Hydrothermal Self-Assembly of Gold Nanoparticles Embed on Carbon Felt for Effective Nitrogen Reduction

Gold-based electrocatalysts are potential candidates for electrocatalytic nitrogen reduction reaction (e-NRR) application due to their high conductivity and low hydrogen evolution tendency. However, the role of nonmetallic Au surfaces is not widely studied. Herein, the self-assembly of gold nanoparticles confined in carbon felts (Au NPs@CFs) containing two different states of Au is reported, showing effective e-NRR performance. The effects of surfactant concentration on the morphology and electrochemical performance of the Au NPs are analyzed. X-ray photoelectron spectroscopy indicates two valence states of Au (Au-0 and Au3+) in Au NPs@CFs. Interestingly, it is found that the e-NRR properties of Au NPs@CFs enhance with the increase of Au3+ content. A typical sample Au NPs@CF-1.0 with the highest Au3+ content exhibits the best e-NRR performance (NH3 yield of 66.1 mu g h(-1) mg(cat.)(-1) and Faradaic efficiency of 24.9% at -0.3 V vs reversible hydrogen electrode), which, in part due to the presence of Au3+, is conducive to nitrogen adsorption. Theoretical calculation results find that a stable Au3+ surface can adsorb N-2 strongly, which in turn can lead to energetically favorable formation of ammonia. This study provides new insights into the relation between oxidation states and performance of gold-based electrocatalyst with high e-NRR performance.