Dinitrogen-Activating Cathode for Faster Haloamine Electroreduction

The patent introduces haloamines (NH2X, NHX2, NX3) as intermediate compounds in the dinitrogen reduction pathway. These haloamine intermediates form through stepwise reduction of N2 with halogen sources, providing alternative reaction pathways that bypass the kinetically sluggish direct 6e-/6H+ reduction to ammonia. The haloamine intermediates facilitate faster electron and proton transfer steps, thereby increasing overall reaction rate while maintaining milder operating conditions.

The patent changes the reaction parameters by introducing halogen-containing compounds (HX, XO−, XO2−, XO3−) into the electrochemical system. This parameter change transforms the traditional N2 reduction pathway by enabling halogenated intermediate formation, which alters the kinetics and mechanism of the reduction process, leading to enhanced reaction rates without requiring extreme temperatures or pressures.

The patent extracts the problematic ammonia/hydrazine products from the traditional reduction pathway by introducing halogen sources that divert the reaction toward haloamine formation. Instead of allowing NH3 or N2H4 to form and block sites, the halogenated intermediates (NH2X, NHX2, NX3) are formed as stable end-products that do not strongly bind to and block the transition metal active sites, thereby maintaining catalytic site availability and reliability.

The patent inverts the traditional approach by not directly reducing N2 to NH3, but rather reducing it to halogenated intermediates first. This inversion of the product formation pathway prevents the blocking issue, as the haloamines are less likely to adsorb strongly on the catalyst surface compared to ammonia or hydrazine, thus maintaining active site accessibility.

The patent segments the complex 6e-/6H+ nitrogen reduction process into multiple stepwise reduction steps involving halogenated intermediates. Instead of attempting the challenging direct 6-electron transfer to ammonia, the reaction proceeds through sequential 2e- steps forming NH2X, then NHX2, then NX3, which can then be hydrolyzed to ammonia. This segmentation breaks down the kinetically difficult multi-electron process into manageable steps with lower individual activation barriers, thereby improving overall reaction efficiency.

The patent uses halogenated species (X•, HX, XO−) as intermediaries to mediate the electron and proton transfer processes during nitrogen reduction. These intermediary species facilitate stepwise electron transfer and bond formation, making the overall 6e- reduction process more kinetically favorable by breaking it into sequential 2e- steps with halogenated intermediates, thereby improving reaction efficiency compared to direct reduction.