Environmental Science-Nano
·
2022
·Vol. 9
·期 9
·3407-3416
·
IF 9.473
Han Song,Xinwen Ou,Mengye Wang,Yan Zhang,Zhang Lin
H2 production during the transformation of Fe(OH)2 into magnetite (i.e., Schikorr reaction), has a significant impact on many environmental applications, including the long-term effectiveness of permeable reactive barriers composed of zerovalent iron and the stability of geological radioactive waste repository. However, the reactivity of the Schikorr reaction is not systematically evaluated and its chemical mechanism still remains controversial. Here, we investigate water reduction on the Fe(OH)2 surfaces with the help of an interface-reaction model between water and Fe(OH)2. The Fe(OH)2 hexagonal nanosheets prepared using a coprecipitation method possess dominantly exposed (001) and (100) facets. As unveiled by the DFT simulations, the (001) Fe(OH)2 facet only exposes OH, which is, therefore, inert to water reduction. Moreover, the active Fe-exposed (100) Fe(OH)2 facet is more thermodynamically favourable for water adsorption and dissociation than the (101) and (102) facets. However, the high energy barrier for water dissociation (2.79 eV) may restrict the rate of water reduction on the Fe(OH)2 facet. In addition, the capacity of (100), (101), and (102) Fe(OH)2 facets to adsorb OH− is stronger than that for H2O, which further inhibits water reduction. Furthermore, DOS calculations manifest that Fe d orbitals play a significant role in H2O adsorption, indicating that manipulating the electronic structure of the Fe site is a critical path to mediate water reduction in Fe(OH)2. Our study provides new insights into the understanding of the mechanism of the phase transformation of Fe(OH)2 under anaerobic conditions in environmental and earth sciences.
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ACS Applied Nano Materials
·
2022
·
IF 6.14
Yue Liu,Xukun Zhu,Ling Qin,Tong Zhang,Shuhan Wang,Yachao Jin,Li Song,Ming-Dao Zhang
The construction of special heterogeneous interface structures without precious metals is found to be efficient for the development of low-cost and high-activity hydrogen evolution reduction (HER) catalysts. Here, we report a moderate method to develop an efficient and stable HER electrode especially composed of the Co2(OH)2CO3 (COC) nanowire substrate modified by benzenehexol (HOB) molecules. This kind of interfacial structure leads to prominent electrocatalytic HER performance in an alkaline environment with a low overpotential of 130.8 mV at a current of 20 mA cm–2. Meanwhile, density functional theory (DFT) calculations reveal that the nanoscale synergistic interfacial mechanism and strong electron interaction between HOB and COC can reduce the activation energy for HER.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuxiang Li,Xi Chen,Lei Zhang,Ruishan Han,Iftikhar Hussain,Xiaoxia Ma,Kaili Zhang
Metastable intermolecular composites (MICs) composed by solid fuel and oxidizer can undergo violent redox reaction with release of huge amount of energy. Integration of MIC with microelectromechanical-system (MEMS) is of particular interest to meet the demand of miniaturization in modern pyrotechnic devices. Meanwhile, fluorine-containing oxidizers are favored in MIC owing to their potential to fluorinate the oxide passivation layer in common elemental fuels. Herein, Co(OH)F was employed for the first time as a novel fluorine-containing oxidizer in Al-based MIC. Vertically aligned Co(OH)F@Al nanobelt arrays (NAs) with tunable morphology were successfully fabricated on a variety of substrates (Si, glass, Ni, Cu, Ti) via a facile hydrothermal synthesis followed by electron beam evaporation. The whole fabrication process is highly compatible with modern MEMS technology. The thermal behavior of pure Co(OH)F and Co(OH)F@Al composites was comprehensively investigated by TG-DSC and a series of ex-situ and in-situ characterization. It was found that, Co(OH)F@Al composites achieved main exothermal reaction before melting of Al regardless of morphology and equivalence ratio. This feature is attributed to the etching of Al 2 O 3 shell by HF released from Co(OH)F which is termed as pre-ignition reaction. To elucidate the effect of micro-structure on the actual specific heat release, we proposed a phenomenological model which can be a reference for future micro-structure design of MIC.
