Abstract
The use of reduced graphene oxide (rGO) suffers from irreparable damage because of topological defects and residual heteroatoms, which degrade the inherent properties of graphene. To restore its electrical transport properties, charge-transfer chemical doping with d-electron-rich heteroatoms has been proposed. Herein, we report the effects of atomic-level selenium doping in rGO. Using first-principles calculations, we found that selenium atoms could be selectively bonded in particular locations, such as the pseudo-edge sites of hole-cluster defects in the basal plane and edge defect sites of graphene; however, we found that the intrinsic topological defects of the basal plane were unfavorable for bonding. Numerous selenium atoms were introduced on the fully amorphorized rGO surface, inducing a dramatic change of its electrical transport properties by electron doping. The large metallic regions formed by the selenium atoms on rGOs led to the enhancement of electrical conductivity by 210 S cm–1 at 300 K. Moreover, the temperature-dependent conductivities (σ)/σ20K of selenium-doped rGOs (Se-rGOs) were almost constant in the temperature range of 20–300 K, indicating that the carrier mobility of Se-rGOs becomes temperature-independent after selenium doping, similar to that of pure graphene. Atomic-thin layers of selenium can turn microscale graphene oxide sheets into enhanced energy-storage devices, reports a new study. Graphene's extraordinary conductivity has attracted interest for applications such as battery anodes, but manufacturers seeking sizeable quantities often use reduced graphene oxide – chemically synthesized carbon films containing oxygen and other defects that hinder charge transport. Hyoung-Joon Jin from Inha University in South Korea and colleagues now demonstrate that heating graphene oxide with elemental selenium returns metal-like conductivity to the carbon sheet through a process called surface transfer doping. Scanning electron microscopy and first-principles calculations revealed that selenium atoms attach to surface edge defect sites and transfer electrons to graphene oxide. These dopants enabled graphene oxide to achieve a similar battery capacity and longevity as pure graphene when incorporated in a prototype lithium-ion device. Selenium atoms were selectively introduced in particular locations such as the pseudo-edge sites of hole-cluster defects in the basal plane and edge defect sites of the fully amorphorized surface of reduced graphene oxide (rGO), inducing a dramatic change of electrical transport properties of rGO by electron doping.
Highlights
Graphene has attracted much attention in physics, chemistry and materials science because of its unique characteristics, such as high electrical conductivity (~106 S cm − 1), high intrinsic mobility (200 000 cm[2] V − 1 s − 1), large Young’s modulus (~1.0 TPa), and exceptional thermal conductivity (~5000 W m − 1 K − 1).[1 − 3] the practical application of graphene is limited because of the difficulty of its large-scale production
transmission electron microscopy (TEM) and electron energy loss spectroscopy mapping images of Se-reduced GO (rGO) shows that a large amount of selenium atoms were doped on the entire area of the carbon hosts structure of rGOs (Figure 1b–d)
We investigated the effects of selenium doping in rGO
Summary
Graphene has attracted much attention in physics, chemistry and materials science because of its unique characteristics, such as high electrical conductivity (~106 S cm − 1), high intrinsic mobility (200 000 cm[2] V − 1 s − 1), large Young’s modulus (~1.0 TPa), and exceptional thermal conductivity (~5000 W m − 1 K − 1).[1 − 3] the practical application of graphene is limited because of the difficulty of its large-scale production. A large number of studies have reported substitutional doping by nitrogen,[9,10,14,15] boron,[14−16] sulfur[17−20] and phosphorus[20−23] in carbon-based materials These types of dopants affect the carbon crystalline structure by acting as defects, while providing the free charge carrier density and electroactive surface properties. Surface transfer doping has been performed using p-type dopants such as NO2, Br2 and I2 vapors,[24−28] and n-type dopants such as K and Rb,[27−31] leading to greatly enhanced electrical properties Since these dopants exhibit air-instability and toxicity, their use in practical applications is limited
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