Black Titania with Nanoscale Helicity

Abstract The fabrication of mesoporous black titanium dioxide (TiO 2− x ) with a chiral nematic organization of core–shell nanorods is reported. Chiral templating of TiO 2 nanoparticles onto gelatin‐functionalized cellulose nanocrystals (CNCs) followed by calcination yields carbonized TiO 2 /CNC helical materials that recover white TiO 2 replicas after carbon removal. The hydrothermal surface reduction of the traditional white TiO 2 by ascorbic acid affords freestanding chiral nematic black TiO 2− x . The black TiO 2− x is a visible light active semiconducting mesoporous structure constructed by chiral nematic crystalline–amorphous TiO 2 core–shell nanorods. The chiral black TiO 2− x nanoparticles supported on mesoporous nanocarbon networks are evaluated as lithium‐ion battery anode electrodes. Beyond the current efforts, these black TiO 2− x materials and their composites may be useful in the fields of energy storage and catalysis.