> ## Content Index > Fetch the complete content index at: https://research-pop.com/llms.txt > Use this file to discover other available public pages before exploring further. # Taiyuan team uses regional isomerisation to orient COF polarisation for O₂ photoactivation - URL: https://research-pop.com/taiyuan-team-uses-regional-isomerisation-to-orient-cof-polarisation-for-o2-photoactivation/ - Published: 2026-09-28T13:30:09.000Z - Updated: 2026-09-28T13:37:35.000Z - Author: ResearchPOP ![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/Screenshot-2026-09-28-at-15.14.44.png) Source: [https://onlinelibrary.wiley.com/doi/10.1002/anie.2540246](https://onlinelibrary.wiley.com/doi/10.1002/anie.2540246?ref=research-pop.com) ## At a glance Researchers at Taiyuan University of Technology created three regioisomeric thiophene covalent organic frameworks to examine how connection position changes dipole alignment, charge dynamics and oxygen reduction. Among BTDA-, DTDA- and TTDA-TAPT-COF, TTDA had the largest calculated dipole moment and the highest photocatalytic H₂O₂ production rate. Under air and the reported reaction conditions, TTDA produced H₂O₂ at 3,218 μmol h⁻¹ g⁻¹. This rate was 2.28 times that of DTDA and 5.36 times that of BTDA. TTDA also reached a solar-to-chemical conversion efficiency of 0.68%, compared with 0.22% and 0.18% for the other two frameworks. Spectroscopy, reactive-species experiments and calculations connect this performance with aligned local dipoles, longer-lived charge separation and an oxygen adsorption geometry involving neighbouring sulfur atoms. The authors use the combined evidence to propose a direct one-step, two-electron oxygen-reduction pathway in TTDA. ## Background Covalent organic frameworks are crystalline porous solids assembled from molecular building units joined by covalent bonds. Because the organic units and their connection positions can be selected before synthesis, COFs offer control over pore size, functional groups, electronic structure and the chemical environment along the pore walls. For photocatalysis, absorbing light is only the first step. Excitation creates electrons and holes that must separate, move through the framework and reach reactants before recombining. Internal electric fields and polar molecular environments can help direct this movement. If local bond dipoles cancel because they point in opposing directions, the overall polarisation remains small. If they align, their collective electrostatic effect can influence charge separation and molecular adsorption. Hydrogen peroxide can be produced by reducing O₂ with two electrons and two protons. This chemistry may proceed through a stepwise route involving superoxide, O₂•⁻, or through a more direct two-electron pathway in which the O–O bond remains intact as oxygen is converted towards H₂O₂. The adsorption geometry matters because it determines how oxygen interacts with catalytic atoms and how electrons and protons reach the bound molecule. The present study uses regional isomerisation as the design variable. The related thiophene building units retain a similar elemental composition but connect through different positions. Those positional changes reorganize sulfur atoms, pore-wall shape and the direction of local dipoles without requiring an entirely different chemical platform. ## Research question Can regional isomerisation induce orientation polarisation in thiophene COFs, extend charge separation, change oxygen adsorption and favour a more direct pathway for photocatalytic H₂O₂ production? ## Inside the study ![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/image-35.png) The team synthesized BTDA-, DTDA- and TTDA-TAPT-COF as a three-material comparison. Their calculated dipole moments were 0.00, 0.14 and 5.45 D, respectively. The large value for TTDA arises from the way its connection pattern aligns local dipoles rather than allowing them to cancel. Neighbouring sulfur atoms also produce concave–convex pore walls, creating an electrostatic and geometric environment distinct from the other regioisomers. Diffraction measurements supported related hexagonal framework structures across the series. High-resolution transmission electron microscopy gave (100) fringe spacings of 3.5 nm for BTDA, 3.4 nm for DTDA and 3.2 nm for TTDA. The corresponding pore sizes were 3.6, 3.4 and 2.9 nm. The surface-area trend moved in the opposite direction from the photocatalytic activity. BET surface areas decreased from 1,541 m² g⁻¹ for BTDA to 1,231 m² g⁻¹ for DTDA and 686 m² g⁻¹ for TTDA. TTDA did not produce the most H₂O₂ simply by offering the largest measured surface area. This comparison directs attention towards polarisation, charge behaviour and the local oxygen-binding environment. Kelvin probe force microscopy measured a surface-potential difference of 44 mV for TTDA, providing experimental evidence of its polar surface environment. The three frameworks also showed different excited-state dynamics. Time-resolved photoluminescence lifetimes increased from 0.34 ns for BTDA and 0.48 