Template-Free Hydrothermal Synthesis of β-FeOOH Nanorods and Their Catalytic Activity in the Degradation of Methyl Orange by a Photo-Fenton-Like Process

The rod-shaped form of crystalline β-FeOOH (akaganeite) was prepared by the template-free hydrothermal method with urea as the homogeneous precipitant. X-ray diffraction, field-emission scanning electron microscope and Fourier transform infrared spectrum were used to characterize the resulting products. The degradation of methyl orange (MO) was studied using the prepared nanostructure materials in a photo-Fenton-like process. MO degradation was effectively achieved by hydroxyl radicals that were generated in the heterogeneous catalysis process. Specific surface area of the prepared β-FeOOH was an important factor affecting the efficiency of MO degradation, which depended on the synthesis conditions such as the reaction temperature, the initial concentration of urea and FeCl3.6H2O as well as the n(urea)/n(Fe3+) ratio. The photodegradation efficiencies slightly decreased with the increase of initial pH in the range of 4.5 - 9.5, which indicated the prepared β-FeOOH catalyst can well overcome the drawback of a narrow pH range of homogeneous Fenton reaction. β-FeOOH catalysts loading and H2O2 concentration also play important effect on the degradation efficiency of MO. The prepared β-FeOOH showed good ability of reuse for multiple trials.

Manipulating d-d orbital hybridization induced by Mo-doped Co_(9)S_(8) nanorod arrays for high-efficiency water electrolysis

Precisely refining the electronic structure of electrocatalysts represents a powerful approach to further optimize the electrocatalytic performance.Herein,we demonstrate an ingenious d-d orbital hybridization concept to construct Mo-doped Co_(9)S_(8) nanorod arrays aligned on carbon cloth(CC)substrate(abbreviated as Mo-Co_(9)S_(8)@CC hereafter)as a high-efficiency bifunctional electrocatalyst toward water electrolysis.It has experimentally and theoretically validated that the 4d-3d orbital coupling between Mo dopant and Co site can effectively optimize the H_(2)O activation energy and lower H^(*)adsorption energy barrier,thereby leading to enhanced hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)activities.Thanks to the unique electronic and geometrical advantages,the optimized Mo-Co_(9)S_(8)@CC with appropriate Mo content exhibits outstanding bifunctional performance in alkaline solution,with the overpotentials of 75 and 234 mV for the delivery of a current density of 10 mA cm^(-2),small Tafel slopes of 53.8 and 39.9 mV dec~(-1)and long-term stabilities for at least 32 and 30 h for HER and OER,respectively.More impressively,a water splitting electrolylzer assembled by the self-supported Mo-Co_(9)S_(8)@CC electrode requires a low cell voltage of 1.53 V at 10 mA cm^(-2)and shows excellent stability and splendid reversibility,demonstrating a huge potential for affordable and scalable electrochemical H_(2) production.The innovational orbital hybridization strategy for electronic regulation herein provides an inspirable avenue for developing progressive electrocatalysts toward new energy systems.

Single palladium atoms stabilized byβ-FeOOH nanorod with superior performance for selective hydrogenation of cinnamaldehyde

Atomically dispersed single atom catalysts represent an ideal means of converting less valuable organics into value-added chemicals of interest with high efficiency.Herein,we describe a facile synthetic approach to create defect-containingβ-FeOOH doped with isolated palladium atoms that bond covalently to the nearby oxygen and iron atoms.The presence of singly dispersed palladium atoms is confirmed by spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements.This single palladium atom catalyst manifests outstanding catalytic efficiency(conversion:99%;selectivity 99%;turnover frequency:2,440 h^(-1))in the selective hydrogenation of cinnamaldehyde to afford hydrocinnamaldehyde.Experimental measurements and density functional theory(DFT)calculations elucidate the high catalytic activity and the strong metal-support interaction stem from the unique coordination environment of the isolated palladium atoms.These findings may pave the way for the facile construction of single atom catalysts in a defect-mediated strategy for efficient organic transformations in heterogeneous catalysis.

