Synthesis of hydrogen peroxide

Why in News?

Researchers have found an efficient, less energy-intensive, and environmentally friendly way of synthesizing hydrogen peroxide.

• Currently, over 95% of H₂O₂ is produced industrially using the anthraquinone oxidation process.
  • It is very energy intensive, expensive and produces many hazardous chemicals as by-products.
• Recent Findings - Scientists discovered a new class of porous and ordered polymers with modifiable catalytic sites and light-harvesting properties in visible range, called covalent organic frameworks (COFs).
• It have emerged as promising photocatalysts.
• Done by - S. N. Bose National Centre for Basic Sciences, Kolkata, an autonomous institute under the Department of Science and Technology (DST).
• They have designed and prepared a series of COFs having good water affinity through careful control of the hydrazone linkage density.
• They also studied their effect on the photocatalytic performance for H2O2 generation.
• It was observed that the hydrazone-linked COFs provide abundant docking sites for water and oxygen, thereby promoting 2 main pathways for photocatalytic H2O2 generation
  • Water oxidation reaction (WOR) and
  • Oxygen reduction reaction (ORR)
• As a result, the hydrazone-linked COF exhibited exceptional photocatalytic H2O2 production without external sacrificial electron donors when irradiated with a 40 W blue LED (λ = 467 nm).
• Interestingly, a significant amount of H2O2 (550 μmol g-1 h-1) was also produced under sunlight irradiation.
• It outperforms most organic photocatalysts under similar conditions, thus demonstrating a clean and sustainable pathway.
• Furthermore, as-synthesized hydrazone-linked COFs can generate H2O2 up to 21641 μmol g-1 h-1 using an aqueous benzyl alcohol solution by preventing the degradation of H2O2.

Aqueous benzyl alcohol consists of (water: benzyl alcohol = 90:10)

• This strategy will be helpful in developing a continuous flow reactor for the sustainable production of H2O2 and will reveal a laboratory-to-industry technology transfer for the benefit of mankind.

References

PIB | Hydrazone-linked COFs