Covalent Organic Frameworks Containing Dual O₂Reduction Centers for Overall Photosynthetic Hydrogen Peroxide Production

Abstract

Covalent organic frameworks (COFs) are highly desirable for achieving high-efficiency overall photosynthesis of hydrogen peroxide (H 2 O 2 ) via molecular design. However, precise construction of COFs toward overall photosynthetic H 2 O 2 remains a great challenge. Herein, we report the crystalline s-heptazinebased COFs (HEP-TAPT-COF and HEP-TAPB-COF) with separated redox centers for efficient H 2 O 2 production from O 2 and pure water. The spatially and orderly separated active sites in HEP-COFs can efficiently promote charge separation and enhance photocatalytic H 2 O 2 production. Compared with HEP-TAPB-COF, HEP-TAPT-COF exhibits higher H 2 O 2 production efficiency for integrating dual O 2 reduction active centers of s-heptazine and triazine moieties. Accordingly, HEP-TAPT-COF bearing dual O 2 reduction centers exhibits a remarkable solar-to-chemical energy efficiency of 0.65 % with a high apparent quantum efficiency of 15.35 % at 420 nm, surpassing previously reported COFbased photocatalysts.

Highly efficient photosynthesis of hydrogen peroxide by a stable Zr(iv)-based MOF with a diamino-functionalized ligand

“…3b). 33 Both UiO-67-NH 2 and UiO-67-(NH 2 ) 2 had rapid photocurrent response and good reproducibility under visible light irradiation (Fig. 3c).…”

“…In the past few decades, a wide range of research studies into the photocatalytic production of H 2 O 2 have been carried out, and catalysts involving bismuth vanadate, 5,6 metal oxide and/or their complexes, 7–12 graphitic carbon nitride, 13,14 cadmium sulphide, 15,16 metal–organic frameworks (MOFs) 17–30 and covalent organic frameworks 31–35 have been reported. Among them, MOFs have attracted special attention not only due to their porosity, large surface area and crystalline nature, but also due to the ready functionalization of their metal nodes and organic ligands.…”

Unveiling the Dynamic Evolution of Single-Atom Co Sites in Covalent Triazine Frameworks for Enhanced H2O2 Photosynthesis

“…A weak absorption peak ranging from 1184.3–1413.2 cm –1 is assigned to – OOH, indicating the progressive activation and hydrogenation of *O 2 at adsorption site. Conversely, Co SA /Py-CTF showing a new vibrational peak at 910 cm –1 attributed to 1,4-endoperoxide intermediate (−O–O−), , suggesting a shift from Pauling-type to Yeager-type O 2 adsorption configuration under light conditions. Furthermore, the emergence of a distinct peak at ∼780 in the quasi in situ Raman spectra (Figure S39) provides additional evidence supporting the existence of the −O–O– intermediate in the H 2 O 2 photosynthesis process facilitated by the Co SA /Py-CTF system. , In addition, the significantly enhanced −OH signal (1300–1374 cm –1 ) derived from H 2 O 2 generation in the Co SA /Py-CTF system .…”

“…The bonding, occupied antibonding, and empty orbitals are located on the right (red region), left (blue region), and upper side (green region), respectively. Specifically, in ES-Co SA /Py-CTF adsorbed O 2 configuration, the integrated COHP (ICOHP) up to Fermi surface for O1−Co1 bond is 30,37 suggesting a shift from Pauling-type to Yeager-type O 2 adsorption configuration under light conditions. Furthermore, the emergence of a distinct peak at ∼780 in the quasi in situ Raman spectra (Figure S39) provides additional evidence supporting the existence of the −O−O− intermediate in the H 2 O 2 photosynthesis process facilitated by the Co SA /Py-CTF system.…”

Donor–acceptor sp2 covalent organic frameworks for photocatalytic H2O2 production and tandem bisphenol-A degradation

“…Despite the demonstrated excellent efficiency of COFs in H 2 O 2 synthesis, 18,25–31 and parallelly in persistent pollutant decontamination, 32 an in-depth exploration of their potential to govern the concomitant degradation of organic pollutants in water via in situ photosynthesized H 2 O 2 -mediated ROS generation remains underexplored. Nevertheless, this undiscovered field is crucial because it expands the research of H 2 O 2 applications by avoiding the time and energy-consuming extraction process of H 2 O 2 .…”