CO2 Reduction to CO in Water: Carbon Nanotube-Gold Nanohybrid as a Selective and Efficient Electrocatalyst (original) (raw)
Related papers
An electrochemical study of carbon dioxide electroreduction on gold-based nanoparticle catalysts
We report here on an electrochemical study of carbon dioxide electroreduction (CO 2 ER) employing electrochemical impedance spectroscopy (EIS) and a rotating ring-disk electrode (RRDE) on different gold based catalysts, namely bulk polycrystalline gold, gold nanoparticles (Au NPs) and Au@Ag core-shell nanoparticles. RRDE measurements allowed the identification of the reduction potential of CO 2 to CO and the characterisation of NPs based on their selectivity for CO 2 ER with respect to hydrogen evolution. Gold-silver combined catalysts were found to be more selective than Au NPs although at higher overpotential. One gold-silver catalyst exhibits a constant selectivity over a wide potential range. For the first time, EIS data showed the existence of two charge transfers during the reduction of CO 2 . These are attributed to two surface confined reactions that involve an adsorbed intermediate which is correlated with a proposed mechanism. The potential range of these reactions is specific for each catalyst with gold-silver catalysts exhibiting a slower electron transfer than Au NPs, Au and Ag polycrystalline electrodes.
Carbon nanotubes-gold nanohybrid as potent electrocatalyst for oxygen reduction in alkaline media
Nanoscale, 2015
Chemicals and materials Chemical reagents were purchased from Sigma-Aldrich and used as received. THF (from Carlo Erba) was distilled over sodium/benzophenone prior to use. Multi-walled carbon nanotubes (CNTs) were Multi-walled carbon nanotubes (MWCNTs) were obtained from Prof. Haiyan Li (Xiamen University, China) and prepared by catalytic decomposition of methane on a NiMgO catalyst according to the previously reported method. 1 Amphiphilic nitrilotriacetic-diyne lipid (DANTA) was synthesized according to our procedure reported elsewhere. 2 Cationic poly(diallyldimethylammonium chloride) (PDADMAC), tetrahydroxymethylphosphonium chloride (THPC) and HAuCl 4 were obtained from Sigma-Aldrich. Nafion® 117 solution (5 wt. % in a mixture of lower aliphatic alcohols and water, Sigma-Aldrich) was used. Oxygen gas (Air Products ultrapur quality) was of 99.995% purity Assembly of the AuCNTs nanohybrid Self-assembly and polymerization of the amphiphile on the CNTs DANTA (20 mg) was dissolved in 25 mM Tris aqueous buffer (2 mL, pH 8) and CNTs (50 mg) were added. The mixture was submitted to probe-sonication (5 min, 300 ms pulses per second, 25 W output power) and a stable suspension was obtained. Sonication was performed using a Branson Sonifier 450 ultrasonicating probe. After transfer into 1.5 mL Eppendorf ® tubes, amorphous carbon was removed by centrifugation (5000 ×g, 3 min). The supernatants were collected and centrifuged again (11000 ×g, 45 min) to separate the DANTA-decorated CNTs from the excess of amphiphile. The supernatant was discarded while the pellets were resuspended in fresh Tris-buffer and centrifuged once more (11000 ×g, 45 min). The final pellets were resuspended in buffer (1.5 mL) and submitted to UV irradiation (254 nm, 8 h) to polymerize the diacetylene groups and yield stabilized nanoring assemblies. Assembly of the second layer on the nanoring-coated CNTs After polymerization, the Tris-buffer volume was readjusted to 1.5 mL (to compensate the loss due to evaporation) and the suspension was stirred in the presence of PDADMAC (700 µL of a 20 % water solution) for 1 h to permit the formation of the two-layer assembly. Polymer in excess was removed by centrifugation (11000 ×g, 30 min) and the pellets were resuspended in Tris-buffer (2 mL). This operation was repeated twice with Tris-buffer and two more times with pure water. The final pellets were resuspended in water (1 mL) and equally distributed in 20 separate Eppendorf ® tubes.
Nature communications, 2014
Highly efficient and selective electrochemical reduction of carbon dioxide represents one of the biggest scientific challenges in artificial photosynthesis, where carbon dioxide and water are converted into chemical fuels from solar energy. However, our fundamental understanding of the reaction is still limited and we do not have the capability to design an outstanding catalyst with great activity and selectivity a priori. Here we assemble uniform gold-copper bimetallic nanoparticles with different compositions into ordered monolayers, which serve as a well-defined platform to understand their fundamental catalytic activity in carbon dioxide reduction. We find that two important factors related to intermediate binding, the electronic effect and the geometric effect, dictate the activity of gold-copper bimetallic nanoparticles. These nanoparticle monolayers also show great mass activities, outperforming conventional carbon dioxide reduction catalysts. The insights gained through this...
