Fe₃S₄/Fe₇S₈-promoted degradation of phenol via heterogeneous, catalytic H₂O₂ scission mediated by S-modified surface Fe²⁺ species

Choe, Yun Jeong,Byun, Ji Young,Kim, Sang Hoon,Kim, Jongsik Elsevier 2018 Applied catalysis. B, Environmental Vol.233 No.-

<P><B>Abstract</B></P> <P>Enhancing OH productivity via heterogeneous, catalytic H<SUB>2</SUB>O<SUB>2</SUB> activation is a long-standing conundrum in H<SUB>2</SUB>O purification and thus requires the renovation of conventional reaction systems. The initial step in realizing advanced H<SUB>2</SUB>O<SUB>2</SUB> decomposition via heterogeneous catalytic manner is the exploration of the solid capable of efficiently cleaving OO bond inherent to H<SUB>2</SUB>O<SUB>2</SUB> and minimizing the loss of catalytic species during vigorous reaction dynamics. While using phenol as a model compound for recalcitrants, this paper highlights the use of Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> as a catalyst to enhance OH productivity and thus promote phenol degradation via electro-Fenton reaction over conventional Fe<SUB>2</SUB>O<SUB>3</SUB>, Fe<SUB>3</SUB>O<SUB>4</SUB>, and other sulfide analogue (FeS<SUB>2</SUB>). Materials’ characterizations and kinetic interpretation of reaction runs under controlled environments served to substantiate the benefits which were provided by Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> during the reaction. Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> incorporated greater amount of S-modified, surface-exposed Fe<SUP>2+</SUP> sites to cleave H<SUB>2</SUB>O<SUB>2</SUB> than FeS<SUB>2</SUB>. This improved catalytic consequence of Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> (i.e., phenol conversion and initial reaction rate), as also evidenced by control runs detailing H<SUB>2</SUB>O<SUB>2</SUB> decomposition in conjunction with <I>tert</I>-butyl alcohol-driven OH scavenging. Filtration control runs as well as recycle runs were also used to verify that Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> could heterogeneously catalyze H<SUB>2</SUB>O<SUB>2</SUB> scission under the mild, adequate reaction environments, which were realized by the use of low electrical powers and the catalyst immobilized on a cathode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> with greater amount of surface Fe<SUP>2+</SUP> species to dissociate H<SUB>2</SUB>O<SUB>2</SUB> compared to FeS<SUB>2</SUB>. </LI> <LI> Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> with supported Fe<SUP>2+</SUP> sites to heterogeneously catalyze H<SUB>2</SUB>O<SUB>2</SUB> fragment. </LI> <LI> Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> with promoted catalytic H<SUB>2</SUB>O<SUB>2</SUB> scission ability compared to Fe<SUB>2</SUB>O<SUB>3</SUB>, Fe<SUB>3</SUB>O<SUB>4</SUB>, and FeS<SUB>2</SUB>. </LI> <LI> Fe<SUB>3</SUB>S<SUB>4</SUB>/Fe<SUB>7</SUB>S<SUB>8</SUB> with enhanced phenol degradation performance over other Fe-analogues. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Recyclable Fe3O4/Au Nanocomopsites for Oxidation Degradation of Methylene Blue in Near Neutral Solution

Yan Xing,Xiao-Hui Bai,Ming-Li Peng,Xiang-Rong Ma,Norbert Buske,Ya-Li Cui 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.10

