Non-aqueous gas diffusion electrodes for rapid ammonia synthesis from nitrogen and water-splitting-derived hydrogen

Electrochemical transformations in non-aqueous solvents are important for synthetic and energy storage applications. Use of non-polar gaseous reactants such as nitrogen and hydrogen in non-aqueous solvents is limited by their low solubility and slow transport. Conventional gas diffusion electrodes improve the transport of gaseous species in aqueous electrolytes by facilitating efficient gas-liquid contacting in the vicinity of the electrode. Their use with non-aqueous solvents is hampered by the absence of hydrophobic repulsion between the liquid phase and carbon fibre support. Herein we report a method to overcome transport limitations in tetrahydrofuran using a stainless steel cloth-based support for ammonia synthesis paired with hydrogen oxidation. An ammonia partial current density of 8.8 +/- 1.4 mA cm(-2) and a Faradaic efficiency of 35 +/- 6% are obtained using a lithium-mediated approach. Hydrogen oxidation current densities of up to 25 mA cm(-2) are obtained in two non-aqueous solvents with near-unity Faradaic efficiency. The approach is then applied to produce ammonia from nitrogen and water-splitting-derived hydrogen.