Transition Metal Nanoparticle-Embedded Nitrogen-Doped Carbon Nanorods as an Efficient Electrocatalyst for Selective Electroreduction of Nitric Oxide to Ammonia

The electrochemical reduction of nitric oxide reaction(eNORR)has gained huge attention due to its ecological approach to producingNH3. We explored various transition metal (TM) active sites(Fe, Co, Ni, Cu, and Zn) with nitrogen heteroatoms in one-dimensional(1D) carbon nanorods to unveil the performance of these candidatesin facilitating the electrosynthesis of NH3 via eNORR.Remarkably, Ni nanoparticle-embedded nitrogen-doped carbon nanorods(Ni-NCNR) exceeded other TM-NCNR catalysts in terms of NH3 faradaic efficiency (FENH3 ) and NH3 yield rate. Furthermore, we addressed the effect of graphitization,porosity, and N-heteroatom doping on eNORR by the strategic designof various Ni-NCNR and systematic control experiments. Above all,Ni-NCNR700 secured the highest FENH3 of 85.5 & PLUSMN; 0.8% at a low overpotential of 610 mV with a substantial NH3 yield rate of 23.8 & PLUSMN; 2.6 & mu;mol cm-2 h-1. The Ni-NCNR700 electrocatalyst showed a robustperformance in cyclability and 24 h long-term stability tests. Ouranalysis reveals that for an efficient eNORR to NH3, theselection of suitable active sites with pertinent tuning is crucial.

Automated summary

The performance of transition metal (TM) active sites (Fe, Co, Ni, Cu, and Zn) with nitrogen heteroatoms in one-dimensional carbon nanorods for electrochemical reduction of nitric oxide reaction (eNORR) to produce NH3 was investigated. The Ni nanoparticle-embedded nitrogen-doped carbon nanorods (Ni-NCNR) showed superior NH3 faradaic efficiency (FENH3) and NH3 yield rate compared to other TM-NCNR catalysts. The strategic design of various Ni-NCNR and systematic control experiments revealed that Ni-NCNR700 achieved the highest FENH3 of 85.5±0.8% at a low overpotential of 610 mV and a substantial NH3 yield rate of 23.8±2.6 μmol cm-2 h-1. The Ni-NCNR700 electrocatalyst demonstrated excellent cyclability and long-term stability.