Freely standing MgAl-layered double hydroxides nanosheets and their derived metal oxides on g-C3N4 thin-layer designed for obtaining synergic effect of adsorption and photocatalysis

Organic compound contamination in water is a serious threat to the public health and other organisms on earth. Here, we report a novel hierarchical architecture of freely standing MgAl-layered double hydroxides (LDH) nanosheets on g-C3N4 nanosheets for ultrafast dye removal from water. This open hierarchical structure consisted of interlaced g-C3N4 and MgAl-LDH nanosheets, and exhibited effective adsorption-photocatalysis synergic effect and high efficient removal of anionic pollutants from water under simulated sunlight irradiation. The rate constant of photocatalytic degradation toward congo red (CR) was high as 0.1011 min−1, which was 3.9 time than that of g-C3N4. It was demostrated that positively charged LDH layers were in favor of the enrichment of anionic pollutants around g-C3N4, which effectively shortened diffusion distance and thus accelerated the degradation of organic pollutant. Furthermore, it was found that –OH groups on surface of LDH suppressed the recombination of photo generated electron-hole pairs by capturing photo generated holes. Moreover, •O2– was demonstrated as the main reactive species in the photocatalytic degradation process. This adsorption-photocatalysis synergic system may be a promising candidate in adsorbing, removing and oxidizing organic contaminants from water body.