Electrochemically active biofilm mediated bio-hydrogen production catalyzed by positively charged gold nanoparticles

An electrochemically active biofilm (EAB) was used for the synthesis of positively charged gold nanoparticles [(+)AuNPs] and in-situ hydrogen production without any external energy input. The EAB generate electrons and protons by decomposing sodium acetate (carbon source) in water at 30 °C. These electrons were used initially to reduce Au3+ to Au0, and later in-situ, these generated electrons and protons were used for hydrogen production. The as-synthesized (+)AuNPs acted as catalyst by providing a charged surface to reduce the protons, leading to the formation of molecular hydrogen according to the Volmer-Heyrovsky mechanism. The hydrogen produced was confirmed and estimated by gas chromatography and a fuel cell test, respectively. The maximum rate of hydrogen production reached ∼105 ± 2 mL/L day. This suggests that hydrogen production is possible in a single chamber reactor using an EAB in the presence of sodium acetate as a substrate and (+)AuNPs as a catalyst.