查找使用阿拉丁产品的科研文献

Effective inactivation of Microcystis aeruginosa by a novel Z-scheme composite photocatalyst under visible light irradiation

Dongxu Wang,Yanhui Ao,Peifang Wang

Microcystis aeruginosa is one of the most famous harmful algae. In this work, Z -scheme g-C 3 N 4 -MoO 3 (Mo-CN) composite photocatalysts were successfully synthesized to alleviate the algae pollution. The obtained composites exhibited excellent performance for the inactivation of M. aeruginosa . The optimal photocatalysts (15Mo-CN) achieved a removal efficiency of 97% for the algal cells after 3 h visible light irradiation, which was attributed to their remarkable surface properties and ingenious structure design. The physiological status of Microcystis aeruginosa were evaluated by the chlorophyll a (chla), relative electron transport rate (rETR) and maximum photochemical efficiency (Fv/Fm), and all of them decreased in different degrees. Furthermore, the as-prepared photocatalysts also show a certain activity for the removal of leaked macromolecule organic compounds during the process of algal cells inactivation. Finally, a possible mechanism on the photocatalytic inactivation of algal cells by the Z -scheme photocatalysts was deduced based on the experimental and characterization results. We believe this study would provide new insights into the development of promising technology and basic theory for remediation of algae pollution.

Enhanced visible-light-driven photocatalytic activity of Bi2WO6-BiSI Z-scheme heterojunction photocatalysts for tetracycline degradation

Rui Zhang,Kunlin Zeng,Tongqing Zhang

Direct Z-scheme α-MnO2@MnIn2S4 hierarchical photocatalysts with atomically defined junctions for improved photocatalytic activities

Min Zhang,Muhammad Arif,Yuxiang Hua,Bo Qiu,Yue Mao,Xiaoheng Liu

The use of semiconductor photocatalysts to generate electrons with efficient reducing capability for organic photoreduction synthesis and the removal of harmful substances has become a hotspot in the field of green chemistry research. In this work, α-MnO2 nanocubes and α-MnO2@MnIn2S4 hybrid photocatalysts with a core–shell structure were synthesized successively by a two-step method. XRD and XPS verified the coexistence of the two substances (α-MnO2 and MnIn2S4) in hybrid systems. According to the SEM and TEM characterization, it is clearly seen that MnIn2S4 nanosheets grow on α-MnO2 nanocubes to form a hierarchical structure. Furthermore, HRTEM showed that the interface contact between α-MnO2 and MnIn2S4 resulted in an atomically defined junction. The photocatalytic performance of the composite catalyst was evaluated by reducing 4-nitroaniline to 4-phenylenediamine and Cr(VI) to Cr(III), respectively. The results show that the catalytic activity of the composite material is effectively improved compared to that of the single components. The Z-scheme electron transport mechanism was proved by ultraviolet-visible diffuse reflectance spectroscopy, valence band XPS, energy band structure calculation and active species detection experiments. The constructed Z-scheme hierarchical α-MnO2@MnIn2S4 system with an atomically defined junction can improve the redox performance of semiconductors for organic synthesis and environmental remediation.

Oxygen defects engineered CdS/Bi2O2.33 direct Z-Scheme heterojunction for highly sensitive photoelectrochemical assay of Hg2+

Shuo Wu,Yan Zhao,Xunxun Deng,Xinlan Yang,Xiuyun Wang,Yanqiu Zhao

This work demonstrates that the photoelectrochemical response of the CdS/Bi 2 O 2.33 direct Z-scheme heterojunction, synthesized by in situ deposition of CdS nanocrystals on the defect engineered Bi 2 O 2.33 , can be modulated by oxygen defect concentration. The appropriate oxygen defects not only increase the visible light absorption, provide active reaction sites to enhance PEC activity, but also promote the separation of carriers. The formation of CdS/Bi 2 O 2.33 direct Z-scheme heterojunction further improves these properties by extending the visible light absorption and promoting separation and transport of carriers, but avoids the usage of noble metal nanoparticles as electron transfer mediators, thus has a low cost and easy fabrication technology. The CdS/Bi 2 O 2.33 direct Z-scheme junction shows significantly improved photocurrent response as compared with those containing less oxygen defects, and is applied as a photoelectrochemical assay platform for Hg 2+ . The specific interaction between Hg 2+ and the S 2− in CdS significantly quenches the photocurrent response of the CdS/Bi 2 O 2.33 due to the formation of HgS. The photocurrent decrease is linear to the concentration of Hg 2+ in the range from 10 −11 to 10 −6  g/mL, with the limit of detection of 3.2 pg/mL. High accuracy and good reproducibility are realized in the real sample analysis of urine, river water, and sea water. The integration of oxygen defect engineering and direct Z-scheme electron transport principle provides a new avenue for fabricating high performance photoelectrochemical materials, which can be further combined with bio-recognition strategy for the ultrasensitive detection of biological molecules.

