Scientists discover primitive photooxidation catalyst

Nitrogen-doped graphite catalyzes reactions to produce early biomolecules.

The sun, which played a pivotal role in powering the first biochemical molecules on Earth, facilitated crucial reactions along with catalysts that accelerated chemical processes. A group of researchers recently proved that the substance is derived from the reaction of ammonia and methane plasma It has the ability to harness light energy to facilitate transitions from an amine to an imine.

It is possible that this mechanism was a major contributor to the formation of the first biomolecules. The results were recently published in the journal Angewandte Kimi.

Between three and four billion years ago, on the primordial Earth, the first biomolecules were forming before life exploded. However, these early chemical reactions required catalysts. Shenchen Wang and a team of researchers from Fuzhou University in China discovered that the primordial atmosphere itself could have acted as a source of these stimuli.

Using methane and ammonia, which were likely present in the hot gas mixture that blanketed the Archean world, the team used chemical vapor deposition to produce nitrogenous carbon compounds as potential catalysts. They found that in the reaction chamber, particles from the ammonia and methane plasma condense on the surface, and grow rapidly to form a solid nitrogen-carbon polymer that looks like nitrogen-doped graphite.

As the team noted, the irregularly fused nitrogen atoms gave this polymer catalytically active sites and an electronic structure that enabled it to be excited by light. Then the researchers turned to proving the ability of the substance to reduce or oxidize other substances under the influence of light.

Perhaps one of the most important reactions that took place on early Earth was the formation of imines. Imines, also referred to as Schiff bases, are a form of dehydrogenated amines, which are compounds composed of carbon, nitrogen, and hydrogen. Many chemists hypothesize that on a primordial Earth, imines may have helped form the first genetic molecules from ribonuclear cells. sour (RNA). Wang and his team are able to show that the plasma-generated catalyst can convert amines into imines using only sunlight.

The team says carbon nitride-based photocatalysts, such as the one generated in the plasma, can last for millions of years and produce important chemical intermediates. In addition, it can serve as a source of carbon- and nitrogen-containing compounds. By demonstrating that it is possible to produce such a catalyst using only the gases and conditions present in the early Earth’s atmosphere, the study sheds new light on the potential evolutionary path that biomolecules took.

Reference: “Plasma-enhanced Chemical Vapor Deposition (PVD) Synthesis of Redox-Activated NOC from NH3 and CH4 Gases” by Yan Wang, Yuan Xingfang, Yankun Wang, Haisoo Wu, Masakazu Anbu, and Jamie C. Yu, and Shenzhen Wang, June 22, 2023, Angewandte Chemie International Edition.
doi: 10.1002/anie.202307236

The study was funded by the National Key Technologies Research and Development Program of China, the National Natural Science Foundation of China, and Project 111.