Synergistic photoelectric and thermal effect for efficient nitrate reduction on plasmonic Cu photocathodes

Recently, electrochemical nitrate reduction reaction (NO3RR) has been intensively explored for the synthesis of ammonia, and copper (Cu) has become one of the most promising materials for NO3RR. Notably, Cu is an important plasmonic metal that absorbs visible light. The plasmonic effect might have a significant influence on the performance of Cu-catalyzed NO3RR but has been seldom reported. Herein, we report the synergistic photoelectric and thermal effect for efficient and stable NO3RR on plasmonic Cu nanowire photocathodes, which is exclusively effective for NO3RR but has no effect on the competing hydrogen evolution reaction. The faradaic efficiency for ammonia production is nearly 100% within a potential range from –0.2 V to –0.4 V vs. RHE, and a high ammonia yield rate of 1.37 mmol h–1cm–2is achieved at –0.2 V vs. RHE. Further operando photoelectrochemical studies and theoretical simulations confirm that the plasmonic excitation efficiently accelerates the rate-limiting desorption of NH3on Cu surfaces. We further demonstrate the versatility of this strategy to other Cu-based nanostructures.