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Oxygen vacancy-rich CeO2/BiOBr was prepared via solvothermal method combined with rGO to design a Z-scheme heterojunction, which was used for photocatalytic oxidation of gaseous elemental mercury. The Z-scheme heterojunction constructed by interface engineering significantly promotes charge carriers transfer at the interface. Moreover, the surface oxygen vacancies and Ce3+/Ce4+ redox centers tend to capture electrons to accelerate the Z-scheme path of charge transfer to maintain efficient redox performance and facilitate molecular oxygen activation to boost photocatalytic removal of Hg0. The collaboration of oxygen vacancies, Ce3+/Ce4+ and heterojunction enhances the photocatalytic oxidation activity, which achieves a removal efficiency of 76.53%, which is 1.29 times that of BiOBr and 1.91 times that of CeO2. The effect of actual flue gas components (SO2, NO and HCl) on the performance of photocatalytic Hg0 removal was further investigated. Combined with DFT theoretical calculations, the photocatalytic reaction mechanism of Z-scheme heterojunction with oxygen vacancies-rich was proposed. It provides a feasible strategy for the development of high-efficiency Z-scheme heterojunction photocatalytic system for environmental purification.

A Z-scheme heterojunction polyhedral-shaped BiOIO3/MIL-53(Fe) photocatalyst is prepared by a solvothermal method. The samples are characterized by XRD, XPS, SEM, TEM, FT-IR, UV–vis, PL, and other m...

Constructing a heterojunction and designing a band gap are effective methods to promote the efficiency of a photocatalyst and solar energy utilization. In this work, g-C3N4/Yb3+-Bi5O7I nanostructur...

A novel gaseous elemental mercury (Hg0) removal agent was successfully synthesized via impregnation method, by using molybdenum trioxide (MoO3) as the active component and carbon aerogel (CA) as the carrier. The as-prepared samples maintained a large specific surface area and excellent pore structure of the pure carbon aerogel, so that MoO3 was better dispersed to obtain enhanced Hg0 removal performance. The maximum efficiency of elemental mercury removal was about 74%, achieved by Mo/C500 sample at 300 °C, while it still had good ability (nearly 60%) in the range of 500–700 °C. The mechanism of mercury oxidation removal was also verified by DFT calculation. This work should help in developing suitable materials for thermocatalytic oxidation of elemental mercury, and also provide some theoretical basis and data support for full-scale application of heavy metal mercury pollution control in coalfired power plants.

A new ternary composite BiOIO3/MoS2/C500 was prepared via sol-gel and hydrothermal method. The energy bands, surface structures and optical properties of the as-prepared samples were characterized by XRD, SEM, TEM, UV–vis DRS, BET, XPS, PL, ESR and electrochemical measurement. The density functional theory (DFT) was adopted to explore the capability as well. It is discovered that BiOIO3/MoS2/C500 possesses excellent Z-scheme heterostructure for separating photogenerated electron-hole pairs mainly provided by BiOIO3/MoS2, and large specific surface area as charge carriers transfer channel mainly provided by C500, which can accelerate charges to transfer to the surface reaction area for photocatalytic oxidation. Then, the ternary catalyst was utilized to remove gas-phase Hg0 including its oxidation product, and possessed the highest removal efficiency of 78.32%, which is much higher than that of its pure component. Meanwhile, the photocatalytic activity of ternary catalyst are of high stability, and the product after the reaction is HgO and can be adsorbed on BiOIO3/MoS2/C500, which is detected by high resolution XPS. The loading manner provides a new vision for both photocatalysis and adsorption.

Bi5O7I nanosheets and Bi5O7I nanorods photocatalysts were successfully fabricated by calcination and hydrothermal methods respectively. The different morphologies of Bi5O7I were characterized by XRD, SEM, HRTEM, UV–vis DRS and PL. The as-prepared samples were used to photocatalytic removal of Hg0 under visible-light irradiation. The results indicated that the photocatalytic activity of Bi5O7I nanorods is better than that of Bi5O7I nanosheets. It can be attributed to the synergistic and internal electric field effects of the (0 0 1) and (1 0 0) facets of Bi5O7I nanorods, which improves the photogenerated charge transfer and separation efficiency.

The flower-like BiOI/Bi5O7I heterojunction photocatalysts were prepared by a pH adjustment method, and the photocatalytic oxidation activity of the as-prepared samples was investigated by gas-phase Hg0 removal. XRD, SEM, TEM, UV-vis, and PL characterization analysis method were adopted to evaluate the physicochemical property of samples. It was found that the sample showed an excellent photocatalytic performance for mercury removal when the pH of the sample fabrication arrived at 10.0. It can be attributed to the formation of an interfacial heterojunction between BiOI and Bi5O7I, which inhibits the recombination of electrons and holes. A possible photocatalytic reaction mechanism for the oxidation of Hg0 has also been proposed.

