Fig. 1. Schematic illustration of the impact of distinct channel microenvironments on mass and electron transfer in COF-PQ (a) and COF-DPPQ (b). (c) One-pot three-component Povarov cyclization for the synthesis of COFs. HOMO/LUMO distributions of COF-PQ (d) and COF-DPPQ (e).

Fig. 2. Experimental and simulated XRD patterns of COF-PQ (a) and COF-DPPQ (b). 13C CP/MAS NMR spectra of COF-PQ (c) and COF-DPPQ (d). TEM images of COF-PQ (e) and COF-DPPQ (f). N2 adsorption (filled symbols) and desorption (open symbols) isotherms of COF-PQ (g) and COF-DPPQ (h). NLDFT-calculated pore diameters (y axis left) and pore volumes (y axis right), and Material Studio-simulated pore diameters of COF-PQ (i) and COF-DPPQ (j) (inset images). Recycled COF-DPPQ after immersion in various solvents, characterized for chemical stability by FT-IR (k) and XRD (l).

Fig. 3. (a) UV-vis DRS spectra of COF-PQ and COF-DPPQ. Mott-Schottky plots at 1500, 2000, and 2500 Hz for VFB determination of COF-PQ (b) and COF-DPPQ (c). (d) Extracted optical band gap energies. (e) Transient photocurrent density. (f) EIS Nyquist plots. (g) PHE rates under visible-light irradiation (> 420 nm) with varying Pt co-catalyst loadings in 0.1 mol L-1 ascorbic acid. (h) Long-term test of COF-DPPQ in PHE. (i) Apparent quantum yield of COF-DPPQ measured at 420, 450, 500, 520, and 650 nm.

Fig. 4. (a) Zeta potentials of COFs at varying AA concentrations and pH values. (b) Comparison of Pt adsorption energies at representative sites. (c) Free-energy diagram of the PHE process over COF-PQ and COF-DPPQ. Calculated Heyd-Scuseria-Ernzerhof electronic band structures of COF-PQ (d) and COF-DPPQ (e). Schematic of electron and hole effective masses at specific active sites for COF-PQ (f) and COF-DPPQ (g). Bader charge analysis of intralayer electron transfer in COF-PQ (h) and COF-DPPQ (i).

Fig. 5. Excited-state electron-hole distributions and ultrafast dynamics. TD-DFT calculated electron (red) and hole (blue) dispersions for COF-PQ (a) and COF-DPPQ (b). 2D mapping TA spectra of COF-PQ (c) and COF-DPPQ (d). TA spectra at selected delay times under 450?nm pump for COF-PQ (e) and COF-DPPQ (f). Kinetic decay traces at 650 nm for COF-PQ (g) and COF-DPPQ (h).

Fig. 6. MD simulations of proton and water transport. (a) Snapshots of H2O and proton distributions on COF-PQ and COF-DPPQ models under simulated liquid diffusion conditions. Purple, gray, black spheres represent protons, H2O molecules, COF skeleton, respectively. Relative concentration profiles of protons and H2O along the z-axis for COF-PQ (b) and COF-DPPQ (c). (d) Schematic of the sandwich structure, with outer layers of water and protons and an inner layer of three COF layers. (e) Comparison of proton diffusion coefficients. RDF for COF-PQ (f) and COF-DPPQ (g).