As one of the most lethal chemical warfare agents (CWAs), mustard gas causes irreversible damage to human health. Selective oxidation of mustard gas into non-toxic sulfoxide using reactive oxygen species (ROS) generated from H2O2 represents an effective detoxification strategy. In this context, nanozymes with peroxidase-like (POD-like) activity have attracted increasing attention because of their ability to activate H2O2 to produce ·OH or ·O2-. Among spinel oxides, CuCo2O4 exhibits intrinsic POD-like activity; however, its catalytic efficiency for mustard gas detoxification remains limited. To improve the POD-like activity of p-type CuCo2O4, a p-n heterojunction was constructed by coupling it with n-type H3PW12O40 (PW12), a polyoxometalate (POM). Theoretical analysis demonstrates that a built-in electric field is formed at the CuCo2O4/PW12 interface, leading to charge redistribution and modulation of the electron spin state at Co3+ active sites. As a consequence, *OH desorption is facilitated and ·OH generation is significantly accelerated. Benefiting from these effects, CuCo2O4/PW12 exhibits enhanced POD-like activity and efficient selective oxidation performance toward 2-chloroethyl ethyl sulfide (CEES), a mustard gas stimulant. These results indicate that nanozymes are effective candidates for mustard gas detoxification, and that heterojunction construction combined with electron spin state regulation is an effective strategy for performance enhancement.

Solar-driven evaporation has emerged as a promising approach for seawater desalination, attracting significant research interest. However, biofouling remains a persistent challenge in solar steam generation systems, as microbial colonization degrades water quality and leads to secondary contamination. Nanozymes represent a viable solution to this issue, owing to their ability to generate reactive oxygen species and effectively inactivate microorganisms. In this work, a cobalt-doped vanadium disulfide (Co-VS2) nanozyme was synthesized via a facile route. Compared to pristine VS2, the Co-VS2 nanozyme exhibits markedly enhanced peroxidase-mimic activity, attributed to the successful incorporation of Co2+ ions. First-principles calculations reveal that the d-band center of Co-VS2 is shifted closer to the Fermi level, thereby facilitating H2O2 adsorption and subsequent activation. Futhermore, Co-VS2 demonstrates excellent photothermal properties, achieving a solar-thermal conversion efficiency of 36.6%. Through electrospinning, Co-VS2 nanoparticles were integrated with polyacrylonitrile (PAN) to fabricate a composite Co-VS2/PAN membrane, which exhibits a high evaporation rate and efficiency. The membrane also demonstrates robust antibiofouling activity, enabling stable long-term operation in water evaporation applications. The quality of the condensed water meets the World Health Organization standards for potable water. These findings indicate that nanozymes with integrated antibiofouling and photothermal functionalities hold substantial potential for next-generation water purification technologies.

The oxygen evolution reaction (OER) plays a crucial role in energy conversion and storage. Nickel-iron layered double hydroxide (NiFeLDH) is a promising non-precious metal-based electrocatalyst for OER. To enhance the OER activity of n-type NiFeLDH, a p-n heterojunction is constructed with p-type CoMoO4. The difference in Fermi levels between NiFeLDH and CoMoO4 in the NiFeLDH/CoMoO4 system generates a built-in electric field, which optimizes the OER interfacial structure. In the OER, the eta 10, eta 100 and eta 400 (overpotentials to achieve 10, 100, and 400 mA cm- 2, respectively) values are 225, 278, and 309 mV, with a Tafel slope of 39.0 mV dec- 1. Additionally, NiFeLDH/CoMoO4 demonstrates excellent stability in OER. Mechanism calculations further confirm the charge distribution and the formation of an internal electric field in the p-n heterojunction. The density of states (DOS) shows that the d-band center of NiFeLDH/CoMoO4 is close to the Fermi level, which facilitates the adsorption of oxygen intermediates in the OER process. This work highlights that the contribution of the p-n heterojunction and the built-in electric field can enhance OER activity, providing a new strategy for developing OER electrocatalysts in energy conversion and storage applications.

