{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T16:00:47Z","timestamp":1792166447533,"version":"4.4.0"},"reference-count":52,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Chem."],"abstract":"<jats:p>\n                    Photocatalytic carbon dioxide (CO\n                    <jats:sub>2<\/jats:sub>\n                    ) reduction offers a promising route for converting greenhouse gas into value-added solar fuels under mild conditions. However, the rational regulation of product selectivity, especially the directional conversion of CO\n                    <jats:sub>2<\/jats:sub>\n                    toward either shallow reduction products such as carbon monoxide (CO) or deep reduction products such as methane (CH\n                    <jats:sub>4<\/jats:sub>\n                    ), remains a major challenge. In this study, two carboxyl-position isomeric covalent organic frameworks covalent organic frameworks (COFs), TpBdda and TpBdad, were constructed to investigate how subtle differences in functional-group spatial arrangement affect CO\n                    <jats:sub>2<\/jats:sub>\n                    photoreduction pathways. Although the two COFs possess similar framework compositions and overall morphologies, the different distribution of carboxyl groups leads to distinct structural features, pore environments, surface chemical properties, and photoinduced reaction behaviors. Photocatalytic CO\n                    <jats:sub>2<\/jats:sub>\n                    reduction tests show that TpBdda mainly produces CO, with a CO evolution rate of approximately 5.2\u00a0\u03bcmol\u00a0g\n                    <jats:sup>-1<\/jats:sup>\n                    h\n                    <jats:sup>-1<\/jats:sup>\n                    and nearly complete CO selectivity. In contrast, TpBdad exhibits a pronounced deep-reduction tendency, delivering CH\n                    <jats:sub>4<\/jats:sub>\n                    as the dominant product with a CH\n                    <jats:sub>4<\/jats:sub>\n                    evolution rate of approximately 1.8\u00a0\u03bcmol\u00a0g\n                    <jats:sup>-1<\/jats:sup>\n                    h\n                    <jats:sup>-1<\/jats:sup>\n                    and a CH\n                    <jats:sub>4<\/jats:sub>\n                    selectivity of about 90%.\n                    <jats:italic>In situ<\/jats:italic>\n                    diffuse reflectance infrared Fourier transform spectroscopy further reveals that TpBdda favors the formation and desorption of *CO-related intermediates, whereas TpBdad promotes the stabilization and subsequent hydrogenation of key intermediates, especially methoxy-related species, thereby facilitating CH\n                    <jats:sub>4<\/jats:sub>\n                    formation. These results demonstrate that carboxyl-group spatial arrangement can effectively modulate intermediate evolution and product selectivity in COF-based photocatalytic CO\n                    <jats:sub>2<\/jats:sub>\n                    reduction, providing a molecular-level strategy for designing selective organic photocatalysts.\n                  <\/jats:p>","DOI":"10.3389\/fchem.2026.1892359","type":"journal-article","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T05:39:24Z","timestamp":1782106764000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Position-dependent carboxyl functionalization in covalent organic frameworks for selective photocatalytic CO2 reduction"],"prefix":"10.3389","volume":"14","author":[{"given":"Jiaxin","family":"Wang","sequence":"first","affiliation":[{"name":"College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials China Three Gorges University","place":["Yichang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunqiu","family":"Han","sequence":"additional","affiliation":[{"name":"College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials China Three Gorges