查找使用阿拉丁产品的科研文献

Synthesis of ZnIn2S4/H2Ti3O7 nanowire heterojunctions for enhanced photocatalytic reduction of Cr(VI)

Pei Yu,Yulong Xiang,Xiaoli Dong,Yu Wang,Jialin Niu

The development of heterojunction photocatalysis provides an efficient, cost-effective, and environmentally sustainable approach to mitigating heavy metal contamination in the ecosystem. In this work, ZnIn 2 S 4 /H 2 Ti 3 O 7 heterojunctions have been successfully constructed via the in-situ growth of ZnIn 2 S 4 on H 2 Ti 3 O 7 nanowires. This rational structure enhances the separation efficiency of photogenerated carriers and suppresses carriers recombination. The ZnIn 2 S 4 /H 2 Ti 3 O 7 heterojunction exhibits significantly enhanced performance in the photoreduction of Cr(VI), and under 8 min illumination, it can achieve 100% photoreduction efficiency. The active species capture experiment confirmed that electrons served as the primary active species in the photocatalytic reduction of Cr(VI). This work offers support for the rational design of highly efficient heterojunction photocatalyst dedicated to environmental remediation.

Highly Efficient Nitrogen Electroreduction on Cr-Doped ReS2 via Synergistic Dopant-Vacancy Pairs

Xufa Peng,Yiyi Yangliu,Bilong Liu,Zhuangzhi Wu,Hao Fei,Dezhi Wang

The electrochemical nitrogen reduction reaction (NRR) offers a sustainable route for ammonia production under ambient conditions, but its efficiency remains limited by sluggish N2 activation and competition from the hydrogen evolution reaction (HER). Rhenium disulfide (ReS2), characterized by weak interlayer coupling and an anisotropic electronic structure, provides a promising platform for nitrogen electrocatalysis; however, the limited abundance and insufficient reactivity of its intrinsic active sites restrict its NRR performance. Here, we introduce a Cr-Vs (sulfur vacancy) pair engineering strategy that transforms the local coordination environment of ReS2 into an electronically differentiated active site. Cr incorporation thermodynamically facilitates the Vs formation, generating a reconstructed Cr-Vs configurations with substantially modified local electronic states. This reconstruction optimizes Re 5d-N 2p orbital hybridization, thereby selectively stabilizing key hydrogenated nitrogen intermediates. Meanwhile, the Cr-Vs pair selectively tunes the competition between NRR and HER, preferentially enhancing the intrinsic NRR activity. Consequently, the optimized RSC-5 catalyst delivers an NH3 yield rate of 67.70 ± 0.72 μg mg-1cat. h-1 and a Faraday efficiency of 10.53 ± 0.38%. This work establishes dopant-vacancy coupling as a generalizable strategy for reconstructing local coordination and decoupling competing reaction pathways, offering design principles for developing selective electrocatalysts for sustainable ammonia synthesis.

The multi-functional system of electrochemical desalination, RhB degradation and Cr (VI) removal

Yuchao Zhu,Qiang Wei,Qinyu He,Deyang Chen,Than Zaw Oo,Su Htike Aung,Fuming Chen

Capacitive deionisation (CDI), as a novel electrochemical technology, has attracted a fast-growing research interest over the past years. However, the single function of salt removal limits further development of conventional CDI systems. Herein, we propose a multi-function CDI device, which can achieve the electrochemical desalination, degradation of organic pollutants and removal of heavy metal ions through the redox electrocatalytic deionisation technology. Sulphur-doped reduced graphene oxide (S@rGO) is utilised as the anode to catalyse the degradation of rhodamine B. The Pt-coated graphite paper is used as a cathode for the removal of dichromate ions by the electro-reduction process. The voltage plateau of S@rGO is reduced by ∼0.35 V compared with the pure carbon cloth electrode, indicating the effectiveness of S@rGO as the catalyser. The salt feed is desalted to ∼0.74 mS·cm−1 level at a current density of 1 mA·cm−2. The degradation efficiency of rhodamine B (RhB) and potassium dichromate are 99.1% and 55.3%, respectively. The effects of different current densities and cycling are also investigated. This work is significant for the multi-functional process of water treatment and the device design.Synopsis : The single function of salt removal limits the further development of the CDI system. A multi-function CDI device is proposed to achieve electrochemical desalination, organics degradation and dichromate ion removal.

