Insight into the significant contribution of intrinsic carbon defects for the high-performance capacitive desalination of brackish water

Abstract

The carbon-based electrodes have experienced great progress for capacitive desalination owning to the high conductivity and low cost. However, the fundamental issue of the origin of capacitive activity is far...

Honeycomb Carbon Nanofibers: A Superhydrophilic O2‐Entrapping Electrocatalyst Enables Ultrahigh Mass Activity for the Two‐Electron Oxygen Reduction Reaction

“…Raman spectra for HCNFs and SCNFs at various potentials are shown in Figure 3 a and b, respectively. Interestingly, both spectra for HCNFs and SCNFs present unchanged G peak, indicating the adsorption site for ORR intermediates is not sp 2 carbon site (Figure 3 a and b) [15, 29, 30] . In sharp contrast, several trends of D 1 and D 2 peaks are observed markedly, especially the shift and broadening of D 1 peak located at 1100 cm −1 for HCNFs, implying the disordered sp 3 ‐hybridized carbon defect sites strongly interact with adsorbed ORR intermediates (O 2 − * or OOH*) at 0.6 V (Figure 3 a).…”

Dimensional optimization enables high-performance capacitive deionization

“…216,[255][256][257] Many approaches have been explored to solve the problem such as modifying the pore size, 231,258 and adding surface functional groups. 259,260 For example the graing of amine and sulfonic functional groups can make a great contribution to the CDI properties of the electrode materials. 26 The uniform functional layer structures can make the ion electrode surface selective and wettable and the functional layer can keep the pore system on the electrode to reduce the parasitic reactions that exacerbate the oxidation of the electrode.…”

Honeycomb Carbon Nanofibers: A Superhydrophilic O2‐Entrapping Electrocatalyst Enables Ultrahigh Mass Activity for the Two‐Electron Oxygen Reduction Reaction

“…The superb 2 e − ORR activity and selectivity for HCNFs can be rationally attributed to the following four reasons: (1) their rich nanocavities favor the exposure of more catalytically active sites, dramatically enhancing their activity and selectivity; (2) the superhydrophilicity arising from rich oxygenated functional groups and surface topography on the carbon matrix allows for effective wetting of the catalyst by the aqueous electrolyte, ensuing more sufficient interaction between the cavity wall's surface and the electrolyte and making active sites extremely accessible, [12, 25, 26] (3) the conductive carbon network [21] promotes the electrode kinetics; (4) O 2 trapped in the cavity of HCNFs is more likely to experience high‐frequency collisions with hollow inner surface of the carbon cavities and greater residence time in there, leading to increased local concentration of gas‐phase O 2 molecules. Thus, abundant three‐phase interfaces were built to enable rapid and efficient O 2 ‐to‐H 2 O 2 conversion [12, 28, 29] . Figure 2 f shows a schematic to illustrate the benefits of this 3‐in‐1 (high surface area, superhydrophilicity, and O 2 entrapment) catalyst for 2 e − ORR.…”

“…In situ Raman spectroscopy was employed to probe any catalyst‐adsorbate interactions during ORR catalysis. The defect site‐related D band with the characteristic modes termed as D 1 , D 2 , D 3 , and D 4 are fitted in Raman spectra, which is based on the change of hybridization in the graphene lattice in close proximity to the hydrogenated carbon atoms [29–31] . Raman spectra for HCNFs and SCNFs at various potentials are shown in Figure 3 a and b, respectively.…”