A NEW STRATEGY FOR THE SYNTHESIS OF HIGHLY ACTIVE CATALYSTS BASED ON <i>g-</i>C₃N₄ FOR THE PHOTOCATALYTIC PRODUCTION OF HYDROGEN UNDER VISIBLE LIGHT

Abstract

In this work, materials based on graphite-like carbon nitride were synthesized by thermal treatment of a mixture of melamine and urea and the effect of synthesis conditions on the photocatalytic activity of the samples was studied. As a cocatalyst, platinum (1 wt. %) was deposited on the surface of the synthesized g‑C3N4 samples. The photocatalysts were characterized by X-ray phase analysis, diffuse reflectance UV-vis spectro-scopy in the UV and visible range, and low-temperature nitrogen adsorption. Photocatalytic activity was determined in the reaction of hydrogen evolution from an aqueous solution of triethanolamine (10 vol. %) under visible light irradiation (λ = 425 nm). The optimal conditions for the synthesis of the photocatalyst 1% Pt/g-C3N4, obtained by calcination of a mixture of melamine and urea (1 : 3), were found, using which the rate of H2 evolution was 5.0 mmol g–1 h–1 with an apparent quantum efficiency of 2.5%. The developed synthetic approach makes it possible to obtain highly active catalysts due to the formation of an intermediate supramolecular melamine-cyanuric acid complex during the synthesis, which, upon further heating, turns into g-C3N4, which is characterized by a high specific surface area exceeding 100 m2 g–1.