Green synthesis of tannin-hexamethylendiamine based adsorbents for efficient removal of Cr(VI)

Qiang Liu,Qinze Liu,Bingsi Liu,Tao Hu,Weiliang Liu,Jinshui Yao

Newly developed adsorbents, poly(tannin-hexamethylendiamine) (PTHA), were fabricated by varying the mole ratio of tannin (TA) and hexamethylendiamine (HA) under one-pot reaction. The specific forming process of the adsorbent which had undergone the transition from hydrogen bonds to covalent bonds was subsequently explored. Based on the efficiency of Cr(VI) removal from aqueous solution over all prepared adsorbents, the PTHA-4 (mole ratio of TA/HA = 1:12.5) exhibited an excellent adsorption behavior. Adsorption experiments affected by contact time and ionic strength have been conducted successively by PTHA-4, and the equilibrium was reached at 24 h. The kinetic data revealed that the adsorption was good agreement with pseudo-second order model and needed to undergo the rate-controlling step. The maximum adsorption capacity was 283.29 mg/g at 30 °C, relying on the isothermal curve suitably described by Langmuir model. Furthermore, toxic Cr(VI) had been reduced to the low toxic Cr(III) during adsorption process. The structures and adsorption performance of adsorbent were confirmed by means of SEM, FT-IR, XPS etc. Thus, the cheap-sustainable adsorbents have a superior feature for Cr(VI)-wastewater purification in future.

Enhanced adsorption and photocatalytic Cr(VI) reduction and sterilization of defective MoS2/PVP

Yingge Zhang,Hongfen Li,Xiaolei Zhang,Hanfang Zhang,Wang Zhang,Hongwei Huang,Hongling Ou,Yihe Zhang

The exploration of novel nanomaterials to resolve the issues of water pollution with the aid of photocatalytic technology has always been a research hotspot. MoS 2 is acknowledged to be one of the promising photocatalysts for its interesting layered structure, suitable band gap, and good chemical stability. However, the fast recombination of photogenerated electrons and holes within the MoS 2 impedes its extensive application. Here, hydrophilic polymer (polyvinyl pyrrolidone, PVP) and sulfur vacancy (Vs) are simultaneously introduced into the MoS 2 nanosheets to achieve high-efficient photocatalytic hexavalent chromium Cr(VI) removal and antibacterial performance. The incorporation of PVP greatly enhances the adsorption capacity of MoS 2 , and creating Vs essentially strengthens the photogenerated carrier separation of MoS 2 . As a result, the Cr(VI) removal efficiency of MoS 2 -PVP with an appropriate Vs concentration is up to 99.5 % for 3 h. Meanwhile, MoS 2 -PVP with a relatively higher Vs concentration displays a superior Escherichia coli (E. coli) removal efficiency of 91.8 % within 30 min with the initial E. coli concentration of ∼1.0 × 10 7 CFU/mL. This study extends photocatalysts to a higher level in designing advanced materials for environmental remediation and establishes a feasible platform for emphasizing the versatility of defect engineering in regulating catalytic activity.

Tailoring kinetics of Cr-chemisorption over La0.6Sr0.4Fe0.8Co0.2O3 cathode material through its porosity variation

Meigeng Gao,Elena Yu Konysheva,Jun Yang

The La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) ceramics with the porosity of 20% (LSCF-20) and 50% (LSCF-50) were fabricated through temperature variation. Kinetics of the Cr-adsorption has been studied at 700 °C over 345 h under air. Different dominant mechanisms of Cr chemisorption over the ceramics with different porosities were identified. The Cr–substitution into the LSCF perovskite grains will dominate in the denser LSCF-20 ceramics, whereas the growth of SrCrO 4 crystals over the LSCF perovskite phase will occur preferably in the more porous LSCF-50 ceramics. The Cr penetrates into a more porous LSCF-50 ceramics up to 12–17 μm and the total Cr amount adsorbed after 345 h over the LSCF-50 ceramics is larger by about 10 times than over the denser LSCF-20 ceramics. The revealed remarkable differences could be associated with the increase in the surface area and with a higher volume of macro- and mesoporosity.

