Quantifying Carbon Edge Sites on Depressing Hydrogen Evolution Reaction Activity

Abstract

To understand the effect of microstructural characteristics of carbon materials on their electrochemical or electrocatalytic performance, an in-depth study of the edges in carbon materials should be carried out. In this study, catalytically grown platelet-type carbon nanofibers (CNFs) with fully exposed edges were physically and chemically passivated to clarify the relationship between the edge density and the hydrogen evolution reaction (HER) activity. Due to the aligned structure along the fiber axis, the edges on the outer surface of the CNFs were easily modified without using a complex process. The edges on the surface of the CNFs were inactivated by sequentially forming single, double, and multiple loops as the heat treatment temperatures increased. The number of edges within the CNFs was quantitatively measured using temperature-programmed desorption (TPD) up to 1800 °C. The surviving edges on the surface of thermally treated CNFs were identified by chemical functionalization via an amination reaction. We identified a close relationship between the HER activity and the edge density. When evaluating the electrochemical and electrocatalytic activity of carbon materials, it is important to know the portion of the edge surface area with respect to the total surface area and edge ratio.

Synthesis of graphene mesosponge via catalytic methane decomposition on magnesium oxide

“…6 Thus, the present TPD provides bulk O-and H-content values which are more precise and reliable than the ones determined by conventional methods such as CHN analysis and X-ray photoelectron spectroscopy with much less detection limit. [23][24][25] As shown in Table S5, the O-and H-contents of MgO-derived GMS are much smaller than those of reference carbons, and therefore, MgO-derived GMS exhibits the best oxidation stability over the reference carbon materials.…”

“…6 Thus, the present TPD provides bulk O-and Hcontent values which are more precise and reliable than the ones determined by conventional methods such as CHN analysis and X-ray photoelectron spectroscopy with much less detection limit. [23][24][25] As shown in Table S5, the O-and Hcontents of MgO-derived GMS are much smaller than those of reference carbons, and therefore, MgO-derived GMS exhibits the best oxidation stability over the reference carbon materials. It is noteworthy that we have achieved an edge-free GMS framework with superior oxidation stability by using MgO template despite its different catalytic behaviour from Al 2 O 3 and significant shrinkage upon template removal (Fig.…”

Clarification of the Effects of Oxygen Containing Functional Groups on the Pore Filling Behavior of Discharge Deposits in Lithium–Air Battery Cathodes Using Surface-Modified Carbon Gels

“…In addition, the total number of edge H can be quantified by heating the sample up to 1800 °C, a temperature that is higher than the temperature range in which edge H desorbs as H 2 (800−1500 °C). 26 The high-sensitivity TPD has been used to clarify the relation between carbon edge sites and electrochemical properties of carbons regarding electrochemical degradation in organic electrolytes, 27,28 hydrogen evolution in an aqueous electrolyte, 29 and stability in supercapacitors. 30 Here, we focused on the effects of OCFGs in the cathode carbon on the characteristics of Li 2 O 2 deposited during charging and the performance of the carbon as a cathode.…”

An interface engineering induced hierarchical NiCo/V2O3/C Schottky heterojunction catalyst for large-current-density hydrogen evolution reaction

“…The characteristic peaks of the D band and G band are approximately located at 1331 cm −1 and 1596 cm −1 respectively. 49 The SAED pattern (Fig. 2g) shows a series of diffraction rings which safely corresponded to the (104) and ( 110 ) eV, while the signals at 855.9 and 873.7 eV can be assigned to the Ni 2+ ions by surface oxidation, and each peak is followed by its satellite peak.…”