α-FeOOH和α-Fe_(2)O3纳米棒的制备及其对高氯酸铵热分解的催化作用

以FeSO_(4)·7H_(2)O和CH_(3)COONa·3H_(2)O为原料,采用水热方法制备α-FeOOH纳米棒,将所得α-FeOOH纳米棒于250℃烧结2 h制备α-Fe_(2)O3纳米棒,采用差热-热重分析法研究了制备的α-FeOOH和α-Fe_(2)O3纳米棒对高氯酸铵热分解的催化性能。结果表明:在100℃水热反应6 h可制备得到平均直径为18 nm的纯相α-FeOOH纳米棒,再于250℃烧结2 h后获得平均直径为16 nm的纯六方相α-Fe_(2)O3纳米棒;α-Fe_(2)O3和α-FeOOH纳米棒对高氯酸铵热分解的催化效果显著,添加质量分数2%的α-Fe_(2)O3纳米棒和α-FeOOH纳米棒可使高氯酸铵的结束分解温度分别降低40,54℃,高温分解峰值温度分别降低51.1,61.6℃;当α-Fe_(2)O3纳米棒添加质量分数达到10%时,高氯酸铵的高温分解峰值温度降低约90.9℃。

Catalytic activities of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol

We report the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of4-chlorophenol（4-CP）. XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O3 and β-FeOOH was evident from the FTIR spectra.The removal efficiency of 4-CP was significantly enhanced in the presence of β-FeOOH compared to ozone alone. Removal efficiency of 99% and 67% was achieved after 40 min in the presence of combined ozone and catalyst and ozone only, respectively. Increasing catalyst load increased COD removal efficiency. Maximum COD removal of 97% was achieved using a catalyst load of 0.1 g/100 m L of 4-CP solution. Initial 4-CP concentration was not found to be rate limiting below 2 × 10^-3mol/L. The catalytic properties of the material during ozonation process were found to be pronounced at lower initial p H of 3.5.Two stage first order kinetics was applied to describe the kinetic behavior of the nanorods at low p H. The first stage of catalytic ozonation was attributed to the heterogeneous surface breakdown of O3 by β-FeOOH, while the second stage was attributed to homogeneous catalysis initiated by reductive dissolution of β-FeOOH at low p H.

α-FeOOH与Ag_(3)PO_(4)异质结复合材料的制备及光催化性能

针对磷酸银(Ag_(3)PO_(4))和羟基氧化铁(α-FeOOH)等材料因光生载流子复合速率过快而导致光催化性能差的问题,通过制备α-FeOOH与Ag_(3)PO_(4)的异质结复合材料(α-FeOOH@Ag_(3)PO_(4))来促进光生载流子的分离,从而提升材料的光催化性能。采用简单的水热法制备由纳米片组成的具有分级结构的α-FeOOH微球,然后使用原位沉积工艺将Ag_(3)PO_(4)颗粒均匀沉积在α-FeOOH微球表面,制备得到α-FeOOH@Ag_(3)PO_(4);分析所得异质结复合材料的微观结构、光吸收性能、亚甲基蓝降解性能和光电性能。结果表明:具有分级结构的α-FeOOH微球有利于Ag_(3)PO_(4)颗粒沉积,Ag_(3)PO_(4)颗粒粒径为3~8 nm;α-FeOOH@Ag_(3)PO_(4)吸收边发生红移,光电性能显著增强;α-FeOOH@Ag_(3)PO_(4)的光催化效率是α-FeOOH的75.0倍,是Ag_(3)PO_(4)的1.8倍;α-FeOOH@Ag_(3)PO_(4)是Type-Ⅱ型半导体异质结,光生载流子在异质结界面有效分离,提高了光催化效率和材料的稳定性。α-FeOOH@Ag_(3)PO_(4)具有较强的光催化活性,在光催化治理水污染领域有着广阔的应用前景。

Molecular dynamics simulation of interaction between nanorod and phospholipid molecules bilayer

Natural and artificially prepared nanorods'surfaces have proved to have good bactericidal effect and self-cleaning property.In order to investigate whether nanorods can kill the enveloped virus,like destroying bacterial cell,we study the interaction between nanorods and virus envelope by establishing the models of nanorods with different sizes as well as the planar membrane and vesicle under the Dry Martini force field of molecular dynamics simulation.The results show that owing to the van der Waals attraction between nanorods and the tail hydrocarbon chain groups of phospholipid molecules,the phospholipid molecules on virus envelope are adsorbed to nanorods on a large scale.This process will increase the surface tension of lipid membrane and reduce the order of lipid molecules,resulting in irreparable damage to planar lipid membrane.Nanorods with different diameters have different effects on vesicle envelope,the larger the diameter of nanorod,the weaker the van der Waals effect on the unit cross-sectional area is and the smaller the degree of vesicle deformation.There is synergy between the nanorods in the nanorod array,which can enhance the speed and scale of lipid adsorption.The vesicle adsorbed in the array are difficult to desorb,and even if desorbed,vesicle will be seriously damaged.The deformation rate of the vesicle adsorbed in the nanorod array exceeds 100%,implying that the nanorod array has a strong destructive effect on the vesicle.This preliminarily proves the feasibility of nanorod array on a surface against enveloped virus,and provides a reference for the design of corresponding nanorods surface.

