Abstract <p>In order to expand the range of inexpensive and non-toxic inorganic materials used in photocatalysis, a comparative characterization of solid (β-) and graphitic (g-) modifications of carbon nitride is presented. Urea was used as a precursor. β-C₃N₄ was obtained using underwater pulsed plasma, and g-C₃N₄ was synthesized by a traditional pyrolysis. The structure, morphology, and surface chemical composition of the obtained materials were studied using X-ray phase analysis, infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The band structure of the solid modification of carbon nitride was calculated using the DFT method. Photocatalytic characteristics were studied by examining the decomposition of three dyes in a mixture under UV and visible light irradiation. It was found that the photocatalytic activity of the samples is determined by their structural characteristics, specifically the modification type and the band gap.</p>