Carbon-doped CuFe_(2)O_(4) with C-O-M channels for enhanced Fenton-like degradation of tetracycline hydrochloride: From construction to mechanism

Carbon-doped copper ferrite(C–CuFe_(2)O_(4))was synthesized by a simple two-step hydrothermal method,which showed enhanced tetracycline hydrochloride(TCH)removal efficiency as compared to the pure CuFe_(2)O_(4) in Fenton-like reaction.A removal efficiency of 94%was achieved with 0.2 g L^(-1) catalyst and 20 mmol L^(-1) H_(2)O_(2) within 90 min.We demonstrated that 5%C–CuFe_(2)O_(4) catalyst in the presence of H_(2)O_(2) was significantly efficient for TCH degradation under the near-neutral pH(5–9)without buffer.Multiple techniques,including SEM,TEM,XRD,FTIR,Raman,XPS M€ossbauer and so on,were conducted to investigate the structures,morphologies and electronic properties of as-prepared samples.The introduction of carbon can effectively accelerate electron transfer by cooperating with Cu and Fe to activate H_(2)O_(2) to generate·OH and·O_(2)^(-).Particularly,theoretical calculations display that the p,p,d orbital hybridization of C,O,Cu and Fe can form C–O–Cu and C–O–Fe bonds,and the electrons on carbon can transfer to metal Cu and Fe along the C–O–Fe and C–O–Cu channels,thus forming electron-rich reactive centers around Fe and Cu.This work provides lightful reference for the modification of spinel ferrites in Fenton-like application.

Plasmonic Ag nanoparticles decorated MIL-101(Fe) for enhanced photocatalytic degradation of bisphenol A with peroxymonosulfate under visible-light irradiation

Photocatalytic activation of peroxymonosulfate (PMS) has garnered a lot of interest in the field of wastewater treatment. Herein, a plasmonic Ag nanoparticles decorated MIL-101(Fe) hybrid was synthesized through a photodeposition process. Upon light irradiation, the Ag/MIL-101(Fe) exhibit reinforced photocatalytic activities for elimination of bisphenol A (BPA) with PMS. The optimized 2.0% Ag/MIL-101(Fe) composite presented the highest photocatalytic activity with kinetic constant k of 0.102 min-1, which was about 10-fold of the pristine MIL-101(Fe). Loading of plasmonic Ag into MIL-101(Fe) boosts photoinduced carrier separation and accelerates PMS activation to generate strong oxidative radicals. Photoelectrochemical tests and multiple spectroscopic studies confirmed the promoted charge carrier separation and transfer capability of Ag/MIL-101(Fe). Combining the results of radical trapping experiments and electron spin resonance (ESR), the formed SO4·-, ·OH, ·O2- and 1O2 had a significant role in the photocatalytic process. According to intermediate study, the degradation pathway was studied, and the possible mechanism was proposed.

Size and near-surface engineering in weak-oxidative confined space to fabricate 4 nm L1_(0)-PtCo@Pt nanoparticles for oxygen reduction reaction

The near-surface structure of the Pt-based alloy including the surface and subsurface structures is prominent to their electrocatalytic performance.Modulating the near-surface structure of PtCo intermetallics with small particle size could efficiently optimize the binding force between Pt and oxygen and finally enhance its oxygen reduction reaction(ORR)performance.Here we simultaneously achieve the size controlling and surface modulation of intermetallic nanoparticles(NPs)in a weak-oxidative confined space with abundant uncoordinated oxygen atoms.1–2 atomic layers of concave Pt-rich surface were successfully constructed on 4 nm L1_(0)-PtCo core after removing Co–O species which is derived from the segregation of the subsurface Co to the surface induced by the uncoordinated oxygen atoms.Owing to the elaborate structure,PtCo-1000/C catalyst shows significant improvement in both activity(1.290 A∙mg_(Pt)^(−1)and 1.529 mA∙cm_(Pt)^(−2) at 0.9 V vs.reversible hydrogen electrode(RHE))and stability(85.2%of initial mass activity after accelerated degression tests(ADTs))even the production is scaled up to gram level.Density functional theory calculations suggest that the cave Pt site optimizes the protonation of*O,which finally boosts the ORR performance.

