Electrocatalytic hydrodechlorination technology possesses great potential in the field of chlorinated organic compound treatment due to the high efficiency, environmental friendliness, etc. The amorphous Pd-P/polypyrrole(PPy)/foam Ni electrode was prepared by electrochemical deposition for electrochemical hydrodechlorination of the pentachlorophenol (PCP). Morphology and chemical structure of Pd-P on the PPy/foam Ni electrode was investigated by the Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscope (XPS). The result indicated that the Pd-P catalyst was evenly dispersed on the PPy/foam Ni electrode with small particles and changed from crystalline state to amorphous state. The electrocatalytic reduction of PCP certificated that the doping of P significantly increased the catalytic activity of the electrode. The degradation efficiency of PCP reached 90.8% after electrocatalytic reduction for 180 min under the condition of n(Pd)/n(P)=1 : 3, Pd loading=0.15 mg/cm ², C_H2SO4=0.20 mol/L and V_cathode=-1.2 V. In addition, the Pd-P/PPy/foam Ni electrode exhibited high electrocatalytic stability after reused for 8 times without any notable deactivation.

Photocatalysis has been regarded as an emerging and promising air purification technology. However, nitrogen dioxide (NO₂) as the by-product is easily generated in the process of photocatalytic NO oxidation, which is more toxic and harmful to human health than NO. To inhibit the generation of NO₂ and promote the deep oxidation of No into nitrate (NO₃^-), boron nitride (BN) nanosheets was used as templates and bismuth oxybromide (BiOBr) nanosheets were introduced by the in-situ growth method to fabricate the two dimensional-two dimensional (2D-2D) BiOBr-BN photocatalysts. After introducing the BN nanosheets, the thickness and diameter of BiOBr nanosheets greatly decrease. At the same time, the specific surface area of 5% BiOBr-BN increases nearly by 15 times compared with the pure BiOBr nanosheets, which could provide more active sites for the reaction. According to the photocatalytic NO removal tests, the composites present the higher photocatalytic activity than pure BiOBr nanosheets and BN nanosheets. Among them, 5% BiOBr-BN sample reveals the best NO removal rate of 39.5%, which is higher than that of pure BiOBr nanosheets (24.6%) under visible light irradiation. More importantly, the NO₂ generation rate is suppressed from 16.4% to 7% and the oxidation selectivity of NO₃^- is increased from 36.6% to 81.5% compared with the pure BiOBr nanosheets. On the one hand, there is a strong interfacial interaction between BiOBr nanosheets and BN nanosheets, identifying by the X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theory (DFT) results. Hence, 0.98 e electrons transfer from BiOBr to BN through the interface area, resulting in the formation of built-in electric field. Benefiting from this, the recombination of photogenerated charge carriers is effectively inhibited. On the other hand, BiOBr as the active surface enhances the adsorption of O₂ and promotes its activation to superoxide radicals (•O₂^-), which is proved by DFT and Electron Spin Resonance (ESR) results. As a result, the generation of toxic by-product NO₂ is effectively inhibited and NO can be directly oxidized into NO₃^-. These findings could provide a facial strategy for the design of 2D-2D photocatalysts and control of the separation of photo-generated electrons and holes.

To clarify the effect of N sources on the photocatalytic reduction of Re (VII) in amorphous TiO₂/g-C₃N₄ (TCN) composites, g-C₃N₄ were prepared via a thermal decomposition of three precursors (Urea, Thiourea and Melamine). Three kinds of TCN composite photocatalysts were then prepared by recombining with amorphous TiO₂ separately. All three photocatalysts were characterized by differnent methods, and their differences in photocatalytic reduction of Re(VII) were compared in detail. The experimental results show that U-TCN using urea as the N source has more uniform appearance, the largest specific surface area (474 m²/g), and the most excellent light absorption performance, leading to its photocatalytic reduction efficiency (90%) for Re (VII) being significantly higher than T-TCN (20%) and M-TCN (15%). Transient photocurrent and electrochemical impedance (EIS) analyses prove that U-TCN exhibits the highest efficiency of photo-generated electron/holes separation. Electron paramagnetic resonance spectroscopy (EPR) analysis shows that U-TCN generates more hydroxyl radicals (?OH), so that there are stronger reducing ?CO₂ radicals produced by the reaction with formic acid, which is more conducive to the reduction of Re (VII). X-ray absorption spectra are employed to analyze the valence state and coordination environment of Ti element, which demonstrates an excellent photochemical stability of U-TCN. The study not only illustrates the effects of N sources on the photocatalytic performance of TCN composites, but also provides a promising photocatalyst for reduction and removal of Tc(VII) from waste water.

