The
electrochemical nitrate reduction reaction (NO3RR)
is an environmentally friendly and low carbon emission method that
is attractive for producing high-value added NH3. However,
NO3RR experiences poor selectivity and slow kinetics because
of its complex reaction intermediates and the complicated process
of eight electron transfer. Herein, the Cu-rich bimetallic nanocomposite
CuPt on nanofibrillar networks of peptide bolaamphiphile hydrogels
is reported as a high-performance NO3RR electrocatalyst
for the conversion of NO3
– to NH3 at ambient temperature. The CuPt(3:1)@hydrogel in comparison
with the CuPt(1:1)@hydrogel and CuPt(1:3)@hydrogel displays exceptional
catalytic performance with a maximum Faradaic efficiency of 72.33%
at −0.1 V (vs RHE) and a relatively high NH3 yield
of 0.71 mg h–1 mgcat
–1 at −0.3 V (vs RHE) in alkaline electrolyte (1 M KOH) containing
100 mM KNO3. The nanofibrillar networks of peptide bolaamphiphiles
provide high catalytic active sites and increase proton transfer kinetics,
which results in the enhancement of NO3RR performance.
The control experiments support that the produced NH3 originated
from NO3
– reduction rather than any impurities.
The durability tests suggest that the CuPt(3:1)@hydrogel maintains
excellent morphological and structural stability after long-term electroreduction.
The as-synthesized CuPt nanostructures were characterized by FE-SEM,
EDS, HR-TEM, XRD, rheology, and XPS analyses. The current strategy
has the potential to create new opportunities for developing nanomaterials
that are designed rationally for future electrocatalysts.