Gas-phase hydrogen evolution at a non-immersed electrode enabled by a gel-polymer electrolyte interface

A gas-fed electrochemical platform is developed to produce hydrogen directly in the gas phase using a CuNi-coated Ni foam cathode coupled with a gel-polymer electrolyte (GPE) interface. In this configuration, hydrogen evolution occurs at a gas-electrode-gel tri-phase boundary where the cathode is exposed to the gas phase while the GPE maintains interfacial hydration and ionic conduction. Unlike conventional alkaline electrolysis, the cathode does not require immersion in bulk electrolyte, which simplifies gas collection and avoids bubble accumulation at the electrode surface.Under an Ar carrier gas, the system produces hydrogen at a rate of 83.2 mL h−1 with near-quantitative Faradaic efficiency at −50 mA cm−2. Under air feed, the Faradaic efficiency remains in the range of 20-80% because of competitive oxygen reduction. Continuous electrolysis in alkaline electrolyte is stable for more than 50 h. These findings show that a GPE-mediated gas-fed configuration can support hydrogen evolution at a gas-electrode interface while enabling direct gas-phase hydrogen generation and collection.