Magnetic MnFe2O4/ZnFe-LDH for Enhanced Phosphate and Cr (VI) Removal from Water

Huang Congxin,Tang Chaochun,Wu Qingqing,Zhu Qing

Due to the layered structure and recycling characteristics, magnetic MnFe 2 O 4 /ZnFe-LDH was prepared by co-precipitation. In this study, we intensively explored MnFe 2 O 4 /ZnFe-LDH for water purification compared with the ZnFe-LDH. The morphological and structural characteristics of the obtained products were systematically characterized. MnFe 2 O 4 /ZnFe-LDH exhibits the maximum adsorption capacity of 94.52 mg/g for phosphate and 49.03 mg/g for Cr (VI), respectively, which is superior to that of the ZnFe-LDH, indicating that the magnetic MnFe 2 O 4 effectively enhanced adsorption performance. Meanwhile, the mechanism of adsorption of phosphate and Cr (VI) was briefly studied, where the metal center ion in MnFe 2 O 4 /ZnFe-LDH and between layers of SO 4 2− serves as capture sites for phosphate and Cr (VI) removal. Furthermore, the MnFe 2 O 4 /ZnFe-LDH can be used for magnetic recycled and still maintained excellent removal efficiency (70%) for phosphate and Cr (VI) after five adsorption–desorption cycles. This work could open a new vista of designing magnetic novel adsorbents in environmental remediation.

Efficient removal of Cr(VI) from aqueous solutions by polypyrrole/natural pyrite composites

Fen Zhang,Luyao Xi,Meiqi Zhao,Yaguang Du,Liying Ma,Shaohua Chen,Hengpeng Ye,Dongyun Du,Tian C. Zhang

Easily agglomeration of polypyrrole (PPy) significantly limits its practical applications. In this study, natural pyrite (NP) was applied to disperse PPy and overcome this agglomeration; a novel composite of PPy/NP was synthesized and applied for the efficient removal of hexavalent chromium [Cr(VI)] from aqueous solutions. Results showed that the PPy/NP composites exhibited better Cr(VI) removal performance than PPy alone. This enhanced removal capacity is attributed to the addition of NP, which prevents PPy agglomeration and reduces Cr(VI) to trivalent chromium[Cr(III)]; Cr(VI) removal was significantly dependent on the solution’s pH. The sorption kinetics of Cr(VI) with PPy/NP was described by the pseudo-second-order model and Elovich models, which highlight the chemicalsorption process. The sorption isotherm was well simulated by Langmuir model and the maximum adsorption capacity of Cr(VI) on PPy/NP was 261.78–395.26 mg/g at 303 – 323 K, which is significantly higher than that of PPy alone (124.84–194.17 mg/g). Thermodynamic analyses confirmed that this adsorption process was spontaneous and endothermic. PPy/NP composites could be used as a recyclable absorbents for four Cr(VI) reduction cycles without any evident loss in adsorption performance. The mechanism Cr(VI) removal by PPy/NP composites is attributed to ion exchange (9.47 %), adsorption (31.03 %), and reduction (59.50 %).

Cellulose bridged carbonate hydroxyapatite nanoparticles as novel adsorbents for efficient Cr(VI) removal

Jing Cui,Xinying Li,Shoucheng Ma,Wei Wei

Morphology control synthesis of Cr-benzenedicarboxylate MOFs for the removal of methylene blue

