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Since the catalyst's surface was the major active location, the inner structure's contribution to catalytic activity was typically overlooked. Here, ZnO–Co 3 O 4−v nanozymes with several surfaces and bulk oxygen vacancies were created. The O atoms of H 2 O 2 moved inward to preferentially fill the oxygen vacancies in the interior and form new "lattice oxygen" by the X-ray photoelectron spectroscopy depth analysis and X-ray absorption fine structure. The internal Co2+ continually transferred electrons to the surface for a continuous catalytic reaction, which generated a significant amount of reactive oxygen species. Inner and outer double-layer electron cycles accompanied this process. A three-dimensional model of ZnO–Co 3 O 4−v was constructed using virtual reality interactive modelling technology to illustrate nanozyme catalysis. Moreover, the bactericidal rate of ZnO–Co 3 O 4−v for Methionine-resistant Staphylococcus aureus and Multiple drug resistant Escherichia coli was as high as 99%. ZnO–Co 3 O 4−v was biocompatible and might be utilized to heal wounds following Methionine-resistant Staphylococcus aureus infection. This work offered a new idea for nanozymes to replace of conventional antibacterial medications. [ABSTRACT FROM AUTHOR]

SrCoO 3 , SrNiO 3 , and SrCoNiO 3-δ were produced by high-temperature calcination method. Among them, SrCoNiO 3-δ trimetallic perovskite exhibited outstanding peroxidase and oxidase activity. Various characterization analyses revealed that the addition of Ni2+ partially replaced Co2+ in the initial perovskite coordination environment, conferring a unique catalytic ability that altered the crystal shape of the original perovskite structure and resulted in a richer electron transfer. This causes the material's surface to exhibit oxygen vacancies (O vs) and OH radicals, which are the primary source of enzyme activity. Based on the material's excellent enzyme activity, we successfully developed a flexible, intelligent, fast, and instant colorimetry detection platform for the detection of dopamine hydrochloride (DAH) and Cd2+ using a smartphone, assisting in the detection of antibiotic residues in soil and water. The linear ranges of DAH and Cd2+ are 2–20 μM, and their respective detection limits are 0.098 μM and 0.343 μM. • SrCoNiO3-δ perovskite with SOD and POD activity was synthesized. • The catalytic mechanism of SrCoNiO3-δ was studied. • The "on-off - on" detection platform of DAH and Cd2+ was constructed. • The smartphone detection platforms of DAH and Cd2+ were constructed. [ABSTRACT FROM AUTHOR]

Clean and sustainable photoelectric technology has been developed rapidly in many fields. One of which is the novel marine corrosion protection technology that directly utilizes the abundant solar energy falling on the ocean to provide photoinduced cathodic protection for metallic structures, and has received increasing attention year by year. Improving the photoelectrochemical conversion and photoelectric cathodic protection performance for metals under sunlight is vital for achieving effective protection. In particular, optimizing the multi-dimensional nanostructured photoanode to accelerate the collection and transfer of photogenerated electrons and to improve the photoelectric and cathodic protection performance is a promising method. Here, an ultrafine branched anatase TiO2 nanolawn (NL) photoanode co-decorated with CdS nanoparticles and reduced graphene oxide quantum dots (rGO QDs) was prepared. Compared with single CdS modified TiO2 NL, the three-phase junction CdS/rGO QDs/TiO2 NL shows further enhanced photoelectrochemical conversion performance under simulated sunlight and visible light irradiation, increased by 66.7% and 83.3% compared to that of CdS/TiO2 NL, respectively. The rGO QDs, which acted as a high-efficiency electron transporter, are uniformly deposited on the TiO2 NL, and further promote the transport efficiency of photogenerated electrons. CdS as a visible-light responder is responsible for broadening the spectral response, and the ultrafine branched TiO2 NL substrate greatly expands the photon capture area and increases the electron collection sites. Finally, the synergy of the above three aspects ensures that the ternary CdS/rGO QDs/TiO2 NL photoanode exhibits further enhanced simulated sunlight-driven and visible light-driven photoelectric conversion efficiency and a photoinduced cathodic protection effect on 316L stainless steel and pure copper. [ABSTRACT FROM AUTHOR]

