Local Modulation of Single-Atomic Mn Sites for Enhanced Ambient Ammonia Electrosynthesis

Rationally tuning the local structures of single-atomtc active sites for the electrocatalytic N-2 reduction reaction (NRR) remains an urgent but worthwhile research topic. Herein, we accomplish the local modulation of single-atomic Mn sites and construct single Mn-O3N1 sites anchored on porous carbon Mn-O3N1/PC) by delicately controlling the Mn-O bonding conditions. The constructed structures are confirmed via the combination of atomic-scale imaging, Raman spectroscopy, synchrotron radiation-based soft and hard X-ray absorption spectroscopies, and X-ray photoelectron spectroscopy. The Mn-O3N1/PC catalyst yields an NH3 yield rate of 66.41 mu g h(-1) mg(cat)(-1) (corresponding to 1.56 mg h(-1) mg(cat)(-1)) at -0.35 V versus reversible hydrogen electrode, which is about four times that on the control Mn-N-4/PC catalyst. The enhanced NRR performance is ascribed to its unique geometry and electronic structures, which not only facilitate the adsorption and activation of the N-2 molecule but also lower the free energy change of the potential-determining step.

Automated summary

The study focuses on optimizing the local structures of single-atomic active sites for the N-2 reduction reaction through controlling Mn-O bonding conditions. By constructing single Mn-O3N1 sites anchored on porous carbon, an enhanced NH3 yield rate was achieved, attributed to unique geometry and electronic structures that facilitate N-2 molecule adsorption and activation.