Direct and indirect Z-scheme heterostructure-coupled photosystem enabling cooperation of CO2 reduction and H2O oxidation

Wang Ying,Shang Xiaotong,Shen Jinni,Zhang Zizhong,Wang Debao,Lin Jinjin,Wu Jeffrey C. S.,Fu Xianzhi,Wang Xuxu,Li Can

The stoichiometric photocatalytic reaction of CO 2 with H 2 O is one of the great challenges in photocatalysis. Here, we construct a Cu 2 O-Pt/SiC/IrO x composite by a controlled photodeposition and then an artificial photosynthetic system with Nafion membrane as diaphragm separating reduction and oxidation half-reactions. The artificial system exhibits excellent photocatalytic performance for CO 2 reduction to HCOOH and H 2 O oxidation to O 2 under visible light irradiation. The yields of HCOOH and O 2 meet almost stoichiometric ratio and are as high as 896.7 and 440.7 μmol g −1  h −1 , respectively. The high efficiencies of CO 2 reduction and H 2 O oxidation in the artificial system are attributed to both the direct Z-scheme electronic structure of Cu 2 O-Pt/SiC/IrO x and the indirect Z-scheme spatially separated reduction and oxidation units, which greatly prolong lifetime of photogenerated electrons and holes and prevent the backward reaction of products. This work provides an effective and feasible strategy to increase the efficiency of artificial photosynthesis.

Design and performance of a novel direct Z-scheme NiGa2O4/CeO2 nanocomposite with enhanced sonocatalytic activity

Guowei Wang,Xue Ma,Jue Liu,Lifan Qin,Bing Li,Yuanan Hu,Hefa Cheng

A novel direct Z-scheme NiGa 2 O 4 /CeO 2 nanocomposite was designed and prepared via simple sol-hydrothermal and calcination methods, and its sonocatalytic activity was tested by studying the degradation of a model antimicrobial agent, malachite green (MG), under ultrasonic irradiation. Near complete (96.2%) degradation of MG (at 10 mg/L) could be achieved by the NiGa 2 O 4 /CeO 2 nanocomposite (at 1.0 g/L) after ultrasonic irradiation (40 kHz, 300 W) for 60 min at 25 °C. Under the same conditions, only 51.2 and 72.0% of the MG degraded in the presence of NiGa 2 O 4 and CeO 2 (at 1.0 g/L), respectively. These results demonstrate that the direct Z-scheme NiGa 2 O 4 /CeO 2 nanocomposite has excellent sonocatalytic activity, which is attributed to the matching band-gaps between NiGa 2 O 4 and CeO 2 . The sonocatalytic activity of NiGa 2 O 4 /CeO 2 nanocomposite decreased by 17% after four cycles of reuse, which is indicative of relatively good reusability. Scavenging experiments revealed that sonocatalytic degradation of MG results from the combined action of hydroxyl radicals ( OH) and holes (h + ), with the latter having a greater contribution. The pathways and mechanism of MG degradation were proposed based on the degradation intermediates detected. The results demonstrate that the prepared direct Z-scheme NiGa 2 O 4 /CeO 2 nanocomposite worked as designed and exhibited high and stable sonocatalytic activity during MG degradation, and could thus serve as a promising candidate in sonocatalytic treatment of other organic pollutants in wastewaters. The findings also provide new insights on the mechanism of sonocatalytic degradation and the design of efficient Z-scheme sonocatalysts.

