Jul 2026· Journal of the American Chemical Society· Vol 148, pp. 30265-30277· 1 citation· 70 references
Medicine
Abstract
Photocatalytic synthesis of hydrogen peroxide (H2O2) offers a sustainable route toward green oxidation and environmental remediation, yet its efficiency is fundamentally constrained by rapid backward charge recombination, underscoring the synthetic challenge of creating molecular architectures capable of enforcing directional and recombination-suppressed charge transfer. Inspired by the stepwise electron transfer within the compartmentalized reaction centers of thylakoid membranes in natural photosynthesis, we design here biomimetic donor-acceptor 1-acceptor 2 (D-A1-A2) organic cages, where donors and acceptors are orderly positioned along an energy gradient to achieve a recombination-suppressed sequential charge transfer (RS-SCT) process, thereby promoting photocatalytic H2O2 production. Two single crystals of D-A1-A2 organic cages, BNC-O and BNC-S, are successfully constructed from in situ generated ditopic boronated monomers and C3-symmetric monomers via B-N dative bonds. Both cages show the RS-SCT process from electron-rich triphenylamines as the D through coordinated pyridines as A1 to more electron-deficient benzoxadiazoles or benzothiadiazoles as A2, which enable sequential charge migration and suppress backward charge recombination with prolonged excited-state lifetimes. As a result, the self-assembled two-dimensional crystalline cages featuring well-organized active sites exhibit significantly enhanced photocatalytic H2O2 production performance, achieving a rate of 4.15 mmol g-1 h-1 for crystalline BNC-O, which is markedly higher than those of the corresponding components lacking RS-SCT, including the individual D, A1, A2, and D-A systems. Furthermore, these D-A1-A2 organic cages are implemented in a photocatalytic microflow reactor for controllable in situ H2O2 generation under sunlight, which is further integrated into a cascade phenol-containing wastewater treatment system.
The insufficient photogenerated charge separation efficiency and low light absorption capacity of carbon nitride (CN) limit the production efficiency of hydrogen. Grafting organic small molecules onto CN to construct a donor-acceptor (D-A) system is an effective strategy for enhancing the photocatalytic performance. This work constructed a fully organic D-A material by grafting 2-benzothiazolamine (BZM) onto tubular CN (TCN) to alter the band structure of TCN. The all-organic D-A system disrupts the structural symmetry of CN and forms new charge transfer pathways, thereby accelerating intermolecular electron separation and transfer. The results of the photocatalytic hydrogen production experiment show that the photocatalytic hydrogen production rate of TCN-BZM0.3 reaches 4.11 mmol g-1 h-1 and exhibits good photocatalytic stability. This work investigates the facilitating effect of D-A structures on charge transfer and elucidates the corresponding photocatalytic mechanism, thereby providing valuable insights into the rational design of highly efficient organic photocatalysts.
Zhihuan Miao, Xuyue Wang, Hao Zhang et al.· Journal of Colloid and Inter...· 0 citations
Solar-driven photocatalytic synthesis of hydrogen peroxide (H2O2) offers a sustainable alternative to the energy-intensive anthraquinone process. Donor-acceptor (D-A) covalent organic frameworks (COFs) are highly promising photocatalysts for this transformation; however, the precise correlation between electronic conjugation, D-A pairing, and catalytic efficiency remains poorly understood. Here, we systematically investigate the threshold of conjugation enhancement on photocatalytic H2O2 production by designing D-A COFs with varying degrees of π-conjugation. Using benzotrithiophene (BTT) as the electron donor, we integrated acceptor units featuring alkyne and extended-ring motifs (yielding TATAB-BTT and TATAP-BTT). We reveal a distinct structure-activity relationship: moderate conjugation (TATAB-BTT) optimizes energy-level matching and maximizes charge separation, achieving an outstanding H2O2 production rate of 1610.8 µmol g-1 h-1, outperforming the less-conjugated literature example, TAPB-BTT (557.0 µmol g-1 h-1). Conversely, excessive conjugation (TATAP-BTT) induces a structural mismatch that shifts the electronic configuration from D-A to D-D, severely trapping excitons and diminishing performance (780.0 µmol g-1 h-1. These findings demonstrate that an optimal conjugation threshold is critical for sustaining D-A charge-transfer dynamics, providing a fundamental molecular design principle for next-generation polymeric photocatalysts.
Mengying Fu, Zhiqing Lin, Song-Yuan Dai et al.· Small· 0 citations
Photocatalytic production of hydrogen peroxide (H2O2) from water and O2 using organic semiconductor photocatalysts is a promising approach for solar-to-chemical energy conversion. Recently, covalent organic frameworks (COFs) consisting of donor (D)-acceptor (A) conjugates have attracted attention owing to the tunable platforms for semiconductor synthesis. In this study, we synthesized a series of COFs consisting of 2,4,6-triformylphloroglucinol (Tp) as an A unit and different N-containing heterocycles bearing different numbers of terminal -NH2 groups as D units. The COF containing 2,4,6-triaminopyrimidine (PmA3) as the D unit exhibited the highest activity for photocatalytic H2O2 generation. Photoelectrochemical measurements and density functional theory calculations revealed that the high activity of PmA3-COF originates from the high electron conductivity owing to the multibranched triamine structure and high hole-trapping capability of the Pm ring. These properties enhanced oxidation of water by the photogenerated holes, resulting in efficient H2O2 generation.
