The development of efficient, low-cost photocatalysts for solar-driven hydrogen production remains a critical challenge in renewable energy research. In this context, polymeric carbon nitride (g-C3N4) has attracted extensive attention due to its favorable band structure, environmental stability, and facile synthesis. However, intrinsic limitations such as narrow visible-light absorption range and rapid charge recombination severely hinder its practical performance. To overcome these drawbacks, this study presents a novel approach to constructing intramolecular donor-acceptor (D-A) conjugated copolymers by integrating 3,7-dihydroxydibenzo[b,d]thiophene 5,5-dioxide (SO) into the g-C3N4 framework via a high-temperature nucleophilic substitution and condensation reaction. The resulting CNSO-X series of materials are systematically investigated to elucidate their structural, optical, and electronic properties.
Structural characterization using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and solid-state ¹³C NMR confirms the successful incorporation of SO units into the g-C3N4 matrix. The presence of characteristic sulfone group vibrations at ~1288 cm⁻¹ and ~1145 cm⁻¹ in FTIR spectra, along with new peaks at 128 ppm and 119 ppm in ¹³C NMR, provides direct evidence of SO integration. XPS analysis reveals a higher C/N ratio and the emergence of S 2p and O 1s signals corresponding to the dibenzothiophene-S,S-dioxide moiety, further supporting the molecular design.PDGFA Antibody References The crystal structure remains largely intact at low SO loading but shows progressive distortion at higher concentrations, indicating structural flexibility during copolymerization.
UV-Vis diffuse reflectance spectroscopy demonstrates a significant red-shift in absorption onset from ~460 nm in pristine CN to over 800 nm in CNSO-20, accompanied by a pronounced “shoulder” feature in the visible region. This enhancement is attributed to the formation of an intramolecular charge transfer pathway from electron-rich nitrogen atoms (donor) to the electron-deficient SO unit (acceptor).ATPB Antibody Epigenetics Tauc plot analysis yields a reduced band gap of 2.18 eV for CNSO-20, compared to 2.72 eV for CN, enabling broader solar spectrum utilization. The conduction band edge shifts from −0.88 V to −0.37 V (vs. NHE), while the valence band remains nearly unchanged, favoring thermodynamic driving force for hydrogen evolution.
Photocatalytic evaluation under visible light irradiation (λ ≥ 420 nm) reveals that CNSO-20 achieves a remarkable hydrogen evolution rate of 251 mmol h⁻¹ per 50 mg catalyst—approximately 8.5 times higher than pure g-C3N4. The apparent quantum yield at 420 nm reaches 10.16%, among the highest reported for organic-based g-C3N4 systems. This performance enhancement is attributed to three synergistic factors: (1) extended visible-light absorption; (2) efficient spatial separation of photogenerated charge carriers, confirmed by quenched photoluminescence and enhanced transient photocurrent; and (3) improved interfacial wettability due to the hydrophilic nature of the sulfone group.PMID:34881800 Electrochemical impedance spectroscopy indicates a significantly reduced charge transfer resistance in CNSO-20, confirming faster electron transport kinetics.
Density functional theory (DFT) calculations provide mechanistic insights into the enhanced activity. The calculated adsorption energy of H* on CNSO-20 is substantially lower than on CN, reducing the activation barrier for hydrogen formation. Bader charge analysis reveals a net charge transfer of 0.964e from the g-C3N4 backbone to the SO acceptor, confirming effective intramolecular charge separation. A proposed photocatalytic mechanism illustrates how the D-A architecture facilitates directional electron flow toward Pt co-catalyst sites, while holes migrate to the surface to oxidize triethanolamine.
This work establishes a robust and scalable strategy for engineering high-performance metal-free photocatalysts through rational molecular design. By leveraging the unique electronic properties of dibenzothiophene dioxide within a g-C3N4 framework, it opens new avenues for developing advanced D-A conjugated polymers with tailored optoelectronic features for sustainable hydrogen production.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com