Composites of In/C hexagonal nanorods and graphene nanosheets for high-performance electromagnetic wave absorption

In recent years,electromagnetic wave(EMW)absorption has been extensively investigated for solving EMW radiation and pollution.The metal-organic frameworks(MOFs)have attracted attention due to their low density and unique structure,which can meet the requirements of strong reflection loss(RL)and wide absorption bandwidth of EMW absorption materials.In this manuscript,indium nanoparticles/porous carbon(In/C)nanorods composites were prepared via the pyrolysis of nanorods-like In-MOFs at a low temperature of450°C.Indium nanoparticles are evenly attached and embedded on porous carbon.Low electrical conductivity of In/C nanorods is unfavorable to EMW absorption performance,which is due to the low temperature carbonization.Thus,graphene(Gr)nanosheets with high electrical conductivity are introduced to adjust electromagnetic parameters of In/C nanorods for enhancing EMW absorption.The minimum RL of the In/C-Gr-4 composite is up to-43.7 dB with a thin thickness of 1.30 mm.In addition,when the thickness is further reduced to 1.14 mm,the minimum RL of-39.3 dB at 16.1 GHz and effective absorption bandwidth of 3.7 GHz(from 14.3 to 18.0 GHz)can be achieved.This work indicates that In/C-Gr composites show excellent EMW absorption performance.

From kesterite 2D nanosheets to wurtzite 1D nanorods:controllable synthesis of Cu-Zn-Sn-S and their application in electrocatalytic hydrogen evolution

As typical quarternary copper-based chalcogenides,Cu–Zn–Sn–S nanocrystals(CZTS NCs)have emerged as a newfashioned electrocatalyst in hydrogen evolution reactions(HERs).Oleylamine(OM),a reducing surfactant and solvent,plays a significant role in the assisting synthesis of CZTS NCs due to the ligand effect.Herein,we adopted a facile one-pot colloidal method for achieving the structure evolution of CZTS NCs from 2D nanosheets to 1D nanorods assisted through the continuous addition of OM.During the process,the mechanism of OM-induced morphology evolution was further discussed.When merely adding pure 1-dodecanethiol(DDT)as the solvent,the CZTS nanosheets were obtained.As OM was gradually added to the reaction,the CZTS NCs began to grow along the sides of the nanosheets and gradually shrink at the top,followed by the formation of stable nanorods.In acidic electrolytic conditions,the CZTS NCs with 1.0 OM addition display the optimal HER activity with a low overpotential of 561 m V at 10 m A/cm^(2) and a small Tafel slope of 157.6 m V/dec compared with other CZTS samples.The enhancement of HER activity could be attributed to the contribution of the synergistic effect of the diverse crystal facets to the reaction.

Au@Ag Core-shell Nanorods Self-assembled on Polyelectrolyte Multilayers for Ultra-High Sensitivity SERS Fiber Probes

We demonstrated a chemical process in the fabrication of a SERS fiber probe with an ultrahigh sensitivity.The synthesis was carried out by preparing Au@Ag core-shell nanorods (Au@Ag-NRs) selfassembled on polyelectrolyte (PE) multilayers,for which Au@Ag-NRs were controlled by adjusting the silver layer thickness.The effect of silver layer thickness of Au@Ag-NRs on the SERS performance of the fiber probe was investigated.The SERS fiber probe shows the best performance when the silver layer thickness is controlled at 8.57 nm.Under the condition of optimizing silver layer thickness,the fiber probe exhibits ultra-high sensitivity (i e,10^(-10) M crystalline violet,CV),good reproducibility (i e,RSD of 3.5%) and stability.Besides,electromagnetic field distribution of the SERS fiber probe was also investigated.The strongest enhancement is found within the core of fiber,whereas a weakened electromagnetic field exists in the fiber cladding layer.The SERS fiber probe can be a good candidate in ultra-trace detection for biomedical and environmental areas.

Structural, Optical and Photocatalytic Properties of Cu2+ Doped ZnO Nanorods with Using HMTA Solvent Prepared by Hydrothermal Method

In this experiment, Cu2+ doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu2+ ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn2+). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn2+:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu2+ doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu2+ doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu2+ doping ratio of 2 mol.%.