ns for DTDA to 0.94 ns for TTDA. Femtosecond transient absorption measurements further supported a longer-lived charge-separated state in TTDA. Taken together, these measurements are consistent with the authors' proposal that orientation polarisation helps retain photogenerated charges long enough for interfacial oxygen chemistry. The evidence links the regioisomeric structure with charge dynamics rather than relying on the calculated dipole moment alone. The photocatalytic tests then place those differences beside H₂O₂ production. Under air and the conditions reported in the article, TTDA reached 3,218 μmol h⁻¹ g⁻¹. Its solar-to-chemical conversion efficiency was 0.68%, while BTDA and DTDA reached 0.18% and 0.22%. These efficiency and production-rate values describe related but distinct measures of light-to-chemical performance. The authors also examined whether the peroxide remained stable during illumination. More than 96% of H₂O₂ remained after one hour of continuous light exposure under the reported test conditions. TTDA completed ten production cycles, adding a repeated-use comparison to the initial activity measurement. Reactive-species experiments were used to distinguish how oxygen reaches peroxide. Electron paramagnetic resonance and scavenger tests supported a direct one-step, two-electron oxygen-reduction route for TTDA. BTDA and DTDA were instead assigned a two-step pathway involving superoxide. These pathway assignments combine several indirect measurements and do not represent direct observation of every elementary reaction step. Calculations provide a structural explanation for the difference. In TTDA, oxygen can adsorb across neighbouring sulfur atoms in a Yeager-type configuration. The other environments favour a single-sulfur Pauling-type interaction. Binding across two adjacent atoms changes the electronic contact with O₂ and provides a geometry consistent with retaining the O–O bond during two-electron reduction. In situ diffuse-reflectance infrared spectroscopy detected a signal assigned to a 1,4-endoperoxide intermediate together with a weaker ∗OOH feature. The relative signals, adjacent-sulfur geometry and reactive-species tests are brought together in the proposed TTDA pathway. The mechanism remains the authors' interpretation of mutually supporting spectroscopic, chemical and computational evidence. The study finally moved beyond a closed batch measurement. In continuous flow, the H₂O₂ concentration remained near 125 μM for 10 h. Outdoor production followed changes in natural sunlight, showing how the reaction responded outside a constant simulated-light environment. An antibacterial experiment with *Escherichia coli* provided an additional demonstration using the generated peroxide. ## Takeaways and outlook The work connects a positional change in a molecular building block with several levels of photocatalytic behaviour. Regional isomerisation changes the pore-wall geometry and alignment of local dipoles. The resulting orientation polarisation accompanies longer-lived charge separation, while adjacent sulfur atoms provide a different oxygen adsorption configuration. Within this three-material series, the COF with the strongest calculated dipole and measured surface-potential response also delivers the highest H₂O₂ production rate and solar-to-chemical efficiency, despite having the lowest BET surface area. The comparison supports the authors' emphasis on electronic organization and adsorption geometry rather than surface area alone. The study presents regional isomerisation as a way to tune photocatalytic COFs while retaining a related elemental and framework platform. Further work can examine how broadly this connection between dipole alignment, multisite oxygen adsorption and reaction-path selection applies across other linkages, pore environments and photocatalytic transformations. ## About the researchers Yang Deng and Jingping Lu (Taiyuan University of Technology) are equal first authors. Yang Deng and Xu Wu (Taiyuan University of Technology) are the corresponding authors. Zhinan Xia, Ruijuan Bian, Pengfei Li, Chunhuang Fan and Nianbo Zhang are also affiliated with Taiyuan University of Technology. ## Original research Yang Deng; Jingping Lu; Zhinan Xia; Ruijuan Bian; Pengfei Li; Chunhuang Fan; Nianbo Zhang; Xu Wu. “Inducing Orientation Polarisation via Regional Isomerisation in Covalent Organic Frameworks for Enhanced O₂ Photoactivation.” *Angewandte Chemie International Edition* (2026). [https://doi.org/10.1002/anie.2540246](https://doi.org/10.1002/anie.2540246?ref=research-pop.com). --- ## Research POP Notes This article reflects the independent interpretation of the Research POP team and does not represent the views of the authors, their institutions or the journal. If you identify any inaccuracies or have concerns regarding the content, figures or attribution, please contact us at [team.researchpop@gmail.com](mailto:team.researchpop@gmail.com). We will review the matter promptly and make corrections or remove the relevant material where appropriate.