Heteroatoms co-doped copper nanocrystals with negatively shifted d-band center for selective nitrate-to-ammonia production

Abstract

To design high-performance electrocatalysts with desired electronic structures is critical to facilitate the conversion of pollutant nitrate (NO3−) to value-added ammonia (NH3) at ambient condition. Nevertheless, the current electrocatalysts for NO3−-to-NH3 still face low Faradaic efficiency and selectivity. We present here a heteroatoms co-doped strategy using phosphorus (P) and oxygen (O) to tune electronic structure of copper (Cu) nanocrystals to form highly active surface for selective NO3−-to-NH3. By combing experimental results and theoretical calculation, it is found that the heteroatom P, O-doping can negatively shift the Cu d-band center, which optimizes adsorption energies of intermediates, especially for *NO3− and *NH3. The P, O-doped Cu nanocrystal exhibits an efficient 8-electron transfer process for NO3−-to-NH3. It achieves both high NO3− conversion rate (91.09 %) and NH3 Faradaic efficiency (91.72 %) in high concentration NO3− electrolyte (1.0 M KOH + 1400 ppm NO3−-N), retaining its potential applications in practical NO3−-to-NH3.