Activation of g-C3N4 by oxidative treatment for enhanced photocatalytic H2 evolution

Abstract

Graphitic carbon nitride g-C₃N₄ has attracted a scientific interest as a visible light active non-metallic photocatalyst for a H₂ evolution. Recently, the techniques aimed at oxidizing g-C₃N₄ surface have been investigated in order to improve its photocatalytic properties. The present study is devoted to the modification of g-C₃N₄ via hydrothermal treatment in aqueous H₂O₂ solution. The treatment led to partial structural decomposition and functionalization of the g-C₃N₄ surface with −C=O and –COOH groups, thereby affecting the structural, textural, and electronic properties. The platinum deposited on the surface of the pretreated g-C₃N₄ was in a special configuration with metal particles surrounded by single atoms. The platinized g-C₃N₄ treated in H₂O₂ solution at 140 °C was shown to be active in H₂ evolution from glucose aqueous solution with a reaction rate of 344 μmol H₂·h⁻¹·(g_cat)⁻¹ (λ_max = 440 nm), while Pt/g-C₃N₄ without hydrothermal treatment demonstrated no activity. Moreover, the activity of platinized g-C₃N₄ after hydrothermal treatment was improved by a factor of 9.5 and 4.3 in ethanol and triethanolamine aqueous solutions, respectively. The study presents a novel simple avenue for the synthesis of g-C₃N₄-based photocatalyst for H₂ generation from different substrates, including plant biomass components, thus expanding the scope of g-C₃N₄ applications.