Crystalline-amorphous interface enabled electron spin polarization in hierarchical porous carbon nitride nanotubes for enhanced simultaneous photocatalytic H2 evolution and emerging contaminant degradation

A hierarchical porous S-doped g-C 3 N 4 nanotube with crystalline-amorphous interfaces is successfully constructed. • The catalyst achieves simultaneous H 2 evolution (7796 μmol g −1 ) and nearly 100% tetracycline removal within 60 min. • Directional charge transport pathways are established to efficiently suppress electron–hole recombination. • Crystalline-amorphous interface induces electron spin polarization, boosting reactive oxygen species generation. • The system exhibits excellent stability and promising potential for real wastewater treatment. Photocatalytic hydrogen evolution and environmental remediation are hindered by sluggish reaction kinetics and rapid charge recombination. Herein, we construct hierarchical porous S-doped g-C 3 N 4 nanotubes featuring abundant crystalline-amorphous interfaces (CA-SCN). The porous nanotube architecture provides more active sites and facilitates reactant diffusion. Notably, the crystalline poly(heptazine imide) phase at the interface acts as an electron donor, directionally injecting unpaired electrons into the amorphous melon domain, creating a charge transport pathway and inducing electron spin polarization, which effectively stabilizes charge separation. As a result, CA-SCN simultaneously achieves nearly 100% tetracycline removal and a high hydrogen yield (7796 μmol g −1 ) within 60 min under visible light, along with excellent stability and broad applicability in real water matrices. Mechanistic studies identify photogenerated holes as key reactive species for pollutant removal, with •O 2 - and •OH also involved. Furthermore, interface-induced electron spin polarization is accompanied by an upshift of the p-band center, optimizing H* adsorption free energy to accelerate hydrogen evolution kinetics, promoting the accumulation of photogenerated holes and the formation of •O 2 - and •OH to enhance contaminant degradation. This study underscores the critical role of interface-induced spin polarization in achieving efficient dual-functional photocatalysis. Download: Download high-res image (179KB) Download: Download full-size image