Fe3O4/Au nanocomopsites (Fe3O4/Au NPs) with much improved catalytic activity were successfully fabricated through a simple seed growth method in aqueous solution. The petal-like structure, high saturation magnetization, the negatively charged sodium citrate-stabilized Fe3O4/Au NPs was characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and vibrating sample magnetometry (VSM). The activated-H2O2 ability of Fe3O4/Au NPs was evaluated by using methylene blue (MB) as a cationic phenothiazines dye to be degraded in near neutral solution. The results showed Fe3O4/Au NPs removed over 95% MB from an aqueous solution within 60 min under the optimum conditions. The apparent rate constant of Fe3O4/Au NPs was 10.8 x 10 -2 min -1 which was 43.2 and 8.3 times higher than pure Fe3O4 (2.5 x 10 -3 min -1) and Au (1.3 x 10 -2 min -1) NPs. The enhanced catalytic activity and increased oxidation rate constant probably owing to the synergistic effect between Fe3O4 and Au NPs to activate H2O2 generate a large amount of strong oxidizing species, such as ·OH. In addition, nanocrystalline structure of Fe3O4/Au NPs was also very important to the peroxidase-like effect, especially the interaction interface between Fe3O4 and Au NPs. Moreover, Fe3O4/Au NPs was stable and could be regenerated and reused for at least five cycles.

Tunneling Magnetoresistance in Sintered Fe_3O_4 Samples Diluted with Fe and α-Fe_2O_3

Kim, Ick-Jun,Moon, Seong-In 대한금속학회 2002 METALS AND MATERIALS International Vol.8 No.1

Electric transport and magnetoresistance characteristics were investigated for Fe_3O_(4-x) Fe(x=0, 10, 20 wt.%) samples and Fe_3O_(4-α)-Fe_2O_3 samples sintered at 500℃. For composition dependence of Fe_3O_(4-x) Fe samples, the largest room temperature MR, 3.3% at 10 kOe, was obtained from a Fe_3O_4-10 Fe sample. For the surface heat treatment dependence of Fe_3O_4 powders, the largest room temperature MR, 4% at 10 kOe, was obtained from a Fe_3O_(4-α)-Fe_2O_3 sample sintered with Fe_3O_4 powders heated at 200℃ in air. It was found that these enhanced MR ratios always appear together with the appropriate excess resistance which is regarded as the tunneling barrier. These enhanced MR ratios of Fe_3O_4-10 Fe and Fe_3O_(4-α)-Fe_2O_3 samples can be explained by the increased interparticle contact sites and the appropriate thickness of α-Fe_2O_3, respectively.

생의학적 응용을 위한 Fe3O4 복합 나노입자의 제조

배성수(Bae, Sung-Su),우엔테쭝(Nguyen, The Dung),김교선(Kim, Kyo-Seon) 강원대학교 산업기술연구소 2016 産業技術硏究 Vol.36 No.1

Superparamagnetic Fe3O4 nanoparticles with particle size from 10 to 20 nm were synthesized by coprecipitation method. Subsequently, the Fe3O4 nanoparticles were used to fabricate Fe3O4 /SiO2 core-shell nanoparticles by sol-gel method. The Fe3O4 /SiO2 nanoparticles synthesized by sol-gel method exhibit the high uniformities of particle size and shape. We also investigated the heating characteristics of Fe3O4 and Fe3O4 /SiO2 nanoparticles for biomedical applications. The Fe3O4 nanoparticles show the faster temperature increase and the higher specific loss power(SLP) value than the Fe3O4 /SiO2 nanoparticles.

Enhanced oxygen evolution reaction over glassy carbon electrode modified with NiOx and Fe3O4

Reham Helmy Tammam,Amany Mohamed Fekry,Mahmoud Mohamed Saleh 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.11

Magnetite iron oxide (Fe3O4)/nickel oxide (NiOx) modified glassy carbon (GC) electrode shows enhancement of oxygen evolution reaction (OER) compared to GC electrode modified with single NiOx or Fe3O4 nanoparticles. Many techniques such as linear and cyclic sweep voltammetry, electrochemical impedance spectroscopy (EIS) have been employed. Field-emission scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) are both used for characterization of the electrocatalysts. Effect of loading amount of both NiOx and Fe3O4 and the order of deposition on the OER was studied. A significant improvement of the electrocatalytic properties of the Fe3O4/NiOx binary catalyst modified GC is obtained when NiOx is electrodeposited on GC/Fe3O4 (i.e. GC/Fe3O4/NiOx) compared to GC/NiOx/Fe3O4 (where NiOx is deposited first on the GC then Fe3O4). The use of GC/Fe3O4/NiOx (where Fe3O4 is deposited first on the GC then NiOx) for OER in alkaline solution support higher currents and consequently negative shifts of the onset potential of OER compared to that of GC/NiOx or GC/Fe3O4. The obtained electrochemical impedance parameters confirmed the above conclusions. Tafel parameters confirm the superior activity of GC/Fe3O4/ NiOx and give insight into the mechanism of the OER on the above electrodes.