Koki Yoshida, Kazuki Terashima, Yasuhiro Shiraishi et al.· ACS Applied Materials and In...· 0 citations
Photocatalytic hydrogen peroxide (H2O2) synthesis via oxygen reduction reaction (ORR) offers a sustainable alternative to energy-intensive anthraquinone processes. However, its efficiency is hindered by poor selectivity and instability stemming from reactive superoxide intermediates through the two-step two-electron (2e-) route. Herein, inspired by the "induced-fit" mechanism of enzymes, a strategy of self-adaptive active sites modulation using flexible conjugated polymers engineered with nonplanar linking units was proposed. The flexible conjugated microporous polymers facilitated a transition of O2 adsorption from Pauling-type to Yeager-type. Among the designed polymers, CMP-B4, which was constructed from 4,4'-position-coupled bipyridine units, exhibited optimal geometric matching capability for O2 activation. Specifically, upon the approach of O2, the interaction between the lone-pair electrons of nitrogen atoms in flexible bipyridine unit and π* orbitals of O2 induced a dihedral rotation (e.g., approximately 10° in CMP-B4), playing a key role in promoting the one-step 2e- ORR pathway, thus overcoming the limitations of poor adaptability to diverse O2 adsorption modes and restricted versatility of dual-nitrogen units in the rigid nitrogen-rich polymers. Such configuration of CMP-B4 suppressed the formation of *OOH intermediates and achieved an excellent photocatalytic H2O2 production rate of 6.21 mmol g-1 h-1 under continuous-flow photocatalytic conditions over 24 h.
Constructing a donor–acceptor (D–A) structure in polymeric carbon nitride (PCN) extends the π‐conjugation for enhanced H2O2 photosynthesis, yet its impact on the excitonic effect remains underexplored. Herein, the exciton behavior and charge dynamics in D–A pairs were systematically regulated via rational donor design. Benzene derivatives (from benzene to perylene) with varied binding sites were employed to construct nine D–A models. A clear donor‐size‐activity relationship is established, revealing that the anthracene donor achieves an optimal balance between π‐extension and exciton dissociation. Guided by the density functional theory calculations, seven photocatalysts are synthesized. Therein,2‐position anthracene‐modified PCN (2‐AnCN) exhibited exceptional H2O2 production efficiency, achieving 3.3 times higher than that of the pristine PCN without any sacrificial agent. This enhancement originates from a fundamental mechanism transition from a 4e−‐dominated oxygen reduction reaction (ORR) process in PCN to a 2e−‐dominated pathway in 2‐AnCN, driven by the extended π‐delocalization and suppressed exciton binding. The system also demonstrates practical efficacy in photocatalytic bacterial inactivation and organic degradation. This work demonstrates that donor size is the key parameter governing exciton behavior, charge separation, and H2O2 production, providing a molecular‐level strategy to balance π‐extension, binding site, and exciton management for rational photocatalyst design.
Yaocheng Deng, Hao Zeng, Yu Shi et al.· Advanced Functional Material...· 0 citations
Efficient photocatalytic H2O2 production in organic polymers requires the coordinated regulation of charge separation, O2 activation, and proton delivery, yet these processes are often optimized independently. Here, we report a postsynthetic thiol–yne editing strategy that converts a passive alkynyl bridge in a donor–acceptor covalent organic polymer into a bridge-adjacent proton-responsive catalytic module. Reaction with mercaptoacetic acid transforms the original C═C linkage into a sulfur-containing unit bearing –SCH2COOH groups, thereby reshaping the local reaction environment rather than simply increasing surface polarity. The edited bridge modulates electronic communication, enhances interfacial hydrophilicity, and introduces a reversible COOH/COO– proton-transfer microenvironment under photocatalytic conditions. Combined experimental and theoretical results show that this click-programmed module promotes photogenerated charge separation, strengthens O2 adsorption and activation, facilitates proton-coupled electron transfer, and stabilizes key *OOH intermediates, directing oxygen reduction toward the selective two-electron pathway. Consequently, the edited polymer CP-COOH achieves an H2O2 production rate of 14.959 mmol g–1 h–1 under sacrificial-agent-free conditions using only water and air, representing a 118.7-fold enhancement over the parent polymer. This work establishes backbone bond editing as an effective strategy for programming local reaction fields in organic photocatalysts.
Xiaoyong Xia, Lujie Jin, Qimeng Sun et al.· ACS Catalysis· 0 citations
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