高电容性能MXene电极对插层修饰离子的选择性

离子插层是提高Ti_(3)C_(2)TxMXene电化学性能的有效方法之一.然而,不同的插层离子对MXene的结构和电化学性能的影响是否相同这一问题尚不清楚.本文系统研究了Li+、Na+、K+、Cs+、Zn2+、Mg2+、SO_(4)2-和OH-等一系列离子插层后的MXene的结构特征和电化学性能.研究结果表明,插层离子的半径、电荷数和化学特性对插层效果都会产生影响.在所研究的插层剂中,由离子半径最大的一价阳离子Cs+和具有强碱性的阴离子OH-组成的插层剂CsOH对MXene具有较好的插层效果.插层后的MXene层间距增大,层间容纳了大量游离水,Ti的价态升高,片层表面有利于氧化还原反应的含O官能团增多,这都大大促进了电解液离子H+的扩散与存储.由此制备的电极的质量比电容大幅度提高,为原始MXene电极的7倍多,而且经过20,000次充放电循环后电容保持率未发生下降.本文为具有高电容性能的MXene和MXene基复合电极的合理设计和制备提供了指导.

rGO空间限域生长超薄In_(2)S_(3)纳米片用于构建高效准一维Sb_(2)Se_(3)基异质结光阴极

硒化锑(Sb_(2)Se_(3))属于窄带隙半导体材料,具有良好的光吸收特性,已逐渐应用于光电催化领域.独特的一维(Sb_(4)Se_(6))_(n)带状结构单元连接方式,使其载流子传输具有高度各向异性.本文通过气相输运沉积法和原位水热法成功构建了还原氧化石墨烯(rGO)修饰的准一维Sb_(2)Se_(3)@In_(2)S_(3)光陷阱异质结.研究结果表明,在rGO空间限域效应下,原位生长的非层状In_(2)S_(3)纳米片厚度从30 nm减小到10 nm,显著增加了光电极的电化学活性比表面积,进一步增强了光陷阱纳米结构对光的捕获能力.rGO和超薄In_(2)S_(3)纳米片共同修饰的准一维毛刷状Sb_(2)Se_(3)@In_(2)S_(3)-rGO纳米棒光电极在0 V(相对于可逆氢电极)的外加偏压下,光电流密度可达1.169 m A cm^(-2),约是Sb_(2)Se_(3)@In_(2)S_(3)和单体Sb_(2)Se_(3)的2倍和16倍,且稳定性良好,在中性条件下平均产氢速率为16.59μmol cm^(-2)h^(-1).实验结果和理论计算均表明,Ⅱ型异质结电荷传输方式是其光电化学增强的物理机制.以上工作为设计基于rGO修饰的复合光电极用于光电化学领域的研究提供了崭新的思路.

Hyperbranched magnetic polymer:highly efficient removal of Cr(Ⅵ)and application in electroplating wastewater

By using a two-step hydrothermal method and trithiocyanuric acid(TTCA),2,4,6-trihydrazino-1,3,5-triazine(THT),and Fe_(3)O_(4)as raw materials,a spherical magnetic adsorbent polymer(TTCA/THT@Fe_(3)O_(4))was synthesized to achieve the efficient removal of Cr(VI)from wastewater.Under optimal adsorption conditions,the maximum adsorption capacity of TTCA/THT@Fe_(3)O_(4)for Cr(VI)can reach 1340 mg∙g‒1.Notably,the removal efficiency can approach 98.9%,even at the lower concentration of 20 mg∙L^(‒1)Cr(VI).For actual wastewater containing Cr(VI),the Cr(VI)concentration was reduced from 25.8 to 0.4 mg∙L^(‒1),a remarkable 20%lower than the current industry discharge standard value.A mechanism for the high adsorption performance of Cr(VI)on TTCA/THT@Fe_(3)O_(4)was investigated using Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,and density functional theory.It can be plausibly attributed to the formation of Cr/N and Cr/S coordination bonds.Additionally,surface electrostatic adsorption,reduction effects,and the spherical polymer structure increase the contact area with Cr(VI),maximizing adsorption.The synergistic effect of adsorption and reduction enhances the adsorption performance of TTCA/THT@Fe_(3)O_(4)for Cr(VI)and total chromium in water.The resultant polymer has a simple preparation process,excellent adsorption performance,easy magnetic separation,and promising application for actual wastewater.

Regulating nitrogen vacancies within graphitic carbon nitride to boost photocatalytic hydrogen peroxide production

Introducing nitrogen vacancies is an effective method to improve the catalytic performance of g-C_(3)N_(4)-based photocatalysts,whereas understanding how nitrogen vacancies types affect the catalytic performance remains unclear.Herein,two different types of nitrogen vacancies were successfully introduced into g-C_(3)N_(4)by pyrolysis of melamine under argon and ammonia atmosphere with subsequent HNO3 oxidation.The pyrolysis atmosphere is found to have a significant influence on the introduced nitrogen vacancies type,where tertiary nitrogen groups(N_(3)C)and sp2-hybridized nitrogen atoms(N_(2)C)were the preferred sites for the formation of nitrogen vacancies under ammonia and argon pyrolysis,respectively.Moreover,nitrogen vacancies from N3C are experimentally and theoretically demonstrated to facilitate the narrowed band gap and the improved oxygen absorption capability.As expected,the optimal catalyst exhibits high H_(2)O_(2)yield of 451.8µM,which is 3.8 times higher than the pristine g-C_(3)N_(4)(119.0µM)after 4 h and good stability after10 photocatalytic runs.