“…ZnO-g-C 3 N 4 and ZnO-g-C 3 N 4 /GO also exhibited several peaks in the 650-1200 cm -1 range; these are attributed to g-C 3 N 4 [35]. Specifically, the peaks at 1210, 1235, and 1318 cm -1 were assigned to CN stretching vibrations, while those at 1406, 1450, 1560, 1638 cm -1 are likely due to heptazine-derived repeating units, as previously reported [36]. In addition, the broad band at around 3100-3400 cm -1 is assigned to the -NH moieties, as well as to the adsorbed hydroxyl groups of H 2 O.…”