Conductive polymer protection strategy to promote electrochemical nitrate reduction to ammonia in highly acidic condition over Cu-based catalyst

Electrochemical nitrate reduction (NO3-RR) is a promising way to produce ammonia by alternating Haber -Bosch process. As one promising catalyst, copper suffers from low activity and instability in acidic electrolyte that hinders practical applications. Herein, we report a conductive polymer protection strategy by decorating polypyrrole on Cu nanoparticles (Cu-PPy), achieving high NO3-RR efficiency under strong acidic conditions. In 0.5 M H2SO4, Cu-PPy exhibits high NH3 yield rate of 0.55 mmol h-1 cm -2 with NH3 selectivity of 99.99 % and FE of 96.0 % at high NO3- conversion. Experimental and theoretical results reveal that PPy plays a pluripotent role for the enhanced NO3-RR, consisting of protecting Cu from corrosion in highly acidic electrolyte, promoting the adsorption of NO3- and NO2 - in local environment, stabilizing Cu in intermediate valence state, and accelerating the electron transfer rate. Furthermore, a co -production system of NH3 and adipic acid is constructed and achieves high combined electron efficiency.