The supplementary materials for the article "Ultrathin covalent organic framework nanosheets for enhanced photocatalytic water oxidation" by Enbo Zhou et al. include a detailed computational study and experimental data. The computational section outlines the methods used to optimize the crystal structure of CoTPP-Bpy using Materials Studio, and to perform photocatalytic calculations with Vienna Ab-initio Simulation Package (VASP). The TOF (time-on-gas) values for CoTPP-CoBpy₃ are calculated based on the amount of Co loaded and the amount of O₂ produced. Experimental data includes various characterization techniques such as XRD, PXRD, EDS-HAADF, BET surface area, FTIR, UV-vis absorbance, and cryo-TEM images. The supplementary materials also provide detailed tables and figures comparing the performance of CoTPP-CoBpy₃ with other photocatalysts, as well as references to relevant literature. Additionally, a movie of contact angle measurement is included.The supplementary materials for the article "Ultrathin covalent organic framework nanosheets for enhanced photocatalytic water oxidation" by Enbo Zhou et al. include a detailed computational study and experimental data. The computational section outlines the methods used to optimize the crystal structure of CoTPP-Bpy using Materials Studio, and to perform photocatalytic calculations with Vienna Ab-initio Simulation Package (VASP). The TOF (time-on-gas) values for CoTPP-CoBpy₃ are calculated based on the amount of Co loaded and the amount of O₂ produced. Experimental data includes various characterization techniques such as XRD, PXRD, EDS-HAADF, BET surface area, FTIR, UV-vis absorbance, and cryo-TEM images. The supplementary materials also provide detailed tables and figures comparing the performance of CoTPP-CoBpy₃ with other photocatalysts, as well as references to relevant literature. Additionally, a movie of contact angle measurement is included.