  Nanocarbons are an important class of energy materials and one relevant
application is for the nitrogen reduction reaction, i.e., the direct synthesis
of NH3 from N2 and H2O via photo- and electrocatalytic approaches. Ammonia is
also a valuable energy or hydrogen vector. This perspective paper analyses
developments in the field, limiting discussion to nanocarbon-based electrodes.
These aspects are discussed: i) active sites related to charge density
differences on C atoms associated to defects/strains, ii) doping with
heteroatoms, iii) introduction of isolated metal ions, iv) creation and in situ
dynamics of metal oxide(hydroxide)/nanocarbon boundaries, and v) nanocarbon
characteristics to control the interface. Discussion is focused on the
performances and mechanistic aspects. Aim is not a systematic state-of-the-art
report but to highlight the need to use a different perspective in studying
this challenging reaction by using selected papers. Notwithstanding the large
differences in the proposed nature of the active sites, fall all within a
restricted range of performances, far from the targets. A holistic approach is
emphasized to make a breakthrough advance.
