The development of efficient, stable photocatalysts that exhibit a high response to a broad spectrum of light is a major challenge in the field of photocatalysis. In this work, Bulk and sheet-like morphologies of graphitic carbon nitride (g-C3N4) were synthesised through a thermal polymerization and thermal exfoliation processes, respectively. The materials were characterized with SEM/EDS, XRD, BET, UV–vis DRS, and FTIR. The photocatalytic efficiency for these materials was further studied by photocatalytic degradation of Naproxen (NPX). The sheet-like g-C3N4 (SCN) exhibits superior photodegradation performance for NPX (77.3 % in only 5 min, and reached 98 % in 30 min) with an apparent rate constant ‘k’ (0.31 ± 0.02 min−1), which is about 3 times higher than that of bulk g-C3N4 (0.116 ± 0.003 min−1). The improved photocatalytic performance is attributed to the higher surface area and the appearance of N vacancies, which mitigate photoinduced electron-hole recombination, leading to the generation of more active species. The photocatalytic efficiency using different irradiation sources (natural and simulated sunlight, and UVA radiation at 365 nm) was investigated. Finally, reusability tests of SCN demonstrate an outstanding stability (four cycles) and an excellent photocatalytic performance, which further highlights its potential as a promising photocatalyst for environmental remediation applications.