The global annual consumption of marine metal corrosion is a significant challenge to the service life of metals and the development of marine strategies. A tri-dimensional AgInS2/In2S3 co-modified TiO2 nanobush (NB) superstructure photoanode is constructed. It shows superior photoelectric cathodic protection (PECP) characteristic for pure copper whose self-corrosion potential is more negative in simulated natural marine environment without additional any hole scavengers under simulated solar light illumination. Origin from the more negative energy level potential of AgInS2/In2S3, the quasi-Fermi level of the photogenerated electrons of TiO2 NB/AgInS2/In2S3 was pull to a more negative position, reinforcing the transmission of photogenerated electrons to the pure copper whose self-corrosion potential is more negative. The sensitizer AgInS2 together with the assistant layer In2S3 dramatically enhances the PECP performance of TiO2 NB/AgInS2/In2S3. The tri-dimensional ultrafine branch-like architecture of TiO2 NB with the nanoparticles quickens the collection and transfer of photogenerated electrons to the metallic pure copper. This environmentally friendly 3D photoanode structure provides a good reference for the optimized construction of photoelectric materials for marine metal corrosion protection. The tri-dimensional AgInS2/In2S3 co-modified TiO2 nanobush superstructure photoanode possesses superior photoelectric cathodic protection characteristic for pure cooper whose self-corrosion potential is more negative in simulated marine environment under simulated solar light illumination. [ABSTRACT FROM AUTHOR]

The novel photoelectrochemical cathodic protection technology is actively researched and developed for alleviating severe corrosion of marine metallic materials. And the corresponding sustained photoelectrochemical cathodic protection in the dark, under the collaboration of the electron storage materials, is also developed and optimized. WO3, as a kind of electron storage material, shows great potential in this area. The WO3/graphene oxide (WO3/GO) nanothorn cluster composites were synthesized via solovthermal method. The nanoscale graphene oxide (GO) sheets, added as templates, result in the formation of WO3 nanothorn clusters in the WO3/GO composite. The hybrid structure of the WO3/GO composite was formed when the GO adding amount is 0.2 wt%, denoted as WO3/GO 0.2. The lattice of WO3 contracted slightly and the crystallinity of WO3 was enhanced. The WO3/GO 0.2 nanothorn cluster composites promote the transfer and storage efficiency of the electrons compared with pure WO3. The high conductivity of the partly reduced GO leads to a faster electron transfer in the WO3/GO composite. The sustained photoelectrochemical cathodic protection performance of the WO3/GO composite under the assistance of TiO2 (i.e., the coupling of WO3/GO 0.2-TiO2) for 304 stainless steel (SS) was promoted. A larger number of photoinduced electrons, generated by TiO2 under white light illumination, can be stored in the WO3/GO composite and be transferred to the coupled 304 SS electrode after shutting off the light. WO3/GO composite exhibits enhanced sustained photoelectrochemical cathodic protection performance for 304 stainless steel under the assistance of TiO2. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of nitrate is a highly promising method for removing nitrate from water bodies. However, slow reaction rates have been a major challenge in its practical application. In this study, a novel CuO/Cu 2 O@CC hetero-electrode was developed by using a precise redox strategy, where CuO and Cu 2 O were simultaneously introduced to provide catalytic active sites for the reduction of nitrate into ammonia. This compositing design could significantly enlarge the electrochemically active surface area, reduce the electron transfer resistance and increase hydroxyl oxygen content on the electrode surface. The effect of operating parameters (cathodic potential, initial pH, supporting electrolyte concentration, initial NO 3 – − N concentration and coexisting Cl – concentration) on nitrate reduction was studied to optimize the reduction efficiency. Under −1.4 V (vs. Ag/AgCl) cathodic potentials and initial pH = 7 parameters, CuO/Cu 2 O@CC 3 achieved a remarkable 92.9% removal of 100 mg L – 1 initial nitrate and a high ammonia selectivity of 78.33% in 1 h using 0.5 mol L – 1 K 2 SO 4 as supporting electrolyte, with a pseudo-first-order kinetic constant of 2.5856 h – 1. Additionally, based on the experimental results, a reaction mechanism for the heterostructures electrode was proposed. The successful construction of CuO/Cu 2 O hetero-electrode provides a unique insight into the electrochemical reduction of nitrate. • Precise redox strategy was proposed to fabricate copper-based hetero-electrodes. • CuO and Cu 2 O dual active sites enhanced the catalytic activity. • High nitrate reduction rate (92.9%) and kinetic constant (2.5856 h – 1) were achieved. • Nitrate was reduced to valuable ammonia resources. [ABSTRACT FROM AUTHOR]

