Ordered Mesoporous Carbon as a Support of Pd Catalysts for CO2 Electrochemical Reduction

Abstract

Ordered mesoporous carbons (OMCs) have been used as catalyst supports of Pd nanoparticles for the electrochemical reduction of CO2 in 0.1 M KHCO3. OMC with tunable porosity and morphology were obtained by the hard-template approach using synthesized SBA-15 templates. SBA-15 materials were prepared using a mass ratio of the silica precursor (TEOS) and the surfactant (P123) of 2 or 5. After removing silica particles by a purification treatment with NaOH-ethanol or HF, different OMCs were obtained, with a developed porosity (up to 1050 m2 g−1) and ordered 2D hexagonal mesostructure (p6 mm). An increase in the TEOS/P123 ratio as well as the treatment with HF resulted in a decrease in the structural ordering of the materials. Pd nanoparticles with an average size of around 3 nm were deposited on the OMC. However, larger nanoparticles were also observed, especially for the materials obtained using a mass ratio TEOS/P123 of 5. Despite these differences, electrochemical experiments showed that CO2 was successfully reduced to other species (mainly COad) for all Pd/OMC electrocatalysts. These reduced species were adsorbed on Pd active sites, inhibiting the hydrogen evolution reaction.

Silica‐Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review**

“…Lázaro and co-workers synthesized Pd-doped porous carbon electrocatalysts using nano-casting, SBA-15 silica templating, impregnation (furan resin: carbon source and Na 2 PdCl 4 : Pd source), carbonization, chemical dissolution of silica, and chemical reduction processes. [122] The effect of silica precursor (TEOS) to surfactant (P123) mass ratio and the nature of the etching agent (HF vs NaOH-ethanol) on the structural ordering of the produced mesoporous samples were investigated. It was observed that increasing TEOS: P123 produced less ordered carbon structures due to the formation of noninterconnecting silica units that disrupted the structural ordering.…”

Mesoporous Carbon-Supported Pd Nanoparticles in the Metallic State-Catalyzed Acylation of Amides with Aryl Esters via C–O Activation

“…Regretfully, the wide application of the catalyst was hindered by the limited reaction types, poor catalytic performance, and lack of effective preparation methods for completely metallic state PdNPs, which are proven to be active species. 33 , 34 …”

“…Mesoporous carbon (MC) materials could improve the shortcomings of AC, such as insufficient anchor points and the aggregation and leaching of metal nanoparticles through the flexibly adjusted pore size. Also, the strong metal–support interactions triggered by the close contact of metal nanoparticles with the mesoporous material could improve the catalytic activity and stability. − Because of the unique physiochemical properties of MC, the mesoporous carbon-supported palladium nanoparticle (PdNP/MC) catalyst has been studied with respect to traditional C–C coupling and hydrogenation reactions. Regretfully, the wide application of the catalyst was hindered by the limited reaction types, poor catalytic performance, and lack of effective preparation methods for completely metallic state PdNPs, which are proven to be active species. , …”

“…Regretfully, the wide application of the catalyst was hindered by the limited reaction types, poor catalytic performance, and lack of effective preparation methods for completely metallic state PdNPs, which are proven to be active species. 33,34 Herein, we prepared various PdNPs/MC catalysts in the metallic state via the impregnation reduction method and first applied these heterogeneous catalysts to facilely construct imide structures using esters as acylation agents via C−O activation, which present a blueprint for the further application of PdNPs/MC in organic synthesis. Compared to commercially available heterogeneous Pd/AC, PdNPs/MC possesses a larger specific surface and exhibits better catalytic performance and stability.…”