查找使用阿拉丁产品的科研文献

Facile Preparation of Co3O4 Hollow Dodecahedron with Superior Peroxidase-like Activity for Selective Detection of Cholesterol

Meili Liu,Liuheng Xue,Qinghua Feng,Yingsha Wang,Jia Liu,Shouting Zhang,Wenping Hu

The Co3O4hollow dodecahedron (Co3O4@CN) was prepared by calcining ZIF-67 in N2and then air atmosphere. In the Co3O4@CN compound material, Co3O4nanoparticles (Co3O4NPs) are anchored in the carbon skeleton, solving the aggregation problem of Co3O4NPs. Because Co3O4@CN retains the porous structure of ZIF-67, and the presence of Co2+and Co3+favors electron transfer between the enzyme substrates, it has excellent peroxidase-like (POD-like) activity. Enzymatic kinetic tests show that Co3O4@CN has approximately six times more affinity for TMB than HRP and the maximal reaction rate is approximately three times that of HRP. The cholesterol sensor was constructed with Co3O4@CN, and its linear range was 20-1000 μM, and the detection limit was 14.33 μM. The application of Co3O4@CN to the detection of human serum cholesterol will be a valuable research direction.Keywords:Co3O4@CN compound material;peroxidase-like activity;cholesterol sensor

Stable all-solid-state Z-scheme heterojunction Bi2O3-Co3O4@C microsphere photocatalysts for recalcitrant pollutant degradation

Xiaoqing Wang,Jing Zhang,Rui Wang,Yujie Ren,Shiyao Jin,Shimin Wang,Hongjing Lu,Yongjiang Wang,Junzi Zhao,Chunhua Xiong

We present a strategy for the modification of an ion-exchange resin (D113) as an inexpensive carbon source to obtain a macrospherical photocatalyst precursor that can be transformed into a stable all-solid-state Z-scheme heterojunction catalyst (denoted Bi 2 O 3 -Co 3 O 4 @C). X-ray diffractometry and Fourier transform infrared and Raman spectroscopy measurements confirmed the presence of highly graphitized carbon in the complex. Significantly, the cost of the as-prepared material was only 1/200 of that of commercial carbon nanotubes and 1/80 of that of graphene oxide . Aided by the organic carbon source, Bi 2 O 3 -Co 3 O 4 @C showed an enhanced light absorption, hindered electron–hole recombination, and an enhanced photocurrent response. Under simulated solar irradiation, Bi 2 O 3 -Co 3 O 4 @C (20 mg/L) showed degradation efficiencies of 100%, 47.52%, 94.28%, and 100% for methylene blue, rhodamine B, tetracycline, and Cr(VI), respectively, after 120 min. Herein, the highest turnover frequency (TOF) obtained under irradiation was 2.5 h −1 for Cr(VI). Further, the degradation efficiency for methylene blue trihydrate remained 91.46% after five cycles, indicating significantly higher stability than that of a catalyst prepared without graphitic carbon. The optimized band structure and photocatalytic mechanism of Bi 2 O 3 -Co 3 O 4 @C were determined based on ultraviolet-visible measurements and plane-wave density functional theory calculations in VASP. The findings of this study indicate the promise of the Bi 2 O 3 -Co 3 O 4 @C macrospheres for industrial applications based on their photocatalytic performance, high stability, low cost, and suitable particle size.

Facile preparation of a nano-Co3O4/C composite catalyst for the thermal decomposition of ammonium perchlorate

Tian Lu,He Jie-Xin,Huang Xin-Yang,Feng Yang,Lu Yue-Wen,Wang Rui-Hao,Wang Qian,Guo Chang-Ping