Construction of magnetically separable hierarchical Z-scheme NiFe2O4@Bi2Sn2O7 heterojunction with enhanced visible-light photocatalytic activity

Wu Chenyan,Huang Feilong,Shen Qianhong,Yu LiXin,Zhang Changteng,Sheng Jiansong,Cheng Di,Yang Hui

Abstract The magnetic photocatalysts play an important role in practical application. Herein, a novel magnetic hierarchical Z-scheme NiFe 2 O 4 @Bi 2 Sn 2 O 7 heterojunction photocatalyst was fabricated by hydrothermal strategy. The structure, micromorphology and physical properties of the as-prepared products were analysed, and the photocatalytic performance was carried out via photocatalytic degradation of tetracycline hydrochloride under visible-light irradiation. The longest average carrier lifetime of the NiFe 2 O 4 @Bi 2 Sn 2 O 7 composite is about 2.9 times longer than that of pure Bi 2 Sn 2 O 7 (2.45 ns), thereby achieving the enhanced photocatalytic activity. After a four-cycle photocatalytic degradation reaction, the NiFe 2 O 4 @Bi 2 Sn 2 O 7 composite still exhibits excellent photocatalytic activity and structural stability due to its magnetic property, and this feature is conducive to its practical application. The results demonstrate that NiFe 2 O 4 nanoparticles are uniformly loaded on flower-like hierarchical Bi 2 Sn 2 O 7 , and thus not only forming nanosized Z-scheme NiFe 2 O 4 @Bi 2 Sn 2 O 7 heterostructure, but also making the composite material magnetic. This work provided new perspectives about construction of heterojunction photocatalysts. Graphic Abstract

Simple fabrication of Z-scheme MgIn2S4/Bi2WO6 hierarchical heterostructures for enhancing photocatalytic reduction of Cr(VI)

Jiaqi Dong,Jianqiang Hu,Anyu Liu,Jiale He,Qingling Huang,Yanru Zeng,Wenjing Gao,Zhen Yang,Yongcai Zhang,Yong Zhou,Zhigang Zou

Direct Z-scheme MgIn2S4/Bi2WO6 hierarchical heterostructures were simply fabricated via immobilising MgIn2S4 nanoflakes onto the surface of Bi2WO6 hierarchical nanosheet-like structures towards photocatalytic reduction of Cr(VI). The analyses of the energy band structure, UPS tests and DMPO-ESR spin-trap experiments confirm that the intimate MgIn2S4/Bi2WO6 heterointerface allows an efficient Z-scheme interfacial charge migration route between MgIn2S4 and Bi2WO6, leading to higher redox ability of photoexcited carriers, and thus favours the separation of photoexcited carriers, proved by the results of PL spectroscopy, photoluminescence decay traces, transient photocurrent densities and EIS. In addition, the MgIn2S4/Bi2WO6 heterostructures also exhibit obviously enhanced ultraviolet-visible-light absorption according to UV-vis DRS analysis, and can generate more electron–hole pairs under UV-visible light illumination, effectively improving the photocatalytic activity. Therefore, because of their synergistic effects, all the MgIn2S4/Bi2WO6 hierarchical heterostructures show distinctly improved photoreduction activities for Cr(VI), compared with pure Bi2WO6. The optimal hybrid (MIS/BWO-0.35) displays nearly 100% Cr(VI) reduction into Cr(III) after 40 min of simulated sunlight illumination, which is better than the majority of the reported Bi2WO6 and other semiconductor photocatalysts before. Its reaction rate constant for the photoreduction of Cr(VI) (0.1063 min−1) is about 4.5 times higher than that of the pristine Bi2WO6 (0.0237 min−1). This work provides a valid approach for developing efficient Z-scheme photocatalytic materials in removing Cr(VI).

Direct Z-scheme CdS–NiPc heterojunctions as noble metal-free photocatalysts for enhanced photocatalytic hydrogen evolution

Jialiang Sheng,Chunqiang Wang,Fang Duan,Shengrong Yan,Shuanglong Lu,Han Zhu,Mingliang Du,Xin Chen,Mingqing Chen

The reasonable construction of Z-scheme heterojunctions is an effective pathway to enhance the photocatalytic performance. In this work, a direct Z-scheme cadmium sulfide–nickel phthalocyanine (CdS–NiPc) heterojunction was successfully constructed by a one-step solvothermal method, which exhibited highly efficient photocatalytic activity for hydrogen evolution and good cyclic stability under visible light irradiation. An optimal sample CdS–10%NiPc with 10 wt% NiPc was obtained, and the photocatalytic hydrogen production rate could reach 17.74 mmol h−1 g−1, which was 19.1 times higher than that of the pure CdS sample. The reasons for the improvement and the photocatalytic mechanism were studied in detail. The result indicated that the formation of a direct Z-scheme heterojunction made a close contact between CdS and NiPc, which effectively accelerated the separation and migration of charges. This study enriches the CdS-based composite photocatalysts for hydrogen evolution and provides a simple method for the construction of efficient Z-scheme inorganic–organic heterojunctions.

