Solar and visible light photocatalytic enhancement of halloysite nanotubes/g-C3N4 heteroarchitectures

Novel heteroarchitectures made of graphitic carbon nitride (g-C3N4) and halloysite nanotubes (HNTs) were prepared by a facile and soft self-assembly strategy. The morphological, structural and electronic properties of the HNTs/g-C3N4 nanocomposites were determined by means of a plethora of techniques including N-2 physisorption, XRD, FT-IR, TEM, UV-Vis absorption, XPS, zeta potential and photoluminescence (PL). Their photocatalytic activity was evaluated under both simulated solar light and pure visible light irradiation against the photodegradation of neutral, positively and negatively charged pollutants, namely phenol, methylene blue (MB) and methyl orange (MO), respectively. The prepared HNTs/g-C3N4 nanocomposites were proven to be durable and significantly more efficient than the pure g-C3N4 reference for the degradation of positively charged and neutral organics. The nanocomposites presented increased charge carrier formation and reduced recombination rates due to the tight contact between the two components. The enhanced photoactivity was attributed to the dual function of HNTs enhancing (a) the abundance and stability of the photogenerated e(-) and h(+) pairs and (b) the adsorption of positively charged organics on the nanocomposite. Both functions originate from the charged surface of HNTs.