Synthesis and Mechanism of Co2+/Sr2+ Codoped Magnetic Lanthanum Cuprate with Excellent Corrosion Resistance.

The special structure of perovskite-like compounds allows the existence of some open spaces in the crystals that play an important role in their crystal function enhancement and can accommodate active oxygen, which helps to solve some problems in the field of corrosion prevention. The magnetic lanthanum cuprate was obtained through the doping of Co2+ and Sr2+, and compared with La2CuO4 and epoxy resin, its corrosion resistance was improved by 215.2 and 566.7%, respectively. The micromagnetic field in the crystal interfered with the state of motion of the electrons and prolonged their transport path. High concentration doping and substitution of unequal states led to the formation of oxygen vacancy defects, which could trap active oxygen molecules and inhibit cathodic corrosion reactions. The unique alternating interlayer structure of perovskite-like compounds was conducive to the release of Cu2+, thus forming a more stable passivator on the surface of the coating. La1.96Sr0.04Cu0.98Co0.02O4 had both magnetic properties and structural advantages, which enhanced the shielding property of epoxy resin and expanded the application of perovskite-like compounds in the field of corrosion prevention.

Design and enhanced anticorrosion performance of a Zn5Mo2O11·5H2O/h-BN nanocomposite with labyrinth of nanopores.

Zinc molybdate (ZMO) is a safe and effective grafting material for anticorrosion. Herein, we reported the synthesis of ZMO/h-BN with the labyrinth of capillary pores owing to the in situ growth of ZMO on flake hexagonal boron nitride (h-BN) using the hydrothermal method. The special morphological structure provided a tortuous path for aggressive species to the steel substrate, which extended and blocked the transmission of aggressive species, enhancing the physical corrosion barrier performance. In addition, the capillary pores of ZMO contributed to the competitive adsorption of Cl- in an electrolyte and reduced the diffusion of aggressive species, thus further delaying the corrosion process. Moreover, the capture of oxygen by forming a B-O bond with h-BN and the formation of a molybdate passive film are beneficial for the inhibition of cathodic and anodic reactions. As verified by electrochemical impedance spectroscopy (EIS), the anticorrosion performance of ZMO/h-BN coating increased by 49.58% and 130.72% compared with ZMO and epoxy resin (EP) coatings after immersing in a NaCl aqueous solution (3.50 wt%) for 72 h. This coating matrix provides an avenue for molybdate-based corrosion remediation.

Gradient Design of Vacancies and Their Positive Correlation with Electrochemical Anticorrosion Protection.

The contribution of defects to electrochemistry is a controversial but practically applicable subject. Meanwhile, it is challenging to obtain precisely a certain nonchemometric single phase in mixed-valence compounds. The precise design of nonchemometric single-phase WO3-x (x = 0, 0.1, 0.28, and 1) mixed-valence metal oxides (MVMOs) was achieved by the gradient intrinsic reduction method, and the correlation between oxygen vacancies and electrochemical anticorrosion protection was explored systematically. Then, the decisive role of periodic oxygen vacancies in electrochemical anticorrosion was confirmed. And the origin was the synergistic reaction of oxygen vacancy-upgraded photocathodic protection, vacancy-induced passivation, and mixed-valence reductive protection, which were brought about by the high oxygen vacancy concentration. Integrating the above three aspects, the WO2.72 MVMO showed the best electrochemical anticorrosion performance by increasing the resistance value to 7.67 times that of the epoxy resin coating. The establishment of a positive correlation between oxygen vacancy and corrosion protection in WO3-x (x = 0, 0.1, 0.28, and 1) materials can not only guide the design of MVMOs but also make an important contribution to the rapid precorrosion performance of the materials.

Oxygen Vacancy Defects and a Field Effect-Mediated ZnO/WO2.92 Heterojunction for Enhanced Corrosion Resistance.

The heterojunction constructed by tungsten oxide and zinc oxide materials can improve the problem of easy deactivation of electrons, which is a new and effective strategy for realizing anticorrosion. Here, the ZnO/WO2.92 heterojunction modified by oxygen vacancies (OVs) serving as the photoelectric conversion center was not consumed to provide continuous light-induced protection for steel, and the impedance value was increased by 185.35% compared to that of epoxy resin after 72 h of corrosion. The enhanced anticorrosion activity was due to OV modification leading to oxygen adsorption and electron capture, which inhibited the cathodic corrosion reaction and effectively hindered electron transport. Additionally, the localized surface plasmon resonance effect produced by OVs improved light utilization efficiency and increased electron density, which enabled numerous photoelectrons to gather on the surface of the iron substrate to reduce the corrosion rate of metals. Besides, the cascade effect of the ZnO/WO2.92 heterojunction promoted the transfer of e-/h+ to form an electric field that allowed the directional flow of electrons to inhibit the anode dissolution process. Thus, exploring the corrosion reaction involving OVs and heterojunction structures was of great significance to the development of nonsacrificial and efficient anticorrosion materials.

Eminently Enhanced Anticorrosion Performance and Mechanisms of X-ZnO (X = C, N, and P) Solid Solutions.