Solar-driven evaporation, as a promising technique for water purification, has attracted widespread attention. However, due to the contamination of solar steam generation systems with bacteria, the water quality is thereby degraded and subjected to secondary contamination. Nanozyme are ideal for reversing this situation as they are highly efficient in generating active radicals and killing bacteria. Herein, a nanozyme, namely Fe/VN@NCNTs (NCNTs =N-doped carbon nanotubes), is synthesized. The superior laccase-mimic activity, a feature of Fe/ VN@NCNTs compared to vanadium nitride (VN), is attributed to the construction of a Mott-Schottky (M-S) heterojunction between metallic Fe and VN. Mechanism calculations confirm M-S heterojunction facilitates charge redistribution at the interface and generates a built-in electric field, thus boosting O2 adsorption and enhancing laccase-mimic activity. By combining Fe/VN@NCNTs with sodium alginate (SA), Fe/VN@NCNTs/SA membrane is prepared. The membrane exhibits solar steam generation performance while maintaining antimicrobial activity in evaporation processes. The quality of evaporated water complies with the drinking water standards. It is expected that nanozymes combining exceptional antimicrobial and photothermal activities will be popularized in water purification.

The hydrogen evolution reaction (HER) is vital for energy conversion and storage. Molybdenum carbide (Mo2C) has emerged as a promising non-precious metal-based electrocatalyst for HER. To improve its catalytic activity, a dual heterojunction comprising CoO and metallic Co was constructed on Mo2C. In the resulting Co/CoO/ Mo2C@NCNTs, the mismatch in Fermi levels induces a dual built-in electric field at the CoO/Mo2C and Co/Mo2C interfaces, which optimizes the HER interfacial environment. Under acidic conditions, the overpotentials required to achieve current densities of 100, 200, and 500 mA cm-2 (8100, 8200 and 8500) are as low as 73, 127, and 265 mV, respectively. Additionally, the catalyst demonstrates excellent long-term stability. Mechanistic calculations further confirm that charge redistribution occurs within the Co/CoO/Mo2C heterojunction, giving rise to the dual built-in electric field. Density of states (DOS) analysis reveals that the d-band center is significantly shifted away from the Fermi level in Co/CoO/Mo2C@NCNTs, facilitating H* desorption and promoting H2 evolution. Moreover, the catalyst exhibits promising HER activity and durability in both alkaline and neutral media. This study underscores the effectiveness of constructing dual built-in electric fields to enhance HER performance, offering a new strategy for designing high-efficiency electrocatalysts for energy conversion and storage technologies.

Regarded as a burgeoning energy conversion and storage device, Zn-air battery achieves charge/discharge through oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). However, the sluggish kinetics of ORR and OER affects charge/discharge performance of Zn-air battery significantly. MoN-based electrocatalysts exhibit ORR and OER activities. However, it is necessary to further improve their performance when they are used in Zn-air battery. Herein, bifunctional electrocatalyst, namely FeCo/MoN@NCNTs (NCNTs = Ndoped carbon nanotubes), is synthesized, with FeCo and MoN particles evenly distributed in NCNTs. It shows typical four-electron character in ORR with perfect activity. In OER, it exhibits low overpotential and Tafel slope. In both ORR and OER, FeCo/MoN@NCNTs demonstrates high stability. When taken as electrocatalyst in Zn-air battery, it achieves a peak power density of 100.4 mW cm- 2. At 1 mA cm- 2, the specific capacitance and energy density reach 860.2 mAh g- 1 and 1101.1 Wh kg- 1. This Zn-air battery also exhibits high rating capacity and stability. By developing an excellent bifunctional electrocatalyst for Zn-air battery, this study contributes a feasible solution to enhancing the ORR and OER activities of MoN-based electrocatalyst.

