Optimal experimental conditions for hydrogen production using low voltage electrooxidation of organic wastewater feedstock

The dependence of electrooxidation on experimental conditions of organic molecules was investigated to optimize the production of hydrogen from potential wastewater sources using low voltage sources (∼1 V dc). Electrooxidation on platinum, gold, and stainless steel anodes with hydrogen production on the cathode was investigated using several different organic reductants, including: methanol, ethanol, glycerol, isopropanol, propanal, glycerol, glucose, sucrose, citric acid, and propionic acid. The electrolyte pH was varied from 2 to 12 in a 1 M Na2SO4 supporting solution. At 1 V, glycerol, citric acid, ethanol and methanol were found to yield the highest currents at low pH values (pH 2 and 7) on platinum electrode, glucose on gold electrode at pH 12 in 1 M Na2SO4 solution produced the highest total current density at 1 V with measured Faradaic efficiency for 1 M glucose of 70%. The hydrogen energy production efficiency was 86%. Practical limitations of glucose oxidation at optimum experimental conditions are discussed. Highlights: We determined optimal conditions for organic wastewater electrooxidation at 1 V. 3 mA/cm2 current density for glucose on Au electrode at 0.5 M and pH 13 obtained. Faradaic efficiency of H2 production was ∼70% for glucose on the Au electrode. These experiments are an alternative to the conventional water photoelectrolysis.