Efficient synergy of photocatalysis and adsorption of hexavalent chromium and rhodamine B over Al4SiC4/rGO hybrid photocatalyst under visible-light irradiation

A novel visible-light-driven Al4SiC4/rGO hybrid photocatalyst was fabricated using carbothermic reduction and hydrothermal methods. The as-prepared samples were characterized using various techniques and different factors during the photocatalytic reaction were well optimized. Compared with the commonly used photocatalysts, e.g. TiO2 (P25), g-C3N4, etc. the Al4SiC4/rGO hybrid not only exhibits super photocatalytic activity in the mixed system containing Cr(VI) and rhodamine B (RhB) but also can degrade different kinds of dyes selectively by modifying surface charge. For the degradation mechanism, there are two stages. The first is the high adsorption capacity owing to surface positive charge on Al4SiC4. The second is the active species including photo-electron (e(-)) and photo-hole (h(+)), which can promote the photocatalytic removal of Cr(VI) and RhB, respectively. In addition, rGO can improve the whole photocatalytic performance via rapid separation and transportation of photoinduced carriers. Furthermore, the cyclic and long-term experiments indicate great reusability and stability of the Al4SiC4/rGO hybrid.