In situ sulfur-doped graphene nanofiber network as efficient metal-free electrocatalyst for polysulfides redox reactions in lithium–sulfur batteries

Zhang, Shijie; Zhang, Peng; Hou, Ruohan; Li, Bin; Zhang, Yongshang; Liu, Kangli; Zhang, Xilai; Shao, Guosheng

doi:10.1016/j.jechem.2020.01.033

Cited by 72 publications

(41 citation statements)

References 58 publications

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“…from the (αhv)1/2 vs. photon energy (hv) plot ( Hou et al, 2020 ; Li et al, 2020d ; Wang et al, 2020a ; Zhang et al, 2020a ; Zhang Y. et al, 2020 ), the optical bandgap of chain g-C 3 N 4 and bulk g-C 3 N 4 was calculated to be approximate 2.88 and 2.93 eV, respectively. When the particle size descends to a certain value, the electron energy level near the Fermi energy level of the metal changes from quasi-continuous to discrete energy level ( Miao et al, 2019 ; Huang et al, 2020b ; Wu et al, 2020 ; Zhang S. et al, 2020 ), and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital energy level (LUMO) of the nano-semiconductor particles have discontinuous energy gap, which leads to the blue shift of the chain g-C 3 N 4 .…”

Section: Resultsmentioning

confidence: 99%

Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution

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The development of graphite-carbon nitride (g-C3N4) photocatalyst is of great significance for various visible utilization applications. Control the nanostructures of g-C3N4 can tailor its photocatalytic performance. In this paper, one-dimensional chain-like g-C3N4 was successfully synthesized by heat-induced polymerization of melamine which was saturated in ethylene glycol. The photocatalytic hydrogen production rate (HER) of the prepared g-C3N4 chain enhanced about 3 times than that of bulk g-C3N4, increasing from 9.6 μmolh−1 to 28.7 μmolh−1. The improved photocatalytic activity of the g-C3N4 chain was attributed to the advantages of porosity and nanostructure. The extraordinary nanopores result in an enlarged specific surface area for adsorption and the production of abundantly available channels for charge transfer. The one-dimensional chain-like structure can facilitate the exposure of internal/external active sites as many as possible, and induce the directional migration of charge carriers.

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Section: Resultsmentioning

confidence: 99%

Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution

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“…The UPS is generally hired to get the actual work function and position of the valence band. [ 25–29 ] UV–vis was employed to figure out the band gap energies of TiO 2 and Ti 3 C 2 . According to the test results and band structure theory, the electrons are found to transfer from Ti 3 C 2 to TiO 2 once the heterojunction is established and the direction of a formed internal electric field is consistent with the theoretical simulations.…”

Section: Figurementioning

confidence: 99%

Photogenerated Electron Transfer Process in Heterojunctions: In Situ Irradiation XPS

et al. 2020

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Photoelectron transfer between heterojuctions is an important process for photocatalysis, and identification of the electron transfer process provides valuable information for catalyst design. Herein, Ti3C2, one of the widely used two‐dimensional materials, is used to produce a heterojunction of TiO2 and Ti3C2 by an in situ growth method and the photogenerated electrons transfer between the two components for photocatalytic water splitting to hydrogen is investigated. Theoretical simulation and experimental tests proclaim that electrons transfer from Ti3C2 to TiO2 forms an internal electric field, which implies that there exists the driving force of electronic movement from TiO2 to Ti3C2. In situ irradiation X‐ray photoelectron spectroscopy shows the binding energies of TiC (in Ti3C2) and TiO (in TiO2) move toward negative and positive positions, respectively, verifying the photogenerated electrons produced from TiO2 and transferring to Ti3C2 driven by the internal electric field. In addition, the amount of TiO2 nanoparticles also affects the hydrogen evolution rate. Several parallel experiments are designed to uncover the fact that less or excess amount of TiO2 nanoparticles leads to a tinier shift of binding energy, which hints the quantity of heterojunction is a considerable factor in photocatalytic performance. This work develops a new method to directly monitor the photoelectron transfer process between heterojuctions.

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“…Among these active electrocatalysts, the electrically conductive TiC (10 4 S cm −1 ) is endowed as a promising candidate with a strong affinity for LiPS 27,29,44 . However, the problem due to uneven deposition of the insulative Li 2 S film is yet to be addressed, which looms large in the way for delivering practical Li–S batteries when high S loading and low E/S ratio are essential requests 45 . A way forward lies in significant enlargement in the specific interfacial area with electrocatalysts, so that Li 2 S could be spread over a large surface to reduce overall film thickness and avoid local aggregation.…”

Section: Introductionmentioning

confidence: 99%

A flexible metallic TiC nanofiber/vertical graphene 1D/2D heterostructured as active electrocatalyst for advanced Li–S batteries

Zhang

et al. 2021

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The realistic application of lithium–sulfur (Li–S) batteries has been severely hindered by the sluggish conversion kinetics of polysulfides (LiPS) and inhomogeneous deposition of Li2S at high sulfur loading and low electrolyte/sulfur ratio (E/S). Herein, a flexible Li–S battery architecture based on electrocatalyzed cathodes made of interfacial engineered TiC nanofibers and in situ grown vertical graphene are developed. Integrated 1D/2D heterostructured electrocatalysts are realized to enable highly improved Li+ and electron transportation together with significantly enhanced affinity to LiPS, which effectively accelerate the conversion kinetics between sulfur species, and thus induce homogeneous deposition of Li2S in the catalyzed cathodes. Consequently, highly active electro‐electrocatalysts‐based cells exhibit remarkable rate capability at 2C with a high specific capacity of 971 mAh g−1. Even at ultra‐high sulfur loading and low E/S ratio, the battery still delivers a high areal capacity of 9.1 mAh cm−2, with a flexible pouch cell being demonstrated to power a LED array at different bending angles with a high capacity over 100 cycles. This work puts forward a novel pathway for the rational design of effective nanofiber electrocatalysts for cathodes of high‐performance Li–S batteries.

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In situ sulfur-doped graphene nanofiber network as efficient metal-free electrocatalyst for polysulfides redox reactions in lithium–sulfur batteries

Cited by 72 publications

References 58 publications

Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution

Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution

Photogenerated Electron Transfer Process in Heterojunctions: In Situ Irradiation XPS

A flexible metallic TiC nanofiber/vertical graphene 1D/2D heterostructured as active electrocatalyst for advanced Li–S batteries

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