As an environmentally friendly, low-cost, and safe power supply device, the alkaline hybrid zinc battery (AHZB) offers high voltage, specific capacitance, and energy density. In AHZB, the reversible Faradaic redox reaction, oxygen reduction reaction (ORR), and oxygen evolution reaction (OER) are integrated at the cell level. However, the performance of AHZB still requires improvement due to the suboptimal activities in the reversible Faradaic redox reaction and the ORR/OER of the cathode material. In this work, NiO/Co3O4, with high electrochemical activity, is synthesized as a cathode material for AHZB. In ORR, it exhibits a typical four-electron process, with a half-wave potential (E1/2) of 0.83 V. In OER, it demonstrates low overpotential. During the reversible Faradaic redox reaction, it also shows high specific capacitance and rate capability. Theoretical studies suggest that a p-p heterojunction forms between NiO and Co3O4, resulting in charge distribution and imparting NiO/Co3O4 with metallic characteristics and high conductivity. The AHZB assembled with NiO/Co3O4 exhibits excellent charge/ discharge performance. This work highlights that constructing an internal electric field and a p-p heterojunction is an effective approach to enhancing electrochemical activity. Furthermore, an efficient cathode material for AHZB is developed.

During the development of Zn-air batteries, designing an affordable, efficient and stable electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) presents a great challenge. Fe2O3 exhibits ORR and OER activities, but when used as a cathode material in Zn-air batteries, its activity requires further improvement. To achieve this goal, Ni is doped into Fe2O3 hexagonal nanorods, derived from a metal-organic framework (MOF) precursor, and further modified by N-doped carbon nanotubes. In ORR, its half-wave potential achieves 0.946 and 0.716 V in alkaline and neutral electrolytes, respectively. In OER, it requires 388 mV to obtain 10 mA cm-2 in an alkaline electrolyte. As illustrated by theoretical calculation, Ni-doping raises the d-band center of Fe2O3, which enhances its adsorption towards relevant oxygen species in electrocatalysis. This improves its ORR and OER activities. Based on these merits, the Zn-air battery is assembled with an alkaline electrolyte. At 10 mA cm-2, its specific capacity and energy density reach 819.8 mA h g-1 and 960.1 W h kg-1, respectively. This battery remains stable after a long time of charge and discharge. In neutral electrolytes, its promising discharge performance is also well retained. This work develops an effective approach to improve ORR and OER activities of Fe2O3-based cathode materials in Zn-air batteries.

The exploration of noble metal free bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is very important for Zn-air batteries (ZABs). Spinel ferrites are famous bifunctional ORR/OER electrocatalysts. Herein, to further improve their ORR and OER activities, we anchor CoFe2O4 on N-doped carbon nanofibers (NCNF) derived from polypyrrole (PPy) and obtain CoFe2O4 loaded NCNF (CoFe2O4@NCNF). In its structure, CoFe2O4 particles with small size distribute evenly on NCNF. The combination of CoFe2O4 and NCNF generates excellent ORR activity with typical four-electron character in both alkaline and neutral electrolyte. In OER, the activity of CoFe2O4@NCNF is also excellent. To explore the superior ORR and OER activities of CoFe2O4@NCNF over other spinel ferrites, theoretical calculation was employed. A rechargeable ZAB is constructed with CoFe2O4@NCNF as cathode material. The specific capacity and energy density of this ZAB reach 807.4 mA·h·g− 1 and 963.6 Wh·kg− 1 at 10 mA·cm− 2, respectively. ZAB can keep stable after continuous charge/discharge test for 120 h. This work not only provides an efficient and low cost cathode material for ZABs, but also clarifies the structure-activity relationship in ORR/OER for spinel ferrites.