Oxidative degradation of the antibiotic oxytetracycline by Cu@Fe₃O₄ core-shell nanoparticles

Pham, Van Luan,Kim, Do-Gun,Ko, Seok-Oh Elsevier 2018 The Science of the total environment Vol.631 No.-

<P><B>Abstract</B></P> <P>A core-shell nanostructure composed of zero-valent Cu (core) and Fe<SUB>3</SUB>O<SUB>4</SUB> (shell) (Cu@Fe<SUB>3</SUB>O<SUB>4</SUB>) was prepared by a simple reduction method and was evaluated for the degradation of oxytetracycline (OTC), an antibiotic. The Cu core and the Fe<SUB>3</SUB>O<SUB>4</SUB> shell were verified by X-ray diffractometry (XRD) and transmission electron microscopy. The optimal molar ratio of [Cu]/[Fe] (1/1) in Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> created an outstanding synergic effect, leading to >99% OTC degradation as well as H<SUB>2</SUB>O<SUB>2</SUB> decomposition within 10min at the reaction conditions of 1g/L Cu@Fe<SUB>3</SUB>O<SUB>4</SUB>, 20mg/L OTC, 20mM H<SUB>2</SUB>O<SUB>2</SUB>, and pH3.0 (and even at pH9.0). The OTC degradation rate by Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> was higher than obtained using single nanoparticle of Cu or Fe<SUB>3</SUB>O<SUB>4</SUB>. The results of the study using radical scavengers showed that OH is the major reactive oxygen species contributing to the OTC degradation. Finally, good stability, reusability, and magnetic separation were obtained with approximately 97% OTC degradation and no notable change in XRD patterns after the Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> catalyst was reused five times. These results demonstrate that Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> is a novel prospective candidate for the pharmaceutical and personal care products degradation in the aqueous phase.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> core-shell nanostructure was synthesized by a simple reduction method. </LI> <LI> The optimal moles ratio of [Cu]/[Fe] in Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> was found is 1/1. </LI> <LI> Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> shows superior catalytic activity than the single Cu NPs and Fe<SUB>3</SUB>O<SUB>4</SUB> NPs. </LI> <LI> Cu@Fe<SUB>3</SUB>O<SUB>4</SUB> possesses less pH dependent and maintain high activity even at pH=9.0. </LI> <LI> Cu NPs was major contributed in the Cu@Fe<SUB>3</SUB>O<SUB>4</SUB>/H<SUB>2</SUB>O<SUB>2</SUB> system for OTC degradation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

활성화된(Fe_1-xMn_x)₃O_4-_δ과 (Fe_1-xCo_x)₃O_4-_δ의 이산화탄소 분해 특성

박원식,오경환,이상인,서동수,Park, Won-Shik,Oh, Kyoung-Hwan,Rhee, Sang-In,Suhr, Dong-Soo 한국재료학회 2013 한국재료학회지 Vol.23 No.4

