Enhanced biohydrogen production with low graphene oxide content using thermophilic bioreactors.

• Graphene oxide supplement yield 73% pure biohydrogen with 85% conversion efficiency. • Graphene oxide (GO) supplement resulted in 297% higher biohydrogen yield. • Acetate fermentation pathway of H 2 production was retained by GO systems. • Optimal GO levels were identified for thermophilic biohydrogen systems. • Biodiversity and microbial community biodynamics were evaluated. Modern society envisions hydrogen (H 2) fuel to drive the transportation, industrial, and domestic sectors. Here, we explore use of graphene oxide nanoparticles (GO NPs) for greatly enhancing bio-H 2 production by a consortium based on Thermoanaerobacterium thermosaccharolyticum spp. Thermophilic batch bioreactors were set up at 60 OC and initial pH of 8.5 to assess the effects of GO NPs supplements on biohydrogen production. Under optimal GO NPs loading of 10 mg/L, the supplemented system yielded ∼ 300% higher H 2 yield (6.78 mol H 2 /mol sucrose) than control. Such an optimized system offered 73% H 2 purity and 85% conversion efficiency by promoted the desirable acetate fermentation pathway. Miseq Illumina sequencing tests revealed that the optimal levels of GO NPs did not alter the microbial composition of consortium. [ABSTRACT FROM AUTHOR]