Phosphorus-Alkynyl Functionalized Covalent Triazine/Heptazine-Based Frameworks for High-Performance Photocatalytic Hydrogen Peroxide Production

Identifying high-efficiency photocatalysts for producing hydrogen peroxide from H2O and O2 is a promising yet challenging research direction for achieving solar-to-chemical energy conversion and storage. Herein, 14 experimentally feasible 2D covalent triazine/heptazine-based frameworks (CTFs/CHFs) are constructed with phosphorus-alkynyl/phosphorus-alkynyl-phenyl functional moieties through topological assembly and four promising visible-light-driven photocatalysts for H2O2 production from H2O and O2 via first-principles computations are filtered out: CTF-1 based on triazine and phosphorus-acetylene, CTF-2 based on triazine and phosphorus-diacetylene, CHF-1 based on heptazine and phosphorus-acetylene, and CHF-2 based on heptazine and phosphorus-diacetylene. The computational results show that introducing electron-rich phosphorus-alkynyl moieties into CTFs/CHFs can effectively modulate their electronic structures, provide sufficient driving force for water oxidation, and facilitate O2 adsorption and activation, thereby significantly boosting the overall photocatalytic process. Among them, CHF-1 and CHF-2 exhibit the highest photocatalytic activity for H2O2 production at pH 7, and their ideal solar-to-chemical conversion (SCC) efficiency for H2O2 generation are theoretically estimated to be 26.06% and 35.37%, respectively, implying their great promise as photocatalysts for industrialized production of H2O2. The work presents a promising way for rationally designing and developing novel photocatalysts for H2O2 production, and provides new inspiration and reference for experimental research in this field. Fourteen 2D covalent triazine/heptazine-based frameworks (CTFs/CHFs) with phosphorus-alkynyl/phosphorus-alkynyl-phenyl functional moieties are constructed through topological assembly, in which CHF-1 (based on heptazine and phosphorus-acetylene) and CHF-2 (based on heptazine and phosphorus-diacetylene) are identified as the optimal photocatalysts for overall H2O2 production from H2O and O2 in pure water with high photocatalytic activity and selectivity.image

Automated summary

This study constructed 14 experimentally feasible 2D covalent triazine/heptazine-based frameworks and filtered out four promising visible-light-driven photocatalysts for producing hydrogen peroxide from water and oxygen. The computational results showed that introducing electron-rich phosphorus-alkynyl moieties effectively modulates the electronic structures and boosts the overall photocatalytic process. Among them, CHF-1 and CHF-2 exhibited the highest photocatalytic activity and theoretical solar-to-chemical conversion efficiency for hydrogen peroxide production.