Effects of the Degree of Graphene Oxidation on the Oxidation Evolution Reaction of Lithium Peroxide: First-Principles Study

Finding graphene oxide (GO) with an optimal oxidation concentration as a catalyst for the oxygen evolution reaction (OER) associated with the decomposition of lithium peroxide (Li2O2) is of great importance for achieving high energy density and reversible lithium–air batteries. In this work, first-principles calculations were carried out to investigate the OER of Li2O2 on GO with different degrees of oxidation. Our studies show that GO enhances the interaction with Li2O2 and LiO2 molecules compared to perfect graphene. As the degree of graphene oxidation increases, the charge transferred from Li2O2 or LiO2 molecules to GOn gradually increases, resulting in a gradual shortening of O–O bond lengths and lengthening of Li–O bond lengths. The Li atoms in the Li2O2 molecule can form up to four bonds with oxygen atoms in GOn, while the Li atom in the LiO2 molecule can form up to three bonds with oxygen atoms in GOn. According to the calculated Gibbs free energy, the rate-determining step (RDS) for GO1 is the first step, while the RDS for GO2–6 is the second step. Among the six oxidation concentrations considered, GO5 and GO6 have the lowest charge overpotentials of 0.05 and 0.06 V, respectively

Schematic diagram of cell fusion using a sequential nanosecond/microsecond electric field pulse combination.

<p>100-ns-long strong field pulse induced many tiny pores in the cell membrane, particularly in the junction region. After a brief delay, fusion process was followed by a low-field 10-microsecond pulse, which enlarged the pores.</p

Time evolution of the pore radius at three locations selected along the two-cell membrane was shown.

In (a). Blue represented the large cell pole, green represented the midpoint of the two-cell junction region, and red represented the small cell pole. (b) Results of the nanosecond pulses, (c) the microsecond pulses, and (d) the combined nanosecond/microsecond pulses.</p

Model parameters.

<p>Model parameters.</p

Constraints on the nature of the basement of the Junggar terrane indicated by the Laba Ordovician continental arc

With the improvement of regional geological research surrounding the Junggar Basin, whether Junggar terrane has a Precambrian basement is becoming one of the most popular topics of study. The Alashankou area, situated in the west of the Laba unit, is a westernmost trailing-shaped part of the Junggar terrane in the Central Asian Orogenic Belt. Precise petrological, geochronological and geochemical constraints of the metamorphic igneous rocks in the Alashankou area provide a better understanding of the tectonic evolution of the Laba unit, and combining these constraints with the previously geochronological and geophysical results is crucial to reevaluate the nature of the basement of the Junggar terrane. In this paper, our diagnostic results reveal that (1) the two-mica plagioclase schist, biotite amphibole plagioclase schist and granitic mylonite were formed in 447.6 Ma, 443.7 Ma and 428.8 Ma, and their protoliths are possible acidic tuff, andesite, and granite (porphyry), respectively; (2) these rocks have geochemical signatures that originated from typical continental arcs, including intermediate-acid calc-alkaline series rocks; the enrichment of enriched in large ion lithophile elements (LILE), Zr, and Hf; the depletion of Ta, Nb, P and Ti; (3) the granitic mylonite has 0.90 Ga–2.58 Ga inherited zircons, low εHf(t) to 8.11 and old TDM2 (Hf) age to 2.91 Ga, suggesting the existence of a Precambrian crust or similar materials as their sources. Based on these parameters, we suggest that (1) the metamorphic igneous rocks were formed in an Early Paleozoic continental arc along the west margin of the Junggar terrane, and (2) the Southern and Eastern Junggar Basin possibly has Precambrian basements, whereas the Northern Junggar Basin consists of accretionary complexes. Southward subduction of the Junggar oceanic plate beneath the Laba unit occurred in the Late Ordovician to Middle Silurian, and the regional continental accretion and metamorphism of the Laba unit happened in the Early Devonian.</p

Cell electrofusion based on nanosecond/microsecond pulsed electric fields - Fig 6

<p>Nanosecond pulse results were shown in (a), the microsecond pulse in (b), and the pulse combination in (c). The dashed purple line represented a pore density of 10¹³ m^-2.</p

Cell electrofusion based on nanosecond/microsecond pulsed electric fields - Fig 2

<p>(a) Modeled electrical pulse shapes, magnitudes, and pulse width. (b) Geometry of the simulation. The two cells were contacted to each other in a rectangular 200-μm-long by 100-μm-wide frame. The inset was magnifying part of the cell junction area.</p

Cell electrofusion based on nanosecond/microsecond pulsed electric fields - Fig 5

<p>(a-c) Two-dimensional pore density distributions along the surface of the two cell membranes. (d) Graph of pore densities along the surface of the two cell membranes. The dashed gray lines indicate the cell contact area.</p

Cell electrofusion based on nanosecond/microsecond pulsed electric fields - Fig 7

<p>(a) represented the TMV simulation region. In 7(b), the red, black, and the green curves represented the TMV under the nanosecond pulse, the microsecond pulse, and the nanosecond/microsecond pulse combination respectively.</p

Distribution of pore radius along the two-cell membrane.

<p>(a) Results of the nanosecond pulses, (b) the microsecond pulses, and (c) the nanosecond/microsecond pulses. (d) Graphical overlay of the results of the three pulses.</p