Biomass-derived oxygen-doped hollow carbon microtubes for electrocatalytic N2-to-NH3 fixation under ambient conditions.

Electrocatalytic N₂ reduction as an alternative approach to the energy-intensive and large CO₂-producing Haber–Bosch process for NH₃ synthesis under mild conditions has attracted extensive attention. Current research efforts on N₂ reduction have mainly focused on metal-based catalysts, but metal-free alternatives can avoid the issue of metal ion release. In this work, oxygen-doped hollow carbon microtubes (O-KFCNTs) derived from natural kapok fibers are reported as a metal-free NRR electrocatalyst for N₂-to-NH₃ conversion with excellent selectivity. In 0.1 M HCl, the O-KFCNTs achieve a high faradaic efficiency of 9.1% at −0.80 V vs. a reversible hydrogen electrode (RHE) and a NH₃ yield rate of 25.12 μg h⁻¹ mg_cat.⁻¹ at −0.85 V vs. RHE under ambient conditions. Notably, this catalyst also demonstrates high stability. [ABSTRACT FROM AUTHOR]