Solar energy-driven photoinduced cathodic protection technology is considered as one of the most promising state-of-the-art and eco-friendly technology for marine metallic corrosion protection, utilizing only solar energy instead of sacrificial anode materials or impressed current to achieve corrosion protection. A 3D Zn-doped Bi 2 S 3 sensitized WO 3 /ZnO multi-heterojunction photoelectrode with both adjustable energy band and electron self-storage characteristics was enlightened and constructed to couple with metallic materials for providing long-term photoinduced cathodic protection both in light and dark conditions. [Display omitted] • An electron self-storage WO 3 /ZnO/Zn-Bi 2 S 3 photoelectrode was constructed. • Doping of Zn makes the energy band of Bi 2 S 3 wider and more negative. • The multijunction promotes the backward transfer of photogenerated electron and hole. • The transformation of Bi3+/Bi5+ promotes the consumption of photogenerated holes. • It exhibits an enhanced sustained photoinduced cathodic protection performance. Solar energy-driven photoinduced cathodic protection (PICP) technology utilizes solar energy to protect marine metallic structures against severe marine corrosion. To enhance the solar energy utilization and strengthen dark-state application for realizing long-term protection, herein, a 3D nanothorn cluster-like WO 3 /ZnO/Zn-Bi 2 S 3 multijunction with electron-storage characteristic and adjustable energy band was constructed. It exhibited an enhanced continuous release of photogenerated electron and sustained cathodic protection in dark conditions. Exposed to only 100 s of simulated sunlight irradiation, the WO 3 /ZnO/Zn-Bi 2 S 3 could store 5.27×10−2 C electrons and provide up to 5460 s of sustained CP for the coupled metal after light stops, which was 10.8 and 3.5 times higher than those of WO 3 /ZnO (4.89×10−3 C) and WO 3 /Zn-Bi 2 S 3 (1.51×10−2 C), respectively. The WO 3 nanothorn cluster-like substrate with reversible valence transformation of W6+/W5+ together with the large surface area and one-dimensional transmission path can store photogenerated electrons under illumination and release photogenerated electrons after light stops efficiently. Notably, the tri-phase heterojunction with introduction of intermediate "Carrier Springboard" ZnO between WO 3 and Zn-Bi 2 S 3 contributed to the building of well-matched energy band gradient to strengthen the directional backward transfer of photogenerated electrons and holes. The energy band of Bi 2 S 3 sensitizer was adjusted towards negative direction by doping with zinc element to boost PICP application performance. The reversible valence transformation of Bi3+/Bi5+ could promote the consumption of photogenerated holes. These synergistically enhanced the sustained PICP performance of the WO 3 /ZnO/Zn-Bi 2 S 3 photoelectrode both in dark and light conditions. This design shed light on energy-storage photoelectrodes for long-term PICP of metallic materials. [ABSTRACT FROM AUTHOR]

In this work, a H 2 O 2 -treated indium oxide (In 2 O 3 ) semiconductor material was prepared. The photoelectrochemical cathodic protection performance and the photoelectrochemical behaviors of the H 2 O 2 -treated In 2 O 3 were investigated. Under visible light illumination, the H 2 O 2 -treated In 2 O 3 exhibits enhanced photoelectrochemical conversion efficiency (the photoinduced current density was increased by approximately 50%) and enhanced photoelectrochemical cathodic protection performance (the photoinduced cathodic protection current density was increased by approximately 81.8%). The concentrations of adsorbed oxygen and oxygen vacancy in In 2 O 3 were increased after H 2 O 2 treatment, resulting in the enhancement of visible light absorption activity of the H 2 O 2 -treated In 2 O 3 . With the increase of the concentration of oxygen vacancy, the Fermi level of In 2 O 3 negatively shifts, which promotes the photoelectrochemical cathodic protection performance of the H 2 O 2 -treated In 2 O 3 . The increased surface adsorbed oxygen groups is beneficial for capturing the photoinduced electrons, resulting in the promotion of the separation efficiency of the photogenerated electron–hole pairs and the electron transfer capability, and hence leading to the increase of the photoelectrochemical cathodic protection performance of the H 2 O 2 -treated In 2 O 3 . [ABSTRACT FROM AUTHOR]

