“…3300 cm −1 should result from the hydroxyl group (−OH) in the structure. 42 As shown by the UV−vis spectrum in Figure 2b, 1 exhibits optical absorption in the visible light region from 400 to 700 nm with a band gap energy of ca. 2.19 eV estimated from the Tauc plot (Figure S7).…”
Photocatalysis is an efficient and sustainable approach to convert solar energy into chemical energy, simultaneously supplying valuable chemicals. In this study, a novel metal−organic framework (MOF) compound is constructed from anthracene-based organic linkers, which shows visible-light absorption and efficient photoinduced charge generation property. It was applied for triggering photooxidation of benzylamines and sulfides in the presence of environmental benign oxidants of molecular oxygen or hydrogen peroxide. Results show that it is a highly selective photocatalyst for oxidation reactions to produce valuable imines or sulfoxides. We further investigate the underlying mechanism for these photocatalytic reactions by recognizing reactive oxygen species in the reactions. It has been demonstrated that the superoxide radical (O 2•− ), generated by electron transfer from a photoexcited MOF to oxidants, serves as the main active species for the oxidations. The work demonstrates the great potential of photoactive MOFs for the transformation of organic chemicals into valuable complexes.
“…3300 cm −1 should result from the hydroxyl group (−OH) in the structure. 42 As shown by the UV−vis spectrum in Figure 2b, 1 exhibits optical absorption in the visible light region from 400 to 700 nm with a band gap energy of ca. 2.19 eV estimated from the Tauc plot (Figure S7).…”
Photocatalysis is an efficient and sustainable approach to convert solar energy into chemical energy, simultaneously supplying valuable chemicals. In this study, a novel metal−organic framework (MOF) compound is constructed from anthracene-based organic linkers, which shows visible-light absorption and efficient photoinduced charge generation property. It was applied for triggering photooxidation of benzylamines and sulfides in the presence of environmental benign oxidants of molecular oxygen or hydrogen peroxide. Results show that it is a highly selective photocatalyst for oxidation reactions to produce valuable imines or sulfoxides. We further investigate the underlying mechanism for these photocatalytic reactions by recognizing reactive oxygen species in the reactions. It has been demonstrated that the superoxide radical (O 2•− ), generated by electron transfer from a photoexcited MOF to oxidants, serves as the main active species for the oxidations. The work demonstrates the great potential of photoactive MOFs for the transformation of organic chemicals into valuable complexes.
“…Recently, the first-row transition catalysts, such as Ni-, Fe-, Co-, Cu-, Mn-based materials, have been used to be the possible alternatives, not only because of their abundant reserves in the earth but also their inexpensive nature compared with the novel metals (Du and Eisenberg, 2012;Gong et al, 2013;Dou et al, 2016;Krehula et al, 2018;Liu et al, 2019). The previous reports have pointed out that Ni-based materials have a large potential as the OER catalysts for water splitting and are regarded as one type of excellent electrocatalysts (Subbaraman et al, 2012).…”
Electrocatalytic water splitting is an efficient route to generate renewable energy sources, in which the noble metal materials are usually used as electrocatalysts. But the high price and scarcity of these catalysts impede their large-scale applications. Ni-based materials are considered to be the most suitable catalytic materials to substitute these noble metal materials. In this paper, the monodispersed α-Ni(OH) 2 microspheres assembled by ultrathin nanosheets were synthesized by a facile solvothermal method. This method was surfactant-free and no precipitator was used. The as-obtained products were well-characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), thermal gravimetric (TG) analysis, and X-ray photoelectron spectroscopy (XPS). The results of N 2 adsorption/desorption isotherm indicate that the BET surface area of the products was 169.94 m 2 g −1 , and the pore-size distribution centered at 3.5 nm. Then, the electrochemical properties were evaluated by linear sweep voltammetry (LSV) in 1 M KOH. At a current density of 10 mA cm 2 , the overpotential for the α-Ni(OH) 2 -MS is 320 mV, and the Tafel slope is 98.7 mV dec −1 , indicating its excellent reaction kinetics for an efficient catalyst toward oxygen evolution reaction (OER).
“…The Fe impurities also play an important role on the crystal structure of precursor samples. As shown in Figure a 3 , all Fe2NCM precursor samples hold the same crystal structure with the VNCM precursor, and their diffraction patterns correspond to the single-phase α-Ni(OH) 2 without any impurity phase . On the other hand, for Fe 3+ -based precursor samples, the 0.2Fe3NCM and 1Fe3NCM precursor samples still keep the single-phase α-Ni(OH) 2 structure, while the 5Fe3NCM precursor exhibits a mixed structure of α-Ni(OH) 2 and β-Ni(OH) 2 .…”
Section: Resultsmentioning
confidence: 86%
“…As shown in Figure 1a 3 , all Fe2NCM precursor samples hold the same crystal structure with the VNCM precursor, and their diffraction patterns correspond to the single-phase α-Ni(OH) 2 without any impurity phase. 47 On the other hand, for Fe 3+ -based precursor samples, the 0.2Fe3NCM and 1Fe3NCM precursor samples still keep the single-phase α-Ni(OH) 2 structure, while the 5Fe3NCM precursor exhibits a mixed structure of α-Ni(OH) 2 and β-Ni(OH) 2 . The appearance of the β-Ni(OH) 2 structure mainly arises from the charge imbalance caused by the presence of trivalent Fe 3+ cations in the structure of α-Ni(OH) 2 , which is neutralized by the incorporation of anions between Ni(OH) 2 layers.…”
Iron
impurities are generally included in the obtained leaching
liquor solution during the hydrometallurgical recycling method of
spent lithium-ion batteries (LIBs) due to the usage of iron in battery
casings and machinery parts of recycling equipment, which would definitely
affect the physical and electrochemical features of the recovered
active materials. In this work, the effects of iron impurity with
different valence states (Fe2+ and Fe3+) and
gradient concentrations (0.2, 1.0, and 5.0 at. %) for the obtained
LiNi0.6Co0.2Mn0.2O2 (NCM622)
cathodes are fully studied. It is found that Fe3+ impurity
could easily lower the tap density and average size of NCM622 particles
and even introduce some impurity phases in the NCM622 structure at
high concentration (5.0 at. %), leading to much lower specific capacity,
worse rate capability, and cycling performance of the Fe3+-based NCM622 cathode. On contrast, with certain concentrations of
Fe2+ impurity (0.2 and 1.0 at. %), the NCM622 cathode material
exhibits comparable and much better electrochemical properties compared
with the virgin NCM622 materials. Based on these results, the valence
of Fe impurity should be considered and controlled as well as its
concentration during the recycling process design for spent LIBs.
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