Metallic TiN nanoparticles loaded on g-C3N4 for plasmon enhanced visible and NIR photocatalytic H2 evolution from water splitting

Abstract

Extending light absorption from visible to near-infrared (NIR) light regions and plasmon-induced hot electrons produced from the decay of surface plasmons of metallic nanoparticles are of significance in the photocatalytic field. Thus, the integration of plasmonic metallic nanoparticles with semiconductors for plasmon-enhanced visible and NIR light-driven photocatalytic H₂ evolution from water splitting has attracted broad interest. Herein, we report a g-C₃N₄/TiN (named CN/TiN) plasmonic nanocomposite photocatalyst constructed from graphitic carbon nitride (g-C₃N₄) and metallic plasmonic titanium nitride nanoparticles (TiN NPs). TiN NPs act as both light absorption antenna and hot electron donors for g-C₃N₄ to enhance photocatalytic H₂ evolution from water splitting under visible and NIR light regions. The transfer of hot electrons from metallic TiN to g-C₃N₄ leads to efficient charge transport and separation of photoexcited charges. The results reveal that photocatalytic activity is boosted by metallic plasmonic TiN in CN/TiN-x nanoheterostructures under visible-light (λ ≥ 420 nm) and NIR light (λ ≥ 700 nm) illumination. The maximum H₂ evolution rate of 1308.80 μmol h⁻¹ g⁻¹ is observed with a corresponding apparent quantum efficiency (AQE) of 6.50% at λ ≥ 420 nm for the optimal CN/TiN-2 sample, which is 5-fold higher than that of g-C₃N₄ (258.0 μmol h⁻¹ g⁻¹). This improved photocatalytic performance is attributed to the efficient charge transport and separation, enhanced light-absorption, and surface plasmon resonance (SPR) effect of metallic TiN NPs. Remarkably, the CN/TiN-2 nanocomposite under NIR light illumination exhibits a H₂ evolution rate of 169.20 μmol h⁻¹ g⁻¹, however, no H₂ evolution is detected over pristine g-C₃N₄ at λ ≥ 700 nm. This study provides a new concept to construct metallic plasmon-based photocatalysts for the wide-spectrum utilization of solar light in practical applications.