The ternary complex photocatalysts of BiOIO3/g-C3N4/MoS2 by solvent-exfoliation method was synthesized for the first time. In the typical procedure, the BiOIO3/g-C3N4 was obtained via hydrothermal synthesis technique, and then the BiOIO3/g-C3N4/MoS2 photocatalysts were prepared via ultrasonic solvent-exfoliation method from bulk commercial MoS2 in the alcohol solution. The samples of BiOIO3/g-C3N4/MoS2 were analyzed by PL, XRD and other characterization analysis methods. The photocatalytic activity of the as-prepared samples was investigated by removing gas phase mercury irradiation under visible light. The as-prepared BCM-0.3 exhibits excellent photocatalytic performance, being with the highest efficiency of 70.58%. Owing to the electronic channels of field-effect, an internal electric field was formed through the corresponding band-gap engineering, improving photocatalytic reaction. Besides, the excellent activity of the ternary photocatalysts BiOIO3/g-C3N4/MoS2 is attributed to heterostructure between BiOIO3/g-C3N4 and MoS2, which enlarges spectral response and improved separation efficiency of charge carriers, and MoS2-composing, which provides more active sites for catalytic oxidation. In addition, the as-prepared samples with excellent photocatalytic performance also offer a perspective insight into the hydrogen evolution, CO2 conversion and degradation of organic pollutants.

A series of colored TiO2/Bi5O7I composites were successfully fabricated. The physicochemical properties of the as-prepared TiO2/Bi5O7I heterostructures were investigated by XRD, SEM, TEM, HRTEM, FT-IR, BET, UV–vis DRS, XPS and PL characterization. The characterization indicates that colored TiO2 nanoparticles are tightly anchored to the Bi5O7I nanorods to form heterojunctions. The photocatalytic activity of the sample was examined by photocatalytic oxidation of gas-phase Hg0 under visible-light irradiation. The results show that TiO2/Bi5O7I composites exhibits highly enhanced visible light photocatalytic activity compared to pure Bi5O7I. Hg0 removal rate of TiO2/Bi5O7I composite is up to 89%. Compared with the pure Bi5O7I, the as-prepared composite photocatalyst enhanced the visible light absorption and increased the specific surface area. More importantly, the heterostructure formed in the composite effectively promotes the charge transfer, ultimately improves the photocatalytic activity. Meanwhile, the cyclic experiments were performed to confirm the stability of TiO2/Bi5O7I composites. The influence of various flue gas components (O2, NO and SO2) on the performance of photocatalytic removal of Hg0 was studied. Based on characterization and experiments, the reasonable charge transfer and photocatalytic reaction mechanism were proposed.

Plant growth-promoting bacteria (PGPB) can promote root uptake and shoot accumulation of cadmium (Cd) in hyperaccumulator plants, but the mechanisms by which PGPB accelerate root-to-shoot transport of Cd is still unknown. A better understanding of these mechanisms is necessary to develop the strategies that can promote the practical phytoextraction of Cd-polluted soils. In this study, we found that Pseudomonas fluorescens accelerates a reversed and a long-distance transport of Cd and sucrose in Sedum alfredii, by examining the xylem and phloem sap and by quantifying the concentrations of Cd and sucrose in shoot and root. The transcriptome sequencing has revealed the up-regulated expressions of starch metabolism and sucrose biosynthesis related genes in the shoots of Cd hyperaccumulator plant S. alfredii that was inoculated with PGPB P. fluorescens. In addition, the genes of sugar, cation and anion transporters were also up-regulated by bacterial treatment, showing a complicated co-expression network with sucrose biosynthesis related genes. The expression levels of Cd transporter genes, such as ZIP1, ZIP2, HMA2, HMA3 and CAX2, were elevated after PGPB inoculation. As a result, the PGPB successfully colonized the root, and promoted the sucrose shoot-to-root transport and Cd root-to-shoot transport in S. alfredii. Since non-photosynthetic root-associated bacteria usually obtain sugars from photosynthetic plants, our results highlight the importance of PGPB-induced changes in hyperaccumlator plants for both the host and the PGPB.

