D-π-A mediated band engineering with directional charge separation for dual-pathway H2O2 photosynthesis

SCN-AP with a D-π-A network was synthesized via sulfur doping and pyridine grafting. • SCN-AP achieves integrated design of 1 O 2 generation and kinetic matching of ORR/WOR. • SCN-AP boosts ·O 2 - / 1 O 2 generation, with a H 2 O 2 yield of 1030 μmol g -1 within 2 h. • Antibacterial assays verify the photoactivated antibacterial potential of SCN-AP. • In-situ XPS and DRIFTS characterize photogenerated electron flow and reaction intermediates. Photocatalytic H 2 O 2 synthesis is commonly dominated by the oxygen reduction reaction (ORR), whereas simultaneously enabling water oxidation reaction (WOR) and directional charge separation through band-structure regulation remains challenging. Herein, sulfur doping and pyridine modification were integrated to construct an intramolecular donor- π -acceptor (D- π -A) network within the carbon nitride framework. The resulting electronic polarization promotes directional separation of photogenerated charge carriers and optimizes the band structure to thermodynamically enable both ORR and WOR pathways. Consequently, the as-synthesized SCN-AP photocatalyst achieves an H 2 O 2 yield of 1030 μmol g -1 within 2 h in pure water, 3.73 times that of pristine PCN, and exhibits effective antibacterial activity against clinically relevant pathogens including Acinetobacter beijerinckii and Klebsiella variicola . The in-situ electron paramagnetic resonance (EPR) spectroscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) collectively support the coexistence of ORR and WOR pathways. The ORR serves as the predominant route and involves a ·O 2 - -mediated stepwise reduction pathway together with a 1 O 2 -associated pathway, while WOR provides a complementary hole-driven contribution to H 2 O 2 formation. This work demonstrates a feasible band-engineering strategy for constructing polymeric photocatalysts with directional charge transfer and dual-pathway H 2 O 2 photosynthesis. This work demonstrates a D-π-A-mediated electronic polarization strategy that directs charge migration in carbon nitride, enabling dual-pathway H 2 O 2 photosynthesis through coupled ORR and WOR processes. Download: Download high-res image (411KB) Download: Download full-size image