Phosphorus is an important nutrient element that affects the growth of algae. The sorption of phosphorus on the sediments plays an important role in its bio-geochemical cycle, with metal oxides such as alumina being one of the important active components for the process. The sorption behavior of phosphorus on two kinds of alumina (γ-Al₂O₃, amorphous alumina) was studied through batch methods. Both kinetics and thermodynamics of the process were investigated, as well as the effects of temperature, salinity, and pH of the medium on the process. The sorption kinetic curves could be described by a two-compartment first order equation, and the isotherms fit Freundlich equation well. The amorphous alumina has a larger specific surface area, and its sorption ability is stronger than that of γ-Al₂O₃. Based on the results of surface acid-base titration, the sorption behavior is also considered to be related to the surface acidity and alkalinity of the aluminum oxides. Compared with NaNO₃ medium, the sorption of phosphorus in seawater was weakened. The sorption capacity decreases with the increase of the ionic strength. pH significantly affected the sorption ability of the oxides with the maximum capacity at pH=5. Higher temperatures are favorable to the sorption progress, which is endothermic and spontaneous with entropy increasing. The difference in the thermodynamic parameters of the two alumina seemed unremarkable.

Organic compounds can be used as additives to regulate the morphology and structure of materials in the process of nanomaterial synthesis, thereby affecting the catalytic and electrochemical properties of the materials. In this paper, the nanomaterial Co₃O₄ was synthesized by hydrothermal method using disodium ethylenediamine tetraacetate (EDTA-2Na) as the additives and cobalt acetate as the cobalt source, and its structure and gas sensing properties were measured. The relationship between structure and gas sensitive properties was studied, and the mechanism of EDTA-2Na in the synthesis of materials was discussed. The results show that the complex formed by Co²⁺ and EDTA^2- regulates the growth direction of Co₃O₄ nuclei to generate the hexagonal nanosheets of Co₃O₄ with a side length of about 50 nm and a mesoporous structure. The response values of gas sensors fabricated by the Co₃O₄ nanomaterials to 100×10^-6 toluene and 100×10^-6 acetone are approximately 104 at 205 ℃ and 70 at 225 ℃, respectively. The high response of the gas sensor to volatile organic compounds (VOCs) is attributed to a large number of defects on the surface of Co₃O₄ synthesized by EDTA-2Na, which improve the adsorbed oxygen content. In addition, the mesoporous structure and large specific surface area are conducive to the adsorption, surface reaction and diffusion of VOCs. In this study, an effective method is proposed to obtain a highly responsive VOCs gas sensor by adding EDTA-2Na to synthesize Co₃O₄ nanomaterials.

Hierarchically porous silica-aluminum is an important support material for metal-catalysts, because of its excellent properties. Herein, an efficient hydrothermal approach for the production of hierarchical aluminum- doped silica (Al-SiO₂) architectures was reported by employing aluminum nitrate as an aluminium source and TEOS as silicon source. Effects of the structure-oriented agent on the structure of Al-SiO₂ were investigated. Structural features of Al-SiO₂ were characterized by XRD, SEM and N₂-physisorption. The results showed that hierarchical Al-SiO₂ with "worm-like" porous of 30-40 nm can be synthesized by using TPAOH as the structure-oriented agent and hydrothermal treatment at 80 ℃. The cobalt catalysts were prepared by the wetness impregnation method. Compared with commercial SiO₂ supported cobalt catalysts, the Fischer-Tropsch synthesis performance of the catalyst Co/Al-SiO₂ is significantly enhanced, i.e., CO conversion nearly doubled, CH₄ selectivity reduced by 19.3wt%, C₂-C₄ selectivity reduced by 13.3wt%, and the selectivity of gasoline products (C₅-C₁₂) reached 53.3wt%.

