A C‐S‐C Linkage‐Triggered Ultrahigh Nitrogen‐Doped Carbon and the Identification of Active Site in Triiodide Reduction

Abstract

An efficient chemical synthesis route, with an aim of reaching an ultrahigh nitrogen (N)‐doping level in carbon materials can provide a platform where the type and amount of N dopant can be tuned over a wide range. We propose a C‐S‐C linkage‐triggered confined‐pyrolysis strategy for the high‐efficiency in situ N‐doping into carbon matrix and an ultrahigh doping level up to 13.5 at %, which is close to the theoretical upper limit (15.2 at %) is realized at a high carbonization temperature of 1000 °C. The pyridinic N is dominant with a maximum percent of 48.7 %. By using I3− reduction as an example, the resultant NCM‐5 exhibits the best activity with a power conversion efficiency of 8.77 %. A pyridinic N site‐dependent activity is demonstrated in which the amount of active sites increases with the increase of pyridinic N, and the carbon atom adjacent to electron‐withdrawing pyridinic N at the armchair edge acts as the most favorable site for the adsorption of I2.

Sodium Metal Anodes with Self‐Correction Function Based on Fluorine‐Superdoped CNTs/Cellulose Nanofibrils Composite Paper

“…For further explanation, the valence band maximum (VBM) and conduction band maximum (CBM) energy levels of these functional structures were simulated by natural bond orbital study on the corresponding atomic models. [24,48,49] As shown in Figure S6b,c, Supporting Information, the simplified CNTs exhibit the largest band gap of 1.111 eV. In comparison, O-doped atomic models with different O species exhibit lower band gaps ranged from 0.149 to 0.797 eV (Figure 3j), which is more favorable for the electron transfer in the trapping of active fluorine fragments during plasma treatment.…”

“…There's a reasonable prospect that the F‐superdoping of F O ‐CNTs may promote the formation of NaF‐enriched SEI during the subsequent sodiation process. [ 23,24,43 ] The high‐resolution O 1s spectrum of O‐CNTs shown in Figure 3e demonstrates CO (531.6 eV), CO (532.6 eV), and COO (533.8 eV) configurations. And the presence of adsorbed/entrapped F, semi‐ionic CF, covalent CF x , covalent CF 1 /CF 2 and perfluorinated CF bonds are confirmed for F O ‐CNTs by the F 1s core level spectra located at ≈685.2, ≈686.5, ≈687.7, ≈688.6, and ≈689.6 eV, respectively (Figure 3f).…”

“…[ 17–19 ] Therefore, fluorine (F) doped carbon materials, with the formation of NaF by reacting with Na, have been widely used to form a stable Na metal anode with a NaF‐consolidated SEI layer and alleviated volume bulge, [ 20–22 ] but the fluorine content is usually scarce and easily depleted. Numerous studies have shown that a high doping level is often needed to obtain carbon materials with motivating potential performance, [ 23–25 ] that is, more favorable F configurations and sufficient NaF are expected to be obtained by adopting carbon materials with high fluorine content to Na anode. To this end, the physicochemical properties, nanoarchitecture, and electronic structure of carbon materials should be well designed and optimized to expose sufficient doping active sites.…”

In situ zinc cyanamide coordination induced highly N-rich graphene for efficient peroxymonosulfate activation

“…As a result, the conned N-containing gases would interact with the formed C lattice, inducing a high N-doping level. 21 Based on the above results, we conrmed an in situ ZnNCN coordination mechanism to well understand the NRG formation. Upon heating the mixture of melamine and Zn, ZnNCN was in situ produced and can effectively coordinate with This journal is © The Royal Society of Chemistry 2022 melamine.…”

“…15 Simple, direct one-step conversion of N-rich organics to NRG at high temperatures is still a great challenge. 21 In addition, regulating N configurations in NRG and disclosing the relationship of PMS activation with different N configurations have never been emphasized and investigated in detail.…”