Surface defect-rich ceria quantum dots anchored on sulfur-doped carbon nitride nanotubes with enhanced charge separation for solar hydrogen production

Designing defect-engineered semiconductor heterojunctions can effectively promote the charge carrier separation. Herein, novel ceria (CeO2) quantum dots (QDs) decorated sulfur-doped carbon nitride nanotubes (SCN NTs) were synthesized via a thermal polycondensation coupled in situ deposition-precipitation method without use of template or surfactant. The structure and morphology studies indicate that ultrafine CeO2 QDs are well distributed inside and outside of SCN NTs offering highly dispersed active sites and a large contact interface between two components. This leads to the promoted formation of rich Ce3+ ion and oxygen vacancies as confirmed by XPS. The photocatalytic performance can be facilely modulated by the content of CeO2 QDs introduced in SCN matrix while bare CeO2 does not show activity of hydrogen production. The optimal catalyst with 10% of CeO2 loading yields a hydrogen evolution rate of 2923.8 μmol h−1 g−1 under visible light, remarkably higher than that of bare SCN and their physical mixtures. Further studies reveal that the abundant surface defects and the created 0D/1D junctions play a critical role in improving the separation and transfer of charge carriers, leading to superior solar hydrogen production and good stability.