Photocatalytic hydrogen production of Co(OH)2 nanoparticle-coated   {\alpha}-Fe2O3 nanorings
  The production of hydrogen from water using only a catalyst and solar energy is one of the most challenging and promising outlets for the generation of clean and renewable energy. Semiconductor photocatalysts for solar hydrogen production by water photolysis must employ stable, non-toxic, abundant and inexpensive visible-light absorbers capable of harvesting light photons with adequate potential to reduce water. Here, we show that a-Fe2O3 can meet these requirements by means of using hydrothermally prepared nanorings. These iron oxide nanoring photocatalysts proved capable of producing hydrogen efficiently without application of an external bias. In addition, Co(OH)2 nanoparticles were shown to be efficient co-catalysts on the nanoring surface by improving the efficiency of hydrogen generation. Both nanoparticle-coated and uncoated nanorings displayed superior photocatalytic activity for hydrogen evolution when compared with TiO2 nanoparticles, showing themselves to be promising materials for water-splitting using only solar light. 
Heberton Wender, Renato V. Gon\c{c}alves, Carlos Sato B. Dias,   Maximiliano J. M. Zapata, Luiz F. Zagonel, Edielma C. Mendo...
cond-mat.mes-hall cond-mat.mtrl-sci