BCN-Encapsulated Nano-nickel Synergistically Promotes Ambient Electrochemical Dinitrogen Reduction

The
electricity provided by solar or wind power can drive nitrogen
in the atmosphere, combining with ubiquitous water to form ammonia,
and distributed production methods can alleviate the irreversible
damage to the environment caused by the energy-intensive Haber–Bosch
process. Here, we have designed a novel Ni-doped BCN heterojunction
(S/M-BOPs-1) as a catalyst for the electrochemical nitrogen reduction
reaction (NRR). The ammonia yield rate and Faraday efficiency in NRR
driven by S/M-BOPs-1 reach up to 16.72 μg–1 h–1 cm–2 and 13.06%, respectively.
Moreover, S/M-BOPs-1 still maintains high NRR activity and excellent
stability after recycling for eight times and long-time operation
of 12 h. Using density functional theory calculations, we reveal a
possible NRR path for N2 to NH3 on Ni, BCN,
and the S/M-BOPs-1 composite surfaces. The interaction between the
BCN matrix and Ni nanoparticles promotes a synergetic effect for the
electrochemical NRR efficiency due to the partial electron transfer
from the Ni particles to BCN that inhibits hydrogen evolution reaction
and decreases the rate-determining step on Ni surfaces toward NRR
by ∼1.5 times. Therefore, efficient NRR performance can be
achieved by tuning the electronic properties of non-noble metals via
the formation of a heterointerface.