[Display omitted] • A three layers FeO x @ZnMnFeO y @Fe-Mn bimetallic organogel was creatively synthesized. • The four-functional sensing platforms for H 2 O 2 , citric acid, norfloxacin and gallic acid were constructed effectively. • The smartphone detection platform for CA and NOR was established successfully. • CA and NOR were detected continuously based on the turn on-off-on signal change. • The nanozyme-like activity mechanism and the detection mechanism were analyzed systematically. In this study, the FeO x @ZnMnFeO y @Fe-Mn bimetallic organogel (FO@ZMFO@FM-MOG) with three layers structure was synthesized. It presented outstanding multi-enzyme (peroxidase, oxidase and catalase) activities. The systematical characterization results showed that Zn and Mn on the surface of FO@ZMFO@FM-MOG were nearly disappeared, and thus a large amount of Fe exposed as the active species. Accordingly, the high ratio of Fe2+/Fe3+ for FO@ZMFO@FM-MOG was conductive to the electron transfer and enzyme activity. Moreover, the multiple detection platforms were constructed based on the different nanozyme activities. As for the peroxidase-mimetic activity, citric acid (CA) and norfloxacin (NOR) were monitored continuously on the basis of the turn on–off-on signal change due to the electron transfer abilities and hydroxyl radicals (•OH) formation. The linear range of 0.415–6.21 μM was obtained with a low detection limit of 79 nM, which was rarely detecting citric acid by nanozyme. And the low detection limit of 52 nM for NOR was superior to the most published NOR assays in nanozyme field. Furthermore, an oxidase platform for gallic acid (GA) was also established due to superoxide anions (O 2 •−) generation. It should be noted that the smartphone detection platforms for CA and NOR were established successfully for on-site analysis. This study provided multifunctional detection platform for valuating CA, NOR and GA in food quality and environment monitoring. [ABSTRACT FROM AUTHOR]

The microstructure of semiconductor materials is of vital importance to its photoelectrochemical performance because the well-optimized special architecture offers rapid electron transport pathways for the photogenerated electrons and provides large areas for light harvesting. In the present paper, an ultrafine hyperbranched TiO 2 nanolawn (TiO 2 UFHBNL) photoanode was prepared through a facile one-step solvothermal method under employing a suitable dosage of H 2 O and diethylene glycol (DEG). Along with varying the dosages of H 2 O and DEG in the solvothermal process, both the crystal structure and morphology of the prepared TiO 2 nanosubstrate changed gradually. With the increase of the dosage of H 2 O and DEG from 5 mL: 35 mL–10 mL: 30 mL and further to 20 mL: 20 mL, the crystal phase of the TiO 2 nanosubstrate transforms from amorphous state to anatase phase and eventually to anatase-rutile mixed phases. And, the morphology of TiO 2 nanosubstrate changes from thick nanotrees to UFHBNL architecture and then to nanoparticles. The TiO 2 UFHBNL photoanode with the ultrafine hyperbranched architecture (diameter of 5–10 nm) after the CdS nanoparticles (5 nm) decoration shows an extremely enhanced photoelectrochemical performance. The ultrafine hyperbranched TiO 2 substrate also induces the super-refinement of the deposited CdS nanoparticles (5 nm) on the sub-branches. A maximum photocurrent density of 5.6 and 3.8 mA cm−2 are obtained under AM1.5 light and visible light illumination, respectively. The highly efficient photoelectrochemical performance is attributed to the decreased charge transfer barrier which contributes to fast charge transport and decreased recombination efficiency of the carriers. This strategy is beneficial for designing the high-performance photoanodes with the ultrafine hyperbranched architecture. A high-efficient TiO 2 photoanode with ultrafine hyperbranched nanolawn (UFHBNL) architecture sensitized with ultrafine CdS nanoparticles was prepared and optimized through a facile one-step hydrothermal method following by sequential ion layer absorption and reaction technique. The ultrafine TiO 2 nanobranches can greatly reduce the charge transfer barrier and promote the rapid transfer of the photoinduced electrons, finally offer the fast electron transport pathways. Image 1 • TiO 2 ultrafine hyperbranched nanolawn (UFHBNL) photoanode with ultrafine CdS nanoparticles was prepared. • The morphology and structure of TiO 2 substrate is adjusted by controlling dosages of H 2 O and DEG. • The CdS/TiO 2 UFHBNL photoanode shows a maximum photocurrent density of 5.6 mA cm−2. • The TiO 2 UFHBNL architecture endows fast charge transport and large light harvest area. [ABSTRACT FROM AUTHOR]

