Researchers have found an efficient, less energy-intensive, and environmentally friendly way of synthesizing hydrogen peroxide, a chemical that is crucial to the industry for disinfection, paper bleaching, and so on.

Hydrogen peroxide (H₂O₂) is a versatile oxidizing agent that is widely used in environmental disinfection, chemical synthesis, paper bleaching, and fuel cells. In addition, the growth of this market is driven by the increasing awareness of disinfection, the rise in the number of surgeries, the prevalence of hospital-acquired infections, and so on. Currently, over 95% of H₂O₂ is produced industrially using the anthraquinone oxidation process, which is very energy intensive, expensive and produces many hazardous chemicals as by-products.

Scientists are therefore looking for an environmentally friendly and economical strategy to produce H₂O₂ from renewable resources with minimal environmental impact. In this context, a new class of porous and ordered polymers with modifiable catalytic sites and light-harvesting properties in visible range, called covalent organic frameworks (COFs), have emerged as promising photocatalysts.

Figure 1.  Sustainable synthesis and versatile applications of hydrogen peroxide.

Researchers at S. N. Bose National Centre for Basic Sciences, Kolkata, an autonomous institute under the Department of Science and Technology (DST), have designed and prepared a series of COFs having good water affinity through careful control of the hydrazone linkage density and 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 water oxidation reaction (WOR) and oxygen reduction reaction (ORR) - two main pathways for photocatalytic H₂O₂ generation.

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, which 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 (water: benzyl alcohol = 90:10) by preventing the degradation of H₂O₂. This strategy of using a mixture of water-benzyl alcohol solution 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.

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NKR/PSM

(Release ID: 2109125) Visitor Counter : 2011