Enhancement effect of hematite nanoparticles on fermentative hydrogen production

► This is the first report on hematite nanoparticles application in dark fermentative hydrogen production. ► Addition of hematite nanoparticles can improve hydrogen yield. ► The hematite nanoparticles can affect the shape of bacteria which became longer and thinner. ► The slow release of hematite nanoparticles was discovered.