X‐Ray Spectroscopic Investigation of Chlorinated Graphene: Surface Structure and Electronic Effects

Abstract

Chemical doping of graphene represents a powerful means of tailoring its electronic properties. Synchrotron‐based X‐ray spectroscopy offers an effective route to investigate the surface electronic and chemical states of functionalizing dopants. In this work, a suite of X‐ray techniques is used, including near edge X‐ray absorption fine structure spectroscopy, X‐ray photoemission spectroscopy, and photoemission threshold measurements, to systematically study plasma‐based chlorinated graphene on different substrates, with special focus on its dopant concentration, surface binding energy, bonding configuration, and work function shift. Detailed spectroscopic evidence of C–Cl bond formation at the surface of single layer graphene and correlation of the magnitude of p‐type doping with the surface coverage of adsorbed chlorine is demonstrated for the first time. It is shown that the chlorination process is a highly nonintrusive doping technology, which can effectively produce strongly p‐doped graphene with the 2D nature and long‐range periodicity of the electronic structure of graphene intact. The measurements also reveal that the interaction between graphene and chlorine atoms shows strong substrate effects in terms of both surface coverage and work function shift.

Understanding Sulfur Redox Mechanisms in Different Electrolytes for Room-Temperature Na–S Batteries

“…After stirring for 5 min in an Ar-filled glove box, the 155S mixture turned brown, while the 300S remained transparent. According to the ultraviolet-visible (UV-Vis) spectroscopy, S 4 2− was detectable from the 155S electrolyte after stirring, whereas there were no obvious peaks from the transparent 300S electrolyte [57]. This result visualizes the 'solid-liquid' and 'solid-solid' conversions, in which the sulfur on the surface of the cathode host will dissolve into the electrolyte after reacts with sodium, while the sulfur stored in the pores of the cathode host will be trapped in the porous structure, even after reacting with sodium.…”

Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

“…is provided by this beamline. 72 Data was collected both by using total electron yield (TEY) with penetration depth of ∼10 nm.…”

Toward graphene chloride: chlorination of graphene and graphene oxide

“…An optimized method based on the treatment of graphene with chlorine plasma using an electron cyclotron resonance reactive ion etcher was successfully applied for surface chlorination. 26,27 These methods usually deal with a complicated and expensive equipment, or can be applied only on a very limited amount of material, like graphene akes paced on silicon wafer. This strongly limits the application of chlorinated graphene in an industrial scale.…”