Tian Zhao,Hexin Zhu,Wei Geng,Minmin Zou,Ming Dong,Jie Ying

Propionic acid could efficiently affect the formation of Cr-benzenedicarboxylate metal-organic frameworks (MOFs), giving rise to yielding products with various structures. Generally, nano-sized crystals of MIL-101(Cr) can be prepared with comparatively lower concentration of propionic acid (0.6 ​M), which possessed high porosity (S BET  ​= ​2720 ​m 2 /g). The hierarchically porous (HP) MIL-101(Cr) was obtained with medium concentration of propionic acid (1.2 ​M), and micro-rod like crystals of MIL-88B(Cr) was formed in high concentration of propionic acid (1.8 ​M). Compare to bulk MIL-101(Cr) and nano-sized MIL-101(Cr), HP-MIL-101(Cr) showed much higher uptake of methylene blue (119.1 ​mg/L) in aqueous. This approach can offer a facile and effective pathway to synthesize stable hierarchically porous Cr-benzenedicarboxylate MOF for the applications in pollutant treatment fields.

Microstructures and Electrical Conduction Behaviors of Gd/Cr Codoped Bi3TiNbO9 Aurivillius Phase Ceramic

Huajiang Zhou,Shaozhao Wang,Daowen Wu,Qiang Chen,Yu Chen

In this work, a kind of Gd/Cr codoped Bi3TiNbO9Aurivillius phase ceramic with the formula of Bi2.8Gd0.2TiNbO9+ 0.2 wt% Cr2O3(abbreviated as BGTN−0.2Cr) was prepared by a conventional solid-state reaction route. Microstructures and electrical conduction behaviors of the ceramic were investigated. XRD and SEM detection found that the BGTN−0.2Cr ceramic was crystallized in a pure Bi3TiNbO9phase and composed of plate-like grains. A uniform element distribution involving Bi, Gd, Ti, Nb, Cr, and O was identified in the ceramic by EDS. Because of the frequency dependence of the conductivity between 300 and 650 °C, the electrical conduction mechanisms of the BGTN−0.2Cr ceramic were attributed to the jump of the charge carriers. Based on the correlated barrier hopping (CBH) model, the maximum barrier heightWM, dc conduction activation energyEc, and hopping conduction activation energyEpwere calculated with values of 0.63 eV, 1.09 eV, and 0.73 eV, respectively. Impedance spectrum analysis revealed that the contribution of grains to the conductance increased with rise in temperature; at high temperatures, the conductance behavior of grains deviated from the Debye relaxation model more than that of grain boundaries. Calculation of electrical modulus further suggested that the degree of interaction between charge carriersβtended to grow larger with rising temperature. In view of the approximate relaxation activation energy (~1 eV) calculated fromZ″andM″ peaks, the dielectric relaxation process of the BGTN−0.2Cr ceramic was suggested to be dominated by the thermally activated motion of oxygen vacancies as defect charge carriers. Finally, a high piezoelectricity ofd33= 18 pC/N as well as a high resistivity ofρdc= 1.52 × 105Ω cm at 600 °C provided the BGTN−0.2Cr ceramic with promising applications in the piezoelectric sensors with operating temperature above 600 °C.Keywords:Aurivillius phase ceramic;Bi3TiNbO9;electrical conduction behaviors;impedance spectrum;electrical modulus

Electrospun Cellulose Acetate/Polyethylenimine Porous Fibers toward Highly Efficient Removal of Cr(VI)

Dan Luo,Shao-zhong Hu,Ting Huang,Nan Zhang,Yan-zhou Lei,Yong Wang

The development of an efficient, economical, and environmentally friendly monolithic adsorbent for the removal of toxic hexavalent chromium Cr(VI) has invariably been a topic of great concern to researchers. In this paper, cellulose acetate (CA) and polyethylenimine (PEI) homogeneously blending porous fiber membranes with high porosity were successfully prepared by electrospinning, and PEI was further immobilized by cross-linking to form a stable biological adsorbent. The adsorption behavior and eliminating mechanism toward Cr(VI) by the CA-c-PEI fibrous membranes were comprehensively explored. The maximum adsorption capacity was up to 285.7 mg/g (25 °C), higher than most of the biomass-based adsorbents. Specifically, the concentration of Cr(VI) could be dramatically reduced from the initial 50 mg/L to 0.03 mg/L, much lower than the concentration standard for drinking water recommended by the World Health Organization. Even after being reused several times, the fibrous membrane still exhibited high removal efficiency.