Activated magnetite ($Fe_3O_{4-{\delta}}$) has the capability of decomposing $CO_2$ proportional to the ${\delta}$-value at comparatively low temperature of $300^{\circ}C$. To enhance the $CO_2$ decomposition capability of $Fe_3O_{4-{\delta}}$, $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$ were synthesized and then reacted with $CO_2$. $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ powders having Fe to Co mixing ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 were synthesized by co-precipitation of $FeSO_4{\cdot}7H_2O$ and $CoSO_4{\cdot}7H_2O$ solutions with a $(NH_4)_2C_2O_4{\cdot}H_2O$ solution. The same method was used to synthesize $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ powders having Fe to Mn mixing ratios of 9:1, 8:2, 7:3, 6:4, 5:5 with a $MnSO_4{\cdot}4H_2O$ solution. The thermal decomposition of synthesized $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ and $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ was analyzed in an Ar atmosphere with TG/DTA. The synthesized powders were heat-treated for 3 hours in an Ar atmosphere at $450^{\circ}C$ to produce activated powders of $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$. The activated powders were reacted with a mixed gas (Ar : 85 %, $CO_2$ : 15 %) at $300^{\circ}C$ for 12 hours. The exhaust gas was analyzed for $CO_2$ with a $CO_2$ gas analyzer. The decomposition of $CO_2$ was estimated by measuring $CO_2$ content in the exhaust gas after the reaction with $CO_2$. For $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$, the amount of $Mn^{2+}$ oxidized to $Mn^{3+}$ increased as x increased. The ${\delta}$ value and $CO_2$ decomposition efficiency decreased as x increased. When the ${\delta}$ value was below 0.641, $CO_2$ was not decomposed. For $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$, the ${\delta}$ value and $CO_2$ decomposition efficiency increased as x increased. At a ${\delta}$ value of 0.857, an active state was maintained even after 12 hours of reaction and the amount of decomposed $CO_2$ was $52.844cm^3$ per 1 g of $(Fe_{0.5}Co_{0.5})_3O_{4-{\delta}}$.

A BIO-INSPIRED POLYDOPAMINE APPROACH TO PREPARATION OF GOLD-COATED Fe3O4 CORE-SHELL NANOPARTICLES: SYNTHESIS, CHARACTERIZATION AND MECHANISM

PENG AN,FANG ZUO,XINHUA LI,YUANPENG WU,JUNHUA ZHANG,ZHAOHUI ZHENG,XIAOBIN DING,YUXING PENG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.6

A biomimetic and facile approach for integrating Fe3O4 and Au with polydopamine (PDA) was proposed to construct gold-coated Fe3O4 nanoparticles (Fe3O4@Au–PDA) with a core–shell structure by coupling in situ reduction with a seed-mediated method in aqueous solution at room temperature. The morphology, structure and composition of the core–shell structured Fe3O4@Au–PDA nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The formation process of Au shell was assessed using a UV-Vis spectrophotometer. More importantly, according to investigating changes in PDA molecules by Fourier transform infrared spectroscopy (FTIR) and in preparation process of the zeta-potential data of nanoparticles, the mechanism of core–shell structure formation was proposed. Firstly, PDA-coated Fe3O4 are obtained using dopamine (DA) self-polymerization to form thin and surface-adherent PDA films onto the surface of a Fe3O4 "core". Then, Au seeds are attached on the surface of PDA-coated Fe3O4 via electrostatic interaction in order to serve as nucleation centers catalyzing the reduction of Au3+ to Au0 by the catechol groups in PDA. Accompanied by the deposition of Au, PDA films transfer from the surface of Fe3O4 to that of Au as stabilizing agent. In order to confirm the reasonableness of this mechanism, two verification experiments were conducted. The presence of PDA on the surface of Fe3O4@Au–PDA nanoparticles was confirmed by the finding that glycine or ethylenediamine could be grafted onto Fe3O4@Au–PDA nanoparticles through Schiff base reaction. In addition, Fe3O4@Au–DA nanoparticles, in which DA was substituted for PDA, were prepared using the same method as that for Fe3O4@Au–PDA nanoparticles and characterized by UV-Vis, TEM and FTIR. The results validated that DA possesses multiple functions of attaching Au seeds as well as acting as both reductant and stabilizing agent, the same functions as those of PDA.

