Efficient H₂O₂ photosynthesis in pure water enabled by multivariate hydrogen-bonded organic framework

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• The global demand for hydrogen peroxide (H2O2) necessitates sustainable synthesis methods beyond the energy-intensive anthraquinone process.
• Metal-organic frameworks (MOFs) show promise as photocatalysts but suffer from high costs and H2O2 decomposition due to metal nodes.
• Developing metal-free, efficient photocatalysts is crucial for solar-driven chemical production.

Purpose of the Study:

• To design and synthesize a novel metal-free hydrogen-bonded organic framework (HOF) for efficient photocatalytic H2O2 production.
• To investigate the synergistic effects of a mixed-linker system incorporating pyrene-based (TBAPy) and porphyrin-based (TCPP) ligands.
• To establish molecular energy-channel engineering as a strategy for high-performance, metal-free solar chemical synthesis.

Main Methods:

• Co-assembly of pyrene-based 1,3,6,8-Tetra (4'-Carboxyphenyl) Pyrene (TBAPy) and porphyrin-based 5,10,15,20-Tetrakis (4carboxyphenyl) porphyrin (TCPP) ligands to form a HOF.
• Utilizing Density Functional Theory (DFT) calculations and experimental investigations to analyze energy transfer and reaction mechanisms.
• Evaluating photocatalytic H2O2 production rates under visible-light irradiation in pure water.

Main Results:

• The optimized 7.5TCPP-TBAPy HOF demonstrated a high H2O2 production rate of 730.45 μmol g⁻¹ h⁻¹, a 3.6-fold increase over single-linker TCPP HOF.
• The mixed-linker HOF exhibited a 13.7-fold improvement compared to the TBAPy HOF, showcasing synergistic effects.
• Intraframework energy transfer from TBAPy to TCPP enhanced charge separation and facilitated key reaction intermediates for H2O2 formation.

Conclusions:

• This work presents the first integration of TBAPy and TCPP within a HOF for photocatalytic H2O2 synthesis.
• The developed metal-free HOF offers a highly efficient and sustainable route for solar-driven H2O2 production.
• Molecular energy-channel engineering is validated as an effective strategy for designing advanced photocatalysts for green chemical synthesis.