University","place":["Yichang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liqun","family":"Ye","sequence":"additional","affiliation":[{"name":"College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials China Three Gorges University","place":["Yichang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,22]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1344","DOI":"10.1039\/c9cs00884e","article-title":"Supramolecular design in 2D covalent organic frameworks","volume":"49","author":"Alahakoon","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"B2","doi-asserted-by":"publisher","first-page":"21438","DOI":"10.1039\/c9ra03487k","article-title":"Rational design of functionalized covalent organic frameworks and their performance towards CO2 capture","volume":"9","author":"An","year":"2019","journal-title":"RSC Adv."},{"key":"B3","doi-asserted-by":"publisher","first-page":"21","DOI":"10.1016\/0022-0728(95)04141-a","article-title":"Photocatalytic reduction of CO2 with H2O on various titanium oxide catalysts","volume":"396","author":"Anpo","year":"1995","journal-title":"J. Electroanal. Chem."},{"key":"B4","doi-asserted-by":"publisher","first-page":"767","DOI":"10.1002\/cptc.202100167","article-title":"(Photo) electrocatalytic versus heterogeneous photocatalytic carbon dioxide reduction","volume":"5","author":"Bellardita","year":"2021","journal-title":"ChemPhotoChem"},{"key":"B5","doi-asserted-by":"publisher","first-page":"523","DOI":"10.1111\/risa.14281","article-title":"Carbon dioxide emissions and environmental risks: long term and short term","volume":"45","author":"Boubaker","year":"2025","journal-title":"Risk Anal."},{"key":"B6","doi-asserted-by":"publisher","first-page":"2177","DOI":"10.1039\/c6ee00383d","article-title":"CO2 photo-reduction: insights into CO2 activation and reaction on surfaces of photocatalysts","volume":"9","author":"Chang","year":"2016","journal-title":"Energy & Environ. Sci."},{"key":"B7","doi-asserted-by":"publisher","first-page":"125499","DOI":"10.1016\/j.apcatb.2025.125499","article-title":"Cu atom pairs within covalent organic frameworks facilitate the photocatalytic reduction of CO2 to C2H6","volume":"377","author":"Chen","year":"2025","journal-title":"Appl. Catal. B-Environment Energy"},{"key":"B8","doi-asserted-by":"publisher","first-page":"2200389","DOI":"10.1002\/aenm.202200389","article-title":"Emerging strategies for CO2 photoreduction to CH4: from experimental to data-driven design","volume":"12","author":"Cheng","year":"2022","journal-title":"Adv. Energy Mater."},{"key":"B9","doi-asserted-by":"publisher","first-page":"4836","DOI":"10.1021\/acs.energyfuels.3c04591","article-title":"Research status, challenges, and future prospects of carbon dioxide reduction technology","volume":"38","author":"Dang","year":"2024","journal-title":"Energy & Fuels"},{"key":"B10","doi-asserted-by":"publisher","first-page":"12723","DOI":"10.1021\/acsnano.1c05194","article-title":"Covalent organic frameworks and supramolecular nano-synthesis","volume":"15","author":"Dey","year":"2021","journal-title":"ACS Nano"},{"key":"B11","doi-asserted-by":"publisher","first-page":"1357","DOI":"10.1039\/c9cs00911f","article-title":"Design and applications of three dimensional covalent organic frameworks","volume":"49","author":"Guan","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"B12","doi-asserted-by":"publisher","first-page":"7372","DOI":"10.1002\/anie.201207199","article-title":"Photocatalytic reduction of CO2 on TiO2 and other semiconductors","volume":"52","author":"Habisreutinger","year":"2013","journal-title":"Angew. Chem. Int. Ed."