The bimetallic organic framework nanoenzyme Cu 2 O/Cu-MOF/Fe-MIL-88B is synthesized by the solvothermal method. The characterizations of transition electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry prove that the amounts of oxygen vacancies are existed on the surface of Cu 2 O/Cu-MOF/Fe-MIL-88B and stronger electron transfer is the key factor for free radical •OH and O 2 ·- production, thus exhibiting excellent peroxidase activity of Cu 2 O/Cu-MOF/Fe-MIL-88B. On the basis of the excellent peroxidase activity, versatile colourimetric and intelligent detection platforms for p-aminophenol and barbituric acid are successfully constructed on site and timely. The linear ranges of p-aminophenol and barbituric acid are 25–75 μM and 5–45 μM, and the lowest limits of detection (LOD) are 0.51 μM and 0.46 μM, severally. Moreover, the mechanisms for detecting p-aminophenol and barbituric acid were displayed by virtual reality technology. Therefore, the colourimetric and intelligent sensor of p-aminophenol and barbituric acid based on the peroxidase of Cu 2 O/Cu-MOF/Fe-MIL-88B have a hopeful prospect in the field of biomedicine. [Display omitted] • Cu2O/Cu-MOF/Fe-MIL-88B presents the peroxidase-like activity. • The peroxidase like mechanism of Cu2O/Cu-MOF/Fe-MIL-88B is studied. • Cu2O/Cu-MOF/Fe-MIL-88B can detect p-aminophenol and barbituric acid. • On-site visual detection platform is established for p-aminophenol and barbituric acid. [ABSTRACT FROM AUTHOR]

