First‐Row Transition‐Metal Cations (Co²⁺, Ni²⁺, Mn²⁺, Fe²⁺) and Graphene (Oxide) Composites: From Structural Properties to Electrochemical Applications

Abstract

Composites of graphene (oxide) (GO) and first-row transition-metal cations( Co 2 + ,N i 2 + ,M n 2 + ,F e 2 + )a re prepared by mixingG Oa nd aqueous metal salt solutions. The amount of metal cation bound to GO nanosheets is calculated by using inductively coupled plasma mass spectrometry (ICP-MS) andt he possible binding sites of the metalsa re investigated by meanso fa ttenuated total reflectance infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. Electrodes loaded with the metal/GO composites are prepared by as imple drop-casting technique without any binderso rc onductive additives.T he effect of electrochemical reduction on the structure of the composite electrodes is investigated by Raman spectroscopy, XPS, X-ray diffraction (XRD) analysis, and field emission scanninge lectron microscopy (FESEM). Ad etailed electrochemical characterization is performed for the utilization of the composite electrodes for electrochemical capacitors and possible oxygen reduction reactione lectrocatalysts by cyclic voltammetry (CV) and rotatingd isk electrode measurements. The highest areal capacitance is achieved with the as-deposited Fe/GO composite (38.7 mF cm À2 at 20 mV s À1 ). In the cyclic stabilitym easurements, rCo/GO, rNi/GO, rMn/GO, and rFe/ GO exhibit ac apacitance retention of 44, 1.1, 73, and 87 % after 3000cycles of CV at 100 mV s À1 ,r espectively.[a] Dr.

A new class of porous materials for efficient CO2 separation: Ionic liquid/graphene aerogel composites

“…Consistently, (CeO) and (C]O) functional groups, and pÀp* shakeup satellite peaks were characterized from XP C1s spectrum of the pristine rGA at the binding energies of 285.9, 288.4, and 290.4 eV, respectively [50,51]. Thus, we inferred that anion of IL is interacting with oxygenated groups on rGA surface consistent with the blue-shifts observed in the corresponding positions of the FTIR and XPS features of the IL.…”

A manganese (II)-based coordinative dendrimer with robust efficiency in intracellular peptide delivery

“…In the spectrum of GT/Mn 2+ , the absorption bands at 1427.55 cm −1 and 794.05 cm −1 ascribed to the terpyridine moieties were shifted to higher wavenumbers compared to those of GT, suggesting the coordination of terpyridine with Mn 2+ ions in the formed complex. According to the XPS spectra shown at Figure S4 , the main elements in GT polymers were C, N and O, and the signal of Mn 2+ appeared after coordination [ 62 ]. The Mn 2p spectra of MnCl 2 were deconvoluted into four photoelectron peaks at 641.21, 642.40, 646.91 and 653.55 eV, respectively, while the nitrogen atoms in GT showed two peaks at 398.34 eV and 400.49 eV, which were assigned to N–H and C N, respectively.…”