},{"key":"B13","doi-asserted-by":"publisher","first-page":"103","DOI":"10.1016\/j.cattod.2022.04.021","article-title":"Review on covalent organic frameworks and derivatives for electrochemical and photocatalytic CO2 reduction","volume":"409","author":"He","year":"2023","journal-title":"Catal. Today"},{"key":"B14","doi-asserted-by":"publisher","first-page":"123663","DOI":"10.1016\/j.apcatb.2023.123663","article-title":"Tandem catalysis for CO2 conversion to higher alcohols: a review","volume":"345","author":"He","year":"2024","journal-title":"Appl. Catal. B Environ. Energy"},{"key":"B15","doi-asserted-by":"publisher","first-page":"637","DOI":"10.1038\/277637a0","article-title":"Photoelectrocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders","volume":"277","author":"Inoue","year":"1979","journal-title":"Nature"},{"key":"B16","doi-asserted-by":"publisher","first-page":"2018","DOI":"10.1021\/acscatal.5b02694","article-title":"Theoretical study on the mechanism of photoreduction of CO2 to CH4 on the anatase TiO2(101) surface","volume":"6","author":"Ji","year":"2016","journal-title":"ACS Catal."},{"key":"B17","doi-asserted-by":"publisher","first-page":"7984","DOI":"10.1021\/acs.chemrev.9b00723","article-title":"Recent advances in carbon dioxide hydrogenation to methanol via heterogeneous catalysis","volume":"120","author":"Jiang","year":"2020","journal-title":"Chem. Rev."},{"key":"B18","doi-asserted-by":"publisher","first-page":"194","DOI":"10.1016\/j.jcou.2016.07.004","article-title":"On the general mechanism of photocatalytic reduction of CO2","volume":"16","author":"Karamian","year":"2016","journal-title":"J. CO"},{"key":"B19","doi-asserted-by":"publisher","first-page":"6579","DOI":"10.1039\/c9cs00920e","article-title":"Photocatalytic CO2 conversion: what can we learn from conventional COx hydrogenation","volume":"49","author":"Kong","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"B20","doi-asserted-by":"publisher","first-page":"486","DOI":"10.1021\/acsenergylett.9b02585","article-title":"Photoelectrochemical conversion of carbon dioxide (CO2) into fuels and value-added products","volume":"5","author":"Kumaravel","year":"2020","journal-title":"ACS Energy Lett."},{"key":"B21","doi-asserted-by":"publisher","first-page":"214835","DOI":"10.1016\/j.ccr.2022.214835","article-title":"Covalent organic framework-based catalysts for efficient CO2 utilization reactions","volume":"473","author":"Kurisingal","year":"2022","journal-title":"Coord. Chem. Rev."},{"key":"B22","doi-asserted-by":"publisher","first-page":"7485","DOI":"10.1021\/acscatal.6b02089","article-title":"Recent advances in heterogeneous photocatalytic CO2 conversion to solar fuels","volume":"6","author":"Li","year":"2016","journal-title":"ACS Catal."},{"key":"B23","doi-asserted-by":"publisher","first-page":"14549","DOI":"10.1002\/anie.201908058","article-title":"Three-phase photocatalysis for the enhanced selectivity and activity of CO2 reduction on a hydrophobic surface","volume":"58","author":"Li","year":"","journal-title":"Angew. Chem. Int. Ed."},{"key":"B24","doi-asserted-by":"publisher","first-page":"690","DOI":"10.1038\/s41560-019-0431-1","article-title":"Selective visible-light-driven photocatalytic CO2 reduction to CH4 mediated by atomically thin CuIn5S8 layers","volume":"4","author":"Li","year":"","journal-title":"Nat. Energy"},{"key":"B25","doi-asserted-by":"publisher","first-page":"4835","DOI":"10.1039\/d0cs00236d","article-title":"Function-oriented synthesis of two-dimensional covalent organic frameworks: from 3D solids to 2D sheets","volume":"49","author":"Li","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"B26","doi-asserted-by":"publisher","first-page":"214882","DOI":"10.1016\/j.ccr.2022.214882","article-title":"Covalent organic frameworks towards photocatalytic applications: design principles, achievements, and opportunities","volume":"475","author":"Liu","year":"2023","journal-title":"Coord. Chem. Rev."},{"key":"B27","doi-asserted-by":"publisher","first-page":"4486","DOI":"10.1021\/jacs.7b00452","article-title":"Isolation of Cu atoms in Pd lattice: forming highly selective sites for photocatalytic conversion of CO2 to CH4","volume":"139","author":"Long","year":"2017","journal-title":"J. Am. Chem. Soc."