In this work, a colorimetric and fluorescent dual-mode probe controlled by NH 2 -MIL-88 B (Fe, Ni) nanozymes was developed to visually detect tetracycline antibiotics (TCs) residues quantitatively, as well as accurately distinguish the four most widely used tetracycline analogs (tetracycline (TC), chrycline (CTC), oxytetracycline (OTC), and doxycycline (DC)). Colorless substrate 3,3′,5,5′-tetramethylbenzidine (TMB) may be oxidized to blue oxidized TMB by the Fe Fenton reaction, which was catalyzed by the NH 2 -MIL-88 B (Fe, Ni) nanozyme with POD-like activity. The colorimetric detection system allows TCs to interact with NH 2 -MIL-88 B (Fe, Ni). This inhibits the production of ·OH, weakens the oxidation process of TMB, and ultimately lightens the blue color in the system by blocking the electron transfer between NH 2 -MIL-88 B (Fe, Ni) and H 2 O 2. Furthermore, TCs can interact with NH 2 -MIL-88 B (Fe, Ni) as a result of the internal filtering effect, which causes the fluorescence intensity to decrease as TCs concentration increases. Additionally, a portable instrument that combines a smartphone sensing platform with colorimetric and fluorescent signals was created for the quick, visual quantitative detection of TCs. The colorimetric and fluorescent dual-mode nano platform enables color change, with detection limits (LODs) of 0.182 μM and 0.0668 μM for the spectrometer and smartphone sensor, respectively, based on the inhibition of fluorescence and enzyme-like activities by TCs. Overall, the colorimetric and fluorescence dual-mode sensor has good stability, high specificity, and an efficient way to eliminate false-positive issues associated with a single detection mode. Colorimetric and fluorescence dual-mode detection of TCs based on NH 2 -MIL-88 B (Fe, Ni). [Display omitted] • Sensing of TCs by NH 2 -MIL-88 B (Fe, Ni) nanozyme with POD-like catalytic activity and fluorescence characteristics. • Oxygen vacancy induced charge transfer modulates the charge of Fe, Ni to accelerate the formation of hydroxyl radical. • A machine learning-assisted colorimetric-fluorescence dual-mode sensor was successfully prepared. • A visual and portable analysis platform based on smartphones has been established. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 /CoS 2 heterostructure nanozyme presented double enzyme-like activity. • The structure–activity relationship of MoS 2 /CoS 2 NFs was investigated deeply. • The antibacterial rate of MoS 2 /CoS 2 NFs reached up to 99%. • Insights into the antibacterial mechanism of MoS 2 /CoS 2 to drug-resistant bacteria. • MoS 2 /CoS 2 effectively treated the wounds infected with drug-resistant bacteria in vivo. Wounds infected by drug-resistant bacteria have become a worldwide health problem, and conventional antibiotics are no longer effective. On this basis, MoS 2 /CoS 2 heterostructure nanozymes was designed by simple molten salt method. Transmission Electron Microscopy confirmed that the clear interface of MoS 2 /CoS 2 was established creatively, which greatly promoted more distorted lattice generation. Benefited from the heterogeneous interfaces of MoS 2 /CoS 2, the transfer of electrons was accelerated and double enzyme-like activities were improved greatly, which had been confirmed by the experimental characterizations and theoretical calculation. Moreover, the mechanism was investigated in depth based on the electronic state change of MoS 2 /CoS 2 during the peroxidase reaction. Based on the peroxidase avtivity, MoS 2 /CoS 2 could effectively kill drug-resistant bacteria as high as 99%, including Gram-positive and Gram-negative bacteria, it proved the broad-spectrum antibacterial effect of MoS 2 /CoS 2. The results showed the superiority of the synergistic effect of the material and low concentration of H 2 O 2. In addition, MoS 2 /CoS 2 NFs greatly promoted the rapid healing of wounds in vivo and had good biocompatibility. This study provides a simple strategy to engineer nanozymes with enhanced catalytic activity and furnished a potential ideas in the treatment of bacterial infections and wound healing. [ABSTRACT FROM AUTHOR]

• Biomass carbon, Ag NPs and Cr-MIL-101 derived Cr 2 O 3 were used to enhance conductivity. • MOF-derived metal oxides retain the MOF morphology. • Bifunctional monomers were used to enhance the specificity of MIP for NFZ. • Wide linear range of 5 × 10−9–1 × 10−5 M were obtained, along with low detection limit of 3 × 10−9 M. In the work, a novel molecularly imprinted electrochemical sensor was proposed for sensitive and rapid detection of nitrofurazone (NFZ). The sensor was modified with Cr 2 O 3 derived from metal-organic framework (MOF), silver nanoparticles (Ag NPs) and biomass carbon (BC) from walnut shells. Among them, Ag NPs are grown on the surface of Cr-MIL-101 to obtain Cr-MIL-101/Ag, and then calcined with BC to obtain a composite material BC/Cr 2 O 3 /Ag. This material improves the effective surface area and electron transfer capability of the electrode to increase current response. Adding molecularly imprinted polymer (MIP) to the surface of composite materials can improve the specific recognition ability of modified electrodes for NFZ. MIP was prepared by precipitation polymerization using acrylamide (AM) and α-methacrylic acid (MAA) as bifunctional monomers and NFZ as the template. Under the most suitable experimental environment, the differential pulse voltammetric (DPV) current response of modified electrode (BC/Cr 2 O 3 /Ag/MIP/GCE) to NFZ showed a good linear relationship between 5 × 10−9 −1 × 10−5 M, and the detection limit was 3 × 10−9 M. This sensor has high sensitivity, selectivity, reproducibility and stability. Moreover, BC/Cr 2 O 3 /Ag/MIP/GCE was applied for the detection of NFZ in real samples. BC/Cr 2 O 3 /Ag/MIP/GCE provides a reliable approach for determination of NFZ in biological fluids. [ABSTRACT FROM AUTHOR]