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Environmental Science-Nano
·
2021
·Vol. 8
·期 12
·3833-3845
·
IF 8.131
Tingting Li,Yangsai Lyu,Jia Li,Chengyan Wang,Ningning Xing,Jie Yang,Min Zuo
Micromotors have held great promise for environmental treatment due to their unique self-propelled movement that can significantly accelerate the chemical process in solution. Herein, we have developed a new AO–Mn2O3/γ-AlO(OH) fluorescent micromotor using renewable and uniquely hollow kapok fibers as biological templates. The AO–Mn2O3/γ-AlO(OH) micromotor was powered by the asymmetric decomposition of hydrogen peroxide fuel catalyzed by Mn2O3, reaching a maximum speed of 139.6 μm s−1 in 3% H2O2 solution. The micromotor revealed a markedly enhanced fluorescence effect compared to both pure AO solution and non-micromotor counterparts and exhibited excellent selectivity and sensitivity for Hg2+ detection. The detection range and limit for Hg2+ were 5 × 10−8–5 × 10−5 M and 2.25 × 10−8 M, respectively. The enhanced Hg2+ sensing benefited from the synergy of enhanced fluorescence via the inhibition of the dimerization of AO, fluorescence quenching induced by charge transfer and the enhanced contact between the micromotor and Hg2+ ions resulted from the self-propelled motion. This micromotor-assisted fluorescence detection idea provided a new strategy for the development of sensors with high sensitivity.
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AICHE JOURNAL
·
2023
·
IF 3.7
Yong Li,Rui Jia,Ruonan Tan,Ziqiang Hong,Jingjing Gu,Peng Cui,Suixin Zhang,Hongwei Shao,Jin Ran,Cen-Feng Fu
OH − sieving membranes provide a valuable means for treating alkaline effluents but their development presents several challenges. In this study, the concept of ionization engineering is applied to two-dimensional (2D) laminated membranes to facilitate OH − separation. This concept is demonstrated through the stacking of the self-designed sulfonated graphene oxide (SGO) nanosheets to fabricate 2D membranes. The SGO membranes enhance synergistically the OH − dialysis coefficients and separation factors when treating simulated NaOH/Na 2 WO 4 alkaline wastewater, compared with the performance of 2D GO membranes and commonly adopted polymeric cation exchange membranes. Furthermore, the separation factor achieved by the SGO membranes is considerably higher than that of most of the existing alkali recovery membranes. Results of molecular dynamics simulations indicate that the high efficiency of OH − separation in the 2D SGO confined channels is attributable to dehydration effects and intensified electrostatic repulsion. Overall, this research provides an alternative strategy for achieving rapid OH − sieving through the ionization of 2D confined channels.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
A.Y. Chen,H.H. Liu,P. Qi,X.F. Xie,M.T. Wang,X.Y. Wang
3D flower-like MoS 2 /NiCo(OH) 2 CO 3 (MoS 2 /NiCoHC) composites are synthesized by a hydrothermal method using MoS 2 nanospheres as precursors. The microstructure of the composite is characterized by X-ray diffraction, Raman spectroscopy , scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The MoS 2 nanospheres are served as nucleating agent to trigger the formation of NiCoHC nanosheets , which self-assemble into 3D flower-like MoS 2 /NiCoHC particles. The MoS 2 /NiCoHC composites exhibit a high supercapacitive performance with a specific capacity of 583 C g −1 (1296 F g −1 ) at 1 A g −1 and a long-term cycling stability by retaining 94.3% after 2000 cycles in 2 M KOH. Moreover, the asymmetric supercapacitor of MoS 2 /NiCoHC as the positive electrode and commercial active carbon as the negative electrode achieves a high power density of 375 W kg −1 at 16.4 Wh kg −1 . The enhanced performance of the MoS 2 /NiCoHC composite can be attributed to the larger surface area provided by 3D flower-like structure and the synergy of the two hybrids.
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CHEMISTRY OF MATERIALS
·
2020
·
IF 9.567
Yangfan Lin,Jingwei Jiang,Yaguang Zhang,Xueqin He,Jianguo Ren,Peng He,Chunlei Pang,Chengmao Xiao,Deren Yang,Ning Du
The promoting effect of hydroxyls on a silicon surface on the decomposition of an electrolyte is studied by comparing the performance of silicon–hydroxyl (Si–OH) and silicon–alkyl (Si–C3H7) electrodes. X-ray photoelectron spectroscopy (XPS) characterization of solid electrolyte interphase (SEI) layers on both electrodes demonstrates the influencing mechanism that hydroxyls can react with LiPF6 to form POF3, which further induces the decomposition of the electrolyte solution. This study provides a new consideration that limiting the amount of hydroxyls on the silicon surface in an appropriate range is significant to the electrochemical performance of silicon-based anode materials.
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Natural Product Communications
·
2020
·
IF 0.468
Qiushan Zhang,Jin Shao,Tong Zhao,Lei He,Huiping Ma,Linlin Jing
In the present study, the antioxidant property of 4 flavones (moslosooflavone, wogonin, isowogonin, and norwogonin) was evaluated using 6 different assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH·), superoxide (O2 •−), and nitric oxide (NO) radical scavenging assays, ferrous iron chelation, reducing power, and total antioxidant capacity. The 4 flavones exhibited antioxidant activities with decreasing order as norwogonin > isowogonin >> wogonin> moslosooflavone. The present results demonstrated that norwogonin and isowogonin exhibited excellent antioxidant activity, which was mainly based on the presence of C-8 hydroxyl group.
