A facile method for preparing porous g-C.sub.3N.sub.4 nanosheets with efficient photocatalytic activity under visible light

g-C.sub.3N.sub.4 nanosheets with porous structures (labelled PGN) were prepared by an extremely facile one-step, template-free method. The method used to prepare porous g-C.sub.3N.sub.4 nanosheets in this research was thermal polycondensation of urea pre-treated with ethanol. These nanosheets were compared with g-C.sub.3N.sub.4 agglomerates (labelled BG) prepared with raw urea. The pre-treatment process did not change the crystal structure of urea but changed the thermal polymerization process of urea to form g-C.sub.3N.sub.4. The change in the thermal polymerization process resulted in the formation of porous g-C.sub.3N.sub.4 nanosheets. The as-prepared PGN photocatalyst has an enlarged surface area of 66.0 m.sup.2 g.sup.-1 and a pore volume of 0.357 cm.sup.3 g.sup.-1, leading to enhanced visible light photocatalytic efficiency. The photocatalytic activity of g-C.sub.3N.sub.4 was evaluated by the photodegradation experiments with methylene blue (MB). The results indicated that PGN exhibited high and stable photocatalytic activity. The effective separation and transmission of photogenerated electron-hole pairs caused by precursor (urea) pre-treatment as well as the large BET surface area are associated with the enhanced photocatalytic activity of PGN.