Intermetallic Single-Atom Alloy In-Pd Bimetallene for Neutral Electrosynthesis of Ammonia from Nitrate

Harvestingrecyclable ammonia (NH3) from theelectrocatalyticreduction of nitrate (NO3RR) offers a sustainable strategyto close the ecological nitrogen cycle from nitration contaminationin an energy-efficient and environmentally friendly manner. The emergingintermetallic single-atom alloys (ISAAs) are recognized to achievethe highest site density of single atoms by isolating contiguous metalatoms into single sites stabilized by another metal within the intermetallicstructure, which holds promise to couple the catalytic benefits fromintermetallic nanocrystals and single-atom catalysts for promotingNO(3)RR. Herein, ISAA In-Pd bimetallene, in whichthe Pd single atoms are isolated by surrounding In atoms, is reportedto boost neutral NO3RR with a NH3 Faradaic efficiency(FE) of 87.2%, a yield rate of 28.06 mg h(-1) mg(Pd) (-1), and an exceptional electrocatalyticstability with increased activity/selectivity over 100 h and 20 cycles.The ISAA structure induces substantially diminished overlap of Pdd-orbitals and narrowed p-d hybridization of In-p and Pd-dstates around the Fermi level, resulting in a stronger NO3 (-) adsorption and a depressed energy barrier ofthe potential-determining step for NO3RR. Further integratingthe NO3RR catalyst into a Zn-NO3 (-) flow battery as the cathode delivers a power densityof 12.64 mW cm(-2) and a FE of 93.4% for NH3 production.