Bio-inspired synthesis of TiO2 hollow nanospheres in agarose gels

► TiO2 hollow nanospheres are synthesized in agarose gels by a bio-inspired method. ► The nanospheres contain mesopores in the shell at about 3.8 and 5.5 nm in size. ► The mesopores are formed after removing agarose fibers embedded in the TiO2 shell. ► TiO2 nanospheres display a comparative photocatalytic activity to Degussa P25.