Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2SElectronic supplementary information (ESI) available: GC-MS graph of the filtrate obtained in solvothermal reaction after 16 h and FESEM images without guanidine carbonate for 16 h. See DOI: 10.1039/c3nr02975a

Nitrogen-doped TiO 2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO 2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO 2 with a thickness of ∼2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m 2 g −1 ). The N-TiO 2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H 2 S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO 2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO 2 from abundant H 2 S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides. The architectured design of N-doped TiO 2 marigold flowers for ecofriendly H 2 production from photocatalytic splitting of hazardous H 2 S under solar light.