To investigate the modification mechanism of mixed heterogeneous on photocatalysis, a series of Nd³⁺-doped BiVO₄ photo-catalysts with different Nd³⁺ contents were synthesized through a facile hydrothermal reaction. The samples exhibit Nd³⁺ content-dependent phase transition from monoclinic to tetragonal phase, as demonstrated by XRD and Raman analyses. SEM images show that the phase transition is accompanied by obvious morphology variation. Less than 1at% Nd³⁺-doped monocline BiVO₄ is composed of irregular particles, while more than 7at% Nd³⁺ doping results in tetragonal phase BiVO₄ of sphere-like or kernel with groove surface. When Nd³⁺content is in the range of 1at%-7at%, the micron cuboid bars appear in the samples. More importantly, monoclinic and tetragonal phase is concomitant in the product and a heterogeneous junction with staggered band structure is formed. The Rhodamine B degradation efficiencies of all Nd³⁺-doped samples are higher than those of undoped samples due to the regular morphology after doping. The formed heterogeneous junction inhibits photo-generated electrons and holes recombination of Nd³⁺-doped BiVO₄, inducing 99.4% catalytic efficiency in 4at% Nd³⁺-doped sample. The novel morphology and the intrinsic mechanism of photocatalysis enhancement upon Nd³⁺-doped BiVO₄ are obtained from the synthesis strategy and the energy band structure.

The hydrothermally treated red phosphorus (HRP) was dispersed on exfoliated bentonite (EB) supporter to prepare the EB/HRP photocatalyst for improving photocatalytic performance. The as-synthesized samples were characterized by different methods. Rhodamine B was selected as the model pollutant to evaluate the photodegradation property of EB/HRP. Results showed that the photodegradation efficiency of the EB/HRP photocatalyst composite increased with increased EB mass fraction, and decreased after reaching the highest value. When the mass fraction of EB was 9%, the EB₉/HRP photocatalyst composite exhibited the maximum adsorption performance and photodegradation activity. Its degradation rate constant k was 0.0641 min^-1, which was two times that of HRP. In addition, after five cycles of photodegradation experiments, EB₉/HRP still had high photocatalytic activity (96.8%). Therefore, the EB₉/HRP catalyst composite had good photocatalytic activity and stability, which can be an efficient and stable photocatalyst for the degradation of pollutants.

Fabricating Z-scheme photocatalysts is a promising method for improving photocatalytic activity by effectively enhancing charge separation. A new Z-scheme BiVO₄/GO/g-C₃N₄ photocatalyst was prepared by two steps of impregnation-calcination and hydrothermal method, and then characterized by different methods. In the photocatalytic process of BiVO₄/GO/g-C₃N₄, GO nanosheet act as fast transmission channels between BiVO₄ and g-C₃N₄ and can suppress electron-hole recombination, which significantly promotes the charge separation and improves the redox ability of the ternary heterojunction. The ternary photocatalyst has good photocatalytic degradation of Rhodamine B (RhB) as compared to the single-component or binary composite. It is capable of degrading 85% of RhB in 120 min under visible light irradiation and the hole (h⁺) plays a major role in the reaction. This work provides a simple preparation method for a ternary photocatalyst system in which g-C₃N₄ coupled with BiVO₄ by GO to significantly improve photocatalytic activity.

Metal-organic frameworks (MOF) as piezoelectrical materials used in mechano-catalytic degradation of organic dye are rarely investigated. In this work, NH₂-UiO-66 was synthesized by the solvothermal method and applied in mechano-catalytic degradation of Rhodamine B under ultrasonic vibration. The results show that NH₂- UiO-66 behaves a high mechano-catalytic decomposition efficiency of 80% for Rhodamine B within 5 h vibration and possesses a good stability. The piezoelectrically induced electric charges on the surfaces of NH₂-UiO-66 via the piezoelectric effect could induce hydroxyl radicals as strong oxidants to decompose Rhodamine B. The piezoelectrical effect of MOFs is potential in utilizing vibration energy for dye wastewater treatment.

BiOBr/Ti₃C₂ composite photocatalyst with highly exposed (001) facets was synthesized by hydrolysis method. Different instruments were employed to characterize the samples. The visible light photocatalytic performance of different samples were evaluated by using Rhodamine B as the target pollutant. The results show that the degradation efficiency of Rhodamine B reaches 97.1% within 60 min over BiOBr/Ti₃C₂ (20.0wt% Ti₃C₂ addidion) composite photocatalyst, which is 34.7% higher than that of BiOBr. With the introduction of layered Ti₃C₂, the interface between BiOBr and Ti₃C₂ forms the Schottky junction energy barrier, which produces effective electron traps to inhibit the combination of photogenic electron-hole pairs, and greatly improves the visible light photocatalytic activity of BiOBr. After 5 cycles, the degradation efficiency of BiOBr/Ti₃C₂ composite photocatalyst remains 91.0%, showing reliable stability. The active species capture experiment shows that superoxide radical (•O₂^-) is the main active species in the photocatalytic degradation of Rhodamine B, and a possible photocatalytic mechanism is proposed accordingly.