Improved performance of visible-light photocatalytic H2-production and Cr(VI) reduction by waste pigeon guano doped g-C3N4 nanosheets

In this study, waste pigeon guano (PG) was re-utilized as an ideal biomass adulterant to improve the photocatalytic activity of the pristine graphitic carbon nitride (g-C3N4). Waste PG and melamine were employed as precursors to fabricate a novel porous multielement-doped g-C3N4 (CN-PG-S) nanosheets photocatalyst via in situ thermal polycondensation coupled with thermal exfoliation strategy. The CN-PG-S owned abundant uniformly porous structures, superior conductivity, and excellent photocatalytic abilities, resulting in highly-efficient H2-production (1950 μmol g–1 h–1) and Cr(VI) reduction (99.1%) under visible light, which increased by 22.9-folds and 5.3-folds more than that of pristine g-C3N4. The non-metallic (P, S, and O) and metallic elements in CN-PG-S played a crucial role in expanding the visible-light absorption range and promoting the separation-migration of photogenerated electron-hole pairs. And the uniformly porous nanosheet structure of CN-PG-S shortens the diffusion paths of photogenerated carriers and exposes more active sites for photocatalytic reactions. This study proposed an eco-friendly resources integration strategy of waste PG to prepare excellent CN-PG-S photocatalysts for highly-efficient H2-production and Cr(VI) reduction.