Effects of Surfactants on the Size Distribution and Electrocatalytic Nitrite Reduction of Uniformly Dispersed Au Nanoparticles

The electrocatalytic nitrite reduction reaction (NO2–RR) occurs under mild conditions at ambient
temperature
and pressure and can convert nitrite pollution into recycled ammonia.
This method has great application potential in the purification of
the water environment and the field of synthetic ammonia. In this
article, we present a method to synthesize relatively uniformly dispersed
gold nanoparticles on the surface of carbon cloth fibers (Au@CC) by
hydrothermal self-assembly growth and calcination without the use
of adhesive in the process. We studied the influence of different
surfactants on the distribution and particle size of gold nanoparticles
on carbon cloth by mechanism study and explored their effects on NO2–RR performance. The results showed that
Au@CC with gold nanoparticles relatively uniformly dispersed on the
surface of carbon cloth fibers and small particle size (≈86.2
nm) could be obtained when the sample was synthesized by the surfactant
sodium dodecyl sulfate (SDS). This is mainly due to the strong coordination
between SDS and the gold precursor and that the hydrophobic group
of SDS can interact with the surface carbon cloth. When performed
in the 0.1 M phosphate buffered saline (PBS) (with 0.1 M NaNO2) solution, the Au@CC-SDS electrode gave a high NH3 yield of 1249.1 μg h–1 cm–2 and faradaic efficiency of 80.7%. The density functional theory
(DFT) calculations clarified the electrocatalytic reaction mechanism
of the NO2–RR to NH3 on the
Au active site. Thus, this study demonstrated that SDS is beneficial
to the formation of relatively uniformly dispersed gold nanoparticles
supported on carbon fiber cloth (Au@CC) and proved that gold-based
nanomaterials are a promising catalyst for electrocatalytic NO2–RR ammonia synthesis.