Herein, nano-Co 3 O 4 /C composite catalyst was successfully synthesized by calcination of cobalt alginate (CA) film, which was prepared by ion exchange method. The morphology and structure of the films and calcined samples were characterized. It was found that the thickness of the film produced by Co 2+ substituted Na + was 20 μm, and the surface and side of the film were smooth and uniform. After the calcination of CA film at 400 °C, Co 3 O 4 nanoparticles grown in situ were loaded onto the carbonized alginate skeleton. The results of the thermal analysis showed that the higher the content of catalyst, the more obvious the catalytic effect on AP. Compared with pure AP, the exothermic peak temperature with 3 wt% nano-Co 3 O 4 /C composite catalysts decreased by 103.1 °C, demonstrating the catalytic effect on the nano-Co 3 O 4 /C. The nanocomposite catalyst could be synthesized quickly and in large quantities in this way, which had certain theoretical and practical value for improving the combustion behavior of AP-based composite solid propellants. Graphical abstract Based on inspiring by biomaterial, we have designed and prepared a nano-Co 3 O 4 /C composite catalyst by a facile ionic crosslinking solidification method, which effectively enhanced the thermal decomposition of the ammonium perchlorate.

Probing the crystal plane effect of Co3O4 for non-enzymatic electrochemistry sensing performance toward hydrogen peroxide

Jiaojiao Jiang,Zhixuan Zhang,Zhiqi Liang,Wenying Chen,Manfei Zhong,Kai Xu,Zhouling Wu

The crystalline structure of catalyst surfaces has an important effect on the catalytic activity. However, the crystal plane effects of Co 3 O 4 catalysts towards H 2 O 2 activation are rarely reported. In this work, Co 3 O 4 hexagon nanosheets, nanosheets, nanorods and nanocubes with respective {1   1   1}, {1   1   2}, {1   1   0} and {0   0   1} dominant exposed facets were synthesized by hydrothermal synthesis, and the crystal plane effects of these Co 3 O 4 nanocrystals were compared with respect to their viability as potential for non-enzymatic H 2 O 2 sensors. Co 3 O 4 as a hexagonal nanosheet with a {1   1   1} crystal plane exhibited the best performance for H 2 O 2 detection, and exhibited a fast response of 3 s, a wide linear range from 0.0005 ∼ 8.5 mM with sensitivity of 1160.2 μA·mM -1 cm - 2 , and detection limit of 0.049 μM. Overall, the H 2 O 2 detection performance of Co 3 O 4 with different exposed facets was ranked as {1   1   1} > {1   1   2} > {1   1   0} > {0   0   1}, which is consistent with the proportion of surface Co 3+ , indicating that the surface Co 3+ exhibit higher activity for H 2 O 2 oxidation. This study indicates that tuning of thecrystal plane of nanocrystals is important to enhancement of non-enzymatic H 2 O 2 detection, and provides an important constraint when developing high efficiency catalysts for non-enzymatic electrochemical H 2 O 2 sensors.

Continuous polypyrrole nanotubes encapsulated Co3O4 nanoparticles with oxygen vacancies and electron transport channels boosting peroxymonosulfate activation

Chen Dingyang,Wu Wanning,Zhao Xinyue,Feng Danyang,Zhao Rui,Zhu Guangshan

Co 3 O 4 particles are promising heterogeneous catalysts for peroxymonosulfate (PMS) activation; whereas they still surfer from the extensive agglomeration, serious Co leaching, poor electronic conductivity, and difficult recovery. Herein, a novel hybrid nanoarchitectonic constructed by encapsulating Co 3 O 4 nanoparticles into continuous polypyrrole (PPy) nanotubes (Co 3 O 4 @PPy hybrids) was developed using electrospun fibers as the templates, which boosted the catalytic degradation toward tetracycline (TC). The continuous polypyrrole nanotubes could provide the confined spaces, offer effective electron transfer pathway, suppress cobalt ion loss, facilitate the oxygen vacancy (O vac ) formation, and accelerate the Co 2+ /Co 3+ cycles. Co 3 O 4 @PPy hybrids thereby exhibited a remarkably enhanced catalytic activity with the TC degradation efficiency of 97.2% ( k obs = 0.244 min −1 ) within 20 min and total organic carbon (TOC) removal rate of 66.8%. Furthermore, the recycle test, real natural water treatment, and fluidized-column catalytic experiments indicated the potential of Co 3 O 4 @PPy hybrids in the practical large-scale applications.