Investigation of photoelectrocatalytic degradation mechanism of methylene blue by a-Fe_(2)O_(3) nanorods array

Efficiently and thoroughly degrading organic dyes in wastewater is of great importance and challenge.Herein,vertically oriented mesoporous a-Fe_(2)O_(3)nanorods array(a-Fe_(2)O_(3)-NA)is directly grown on fluorine-doped tin oxide(FTO)glass and employed as the photoanode for photoelectrocatalytic degradation of methylene blue simulated dye wastewater.The Ovsites on the a-Fe_(2)O_(3)-NA surface are the active sites for methylene blue(MB)adsorption.Electrons transfer from the adsorbed MB to Fe-O is detected.Compared with electrocatalytic and photocatalytic degradation processes,the photoelectrocatalytic(PEC)process exhibited the best degrading performance and the largest kinetic constant.Hydroxyl,superoxide free radicals,and photo-generated holes play a jointly leading role in the PEC degradation.A possible degrading pathway is suggested by liquid chromatography-mass spectroscopy analysis.This work demonstrates that photoelectrocatalysis by a-Fe_(2)O_(3)-NA has a remarkable superiority over photocatalysis and electrocatalysis in MB degradation.The in-depth investigation of photoelectrocatalytic degradation mechanism in this study is meaningful for organic wastewater treatment.

γ-FeOOH催化臭氧微气泡联合BAF工艺深度处理造纸废水

随着“双碳”目标的制定以及造纸废水重复利用政策的颁布,开发清洁高效、无二次污染的造纸废水深度处理技术意义重大。研究通过干湿交替-曝气氧化的技术方案制备了铁基催化剂,XRD、XPS等表征结果显示该催化剂的表层负载物为纤铁矿(γ-FeOOH)。建立了γ-FeOOH催化臭氧微气泡的反应体系,并系统研究了该体系对造纸废水生化出水中COD_(Cr)的去除效果。试验结果显示,当pH值为7、催化剂投加量为300 g/L、臭氧投加量为9.9 mg/min时,该体系对COD_(Cr)的去除率约为58%。基于上述结果,进一步建立γ-FeOOH催化剂-臭氧微气泡催化与曝气生物滤池(BAF)的联合降解体系,该联合体系连续运行时,对造纸废水生化出水中COD_(Cr)去除率为60%~70%。该联合体系在有效降解有机污染物的同时,无二次污染产生,无总盐引入,有利于造纸废水的循环利用,践行了“双碳”理念。

Manifolding active sites and in situ/operando electrochemical-Raman spectroscopic studies of single-metal nanoparticle-decorated CuO nanorods in furfural biomass valorization to H_(2) and 2-furoic acid

Here,CuO nanorods fabricated via pulsed laser ablation in liquids were decorated with Ir,Pd,and Ru NPs(loading~7 wt%) through pulsed laser irradiation in the liquids process.The resulting NPs-decorated CuO nanorods were characterized spectroscopically and employed as multifunctional electrocatalysts in OER,HER,and the furfural oxidation reactions(FOR).Ir-CuO nanorods afford the lowest overpotential of~345 mV(HER) and 414 mV(OER) at 10 mA cm^(-2),provide the highest 2-furoic acid yield(~10.85 mM) with 64.9% selectivity,and the best Faradaic efficiency~72.7% in 2 h of FOR at 1.58 V(vs.RHE).In situ electrochemical-Raman analysis of the Ir-CuO detects the formation of the crucial intermediates,such as Cu(Ⅲ)-oxide,Cu(OH)_(2),and Ir_x(OH)_y,on the electrode-electrolyte surface,which act as a promoter for HER and OER.The Ir-CuO ‖ Ir-CuO in a coupled HER and FOR-electrolyzer operates at~200 mV lower voltage,compared with the conventional electrolyzer and embodies the dual advantage of energy-saving H_(2) and 2-furoic acid production.

Au@α-Fe_(2)O_(3)纳米棒的制备及光催化性能

本工作通过水热法与磁控溅射法结合成功构建了表面均匀沉积纳米Au粒子的α-Fe_(2)O_(3)(Au@α-Fe_(2)O_(3))纳米棒,纳米Au粒子的负载量和形态分别由磁控溅射时间和热处理温度调控。在沉积5.1%的纳米Au粒子后,因纳米Au的表面等离子体共振(SPR)效应,Au@α-Fe_(2)O_(3)纳米棒在550 nm处出现了一个新的吸收峰,其带隙由2.20 eV变窄至1.95 eV。Au@α-Fe_(2)O_(3)纳米棒的荧光强度和电化学阻抗显著降低,光电流从0.27μA·cm^(-2)增大至0.45μA·cm^(-2)。纳米Au粒子既拓宽了Au@α-Fe_(2)O_(3)纳米棒的可见光吸收性能,又抑制了电子-空穴对的复合。与α-Fe_(2)O_(3)纳米棒相比,Au@α-Fe_(2)O_(3)纳米棒的光催化性能变得更加稳定,Au@α-Fe_(2)O_(3)纳米棒的光催化效率提高约一倍。

