Tandem Electrocatalytic Reduction of Nitrite to Ammonia on Rhodium-Copper Single Atom Alloys

Electrocatalytic reduction of NO2- to NH3 (NO2RR) presents a fascinating approach for simultaneously migrating NO2- pollutants and producing valuable NH3. In this study, single-atom Rh-alloyed copper (CuRh1) is explored as a highly active and selective catalyst toward the NO2RR. Combined theoretical calculations and in situ FTIR/EPR spectroscopic experiments uncover the synergistic effect of Rh1 and Cu to promote the NO2RR energetics of CuRh1 through a tandem catalysis pathway, in which Rh1 activates the preliminary adsorption and hydrogenation of NO2- (NO2- -> *NO2 -> *NOOH -> *NO), while the generated *NO on Rh1 is then transferred on Cu substrate which promotes the rate-determining step of *NO -> *NHO toward the NH3 synthesis. As a result, CuRh1 equipped in a flow cell presents an unprecedented NH3 yield rate of 2191.6 mu mol h-1 cm-2 and NH3-Faradaic efficiency of 98.9% at a high current density of 322.5 mA cm-2, as well as long-term stability for 100 h electrolysis. Single-atom Rh-alloyed copper (CuRh1) is explored as a highly active and selective catalyst toward the NO2RR, arising from the synergistic effect of Rh1 and Cu to promote the NO2- adsorption and hydrogenation through a tandem catalysis pathway, in which Rh1 activates NO2- -> *NO2 -> *NOOH -> *NO while Cu promotes the *NO -> *NHO key step toward the NH3 synthesis. image