Deposition of Fe₃O₄ on oxidized activated carbon by hydrazine reducing method for high performance supercapacitor

Oh, Ilgeun,Kim, Myeongjin,Kim, Jooheon Elsevier 2015 Microelectronics and reliability Vol.55 No.1

<P><B>Abstract</B></P> <P>Oxidized activated carbon/Fe<SUB>3</SUB>O<SUB>4</SUB> (AC/Fe<SUB>3</SUB>O<SUB>4</SUB>) composites for supercapacitor electrodes were synthesized by a reduction method. Poly(vinylpyrrolidone) was added as a dispersing agent for homogeneous deposition of Fe<SUB>3</SUB>O<SUB>4</SUB> on AC. The obtained products were identified as AC/Fe<SUB>3</SUB>O<SUB>4</SUB> by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Morphological characterization of AC/Fe<SUB>3</SUB>O<SUB>4</SUB> was carried out by field emission scanning electron microscopy (FE-SEM); the results clearly showed the formation of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles about 30nm in diameter on AC. Moreover, by using N<SUB>2</SUB> adsorption/desorption isotherm analysis, we confirmed that surface areas and pore volumes decreased with increasing Fe<SUB>3</SUB>O<SUB>4</SUB> content. We also carried out electrochemical characterization of AC and AC/Fe<SUB>3</SUB>O<SUB>4</SUB> composites. Remarkably, we found that the value of specific capacitance increased significantly from 99.4Fg<SUP>−1</SUP> of raw AC to 202.6Fg<SUP>−1</SUP> of AC/Fe<SUB>3</SUB>O<SUB>4</SUB> composites at 10mVs<SUP>−1</SUP> of scan rate. This result can be ascribed to a synergistic effect of the combination of electrical double-layer capacitance and pseudo-capacitance properties. This research represents a valuable contribution to the application of supercapacitor electrodes in regard to cost effectiveness and simple fabrication.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nano-sized Fe<SUB>3</SUB>O<SUB>4</SUB> is formed on activated carbon surface as a hybrid material. </LI> <LI> Fe precursor was reduced to Fe<SUB>3</SUB>O<SUB>4</SUB> via chemical reduction by hydrazine method. </LI> <LI> Fe<SUB>3</SUB>O<SUB>4</SUB> contents in the composites optimized for electrochemical performance. </LI> <LI> Higher electrical performance than other carbon/Fe<SUB>3</SUB>O<SUB>4</SUB> composite electrodes. </LI> <LI> Fe<SUB>3</SUB>O<SUB>4</SUB> and activated carbon is cost effective and eco-friendly materials. </LI> </UL> </P>

In uence of Fe3O4 on the BiSb4Te7.5 Thermoelectric Materials Prepared by Mechanical Alloying

최우석,황성두,박익민,박용호 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

Because of their high figure of merit (Z) value, bismuth antimony tellurides are widely used in various thermoelectric cooling devices operating at temperatures near room temperature. The in uence of Fe3O4 (0 ~ 0.1 wt.%) addition on the thermoelectric properties of p-type BiSb4Te7.5 alloy is reported. Specimens were fabricated by mechanical alloying and pulse discharge sintering. The electrical conductivity and the power factor were decreased and the Seebeck coefficient was increased with increasing Fe3O4 content. The thermal conductivity decreased with the addition of Fe3O4 and the measured value in the alloy containing 0.1 wt.% Fe3O4 was 0.814 W/Km, 20 % lower than that of the Fe3O4 free alloy. The highest Z value was, therefore, achieved in the alloy containing 0.01 wt.% Fe3O4 and was 3.1 × 10-3 /K. Because of their high figure of merit (Z) value, bismuth antimony tellurides are widely used in various thermoelectric cooling devices operating at temperatures near room temperature. The in uence of Fe3O4 (0 ~ 0.1 wt.%) addition on the thermoelectric properties of p-type BiSb4Te7.5 alloy is reported. Specimens were fabricated by mechanical alloying and pulse discharge sintering. The electrical conductivity and the power factor were decreased and the Seebeck coefficient was increased with increasing Fe3O4 content. The thermal conductivity decreased with the addition of Fe3O4 and the measured value in the alloy containing 0.1 wt.% Fe3O4 was 0.814 W/Km, 20 % lower than that of the Fe3O4 free alloy. The highest Z value was, therefore, achieved in the alloy containing 0.01 wt.% Fe3O4 and was 3.1 × 10-3 /K.