Synthesis and Evaluation of Copper-Supported Titanium Oxide Nanotubes as Electrocatalyst for the Electrochemical Reduction of Carbon Oxide to Organics

Abstract

Carbon dioxide (CO2) is considered as the prime reason for the global warming effect and one of the useful ways to transform it into an array of valuable products is through electrochemical reduction of CO2 (ERC). This process requires an efficient electrocatalyst with high faradaic efficiency at low overpotential and enhanced reaction rate. Herein, we report an innovative way of reducing CO2 using copper-metal supported on titanium oxide nanotubes (TNT) electrocatalysts. The TNT support material was synthesized using alkaline hydrothermal process with Degussa (P-25) as a starting material. Copper nanoparticles were anchored on the TNT by homogeneous deposition-precipitation method (HDP) with urea as precipitating agent. The prepared catalysts were tested in a home-made H-cell with 0.5 M NaHCO3 aqueous solution in order to examine their activity for ERC and the optimum copper loading. Continuous gas-phase ERC was carried out in a solid polymer electrolyte (SPE) reactor. The 10% Cu/TNT catalysts were employed in the gas diffusion layer (GDL) on the cathode side with Pt-Ru/C on the anode side. Faradaic efficiencies for the three major products namely methanol, methane, and CO were found to be 4%, 3%, and 10%, respectively at −2.5 V with an overall current density of 120 mA/cm2. The addition of TNT significantly increased the catalytic activity of electrocatalyst for ERC. It is mainly attributed to their better stability towards oxidation, increased CO2 adsorption capacity and stabilization of the reaction intermediate, layered titanates, and larger surface area (400 m2/g) as compared with other support materials. Considering the low cost of TNT, it is anticipated that TNT support electrocatalyst for ECR will gain popularity.

Synthesis of Cu2O Nanostructures with Tunable Crystal Facets for Electrochemical CO2 Reduction to Alcohols

“…Hossain et al reported that the Cu/TiO 2 catalyst showed a very low methanol selectivity of 5% under −2.5 V vs NHE, while the catalyst showed higher selectivity toward CO and H 2 . The addition of TiO 2 nanotubes promoted CO 2 adsorption and stabilized the essential reaction intermediate and therefore afforded the Cu/TiO 2 catalyst a stable ECR process . To improve the ECR performance of copper-based catalysts, CuO and Cu 2 O had been doped with TiO 2 and ZnO, respectively. , The total FEs for alcohol products of CuO/TiO 2 and Cu 2 O/ZnO were 42.6 and 31.4%, respectively.…”

CO Oxidation at Near-Ambient Temperatures over TiO2-Supported Pd-Cu Catalysts: Promoting Effect of Pd-Cu Nanointerface and TiO2 Morphology

“…All these peaks correlate well with the Joint Committee on Powder Diffraction standard (JCPDS No. 21-1272) for the TiO 2 anatase phase [ 29 , 30 , 31 ]. In general, in all of the prepared catalysts, the crystal structure was maintained after mono (Cu or Pd) and bimetallic (Cu-Pd) addition on the titanium oxide support, in any of the studied morphologies, was performed.…”

“…The presence of a small peak at 2θ = 27.32°, in some cases, such as in the Cu/TNS catalyst, has been linked to rutile phase impurities as it corresponds to (110) crystal plane of rutile phase of titanium oxide (JCPDS Card no. 21-1276) [ 29 , 32 ]. In all of the herein prepared catalysts, a slight upshift was found in the main (101) 2θ value peak compared to pure TiO 2 ( Figure 2 B).…”

“…Similar decrease of BET surface area upon metal doping was reported by De Queiroz et al and Wang et al in their study of Cu/TiO 2 –Cu/Al 2 O 3 catalysts and Pd/Cu/MOx (MOx=TiO 2 and Al 2 O 3 ) catalysts, respectively [ 9 , 40 ]. Hossain et al also shows that both pore volume and surface area decreased upon incorporation of Cu in the titanium nanotube structure [ 29 ]. BJH size distribution in ( Figure 3 c) shows that Cu-TNW and Pd-Cu/TNW poses major size peak at around 9 nm with 0.83 and 0.62 cc/g total pore volume, respectively.…”

Imine‐Nitrogen‐Doped Carbon Nanotubes for the Electrocatalytic Reduction of Flue Gas CO2

“…Finding new types of active N sites can be insightful to increase the reduction efficiency. [20] Nitrogen-doped carbon materials can be produced from various carbon sources, [21][22][23][24] such as metal organic framework, macromolecular compound and small organic molecules, etc. Aniline polymers have attracted many attentions because of the environmental stability, high electrical conductivity, and redoxrelated characteristics of nitrogen.…”