Activation of Na2S2O8 by MIL-101(Fe)/Co3O4 composite for degrading tetracycline with visible light assistance

Zihao Hu,Huiqi Wu,Fang Zhu,Sridhar Komarneni,Jianfeng Ma

MIL-101(Fe)/Co 3 O 4 composites were synthesized using a facile solvothermal method to establish the superiority of a heterogeneous photochemical catalysis system in the presence of Na 2 S 2 O 8 with visible light irradiation. In the present system, the MIL-101(Fe)/Co 3 O 4 catalyst showed better catalytic performance than the single photocatalytic or chemical catalytic system, implying that the MIL-101(Fe)/Co 3 O 4 catalyst can combine both photocatalysis and chemical catalysis well. When tetracycline (TC) is the target pollutant, the highest degradation efficiency can be achieved within 40 min, reaching to 86 %. Crystallinity, morphology, and elemental valence of the MIL-101(Fe)/Co 3 O 4 composite were explored by using X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as X-ray photoelectron spectroscopy (XPS). From the quenching experiments, it was found that 1 O 2 , SO 4 ‾, OH, and O 2 ‾ make contributions to the effective removal of tetracycline. Apart from that, the recovery and reuse characteristics of MIL-101(Fe)/Co 3 O 4 may facilitate the sustainable wastewater treatment.

NCQDs active sites as effective collectors of charge carriers towards enhanced photocatalytic activity of porous Co3O4

Xiaoxu Zhao,Yueqin Liu,Jianfeng Guo,Na Chang,Haitao Wang

In this work, different proportions of N-doped carbon quantum dots/porous Co3O4 (NCQDs/p-Co3O4) NCQDs/Co3O4 composite photocatalysts were prepared by a simple self-assembly method. It was demonstrated by a series of characterizations that 50% NCQDs/Co3O4 has a good visible light response and low electrochemical impedance. The photocatalytic degradation of TC was investigated by the 50% NCQDs/p-Co3O4 composite photocatalyst, and the results showed that the degradation effect of TC reached 81.2% within 120 min. The higher photocatalytic activity of 50% NCQDs/p-Co3O4 was analyzed probably because NCQDs can improve the separation efficiency of photogenerated electron–hole pairs and p-Co3O4 can provide a larger specific surface area and thus has more active sites. This study provides a new strategy for improving the photodegradation activity of Co3O4 photocatalysts.

Facile Synthesis of MOF-Derived Hierarchical Flower-Like Sr-Doped Co3O4 Structure for Effective TEA Sensing

Heming Sun,Xiaonian Tang

Engineering oxygen vacancies in Co3O4 to boost p-d hybridization for hydrogeneration of nitrogen and oxygen

Xianwei Li,Shuangxiu Ma,Fang Luo,Zehui Yang

Electrochemical hydrogenerations of nitrogen and oxygen molecules are of significance for nitrogen reduction and oxygen reduction reactions. Strengthening the binding between active sites and gaseous molecules is beneficial for enhancing the catalytic performance, especially in NRR catalysis. In this work, we have engineered the oxygen vacancies in Co 3 O 4 nanoparticles to boost the catalytic activity towards NRR and ORR. Ascribing to the p-d hybridization between Co and N atoms, N 2 electrochemical adsorption is promoted and the related energy barrier of N 2 protonation is significantly decreased by 50%; as a consequence, Faradaic efficiency is 11.2% at −0.4 V vs. RHE, 3-fold higher than Co 3 O 4 /CNT; moreover, due to the oxygen vacancies in Co 3 O 4-x /CNT leading to a higher oxophilicity, Co 3 O 4-x /CNT showed a better selectivity in ORR catalysis and kinetic current density at 0.85 V vs. RHE is boosted by 2.4 times. Consequently, Co 3 O 4-x /CNT exhibits a better rechargeable zinc air battery performance than Pt/C-IrO 2 by a factor of 2.2.

