Improving effect of metal and oxide nanoparticles encapsulated in porous silica on fermentative biohydrogen production by Clostridium butyricum

► Encapsulated nanoparticles (NP) were tested for biohydrogen production improvement. ► Pd, Ag, Fe and Cu NP were added in Clostridium butyricum BHP tests. ► Fe NP showed an improvement of the hydrogen volume and rate of production. ► In pH controlled AnSBR, Fe NP showed +113% of hydrogen production rates. ► NP addition had no effect on the yields and metabolic pathway.