A spontaneous hydrogen fuel purifier under truly ambient weather conditions

Abstract

Hydrogen is an ideal energy vector to offer a carbon-neutral energy pathway. However, produced hydrogen is contaminated with carbonaceous and non-carbonaceous impurities that are beyond the tolerance level of a fuel cell, thus demanding exceptionally endergonic fuel-separation modules that require multiple-steps and extreme temperatures and pressures (−85 °C to −15 °C and 7 to 30 bar). These contribute to a serious energy imbalance between the key steps of hydrogen production and hydrogen utilization. By directly harvesting the energy of water formation, we show spontaneous fuel purification under truly ambient weather conditions that include the open-air environment, wherein contaminated hydrogen streams can be refined to nearly 99.9% purity in a single-step at an expenditure of ∼24 kJ mol_H2⁻¹ and with an electrical energy output of ∼90 kJ mol_H2⁻¹. As a major leap in the hydrogen economy, a laboratory-level prototype can spontaneously generate ∼99.4% pure hydrogen in a single-step, even from a quaternary mixture of impurities that include hydrocarbons, CO₂ and N₂.