A pyrolysis-phosphorization approach to fabricate carbon nanotubes with embedded CoP nanoparticles for ambient electrosynthesis of ammonia

We report a pyrolysis-phosphorization approach to fabricate carbon nanotubes with embedded CoP nanoparticles (CoP/CNs) using ZIF-67 as a precursor for electrocatalytic nitrogen (N-2) reduction to ammonia (NH3) under ambient conditions. The results demonstrate that the as-synthesized CoP/CNs as electrocatalysts exhibit high electrocatalytic activity toward the N-2 reduction reaction (NRR), affording a large NH3 yield rate of 48.9 mu g h(-1) mg(cat.)(-1) with a faradaic efficiency (FE) of 8.7% at -0.4 V (vs. RHE) in 0.1 M Na2SO4 electrolyte. The N-15 isotopic labelling experiments confirm that the NH3 obtained is indeed from the CoP/CN catalyzed NRR process. Our theoretical calculation results reveal that the N-2 molecules prefer to be adsorbed on the highly unsaturated three coordinated Co sites of the CoP(112) plane following an associative distal hydrogenation process.