Hydrogen Exhaling Metal-H 2 O Battery

Sustainable production and utilization of hydrogen or “hydrogen economy” offers a carbon neutral energy pathway for stabilizing global mean temperatures. However, molecular hydrogen production by state-of-the-art steam reforming is prohibitively expensive, often requiring high temperatures ≥ 200 degree celsius and high pressures ≥ 25 bar, eventually mitigating its environmental advantages. This steam reforming pathway is well-known to carbonize the hydrogen fuel stream beyond the tolerance levels to be directly utilized in a fuel cell, consequently; energy intensive purification modules are often inevitable. Here we show an unusual battery chemistry which can exhale pure molecular hydrogen during electricity generation with the net cell reaction being the oxidation of the metal anode and the reduction of H2O to H2 fuel at the electrocatalytic cathode. It comprises a non-noble metal anode, an aqueous electrolyte and a cathode that is active towards electrocatalytic H2 evolution. During the discharge, the fuel exhaling battery delivered a power density of ~75 mW/cm2 while evolving ~3730 μmoles/hour of H2 fuel. Coupling of battery and water electrolyzer in a single device offers an unprecedented pathway for realizing “hydrogen economy” as electric power is harnessed during hydrogen fuel generation as well as its utilization.