CO₂ Reduction to CO in Water: Carbon Nanotube–Gold Nanohybrid as a Selective and Efficient Electrocatalyst

Abstract

A gold-based nanostructure has been demonstrated as promising materials for the selective electroreduction of CO2 to CO in aqueous conditions. In this work, we present a carbon nanotube-gold nanohybrid as a selective and efficient electrocatalyst for the reduction of CO2 in 0.5 m NaHCO3 . The hybrid material exhibits remarkable activity with a current density of 10 mA cm(-2) at -0.55 V versus standard hydrogen electrode with a stable CO production rate (0.52 μmol s(-1) ) after 4 h electrolysis. Monodispersed gold nanoparticles anchored on carbon nanotubes through a layer-by-layer method allows very little Au loading and thus minimization of the cost of electrode fabrication with a mass activity up to 100 A g(-1) at -0.55 V versus reversible hydrogen electrode. It is 33 times higher than a previous report for monodisperse Au nanoparticles (3 A g(-1) ) while ensuring selectivity (70 % faradaic yield of CO) at comparable reduction potential.

Highly Dispersive Gold Nanoparticles on Carbon Black for Oxygen and Carbon Dioxide Reduction

“…À0.725 V. Unfortunately, reliable quantitative results were not obtained at À0.725 and À0.825 V (vs SCE) using FID and TCD due to the difficulty in obtaining sufficient amounts of products at the low potentials ( Figure S8). All the results obtained using both GC and SECM techniques verified consistently that Au NPs/CB_0.2 reduced CO 2 at a significantly more positive potential (À0.62 V (vs SCE)) compared to the other previous reports [33][34][35]. As seen in the above, GC method was difficult to analyze at low overpotential region but good at high overpotential region.…”

System Design Rules for Intensifying the Electrochemical Reduction of CO2 to CO on Ag Nanoparticles

“…This process can now be used to generate a direct CO feed for the Fischer‐Tropsch process or be used to generate CO feed for a tandem/cascade reactor for further CO reduction to other carbon‐based chemicals. Figure shows a comparison of the results obtained in this work to some of the state‐of‐the‐art values reported in the literature . Figure a shows how a combination of optimized operating conditions (increased electrolyte flow rate and/or increased electrolyte concentration) and electrolyte engineering (changing electrolyte composition from the widely used KHCO 3 to CsOH) can significantly improve the j CO values obtained at various cathode overpotentials.…”

Progress in development of electrocatalyst for CO2 conversion to selective CO production

“…For instance, one example has a membrane between cathode and anode (Figure B), whereas another has no membrane, as the cathode and anode share the electrolyte (Figure C). The Kenis group has applied these devices in the CO 2 RR and proposed many pioneering insights from the use of this system (eg, ionic liquid) . They also studied the structure of GDE to expand the system scale and increase the system efficiency.…”

“…The most popular solution is the introduction of a gas diffusion electrode (GDE), allowing CO 2 gas to be supplied to the catalyst by a separate flow path different from that for the electrolyte (Figure 10B,C). 33,111,126,133,137 These types of gas flow devices have been diversely customized depending on experimental conditions and flow path designs. For instance, one example has a membrane between cathode and anode ( Figure 10B), whereas another has no membrane, as the cathode and anode share the electrolyte ( Figure 10C).…”

“…By engineering the composition and/or sequence of deposited layers on the gas diffusion layer, which is composed of the Ag catalyst and CNT supporter, they recorded an unprecedented J CO of 350 mA cm −2 (CO FE >95%) with an energy efficiency of 45%. 33 To improve the efficiency of the total device system, it is important to decrease the overpotential, which is usually induced by series resistance and transport as well as kinetic overpotentials. To circumvent this issue, a membrane electrode assembly (MEA), which uses a polymer electrolyte instead of aqueous electrolyte inspired by the fuel cell, has been recently adopted in the CO 2 RR device ( Figure 10D).…”