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.