Electrochemical Reduction of Carbon Dioxide on Au Nanoparticles: An in Situ FTIR Study

Abstract

For the conversion and storage of renewable energy, the electrochemical reduction of CO2 to hydrocarbon fuels and chemicals comprises one of the most promising strategies. A number of studies have focused on the development of robust electrocatalysts for the reduction of CO2 with high efficiency and selectivity. Most of the proposed mechanisms of the CO2 reduction are based primarily on theoretical calculations. Although a few studies have been dedicated to the in situ direct detection of intermediates, the mechanisms are still unclear and questionable. As Au is one of the most efficient catalysts for CO2 reduction, it is selected as an electrocatalyst model for this work to examine intermediates and to explore the kinetics of the electrochemical reduction of CO2. In this study, gold nanoparticles were prepared by a facile sputtering method. In situ attenuated total reflection Fourier transform infrared spectroscopy (FTIR) was employed to investigate the reaction mechanism of the electrochemical reduction of CO2 at the Au nanoparticles. To assign the IR peaks and to identify the formed intermediates and products, H2O and D2O were used as solvents. Our experimental results have provided the direct evidence of the formation of *COO– species on the Au nanoparticles, confirming that *COO– is one of the main intermediates during the CO2 activation. Besides the main product CO, another product HCOO– was detected during the CO2 reduction on gold nanoparticles. The amount of the formed CO and formate products depends on the applied cathodic potential. The mechanism of CO and formate formation on the Au nanoparticle surface is proposed; the kinetics of the CO2 reduction has been further studied using the in situ FTIR technique. The findings from this study provide direct IR spectroscopic evidence of the CO2 reduction mechanism at the Au nanoparticles; the approaches reported in the present study would be useful to investigate various electrocatalytic reactions for energy and environmental applications.

A Self‐Assembled CO2 Reduction Electrocatalyst: Posy‐Bouquet‐Shaped Gold‐Polyaniline Core‐Shell Nanocomposite

“…It has been reported that Au NPs in size of more than 8 nm exhibit a low current density . Our results are comparable to the reported current density of 0.35 mA cm −2 at −0.5 V for Au NPs with an average size of more than 20 nm and −1.3 mA cm −2 at −0.7 V for Au NPs with an average size of more than 9 nm . It further evidences the critical role of PANI in the AU−PANI composite for CO 2 reduction.…”

Photocatalytic CO2 Reduction to CO over Ni Single Atoms Supported on Defect‐Rich Zirconia

“…[27] This COOH species intensified with light irradiation, which has been identified as a key intermediate in the production of CO. [8] Besides, a peak due to OH bending (1655 cm −1 ) remained prominent throughout the reaction. [28] Taken collectively, the DRIFT data provide strong evidence that during the photoreduction of CO 2 over Ni-SA-5/ZrO 2 , adsorbed CO 2 is converted to a COOH intermediate, with O COH bond scission then yielding CO and a surface OH group. Finally, temperature programmed desorption of CO (CO-TPD) over the various photocatalysts was studied ( Figure S23, Supporting Information).…”

Electrochemical Stability and Degradation Mechanisms of Commercial Carbon-Supported Gold Nanoparticles in Acidic Media

“…In electrochemical energy storage and conversion devices, as well as in electrochemical synthesis, noble metals are widely used catalysts in the form of nanoparticles (NPs) dispersed on high area carbon supports. For example, Pt NPs are a state-of-the-art catalyst for several reactions, such as oxygen reduction and hydrogen oxidation/evolution; 1 − 3 Ir-oxide and Ru-oxide are the best catalysts for oxygen evolution, 4 , 5 while Au is used for electrochemical CO 2 reduction 6 − 8 and H 2 O 2 production through selective 2e – oxygen reduction reaction. 8 − 12 Besides activity, a suitable catalyst must provide long term durability and stable running of the given electrochemical process to fulfill the basic demands for commercial applicability, so it is necessary to understand electrochemically induced dissolution and other structural changes of noble metals.…”

“… 20 , 34 Interestingly, in the case of Au NPs, there is a lack of AST in the literature even though Au NPs are widely used in electrocatalysis. 6 − 12 They can also be applicable in fuel cells since the addition of gold increases the stability of Pt during oxygen reduction. 39 − 41 With that in mind, the AST performed solely for Au NPs would provide a benchmark and shed some light on their long-term stability and possible usage as durable electrocatalysts, for instance, for hydrogen peroxide production or carbon dioxide reduction.…”

“… 39 − 41 With that in mind, the AST performed solely for Au NPs would provide a benchmark and shed some light on their long-term stability and possible usage as durable electrocatalysts, for instance, for hydrogen peroxide production or carbon dioxide reduction. 6 − 12 …”