Roles of Oxygen Functional Groups in Carbon Nanotubes‐Supported Ag Catalysts for Electrochemical Conversion of CO₂ to CO

Abstract

Carbon nanotubes (CNTs)-supported metal-based catalysts applied in the electrochemical reduction of CO 2 (CO 2 ER) have attracted extensive research recently. Nevertheless, insight into the roles of surface oxygen functional groups in these catalysts on CO 2 ER is still deficient. Herein, three catalysts were reasonably fabricated by chemically loading Ag nanoparticles (NPs) on the oxygenic CNTs (CNTÀ COOH, CNTÀ OH and CNTÀ CO) with precise tuning oxygen functional groups, and then used to explore the effect of oxygen functional groups on the electrocatalytic performance of Ag NPs for CO 2 ER. Com-pared with the other two counterparts, Ag/CNTÀ COOH with the highest content of carboxyl groups possesses the most uniform size and dispersion of Ag NPs and the strongest surface acidic environment, which enable it to exhibit the highest current density and Faradaic efficiency for CO production at high overpotential region (E � À 1.0 V vs. RHE). This work broadens the understanding of surface oxygen functional groups of catalysts in enhancing CO 2 ER performance, and provides guidance for the design and synthesis of high-performance catalysts.[a] J.

Polyacrylamide‐Mediated Silver Nanoparticles for Selectively Enhancing Electroreduction of CO2 towards CO in Water

“…The measured Tafel slope for AgNPs@PAM is 133 mV dec −1 , which is comparable to the 118 mV dec −1 expected for rate‐limiting single‐electron transfer from the adsorbed *CO 2 to form the surface‐adsorbed *CO 2 .− [45] . However, the smaller Tafel slope for AgNPs@PAM relative to our previously reported values for Ag NPs with sizes of approximately 5 nm [46] also suggests that the introduction of PAM may contribute to the enhancement of the intrinsic activity of Ag NPs. In addition, the electrochemical stability of AgNPs@PAM was measured at −0.79 V by prolonging the electrolysis.…”

Comparison of the Level and Mechanisms of Toxicity of Carbon Nanotubes, Carbon Nanofibers, and Silicon Nanotubes in Bioassay with Four Marine Microalgae

“…Due to its unique properties [3,4], carbon nanotubes and nanofibers are one of the most promising classes of NMs, which currently are in the growth phase of large-scale bulk production [5]. Carbon nanotubes were successfully used in electronics [6], catalysis [7,8], environmental purification [9,10], biomedicine [11,12], and other fields. Carbon nanofibers have an application in energy storage [13,14], electronics [15], catalysis [16,17], biosensing [18], etc.…”

Electric Field Mediated Selectivity Switching of Electrochemical CO2 Reduction from Formate to CO on Carbon Supported Sn

“…The X-ray diffraction (XRD) patterns indicated that the deposited Sn nanoparticles existed as oxide forms (SnO and SnO 2 ) (cf., Figure S4a in the Supporting Information), and the characteristic Raman peaks of CNTs at 1358 cm –1 (D band) and 1582 cm –1 (G band) in Figure S4b in the Supporting Information verified that the original property of CNT was maintained in the Sn-CHF . The X-ray photoelectron spectroscopy (XPS) for deconvolution of C 1s and O 1s spectra (cf., Figure S5 in the Supporting Information) indicated identical functional groups for the Sn-CHF with different Sn loadings. − The Sn 3d 5/2 and 3d 3/2 spectra of the Sn-CHF from the high-resolution XPS were indicated at 487.5 and 496.5 eV, respectively (cf., Figures h and S5 in the Supporting Information) and could be deconvoluted into SnO x and Sn. , We note that metal oxides are thermodynamically unstable, − and SnO x should be reduced to metallic states under neutral to acidic CO 2 reduction conditions, while under alkaline conditions, oxide phases could coexist . The Brunauer–Emmett–Teller (BET) analysis of the Sn-CHF at different loadings showed mesopores with an average pore size from 13.4 to 19.58 nm, and the calculated specific surface area was ranged from 60.83 to 86.7 m 2 /g (Table S1 of the Supporting Information).…”