Recently, a research team led by Professor YU Zhiwu from Hefei Institutes of Physical Science of the Chinese Academy of Sciences, developed a new type of carbon nitride catalyst, T-0.9ODHCN, by combining two advanced techniques: supramolecular self-assembly and defect engineering. 

This catalyst, which has nitrogen (N) vacancies and unique electronic properties, performs over 30 times better in photocatalytic hydrogen production compared to traditional carbon nitride.

Results of the achievement were published in Chemical Engineering Journal.

Since carbon nitride was first utilized for photocatalytic water splitting in 2009, researchers have been actively working to enhance its performance. However, pure carbon nitride has several limitations, including a small surface area, inefficiencies in separating light-induced electron-hole pairs, and a limited capacity for utilizing visible light.

The T-0.9ODHCN catalyst developed in this study addresses these challenges. By introducing nitrogen vacancies into the carbon nitride structure, the team was able to enhance the material’s ability to absorb visible light. Additionally, the catalyst's unique tubular shape increases surface area, thereby enhancing light absorption efficiency. The nitrogen vacancies also reduce the material's bandgap, making it easier for electrons to participate in the hydrogen production process.

A key discovery of this study is that the nitrogen vacancies induce an electronic transition known as the n-π* transition within the carbon nitride. This transition enhances the material’s light absorption capability and improves the efficiency of electron separation and transport, resulting in superior performance for hydrogen production.

These findings offer new insights into the optimization of carbon nitride-based catalysts and may pave the way for more effective methods of clean hydrogen production in the future.

Schematic diagram of electronic transition based on fs-TAS test results. (Image by YU Zhiwu)