Dibenzyldithiocarbamate-Functionalized Small Gold Nanoparticles as Selective Catalysts for the Electrochemical Reduction of CO₂ to CO

Abstract

Dibenzyldithiocarbamate-functionalized gold nanoparticles (DBDTC-Au NPs) were synthesized in the laboratory, and the effects of the DBDTC ligand on the Au electrocatalytic activity for CO2 reduction reaction to CO were investigated in CO2-saturated KHCO3 electrolyte. Our synthesis route produced sub-2.0 nm Au particles, with the number of gold atoms in the range of 67–120, and with strongly bonded and stable DBDTC ligands on the surface. Online differential electrochemical mass spectrometry (DEMS) experiments on the DBDTC-Au nanoparticles showed higher faradic current and higher CO/H2 ratio of their ionic signals compared to those for citrate-capped Au NPs. Quantitative analyses via gas chromatography (GC) showed that our DBDTC-Au catalyst converts CO2 into CO with a faradic efficiency of approximately 100 ± 1% at −0.8 V and 93 ± 0.5% at −1.0 V vs RHE. The higher activity of the synthesized DBDTC-Au electrocatalyst was attributed to the following important functionalities of the DBDTC ligand: (i) the strong bonding to the surface stabilizes the Au NPs, inhibiting the formation of large agglomerates, and (ii) the hydrophobic character of the dibenzyl moieties allows the permeation of CO2, but repels water from the Au surface, minimizing the electrochemical reduction of water and, therefore, enhancing the faradic efficiency for CO formation.

Electrochemical Mass Spectrometry: Evolution of the Cell Setup for On‐Line Investigation of Products and Screening of Electrocatalysts for Carbon Dioxide Reduction

“…However, the results showed stable production of ethylene (m/z=26), methane (m/z=15), and molecular hydrogen (m/z=2) during this initial time. Figure 2C shows a new adaptation of this cell developed recently by Lima et al [121] …”

Interfacial Electrolyte Effects on Electrocatalytic CO2 Reduction

“…However, the traditional solvents and supporting electrolytes for large-scale CO 2 reduction are still limited by relatively low energy efficiency including the cost of raw materials, the reaction activity, and selectivity. Thereby, the modification of EEI with additives and/or modifiers is showing great prospect to further promote the catalytic properties of catalysts, because of their economic and effective procedures. ,,,,,− Until now, nitrogenous molecules are the most used chemicals, because of the distinctive and adaptable electronic structure of N atoms. Specifically, the pyridine-based and other nitrogenous/non-nitrogenous molecules are reviewed and discussed in this section.…”

Effects of Ligands on Synthesis and Surface‐Engineering of Noble Metal Nanocrystals for Electrocatalysis

“…As a result, the adsorption energies of the reactants, reaction intermediates, and products on the metal surface vary with the type of the ligands, leading to distinctive catalytic properties. [37][38][39]42,[131][132][133][134][135] Therefore, ligand engineering may become a powerful tool for effectively tuning the performance of noble metal catalysts.…”

“…Generally, the modification of noble metal nanocrystals by a ligand can significantly change the electronic and thus physicochemical properties of noble metal nanocrystals, due to the metal‐ligand electron transfer. As a result, the adsorption energies of the reactants, reaction intermediates, and products on the metal surface vary with the type of the ligands, leading to distinctive catalytic properties [37–39,42,131–135] . Therefore, ligand engineering may become a powerful tool for effectively tuning the performance of noble metal catalysts.…”