p‐Nitrophenol (PNP), a highly toxic water pollutant, poses significant risks to human health and the environment. For detecting PNP, a colorimetric method utilizing a nanozyme that mimics laccase activity presents a viable approach. In this study, PV14@MIL‐88A, a robust nanozyme with superior laccase‐mimic capabilities, was synthesized by incorporating Na7H2[PV14O42] (PV14) into MIL‐88A, a metal‐organic framework (MOF). This nanozyme demonstrates optimal laccase‐mimicking activity, enabling effective PNP detection via colorimetry and digital image colorimetry using smartphones. Theoretical analyses suggest that the outstanding laccase‐mimic activity of PV14@MIL‐88A is derived from the optimized d‐band center in PV14. Upon calcination with dicyandiamide (DCDA), PV14@MIL‐88A transforms into Fe2O3/VO2@NCNF. In the presence of NaBH4, Fe2O3/VO2@NCNF facilitates the conversion of PNP to p‐aminophenol (PAP), an essential precursor in paracetamol synthesis. The interaction between Fe2O3 and VO2 in Fe2O3/VO2@NCNF enhances adsorption and subsequent reduction of PNP. The saturation magnetization of Fe2O3/VO2@NCNF reaches 25 emu·g‐1, which supports efficient magnetic separation in the reduction process. This study not only advances an effective method for PNP detection but also facilitates its transformation from a hazardous pollutant into a valuable chemical precursor.

Fe-based materials are famous electrocatalysts in oxygen reduction reaction (ORR), but their selectivity towards four- or two-electron ORR still requires further research in detail. Herein, two Fe-based ORR electrocatalysts are synthesized from MIL-101, a metal-organic framework (MOF). After calcined with dicyandiamide (DCDA) under N2 protection, Fe3O4@NCNTs (NCNTs =N-doped carbon nanotubes) is synthesized, in which small Fe3O4 particles reside in NCNTs homogeneously. It is a typical four-electron electrocatalyst in both alkaline and neutral electrolyte. Without DCDA, Fe2O3 forms and it acts as two-electron electrocatalyst in ORR. Theoretical calculation suggests the discrepancy in ORR selectivity between Fe3O4@NCNTs and Fe2O3 roots from their different interactions with OOH*. If Fe3O4@NCNTs serves as cathode material, peak power density of Zn-air battery reaches 125.1 mW & sdot;cm- 2 in alkaline electrolyte. When discharge at 10 mA & sdot;cm- 2, the specific capacitance and energy density reach 799.7 mAh & sdot;g- 1 and 839.7 Wh & sdot;kg- 1. The performance of Fe3O4@NCNTs is also well kept in neutral Zn-air battery. We expect this work elucidates the effect of structure on ORR selectivity for Fe-based electrocatalysts.

Nanozymes-involving colorimetry may represent an effective solution to tetracycline detection due to its affordability and simplicity. To improve the performance in selectivity, molecular imprinting technology has emerged as a promising approach to simulating the interaction between antibodies and receptors. Herein, Mn2V2O7, a form of nanozyme with oxidase-mimicking activity, was synthesized. With tetracycline as the template, the cavities with unique dimensions were constructed through the self-polymerization of dopamine (DA) on Mn2V2O7. In Mn2V2O7@MIP, polydopamine (PDA) acts as molecularly imprinted polymer (MIP) and its cavities are compatible with tetracycline in dimension. It also exhibits oxidase-mimicking activity. With the introduction of tetracycline, the cavity of PDA is blocked, which leads to obvious color fading, which enables precise tetracycline detection with colorimetry. The range of linear detection is from 10 to 100 mu M, and the lower limit of detection is 0.82 mu M. It is anticipated that the combination between nanozymes-involving colorimetry and molecular imprinting technology would contribute to the accurate detection of organic pollutants in the aquatic environment.

Biofouling significantly impacts marine environments and economies through pollution and economic loss. Artificial nanozymes, resembling haloperoxidase, are highly effective in combating biofouling due to their ability to facilitate the conversion of Br− to HBrO, thereby inhibiting the survival and proliferation of microorganisms. However, this process necessitates the presence of H2O2. To achieve haloperoxidase mimicry in biofouling prevention without external H2O2, a bifunctional polyoxometalate (POM) with abundant oxygen vacancies has been developed. This compound simultaneously exhibits haloperoxidase mimicry and photocatalytic H2O2 generation. Theoretical analyses suggest that oxygen vacancies elevate the d-band center, improving the adsorption of H2O2 and Br-, and thus enhancing haloperoxidase mimicry. The POM compound demonstrates notable H2O2 production capabilities, with a rate of 1.77 mmol·h−1·g−1, attributed to oxygen vacancies facilitating electron-hole pair separation. This advancement allows for haloperoxidase mimic biofouling prevention without the need for added H2O2. This study not only elucidates the structure–activity relationship in haloperoxidase mimicry and photocatalytic H2O2 production but also presents an effective and eco-friendly method for biofouling prevention.