Lewis acid promoted double bond migration in O-allyl to Z-products by Ru-H complexes

Haibin Wang,Shaodong Liu,Tingting Sun,Zhanao Lv,Zhen Zhan,Guochuan Yin,Zhuqi Chen

In catalytic double bond migration reaction, E -configuration olefins were normally generated as the dominant product because E -configuration was thermodynamically favored. However, Z-configuration products are sometimes desired in pharmaceutical chemistry owing to the structure-activity relationship. In this paper, we have demonstrated a new strategy that Lewis acid promoted an widely employed and convenient ruthenium(II) complex for the catalytic isomerization of O-allylethers, leading to thermodynamic-unfavored Z-product under mild conditions. The model substrate of allyl phenyl ether can be simply scaled up to 20 mmol to produce Z-product with TON of 2453 and TOF of 13,430 h −1 at 40–60 °C. The system of Ru(II)/Lewis Acid catalysts was suitable for various substituted O -allylethers and other types of substrates. Through mechanism study including kinetic study, ligand inhibition effect and molecular spectroscopy, the dissociation of PPh 3 ligand by the addition of Lewis acid, and the formation a five-membered Ru complex from anchimeric assistance were both recognized as essential steps to improve the reactivity and to control the stereoselectivity of catalytic double bond migration reaction through metal hydride addition-elimination mechanism. This new strategy may provide a new opportunity to produce thermodynamic-unfavored product in heterocyclic compounds for pharmaceutical chemistry.

Polarization-Enhanced direct Z-scheme ZnO-WO3-x nanorod arrays for efficient piezoelectric-photoelectrochemical Water splitting

Ying Chen,Li Wang,Ruijie Gao,Yong-Chao Zhang,Lun Pan,Chenyu Huang,Kan Liu,Xin-Yuan Chang,Xiangwen Zhang,Ji-Jun Zou

Photosynthesis with Z-scheme charge transfer has been recognized as an efficient pathway to achieve solar-energy conversion. Herein, the all-solid-state direct Z-scheme ZnO-WO 3-x nanorod arrays were synthesized by in-situ solvothermal treatment for highly piezoelectric (PE)-photoelectrochemical (PEC) water splitting. The chemical bonding between WO 3-x and ZnO via W-O-Zn and the inherent band structures/Fermi levels drive the formation of direct Z-scheme charge-transfer pathway. Importantly, the optimized structure (Zn-W-5) shows higher PEC activities with high photocurrent density of 2.39 mA/cm 2 at 1.23 V vs. RHE, which is 2.13 times higher than pure ZnO. Surprisingly, the obvious PE polarization of ZnO increases its Fermi level toward conduction band and significantly enhances Z-scheme effect between ZnO and WO 3-x . Especially, the best sample (Zn-W-5-1000 rpm) shows a photocurrent of 3.38 mA/cm 2 at 1.23 V vs. RHE, which is 3.02 times higher than pure ZnO. This work provides a facile PE polarization approach for enhancement of Z-scheme charge-transfer process.

A Z-scheme Bi2MoO6/CdSe-diethylenetriamine heterojunction for enhancing photocatalytic hydrogen production activity under visible light

Feifei Mei,Jinfeng Zhang,Kai Dai,Guangping Zhu,Changhao Liang

Recently, cadmium selenide (CdSe) has been deeply studied because of its excellent photocatalytic hydrogen (H2) production performance. However, pure CdSe has poor stability and severe photocorrosion, which seriously affect its application prospect. In this work, we successfully deposit Bi2MoO6 on an inorganic–organic CdSe-diethylenetriamine (DETA) hybrid to design Bi2MoO6/CdSe-DETA composites by an in situ solvothermal method. The morphology, crystal structure, electrochemical properties, H2 evolution performance and the photostability of Bi2MoO6/CdSe-DETA composites are explored using various techniques. The results show that the as-prepared Bi2MoO6/CdSe-DETA composites exhibit excellent photocatalytic performance and photostability under visible light irradiation. Among them, the Bi2MoO6/CdSe-DETA hybrid system exhibits excellent photocatalytic H2 production performance (5.92 mmol g−1 h−1), which is approximately 3.6 and 1.8 times higher than that of pure CdSe and CdSe-DETA, respectively. After 4 cycles, the photocatalyst still maintains high H2 production. This study develops a new type of photocatalyst that can respond to visible light. This provides an effective way to solve the energy problem by using solar energy.