Supported single metal atoms have attracted widespread attention due to their high efficiency in single metal catalysis. However, the preparation of such catalysts remains challenging because neutral metal atoms have a strong tendency to aggregate into metal particles in typical formulations.

Researchers at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences (Dalian Institute of Chemical Physics) and the University of Delaware reported a method to produce a colorless liquid that stores metal -like discrete platinum atoms. Their findings were published in Nature Communications .

In environmentally friendly liquid surfactants, the chlorinated platinum salt is reduced to a monoplatinum metal atom by an alcohol. Each Pt atom is covered by a hydrochloride salt and remains in the liquid through a rich oxygen atom. The preparation of metal-like Pt atoms is scalable.

As a noble metal, metal Pt nanoparticles on carbon or oxide supports are widely used in the petroleum refining and chemical industries due to their unique catalytic functions. “The reserves of Pt on the planet are limited and consume only about 5.6 tons of Pt per year in the silica gel industry,” said Z. Conrad Zhang, who is in charge of the study.

The researchers tested the catalytic properties of liquids loaded with Pt atoms. "We found that the electron-deficient Pt atoms in the liquid have superior activity and selectivity to the reaction compared to known Pt catalysts," said graduate student, the first author of the paper, Liu Kairui.

The docked discrete Pt atoms do not aggregate under the reaction conditions - remain highly active and remain colorless by repeated use. "The high activity, selectivity and stability of this catalyst may greatly reduce the amount of Pt consumed by the silicone industry and may be widely applicable to other applications," Zhang said.

Although the liquid carrying the Pt atoms is stable at 120 ° C and kept clean on the shelf for more than six months at ambient temperature , the researchers found that when exposed to X-rays or electrons, due to the accumulation of Pt atoms Darkening usually uses a beam of light to characterize the Pt atoms. To address this challenge, the researchers turned to 195Pt nuclear magnetic resonance (NMR) spectroscopy as a tool and found that it provides clear evidence for the Pt atoms generated.

"Liquid NMR spectroscopy data not only clearly shows the discrete nature of mononuclear Pt atoms, but also shows that there is only one carbon monoxide coordinated to the Pt atom," said Professor Bai Shi of the University of Delaware.

"We are expanding the storage of various metal atoms in our current research. The successful synthesis of hoods in the liquid phase where Pt atoms are easily removed may make it possible to design atomically controllable catalytic materials and metallic materials by design," Zhang said.

Further exploration: placing atoms to get the best catalyst

More information: Kairui Liu et al. The cause of electron-deficient Pt1(0) in PDMS-PEG aggregates, Nature Communications (2019). DOI: 10.1038 / s41467-019-08804-y