ACS Omega, 2022
Solar-to-chemical energy conversion is a potential alternative to fossil fuels. A promising approach is the electrochemical (EC) reduction of CO 2 to value-added chemicals, particularly hydrocarbons. Here, we report on the selective EC reduction of CO 2 to CO on a porous Au nanostructure (pAu) cathode in 0.1 M KHCO 3. The pAu cathode anodized at 2.6 V exhibited maximum Faradaic efficiency (FE) for conversion of CO 2 to CO (up to 100% at −0.75 V vs reversible hydrogen electrode (RHE)). Furthermore, commercial Si photovoltaic cells were combined with EC systems (PV-EC) consisting of pAu cathodes and IrO 2 anodes. The triple-junction cell and EC system resulted in a solar-to-CO conversion efficiency (SCE) of 5.3% under 1 sun illumination and was operated for 100 h. This study provides a PV-EC CO 2 reduction system for CO production and indicates the potential of the PV-EC system for the EC reduction of CO 2 to value-added chemicals.
Electrochemical CO2 to CO reduction at high current densities using a nanoporous gold catalyst
Materials Research Letters
We report on integrating ultrathin monolithic nanoporous gold (npAu) catalyst coatings for CO 2 reduction in a large electrode area (25 cm 2) electrochemical membrane reactor with gas diffusion electrodes at 100 mA/cm 2. The CO Faraday efficiency increases with increasing thickness, from 65% to 75% and 80% for 1, 5, and 10 layers of npAu leaves where each npAu leaf layer is 100 nm thick. For the one npAu leaf layer configuration, this corresponds to an extremely high CO current density of 955 A/g gold thus demonstrating the potential for commercial applications. IMPACT STATEMENT By device level optimization of catalyst integration we significantly improved the utilization of gold catalysts for electrochemical CO 2 reduction to syngas at industrial relevant current densities of 100 mA/cm 2 .
Journal of Colloid and Interface Science, 2022
Electrochemical CO 2 reduction represents a sustainable approach for the conversion of CO 2 into valuable fuels and chemicals. Here, we fabricated a series of composite nanomaterials through template-oriented polymerization of covalent organic frameworks (COFs) with isolated cobalt porphyrin units on amino-functionalized carbon nanotubes (CNTs) for efficiently electrocatalytic CO 2 reduction reaction (CO 2 RR). Compared with pure COFs, the hybrid form of ultrathin COF nanolayers wrapped on the conductive scaffold leads to distended current density and stable Faradaic efficiency (FE) for CO 2-to-CO conversion over a wide potential range. Specifically, the catalytic performances of the system can be finely optimized by the modification of the reticular structure with different functional groups. Our work gives a new strategy for the preparation of highly active and selective electrocatalysts for CO 2 RR.
On the electrocatalytic reduction of CO2 using Cu-nanoparticles decorating Au electrode
Desalination and Water Treatment, 2020
CO2 is electrocatalytically reduced in aqueous solutions (NaHCO3 and Na2SO4) at polycrystalline gold (Au) both bare and modified with copper nanoparticles (nano-Cu) (nano-Cu/Au). Copper nanoparticles were deposited by the cycling of potential in the range (–0.2–0.7 V) for various potential cycles. The effect of the electrolyte, as well as the nano-Cu loading on the electroreduction of CO2, has been investigated. Nano-Cu/Au electrode has been voltammetrically and morphologically characterized. It has been found that the type of electrolyte, that is, NaHCO3 and Na2SO4, is critical in the electrochemical reduction of CO2; for instance, the CO2 reduction is obscured by hydrogen evolution in NaHCO3 solutions (pH 9.2) at both electrodes, that is, bare Au and nano-Cu/Au electrodes, the well-defined redox peak is obtained at both electrodes in Na2SO4 solution (pH 7), even though the pH of Na2SO4 is smaller. The extent of catalysis is based on the copper loading at the nano-Cu/Au electrode a...
Active and selective conversion of CO2 to CO on ultrathin Au nanowires
Journal of the American Chemical Society, 2014
In this communication, we show that ultrathin Au nanowires (NWs) with dominant edge sites on their surface are active and selective for electrochemical reduction of CO2 to CO. We first develop a facile seed-mediated growth method to synthesize these ultrathin (2 nm wide) Au NWs in high yield (95%) by reducing HAuCl4 in the presence of 2 nm Au nanoparticles (NPs). These NWs catalyze CO2 reduction to CO in aqueous 0.5 M KHCO3 at an onset potential of -0.2 V (vs reversible hydrogen electrode). At -0.35 V, the reduction Faradaic efficiency (FE) reaches 94% (mass activity 1.84 A/g Au) and stays at this level for 6 h without any noticeable activity change. Density functional theory (DFT) calculations suggest that the excellent catalytic performance of these Au NWs is attributed both to their high mass density of reactive edge sites (≥16%) and to the weak CO binding on these sites. These ultrathin Au NWs are the most efficient nanocatalyst ever reported for electrochemical reduction of CO2...
Gold catalyst reactivity for CO 2 electro-reduction: From nano particle to layer
CO 2 electro-reduction is a promising method for sustainable production of carbon fuels as well as valuable chemicals. Herein, we investigated a direct electro-catalytic CO 2 conversion to CO by nanostructured gold catalysts from the small nanoparticles to aggregated clusters to layered film. The selectivity of CO formation was found to increase as the gold amount increased and it reached a saturation point of ∼78% (−0.59 V vs. RHE) at the morphological transition from aggregated cluster to layered film. Furthermore, the ∼4 nm gold nanoparticle exhibited a remarkable CO formation mass activity value at 166.1 A/g (−0.59 V vs. RHE).