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ATMOSPHERIC ENVIRONMENT
·
2020
·
IF 4.039
Fenghua Li,Shanshan Tang,Narcisse T. Tsona,Lin Du
Kinetics and mechanism of α-terpineol oxidation by OH radicals were studied in the aqueous phase under acidic condition, and the optical properties of the reaction products were examined. Using the relative rate method, the rate constant of α-terpineol reaction with OH radicals was determined to be (1.3 ± 0.3) × 10 10 M −1 s −1 . The reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS) and the reaction mechanism was proposed. The absorbance changes of the products were monitored by a UV–vis spectrophotometer, and α,β-unsaturated ketone compounds were observed. A certain distribution of α-terpineol in the aqueous phase has the potential to be conducive to the formation of aqueous secondary organic aerosols. At the same time, in order to investigate the persistence of α-terpineol in the atmosphere, its lifetime towards reaction with OH in atmospheric water was determined to be 6.2 h and 1.0 h in urban and remote area, respectively.
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APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Ni Han,Qixiang Xu,Gashaw Beyene,Qinfang Zhang
Photocatalytic degradation has been regarded as a promising method for environmental remediation. In this work, layered g-C 3 N 4 /(BiO) 2 (OH) x Cl 2− x (NBHC) heterojunction composites were synthesized by a hydrothermal method. The two-dimensional (2D)/2D porous layered Z-scheme heterojunction leaded to the suppressed recombination and the efficient separation of photogenerated electron-hole pairs. Meanwhile, NBHC composites exhibited a high specific surface area and rich mesopores for more reactive active sites. Thus, NBHC had an excellent photocatalytic degradation performance of pollutant trypan blue (TB). Furthermore, we found that the active species of superoxide radical ( O 2 − ) played a more important role, while hydroxyl radical ( OH) contributed to a lesser extent in photocatalytic degradation of TB based on the active species capture experiment and electron spin resonance (ESR) spectra. A Z-scheme photocatalytic mechanism was proposed to understand the photodegradation of TB. This study may provide a new horizon for constructing novel Z-scheme heterostructure photocatalysts with an excellent performance.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Songmei Li,Yimin Yu,Xiaoyan Sun,Xifeng Ding,Huafang Yang,Shibing Pan,Lixi Wang,Qitu Zhang
Ni(OH) 2 has been acknowledged as a promising oxygen evolution reaction (OER) electrocatalyst owing to its good electrochemical activity and low cost. However, application of the pristine Ni(OH) 2 is limited by the poor conductivity and low exposure of the active sites. Herein, a [email protected] (OH) 2 composite is prepared through a hydrothermal reaction. Heat treatment temperature proves to have a great influence on the electrocatalytic activity. In 0.1 M KOH electrolyte, the composite treated at 175 °C shows an overpotential of only 287 mV to reach the current density of 10 mA·cm −2 . Besides, the low Tafel slope (42 mV·dec −1 ) and superior stability (15 h at 10 mA·cm −2 ) also confirm the composite as an excellent OER electrocatalyst. The brilliant activity and stability toward OER can be attributed to the promoted coupling between Ni and Fe centers and the improved conductivity due to the 2D 18 p-electrons ring conjugate structure of hemin. Besides, effective hydrogen bonds between Ni(OH) 2 and hemin hinder the aggregation of Ni(OH) 2 , which ensures the catalyst enormous accessible active sites. This work offers a new method for the modification of Ni(OH) 2 as OER electrocatalysts. And the application of hemin also serves as a successful case for the use of biomass materials in OER electrocatalysis .
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Nanoscale
·
2019
·Vol. 11
·期 19
·9444-9456
·
IF 6.97
Xinyi Lian,Zhou Chen,Xiang Yu,Tingting Fan,Yunyun Dong,Hesheng Zhai,Weiping Fang,Xiaodong Yi
To solve the intrinsic deficiency inherited from the large band gap of ZnSn(OH)6 (ZSH), a gradual sulfur doping strategy is first proposed here to expand the optical absorption range, improve the separation efficiency of photogenerated electron–hole pairs, and thus enhance the photocatalytic activity. It is demonstrated that the distribution of sulfur in the flower-like ZSH (the sulfur doped sample is denoted as S-ZSH) tends to be largest on the outer most surface and becomes smaller towards the interior. The S-ZSH therefore has a gradual bandgap structure that is beneficial for transferring photogenerated charge carriers from the interior to the surface, which will greatly enhance the utilization of photoelectrons. As a result, the visible light photocurrent density of S-ZSH and the photocatalytic degradation rate of rhodamine (RhB) are about 5 and 10 times higher than with pristine ZSH, respectively.
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