Marimo-Bead-Supported Core–Shell Nanocomposites of Titanium Nitride and Chromium-Doped Titanium Dioxide as a Highly Efficient Water-Floatable Green Photocatalyst

The release of untreated industrial wastewater creates a hazardous impact on the environment. In this regard, the development of an environmentally friendly catalyst is of paramount importance. Here, we report a highly efficient and reusable core–shell TiN/SiO2/Cr-TiO2 (TSCT) photocatalyst that is composed of SiO2-cladded titanium nitride (TiN) nanoparticles (NPs) decorated with Cr-doped TiO2 NPs for the removal of organic contaminants from water. The TiN NPs serve as the main light absorber component with excellent visible-light absorption along with Cr-TiO2 NPs. The TSCT shows remarkable improvement in the photodecomposition of methylene blue (MB) over Cr-TiO2 and TiO2 NPs. An efficient structural design is proposed by adopting calcium alginate beads (P-Marimo beads) as a transparent scaffold for supporting our TSCT, which floats nature on the water surface and realizes easy handling as well as excellent reusability for multipurpose water purification. Surprisingly, our TSCT is found to keep its catalytic activity even after the illumination is turned off. Our proposed P-Marimo-encapsulated TSCT can be utilized as an excellent green photocatalyst with high photocatalytic performance, good recyclability, and easy handling.