As a kind of aminoglycoside antibiotics, kanamycin (KAN) is widely applied to animal husbandry and aquaculture. However, the abuse of KAN causes the large-scale discharge of it into rivers, lakes and groundwater, which threatens environmental safety and human health. Therefore, it is imperative to develop a method that is applicable to detect KAN in an efficient and accurate way. The colorimetric method based on enzymes provides a feasible solution for the detection of organic pollutants. However, the extensive application of natural enzymes is constrained by high cost and low stability. Herein, a polyoxometalate-based nanozyme, namely [H7SiW9V3O40(DPA)3]·4H2O (SiW9V3/DPA) (DPA = dipyridylamine), is synthesized. As a low-cost nanozyme with high stability compared to natural enzymes, SiW9V3/DPA performs well in laccase-mimicking activity. It can be used to induce chromogenic reaction between 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP), which generates red products. With the addition of KAN, the color fades. That is to say, KAN can be detected with colorimetric assay in the concentration range 0.1 to 100 μM with high selectivity and low limit of detection (LOD) of 6.28 μM. Moreover, SiW9V3/DPA is applied to KAN detection in lake and river water and milk with satisfactory results. To sum up, polyoxometalate-based nanozyme is expected to provide a promising solution to the detection of organic pollutants in the aquatic environment.

An “additional H2O2 free” antibiofouling method is developed using Ni16Mo16P24, which possesses haloperoxidase mimic and electrocatalytic H2O2 production properties.

Abstract Water electrolysis is a common method for hydrogen production; a catalyst can lower the required voltage, known as electrocatalytic hydrogen production. Pt is an ideal catalyst due to high activity, but limited supply and cost impede use. Thus, we synthesized a novel composite electrocatalyst Mo2C@NC using versatile N-doped mesoporous carbon from camphor leaves, incorporating 7 to 12 nm Mo2C particles into nitrogen-doped mesoporous carbon matrix. This innovative electrocatalyst has unique properties, particularly nitrogen incorporation, making Mo2C@NC highly active in electrocatalytic hydrogen production. Under alkaline conditions, Mo2C@NC needs a low 79 mV overpotential for 10 mA·cm− 2 current density, showing durability after 1000 cycles and remaining stable for 10 hours. Mo2C@NC also efficiently catalyzes the reduction of 4-nitrophenol to 4-aminophenol, requiring only 5 mg to complete the reaction in under 5 minutes. It also degrades methylene blue, a common organic dye, suggesting potential in large-scale H2 production and water purification.

A kind of composite magnetic field for flow control in slab mold is proposed, in which an electromagnetic stirring (EMS) is carried out near the meniscus and an electromagnetic braking (EMBr) is carried out near the outlet of the submerged entry nozzle (SEN), simultaneously. The yoke for the EMS and the EMBr is made independent from each other, with a ruler type for the EMBr. A three-dimensional model of the magnetic field calculation is established. The simulation results show that the magnetic induction intensity generated with the EMS mainly concentrates in the EMS area. The magnetic induction intensity generated with the EMBr has a large component in the EMS results, which has little effect on the flow of this area. Based on the composite magnetic field calculation results, the three-dimensional numerical simulation of the flow field is carried out, and the flow field obtained is compared to that without the magnetic field but with the EMS and the EMBr only, respectively. The results show that under the composite magnetic field, EMBr and EMS can play their respective roles well under certain conditions, the impact of the jet flow on the narrow face is reduced, and the stirring beneath the meniscus is intensified.

通过风能科学与工程课程传统教学和PBL教学模式进行对比,讨论了PBL教学模式及主动学习在课程教学中的效果.采用线下线上结合形式进行课程教学互动和考核.PBL及主动学习模式促进了学生自主学习意识,培养了社会性能力,锻炼了高层次思维.