High performance ammonia gas sensor based on electrospinned Co3O4 nanofibers decorated with hydrothermally synthesized MoTe2 nanoparticles

Fengjiao Chen,Yong Zhang,Dongyue Wang,Tian Wang,Jianhua Zhang,Dongzhi Zhang

This paper introduces a room temperature NH 3 gas sensor with excellent performance based on cobalt trioxide and molybdenum telluride (Co 3 O 4 -MoTe 2 ) nanocomposite. Co 3 O 4 nanofiber was synthesized by electrospinning, and MoTe 2 nano particle was synthesized by simple hydrothermal method . MoTe 2 , Co 3 O 4 and Co 3 O 4 -MoTe 2 film sensors were prepared on interdigital electrode substrate by drop coating method. X-ray photoelectron spectroscopy (XPS), dispersive spectrometer (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to observe the morphology, microstructure, and composition of the prepared nano-materials. The gas sensing performance of the pristine Co 3 O 4 , MoTe 2 and Co 3 O 4 -MoTe 2 composite film sensors were tested at room temperature. The results of experimental research show that the Co 3 O 4 -MoTe 2 gas sensor has better sensing performance for ammonia than the pure sensor, such as high response (56.20%@1ppm), excellent selectivity, good stability, short response/recovery time (7s/7s@1ppm) and low detection limit (26 ppb). The performance enhancement of the Co 3 O 4 -MoTe 2 film sensor was mainly attributed to the p-n heterojunction formed between MoTe 2 and Co 3 O 4 .

Enhanced photocatalytic water splitting of g-C3N4 loaded with Fe doped Co3O4 and Pt dual-cocatalysts

Kailin Wang,Songyu Yang,Yan Wu

Dual cocatalysts play an important role in photocatalytic water splitting to hydrogen production . In this paper, Fe-doped Co 3 O 4 (Fe-Co 3 O 4 ) and Pt were loaded on the surface of g -C 3 N 4 to enhance the water photocatalytic splitting, in which Fe-Co 3 O 4 was used as an oxidation cocatalyst to capture the photo-generated holes of g -C 3 N 4 , and Pt was used as a reduction cocatalyst to transfer photo-generated electrons. Under the irradiation of visible light, its hydrogen production rate reaches up to 3.015 mmol g −1 h −1 , which is 3.01 times higher than that of g -C 3 N 4 loaded with Pt. Pt and Fe-Co 3 O 4 dual cocatalysts not only promote the migration rate of photo-generated electrons and holes on the surface of g -C 3 N 4 , but also improve the light absorption capacity of visible light. The interfacial electric field built from the p-n heterojunction of Fe-Co 3 O 4 / g -C 3 N 4 drives photo-generated electrons in Fe-Co 3 O 4 flowing to the holes of g -C 3 N 4 , which further inhibiting the recombination of g -C 3 N 4 photo-generated carriers. This work provides a reference for the development of high-efficiency photocatalyst and an effective support for the development of semiconductor cocatalyst.

Electrocatalytic Reduction of Nitrate via Co3O4/Ti Cathode Prepared by Electrodeposition Paired With IrO2-RuO2 Anode

Wang Chuan,Cao Zhifen,Huang Hongtao,Liu Hong,Wang Sha

Nitrate pollution is already a global problem, and the electrocatalytic reduction of nitrate is a promising technology for the remediation of wastewater and polluted water bodies. In this work, Co3O4/Ti electrodes were prepared by electrodeposition for the electrocatalytic reduction of nitrate. The morphology, chemical, and crystal structures of Co3O4/Ti and its catalytic activity were investigated. Then, the electrocatalytic nitrate reduction performance of Co3O4/Ti as the cathode was evaluated by monitoring the removal efficiencies of nitrate (NO3−-N) and total nitrogen (TN), generation of reduction products, current efficiency (CE), and energy consumption (EC) at different operating conditions. Under the catalysis of Co3O4/Ti, NO3− was reduced to N2 and NH4+, while no NO2− was produced. After the introduction of chloride ions and IrO2-RuO2/Ti as the anode, NH4+ was selectively oxidized to N2. The removal efficiencies of NO3−-N (at 100 mg/L) and TN after 2 h were 91.12% and 60.25%, respectively (pH 7.0; Cl− concentration, 2000 mg/L; current density, 15 mA/cm2). After 4 h of operation, NO3−-N and TN were completely removed. However, considering the EC and CE, a 2-h reaction was the most appropriate. The EC and CE were 0.10 kWh/g NO3−N and 40.3%, respectively, and electrocatalytic performance was maintained after 10 consecutive reduction cycles (2 h each). The cathode Co3O4/Ti, which is prepared by electrodeposition, can effectively remove NO3−-N, with low EC and high CE.