},{"key":"B28","doi-asserted-by":"publisher","first-page":"118856","DOI":"10.1016\/j.apcatb.2020.118856","article-title":"Assembling ultrafine TiO2 nanoparticles on UiO-66 octahedrons to promote selective photocatalytic conversion of CO2 to CH4 at a low concentration","volume":"270","author":"Ma","year":"2020","journal-title":"Appl. Catal. B Environ."},{"key":"B29","doi-asserted-by":"publisher","first-page":"8252","DOI":"10.1021\/jacs.0c00555","article-title":"Connecting microscopic structures, mesoscale assemblies, and macroscopic architectures in 3D-printed hierarchical porous covalent organic framework foams","volume":"142","author":"Mohammed","year":"2020","journal-title":"J. Am. Chem. Soc."},{"key":"B30","doi-asserted-by":"publisher","first-page":"217705","DOI":"10.1016\/j.ccr.2026.217705","article-title":"Photocatalytic carbon dioxide reduction to value-added hydrocarbons products","volume":"557","author":"Pang","year":"2026","journal-title":"Coord. Chem. Rev."},{"key":"B31","doi-asserted-by":"publisher","first-page":"1910768","DOI":"10.1002\/adfm.201910768","article-title":"Heterostructured catalysts for electrocatalytic and photocatalytic carbon dioxide reduction","volume":"30","author":"Prabhu","year":"2020","journal-title":"Adv. Funct. Mater."},{"key":"B32","doi-asserted-by":"publisher","first-page":"8063","DOI":"10.1039\/d2ma00600f","article-title":"Recent trends in covalent organic frameworks (COFs) for carbon dioxide reduction","volume":"3","author":"Sarkar","year":"2022","journal-title":"Mater. Adv."},{"key":"B33","doi-asserted-by":"publisher","first-page":"014032","DOI":"10.1088\/1748-9326\/ae2af5","article-title":"Efficacy of individual and combined terrestrial and marine carbon dioxide removal","volume":"21","author":"Sathyanadh","year":"2026","journal-title":"Environ. Res. Lett."},{"key":"B34","doi-asserted-by":"publisher","first-page":"5635","DOI":"10.1039\/c5cs00878f","article-title":"Covalent organic frameworks based on schiff-base chemistry: synthesis, properties and potential applications","volume":"45","author":"Segura","year":"2016","journal-title":"Chem. Soc. Rev."},{"key":"B35","doi-asserted-by":"publisher","first-page":"6950","DOI":"10.1039\/c7ce01647f","article-title":"CO2 adsorption and separation in covalent organic frameworks with interlayer slipping","volume":"19","author":"Sharma","year":"2017","journal-title":"CrystEngComm"},{"key":"B36","doi-asserted-by":"publisher","first-page":"1900546","DOI":"10.1002\/solr.201900546","article-title":"Photocatalytic reduction of CO2 by metal-free-based materials: recent advances and future perspective","volume":"4","author":"Shen","year":"2020","journal-title":"Sol. RRL"},{"key":"B37","doi-asserted-by":"publisher","first-page":"9450","DOI":"10.1021\/jp300122v","article-title":"Photoredox reactions and the catalytic cycle for carbon dioxide fixation and methanogenesis on metal oxides","volume":"116","author":"Shkrob","year":"2012","journal-title":"J. Phys. Chem. C"},{"key":"B38","doi-asserted-by":"publisher","first-page":"9831","DOI":"10.1039\/d2cs00727d","article-title":"Porous organic polymers for CO2 capture, separation and conversion","volume":"51","author":"Song","year":"2022","journal-title":"Chem. Soc. Rev."},{"key":"B39","doi-asserted-by":"publisher","first-page":"169","DOI":"10.1016\/s0926-3373(99)00079-x","article-title":"A screening for the photoreduction of carbon dioxide supported on metal oxide catalysts for C1-C3 selectivity","volume":"23","author":"Subrahmanyam","year":"1999","journal-title":"Appl. Catal. B Environ."},{"key":"B40","doi-asserted-by":"publisher","first-page":"734","DOI":"10.1016\/j.cclet.2018.03.017","article-title":"Photocatalytic carbon dioxide reduction by photocatalyst innovation","volume":"29","author":"Tjandra","year":"2018","journal-title":"Chin. Chem. Lett."},{"key":"B41","doi-asserted-by":"publisher","first-page":"101029","DOI":"10.1016\/j.coche.2024.101029","article-title":"Present achievements and future directions of advanced carbon dioxide reduction strategies","volume":"45","author":"Vadivel","year":"2024","journal-title":"Curr. Opin. Chem. Eng."