Protonated carbon nitride nanosheet supported IrO2 quantum dots for pure water splitting without sacrificial reagents

Abstract

A novel photocatalyst with protonated carbon nitride (p-C₃N₄) loaded with IrO₂ quantum dots (QDs) was fabricated via a facile hydrothermal method. Structure characterization studies (XRD, STEM, XPS, UV–vis spectra and PL spectra) revealed that the IrO₂ QDs with an average diameter of ca. 2 nm were highly dispersed and anchored to the surfaces of p-C₃N₄. The introduced IrO₂ QDs promoted the electron–hole separation efficiency of p-C₃N₄ and increased the absorbance capacity within the visible light range. The photocatalytic activity was evaluated using hydrogen and oxygen evolution from water splitting under visible light illumination. The optimum IrO₂/C₃N₄-0.6 wt% photocatalyst exhibits the highest hydrogen evolution rate of 45 μmol h⁻¹ and oxygen production rate of 20 μmol h⁻¹. Under visible light irradiation, the composite photocatalyst shows higher photocurrents, more negative onset potential and lower photoluminescence intensity compared with those of p-C₃N₄, which demonstrated that the modification of IrO₂ QDs accelerated the transformation, separation, and utilization of photoelectrons and thereby significantly improved the photocatalytic performance.