Use of an intermediate solid-state electrode to enable efficient hydrogen production from dilute organic matter

Abstract Molecular hydrogen, a valuable clean energy fuel and industrial feedstock, is commonly produced by steam reforming of fossil fuels, a process that results in the co-generation of CO 2 . Strategies that produce H 2 without CO 2 emissions focus on water-splitting powered by solar or wind energy. Here, we introduce a new approach in which energy derived from the oxidation of waste organic matter is used to subsidize the electrical energy consumed by electrochemical H 2 generation. The primary gas product is H 2 , with minimal O 2 contamination, avoiding the purification step required for conventional water electrolysis. The energy efficiency (i.e., energy from H 2 combustion ÷ input electrical energy × 100%) ranges from 214% to 304%. We also demonstrate a sustained cycling operation with concomitant treatment of domestic and industrial wastewater. These findings open the door to recovery of H 2 from other dilute reservoirs of organic matter, such as marine sediment.