synthesis.

Chemical utilization of vast fossil and renewable feedstocks of methane remains one of the most important challenges of modern chemistry. Herein, we report direct and selective methane photocatalytic oxidation at ambient conditions into carbon monoxide, which is an important chemical intermediate and a platform molecule. The composite catalysts on the basis of zinc, tungstophosphoric acid and titania exhibit exceptional performance in this reaction, high carbon monoxide selectivity and quantum efficiency of 7.1% at 362 nm. In-situ Fourier transform infrared and X-ray photoelectron spectroscopy suggest that the catalytic performance can be attributed to zinc species highly dispersed on tungstophosphoric acid /titania, which undergo reduction and oxidation cycles during the reaction according to the Mars–van Krevelen sequence. The reaction proceeds via intermediate formation of surface methyl carbonates.

Constructing solid-solution-alloy electrocatalysts with tunable surface electronic configurations is the key to optimize intermediate bindings and thereby to promote the activity and selectivity of the CO2 reduction reaction (CO2RR). Herein, Pd1–x Ag x alloy electrocatalysts are investigated as a platform to uncover the electronic effects on the CO2RR. The optimal Pd0.75Ag0.25/C affords a superior CO Faradaic efficiency of 95.3% at −0.6 V (vs RHE) in 0.5 M KHCO3, performing at a high level among recently reported electrocatalysts. Experimental and theoretical analysis further evidence that varying the composition of Pd1–x Ag x alloys can effectively alter the electronic configurations and consequently break the inherent scaling relationship of the binding energy of different intermediates (*COOH and *CO). Among Pd1–x Ag x , Pd0.75Ag0.25 gains the obviously weakened *CO and *H bindings but retained well the binding with *COOH, contributing to the facilitated kinetics toward CO product. Elucidating a feasible way to break the scaling relationship and further uncover the underlying mechanism, this work will inspire new design strategies toward active and selective electrocatalysts.

Selectivity control is ac hallenging goal in Fischer-Tropsch (FT) synthesis.H ydrogenolysis is knownt oo ccur during FT synthesis,b ut its impact on product selectivity has been overlooked. Demonstrated herein is that effective control of hydrogenolysis by using mesoporous zeolite Y-supported cobalt nanoparticles can enhance the diesel fuel selectivity while keeping methane selectivity low. The sizes of the cobalt particles and mesopores are key factors whichd etermine the selectivity both in FT synthesis and in hydrogenolysis of nhexadecane,amodel compound of heavier hydrocarbons.The diesel fuel selectivity in FT synthesis can reach 60 %with aCH 4 selectivity of 5% over aN a-type mesoporous Y-supported cobalt catalyst with medium mean sizes of 8.4 nm (Co particles) and 15 nm (mesopores). These findings offer an ew strategy to tune the product selectivity and possible interpretations of the effect of cobalt particle sizea nd the effect of support pore sizei nF Tsynthesis.Fischer-Tropsch (FT) synthesis,aprocess for the conversion of syngas (CO/H 2 )d erived from nonpetroleum carbon resources such as natural gas (also shale gas), coal, and biomass,i nto hydrocarbon fuels and chemicals,h as received renewed interest because of the growing global demand for liquid fuels and the depletion of petroleum. Extensive studies have been devoted to developing efficient catalysts for FT synthesis, [1] but the effective control of product selectivity remains one of the grand challenges.T he FT products generally follow the Anderson-Schulz-Flory (ASF) distribution, which is unselective for the middle-distillate products. [1b] Fore xample,t he selectivities of products in gasoline (C 5-11 ) and diesel (C 10-20 )f ractions are limited to 45 and 39 %, respectively.Conventionally,the FT products are subjected to further hydrotreatment to increase liquid fuel selectivity. Compared to this two-stage process,the direct production of specific-range liquid fuels would be more energy and cost efficient.Recently,bifunctional FT catalysts,which combine either ruthenium, cobalt, or iron nanoparticles for CO hydrogenation, and acid sites in az eolite like H-ZSM-5 for hydrocracking,h ave been harnessed to enhance the C 5-11 selectivity. [2,3] However,few studies have succeeded in the direct and selective production of C 10-20 hydrocarbons, [4] even though the FT-based diesel fuel is known to possess many advantages such as low sulfur and aromatic content, and reduced NO x and particulate matter emissions. [5] Herein, we report an ew strategy to improve the C 10-20 selectivity by effective control of hydrogenolysis.We expected that the use of zeolite H-Y,having aweaker Brønsted acidity than H-ZSM-5, might cause milder hydrocracking of heavier primary hydrocarbons formed on FT metals and lead to higher C 10-20 selectivity.H owever,the Co/ H-Y catalyst did not show enhanced C 10-20 selectivity compared to that of Co/SiO 2 and Co/Al 2 O 3 ,w hich are two conventional FT catalysts,b ut its C 21+ selectivity was lower because of the Brønsted a...

The nanostructure of a semiconductor is a crucial parameter for efficient photocatalytic performance. Hereby, we have synthesized monoclinic bismuth vanadate (BiVO 4 ) crystals with controlled ratio of {010} and {110} facets. The selective deposition of CuO x and CoO x over {010} and {110} facets has been performed using photo-reduction and photo-oxidation methods, respectively. It resulted in a highly efficient charge separation of photogenerated electrons and holes and enhancement of the photocatalytic reduction of CO 2 by H 2 O into hydrocarbons, including CH 4 , C 2 H 6 and C 3 H 8 . The controlled co-catalyst deposition over different semiconductor facets provides a strategy for the synthesis of hydrocarbons from CO 2 and H 2 O by efficient charge separation.[a] Dr. X. Yu, Dr.

We report new efficient core–shell nanocomposites for photocatalytic CO2 to CO conversion at ambient temperature with enhanced yield and selectivity.

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