Shanxi Coal Chemical Institute, etc. Obtained in the research of photocatalytic organic synthesis of metal/silicon carbide

2021-04-25

The research team led by Guo Xiangyun, a researcher at the State Key Laboratory of Coal Conversion in the Institute of Coal Chemistry of the Chinese Academy of Sciences in Shanxi Province, collaborated with Yang Hong, professor at the University of Illinois at Urbana-Champaign, to use cubic high-surface area silicon carbide (SiC) capable of responding to visible light as carrier, using gold. (Au) Effect of Surface Plasmon Resonance on Nanoparticles. New Au/SiC photocatalytic system was designed. Under room temperature and visible light conditions, the selective hydrogenation of fluorene and β-unsaturated aldehydes was successfully achieved. -Unsaturated alcohols, related work was recently published in "J. Am. Chem. Soc. 2016, 138, 9361-9364".

Beryllium, β-unsaturated alcohol is an important raw material and reaction intermediate in the production of pharmaceuticals, spices and other fine chemical products, and has a wide range of applications in organic synthesis. Niobium, the selective hydrogenation of β-unsaturated aldehydes is one of the effective ways to make ɑ,β-unsaturated alcohols. However, in the oxime and β-unsaturated aldehyde molecules, there are both C=C bonds and C=O bonds. The former has lower bond energy than the latter, and its hydrogenation is more thermodynamically favorable, thus hydrogenating to form unsaturated alcohols. Poor selectivity. In the Au/SiC photocatalytic system, the strong localized electromagnetic field generated by the surface plasmon resonance effect of Au nanoparticles can excite the Au nanoparticles to generate high-energy “hot” electrons. These "hot" electrons are injected into the conduction band of SiC, causing positive and negative charges on Au and SiC surfaces respectively. The former activates isopropanol to form active hydrogen, and the latter cooperates with the steric hindrance effect of SiC/Au interface, adsorption and activation. The C=O bond in the β-unsaturated aldehyde molecule allows it to be converted to quinone, β-unsaturated alcohol with high selectivity.

Photocatalysis can effectively use solar energy, speed up the reaction process under mild conditions, and can be targeted synthesis of target products, increase the yield of the target product, so it has been widely concerned in organic synthesis. At present, photocatalysis has been applied to many organic reactions such as polymerization, hydroxylation of aromatic hydrocarbons, oxidation of amines, epoxidation of olefins, and carbonylation. Guo Xiangyun's research group is based on cubic high-surface-area SiC that can respond to visible light and has high conductivity. By designing different metal/SiC catalyst systems, it can realize the construction of different interface electric fields and further enable the effective separation of photo-generated carriers. The nucleophilic/electrophilic reactants are activated by adsorption at active sites with different charge properties, thereby increasing the photocatalytic reaction rate. In the previous work, the research group used SiC to load Pd with a large work function to form a Mott-Schottky contact at the interface between Pd and SiC, so that the photogenerated electrons of SiC were transferred to the metal Pd, making Pd and SiC negatively and positively charged, respectively. Under the irradiation of visible light, Pd/SiC catalyst can realize hydrogenation of furan under the mild conditions of 25oC and H2 pressure of 1MPa, and tetrahydrofuran is produced with a conversion frequency (TOF) of 70 h-1 (Catal. Sci. Technol., 2014, 4, 2494-2498); iodobenzene and phenylboronic acid can be coupled at 30oC and atmospheric pressure Ar atmosphere, the product biphenyl yield is greater than 99%, TOF reaches 1053h-1, much higher than the traditional catalyst (J. Phys. Chem C, 2015, 119, 3238-3243), and the catalyst has excellent stability and universality.

This research was supported by the National Natural Science Foundation of China (21403270 and 21473232), the Major Science and Technology Project of Shanxi Province (20131101035), the State Key Laboratory of Coal Conversion (2014BWZ006) and the Open Project (J15-16-909), and the Youth Innovation Promotion of the Chinese Academy of Sciences. Will be funded (2013115).