基于金纳米棒刻蚀比色法检测铁、铜离子

采用种子生长法制备金纳米棒(AuNRs)以构建光学传感器,用于Fe^(3+)和Cu^(2+)的高选择性快速可视化检测。在酸性环境中,Fe^(3+)和Cu^(2+)通过与KI溶液反应,将I-氧化成I2。I2刻蚀AuNRs,导致其纵向表面等离子体共振(LSPR)吸收峰蓝移,从而实现对Fe^(3+)和Cu^(2+)的检测。结果表明,反应温度为50℃时,添加0.8 mL 0.1 mol·L^(-1)HCl、2 mL AuNRs生长液和20 mmol·L^(-1)KI溶液,与2 mL 500μmol·L^(-1)Fe^(3+)或30μmol·L^(-1)Cu^(2+)反应25或90 min,可将AuNRs刻蚀至LSPR吸收峰消失。该方法对Fe^(3+)和Cu^(2+)检测具有高选择性和准确性,对于Fe^(3+)、Cu^(2+)共存体系的检测,可通过加入适量F-与Fe^(3+)生成配合物[FeF_(6)]^(3-)完成对Fe^(3+)的化学掩蔽,消除Fe^(3+)的干扰,实现共存体系中Cu^(2+)的准确检测。

α-FeOOH纳米棒的制备及其在催化降解甲基橙中的应用

采用空气氧化法制备了分散性较好的α-FeOOH纳米棒,并用XRD,SEM,N2吸附-脱附等手段对其进行了表征,在H2O2/α-FeOOH类Fenton条件下对甲基橙(MO)溶液进行处理,考察各种因素对溶液中MO降解的影响.结果表明,在酸性介质中α-FeOOH能有效催化降解水溶液中的MO,降解率随H2O2初始浓度增加而增加,但当H2O2初始浓度达5.47mol/L时,降解率反而下降.UV-Vis谱图显示,MO在80℃水浴中达到了很好的降解效果.

可见光照射下α-FeOOH光催化降解有机污染物的研究

以α-FeOOH为光催化剂,酸性桃红(SRB)为目标化合物,研究了可见光照射下光催化剂对SRB的降解,结果表明:在可见光(λ>420nm)照射下,SRB浓度为1·2×10-5mol·l-1,H2O2浓度为1·5×10-3mol·l-1,α-FeOOH为0·16g·l-1,pH=7·05时,SRB的降解效果最好,红外光谱分析表明,SRB降解产物为羧酸及胺类化合物.另外,采用苯甲酸荧光分析法间接测定体系中自由基的含量,表明此光催化降解过程主要涉及·OH历程.

β-FeOOH气凝胶的制备及表征

用氯化铁和氢氧化钠溶液为原料制得了块状β-FeOOH气凝胶，构成气凝胶的基本粒子为长约18um、直径约5um的棒状粒子，制备过程包括聚合铁水凝胶的制备和超临界干燥两部分．初步研究了溶液羟铁摩尔比（OH-／Fe(3+)）对气凝胶密度和比表面的影响，应用BET、TEM、XRD和Mossbauer谱等手段对气凝胶样品进行了表征．结果表明，气凝胶样品是由β-FeOOH超细微粒构成的具有连续网络结构的多孔性块状固体，随着溶液的羟铁摩尔比（OH-／Fe(3+)）的增大，气凝胶的密度增大，比表面减小．

均匀纺锤形α-FeOOH微晶的生长

用 Na_2CO_3作沉淀剂,在 FeSO_4水溶液中所形成的 FeCO_3悬浮液体系中,空气氧化合成均匀纺锤形α-FeOOH 微晶。用 K_2Cr_2O_7滴定法测定了不同碱比条件下的氧化反应速率;用 XRD 确定产物组成;用TEM 观察产物粒子的形貌。发现原料液碱比增大,铁离子浓度提高,反应温度提高及反应时间延长,都有利于使α-FeOOH 微晶尺寸增大和均匀性提高;掺入少量金属离子 Mn^(2+)、Cr^(3+)、Sn^(2+),亦有利于均匀纺锤形α-FeOOH 微晶轴比的提高。