Visible-light photocatalytic activity enhancement of red phosphorus dispersed on the exfoliated kaolin for pollutant degradation and hydrogen evolution

The semiconductor photocatalyst is crucial for dealing with the current environmental and energy crises. However, the large-scale applications of the reported semiconductor materials are hampered by the recombination of electrons and holes, low kinetic properties, and slow reaction rates. Herein, a three-dimensional structured kaolin/hydrothermally treated red phosphorus (K/HRP) composite photocatalyst was synthesized. The composition ratio was optimized, and the K₇/HRP composites (contained 7%) exhibited the highest photocatalytic activity. The rhodamine B photodegradation rate constant and the hydrogen production rate were 0.25 min^-1 and 252 μmol h^-1 g^-1, which were higher than those of HRP by 12.4 and 7.2 times, respectively. The enhancement of the HRP photocatalytic activity was attributed to the presence of K, which inhibited the overgrowth and the agglomeration of HRP and shortened the carrier migration distance. The electrostatic interaction between the K and the HRP effectively promoted the separation of photogenerated charge carriers. In addition, the three-dimensional structure of the K and the HRP construct enhanced the light absorption and provided a pollution-free and large-area transport interface for carriers. This work has paramount guiding importance in the preparation of high-efficiency, cheap, and recyclable nanocomposite photocatalyst materials.