Molten salt strategy to activate biochar for enhancing biohydrogen production

Generally, dark fermentation (DF) of hydrogen (H₂) synthesis has low H₂ production from industrial-scale plants. In this study, campus greening wastes-ginkgo leaves were used to produce molten salt-modified biochar (MSBC) and nitrogen (N₂)-atmosphere BC (NBC) in molten salt and N₂ environment at 800 °C, respectively. MSBC showed excellent properties including high specific surface area and electron transfer ability. After supplementation with MSBC, H₂ yield rose by 32.4% compared to the control group without carbon material. Electrochemical analysis revealed MSBC improved the electrochemical properties of sludge. Furthermore, MSBC optimized the microbial community structure and increased the relative abundance of dominant microbes, thus promoting H₂ production. This work provides a deep understanding of two carbons that play vital roles in increasing microbial biomass, supplementing trace element and favoring electron transfer in DF reactions. Salt recovery achieved 93.57% in molten salt carbonization, which has sustainability compared with N₂-atmosphere pyrolysis.