Solar energy-driven H₂O₂ photosynthesis from water and oxygen using Ba-implanted ordered carbon nitride

H₂O₂, a green oxidant and clean fuel, is in high demand across chemical industries, environmental treatments, and even aerospace. However, traditional production methods rely on energy-intensive processes that are not environmentally friendly. Scientists have been seeking a greener alternative, and semiconductor photocatalysis using solar energy to drive chemical reactions has emerged as a promising solution.

To date, various photocatalysts, such as TiO₂, BiVO₄, metal-organic complexes and organic polymers, have been explored for H₂O₂ photosynthesis. Cost-effective graphitic carbon nitride (g-C₃N₄) has caught widespread attention in H₂O₂ photosynthesis due to its elemental abundance, high structure stability and appropriate band structure.

However, the H₂O₂ production efficiency of traditional g-C₃N₄ is severely limited due to poor crystallinity and selectivity in two-electron oxygen reduction reaction (2e^–-ORR). Therefore, improving the in-plane crystallinity of bulk g-C₃N₄ is greatly requisite to sufficiently trigger oxygen reduction reaction for efficient photocatalytic H₂O₂ production.

Recently, a research team led by Prof. Yaorong Su from Shenzhen Technology University, China, ingeniously overcomes these obstacles. They developed a new type of photocatalyst, in-plane highly ordered g-C₃N₄ nanorods with barium (Ba) atoms implanted. This innovation not only enhances the in-plane crystallinity but also induces a highly selective 2e^–-ORR, which is the key to efficient H₂O₂ production.

The Ba-implanted nanorods work their magic by altering the way oxygen molecules (O₂) interact with the photocatalyst. Instead of the typical side-on binding that favors water production, the Ba atoms encourage a more favorable end-on binding. This change significantly reduces the possibility of O-O bond breaking, effectively suppressing the competing four-electron reaction and boosting the production of H₂O₂.

An outstanding 6.1 times increase in H₂O₂ production rate compared to the original g-C₃N₄ was achieved. This breakthrough not only optimizes the photocatalytic process of solar energy-driven H₂O₂ photosynthesis but also opens up new possibilities for designing efficient catalysts for solar-to-fuel conversion, bringing us closer to a sustainable future.

This work was published in the Chinese Journal of Catalysis.