Ultrathin g-C3N4 nanosheets with hexagonal CuS nanoplates as a novel composite photocatalyst under solar light irradiation for H2 production

Abstract

Using photocatalysts and solar energy to split water into hydrogen is an ideal energy source, hereto, a novel hybrid multifunctional g-C₃N₄–CuS nanocomposite photocatalyst was synthesized for H₂ evolution by integrating g-C₃N₄ nanosheets with hexagonal CuS nanoplates via a facile hydrothermal method at room temperature. The ultrathin large surface area g-C₃N₄ nanosheets were prepared by a “green” liquid exfoliation route from bulk g-C₃N₄ in isopropanol. Different nanostructural g-C₃N₄ materials were compared and the results confirmed that the g-C₃N₄ nanosheet had better hydrogen evolution than the bulk material under solar irradiation due to its larger surface area and higher light absorption efficiency. Furthermore, given the improved charge separation efficiency, the novel nanocomposite g-C₃N₄–CuS-1 demonstrated a much better hydrogen evolution rate (126.5 μmol h⁻¹) than the pure g-C₃N₄ nanosheet under solar light. Its performance is also superior to that of other semiconductor modified g-C₃N₄ materials, making it a promising photocatalyst for future hydrogen generation application. The optical properties, crystal phase and morphology of the obtained composites were characterized systematically using various analytical methods. It was concluded that O²˙⁻ was the dominant radical for hydrogen evolution through photoluminescence (PL) and electron paramagnetic resonance (EPR) analysis.