Nonmetal (C, N, P) doped zinc oxide solid solutions (ZnO SSs) prepared through one-step calcination method exhibited novel anticorrosion capability. The anticorrosion property was identified by electrochemical impedance spectroscopy and polarization curve technique. The maximal impedance belonged to C-ZnO SS, which was 12 times higher than pure ZnO materials. Then, a synergistic anticorrosion mechanism was proposed: the photoelectron flow suppression effect and the self-cohering process formed by doping. The tiny particle size as well as the minor zeta-potential of X-ZnO SSs eminently promoted the intermolecular cohesion and the formation of the compact surface automatically. Moreover, the photocatalytic experiments successfully verified the product and the corrosion inhibition effectiveness of the photoelectrons. Additionally, a positive correlation conclusion between the anticorrosion performance and the photocatalytic performance of the X-ZnO SSs was obtained. Consequently, developing the self-cohering anticorrosion materials is of crucial industrial application prospect and value.

Enhanced photoelectric properties by the coordinating role of doping and modification.

Dual technique design in this research has successfully enriched the complementation between doping and surface modification. Here, Co(2+) doped Ag-ZnO nanocomposites (CAZ NCs) are mass produced by the combustion method. The HRTEM image shows that the doped Co(2+) and the surface modified Ag nanoparticles on the ZnO NCs are influential on the preferential orientation. Based on the conductivity formula σ = nqµ and the actual verification, the improved photoelectric properties of CAZ NCs under visible light irradiation are attributed to the enhanced light absorption and the weakened recombination of photogenerated electron-hole pairs. It would be instructive for the sound design concept of subsequent material development.

An efficient photocatalyst for degradation of various organic dyes: Ag@Ag2MoO4-AgBr composite.

The Ag2MoO4-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag2MoO4-AgBr composite. The in-situ Br(-) replacement in a crystal lattice node position of Ag2MoO4 crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag2MoO4-AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O2 as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag2MoO4-AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag2MoO4-AgBr composite compared to pure AgBr and Ag2MoO4 crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag2MoO4-AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7min.

Mass preparation and novel visible light photocatalytic activity of C and Ag Co-modified ZnO nanocrystals.

A combustion method was developed to synthesize the C and Ag co-modified ZnO NCs to enhance its photocatalytic efficiency and practicability. The results showed that the doped Ag was significant to promote the photocatalytic activity, and the optimum content was 2% molar ratio of Ag to Zn atom. The degradation rate under visible light increased by 150% compared with C-ZnO NCs, while by more 1233.3% than pure ZnO photocatalyst. There were some new little particles with grain size about 10 nm on the C-ZnO NCs surface, which may state for the existence of Ag atoms. The synergy effect of Ag and carbon elements was proposed to explain the mechanism of enhanced photocatalytic performance under visible light irradiation.

The biotoxicity of hydroxyapatite nanoparticles to the plant growth.

In the present study, hydroxyapatite (HAP) nanoparticles of different particle sizes with high crystallinity and similiar structure were prepared by hydrothermal method. The crystal structure and particle size were characterized by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. Mung bean sprouts were first used as experimental models. Instead of by MTT assay, the cytoxicity of HAP nanoparticles were proved and evaluated by measuring the hypocotyle length of mung bean sprouts in the culture media. The result showed that the inhibition effect to the growth of mung bean sprouts enhanced when HAP nanoparticles existed. Culture media of HAP nanoparticles with different concentrations and particle sizes was prepared to investigate the level of inhibition effect to the growth of mung bean sprouts. The result found that hypocotyl length of mung bean sprouts were the shortest cultured in 5mg/mL culture media in which the HAP nanoparticles were prepared by hydrothermal method for 24h. It was concluded the inhibition effect depended on the amount of intracellular HAP nanoparticles. The nanostructure and Ca(2+) concentration were considered as the main factors to cause cell apoptosis which was the reason of inhibition. The study provided a preliminary perspective about biotoxicity of HAP nanomaterials to the plant growth.

Preparation and enhanced catalyst effect of assembled hydroxylapatite microsphere chains.

The hydroxyapatite (HAP) assembled microsphere chains with high surface area and large size in length (20-35 microm) were prepared by a facile and efficient cooperation template method. The products were characterized by XRD, TEM, SEM, FT-IR, EDS, BET, etc. The possible mechanism for the formation of HAP assembled microsphere chains was also discussed. In addition, the products were used as carried materials to synthesize HAP/TiO2 (anatase phase) composite catalyst, the bandgap of TiO2 nanomaterials was enlarged. The degradation speed of methyl orange (MO) was increased to 150% when using the composite as catalyst compared with using TiO2 nanoparticles. At the same time, the composite catalyst can be separated and recycled more easily than existing carry materials.

Preparation and characterization of fluorescence probe from assembly hydroxyapatite nanocomposite.

A new nanocomposite fluorescence probe with thioglycolic acid (TA) functional layers embedded inside the hydroxyapatite nanoribbon spherulites has been synthesized. The fluorescence intensity of the novel probe is about 1.5-3.3-fold increase compared with the probe containing no TA. When used to detect cadmium ion, the most of original assembly nanoribbon spherulites structure in the novel probe is found to have been damaged to new flake structures. The mechanism of determining cadmium ion in alcohol solution has been studied. The present systematic study provides significant information on the effect of assembly nanostructure on the metal-enhanced fluorescence phenomenon.