},{"key":"B42","doi-asserted-by":"publisher","first-page":"1901825","DOI":"10.1002\/adfm.201901825","article-title":"Critical aspects and recent advances in structural engineering of photocatalysts for sunlight-driven photocatalytic reduction of CO2 into fuels","volume":"29","author":"Vu","year":"2019","journal-title":"Adv. Funct. Mater."},{"key":"B43","doi-asserted-by":"publisher","first-page":"3053","DOI":"10.1021\/acs.accounts.5b00369","article-title":"Chemistry of covalent organic frameworks","volume":"48","author":"Waller","year":"2015","journal-title":"Accounts Chem. Res."},{"key":"B44","doi-asserted-by":"publisher","first-page":"8366","DOI":"10.1039\/c8ta01309h","article-title":"Photoreduction of carbon dioxide of atmospheric concentration to methane with water over CoAl-layered double hydroxide nanosheets","volume":"6","author":"Wang","year":"2018","journal-title":"J. of Mater. Chem. A"},{"key":"B45","doi-asserted-by":"publisher","first-page":"708","DOI":"10.1039\/c9cs00827f","article-title":"Covalent organic frameworks for separation applications","volume":"49","author":"Wang","year":"2020","journal-title":"Chem. Soc. Rev."},{"key":"B46","doi-asserted-by":"publisher","first-page":"115754","DOI":"10.1016\/j.rser.2025.115754","article-title":"Tailoring the structural design of covalent organic frameworks for enhanced photocatalytic carbon dioxide reduction: a review","volume":"217","author":"Wang","year":"2025","journal-title":"Renew. & Sustain. Energy Rev."},{"key":"B47","doi-asserted-by":"publisher","first-page":"35","DOI":"10.1039\/c5cc07613g","article-title":"Photocatalytic and photoelectrocatalytic reduction of CO2 using heterogeneous catalysts with controlled nanostructures","volume":"52","author":"Xie","year":"2016","journal-title":"Chem. Commun."},{"key":"B48","doi-asserted-by":"publisher","first-page":"6657","DOI":"10.1021\/acsaem.8b01345","article-title":"Photocatalysis: from fundamental principles to materials and applications","volume":"1","author":"Yang","year":"2018","journal-title":"ACS Appl. Energy Mater."},{"key":"B49","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/j.jcat.2011.08.005","article-title":"Mechanistic study of hydrocarbon formation in photocatalytic CO2 reduction over Ti-SBA-15","volume":"284","author":"Yang","year":"2011","journal-title":"J. Catal."},{"key":"B50","doi-asserted-by":"publisher","first-page":"119174","DOI":"10.1016\/j.apcatb.2020.119174","article-title":"Covalent organic frameworks for photocatalytic applications","volume":"276","author":"Yang","year":"2020","journal-title":"Appl. Catal. B Environ."},{"key":"B51","doi-asserted-by":"publisher","first-page":"21804","DOI":"10.1021\/acsnano.4c06783","article-title":"Covalent organic frameworks for photocatalytic reduction of carbon dioxide: a review","volume":"33","author":"Yang","year":"2024","journal-title":"ACS Nano"},{"key":"B52","doi-asserted-by":"publisher","first-page":"216167","DOI":"10.1016\/j.ccr.2024.216167","article-title":"A review on the advancements in covalent organic frameworks for photocatalytic reduction of carbon dioxide","volume":"521","author":"Yeo","year":"2024","journal-title":"Coord. Chem. Rev."}],"container-title":["Frontiers in Chemistry"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fchem.2026.1892359\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T05:39:25Z","timestamp":1782106765000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fchem.2026.1892359\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,22]]},"references-count":52,"alternative-id":["10.3389\/fchem.2026.1892359"],"URL":"https:\/\/doi.org\/10.3389\/fchem.2026.1892359","relation":{},"ISSN":["2296-2646"],"issn-type":[{"value":"2296-2646","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,22]]},"article-number":"1892359"}}