Selectively exposing different facets of the photocatalysts to enhance the photocatalytic activity is a promising method. However, the role of exposed specific facets in a photocatalytic process is not fully understood. In order to clarify this mechanism, we have systemically explored the relationships between selectively exposed facets and photocatalytic activity of the nanoplate bismuth oxyiodide (BiOI). The BiOI was synthesized by pH-induced transformation method, and the photocatalytic activity was evaluated by photocatalytic oxidation of gas-phase mercury. The exposed specific facet ratios can be adjusted, and depend on the pH of the precursors. Our results showed that the BiOI with exposed (1 1 0) facets possesses an excellent photocatalytic oxidation activity on gas-phase mercury than the BiOI with exposed (0 0 1) facets. Characterization analysis indicated that the BiOI with exposed (1 1 0) facets can generate more superoxide radical ( · O 2 - ) than the BiOI with exposed (0 0 1) facets. Furthermore, both the BiOI with exposed (1 1 0) and (0 0 1) facets can not produce free hydroxyl groups ( · OH ) directly, but can generate it by transformation of the surface absorbance oxygen process. The BiOI with exposed (1 1 0) facets can generate more · O 2 - , which accumulate on the conduction band of the BiOI and transform to · OH by process of O2 → · O 2 - → H2O2 → · OH . Thus, the BiOI with exposed (1 1 0) facets can produce more · OH than the BiOI with exposed (0 0 1) facets as well. This finding may enhance the comprehension of the mechanism between the selectively exposed facets and the photocatalytic activity of the as-prepared samples.

Bismuth oxide iodate (BiOIO3) has recently been discovered to apply to the research on photocatalytic territory in environmental pollutants solution. However, its weak response to the visible light and high recombination rate of electron–hole pairs have been the stumbling block on the road to application. In this work, to remit the drawbacks, carbon modified BiOI/BiOIO3 heterostructures are prepared by a facile hydrothermal method and a simple calcination method. The prepared structure can effectively promote the separation of charge and suppress recombination of electron–hole pairs. When the ternary photocatalyst is applied to remove gas phase elemental mercury (Hg0) in the condition with visible light irradiating, it exhibits excellent photocatalytic properties. Compared with pure BiOIO3, the removal efficiency of ameliorated samples has been drastically increased. On the basis of the results of experiments, the possible charge migration and recombination mechanism are put forward. As a novel and promising method to enhance photocatalytic performance, this method presents a strategy, which yields tremendous benefits in designing efficient photocatalyst and environmental remediation applications.

In-situ reduction method was successfully taken out to control the highly reactive (010) facets and decline band gaps in interlining-I/BiOIO3. It gave a fairly easy way to coordinate the control of bandgap engineering and structural engineering. The interlining-I provided an impurity level served as a plate for photo-generated electron to hop, which expanded the light reaction intensity and displayed excellent photocatalytic performance as well. The as-prepared samples were characterized and estimated for removing gas-phase Hg°. It demonstrated that there existed an optimization of I− to construct a suitable impurity level for effectively separating and transferring electron-hole pairs. The corresponding structural engineering made the internal electric field(IEF) intensify, which was attributed to its increasing exposed surface in favor of obstructing their recombination in the bulk, generating a large number of essential species related to the larger exposed (010) facets to oxidize Hg° into Hg2+ under visible light. BI-1 showed the highest efficiency of 92.15%. However, because of the existence of light corrosion, a small part of the iodine ions may be oxidized to elemental iodine to volatilize, fortunately it could be regenerated to the original efficiency in the same preparation method. In addition, the samples with super photocatalytic properties and excellent electron transport properties also gave out a capacious prospect in CO2 conversion, hydrogen evolution, NO removal, degradation of organic pollutants, also the super capacitors and batteries.

Iodate oxygen bismuth (BiOIO3) is a kind of bismuth-based materials with favourable photocatalytic performance which has profound effect on the problem of severe energy shortage and environmental pollution. In this work, a high-efficiency photocatalyst of bismuth vanadate combined with iodate oxygen bismuth (BiVO4/BiOIO3) are prepared via a single hydrothermal method. The as-prepared novel photocatalyst exhibit high photocatalytic performance resulting from high visible light absorbance ability and the formed heterojunction, which is beneficial to the generation and migration of photonic electron hole pairs and inhibit their recombination meanwhile. The photocatalytic oxidation ability of samples is evaluated by removal efficiency of element mercury (Hg0), which is very-hard to be oxidized, under LED (9W) light radiation with the wavelength of approximately 380–450 nm. The experimental results have indicated that the as-prepared composite catalyst show higher efficient in oxidizing Hg0, which could reach up to about 75%. Furthermore, the photocatalytic reaction mechanism about double electron transfer phenomenon between heterostructures is proposed based on characterization and experimental results.

A series of BiOIO3 were prepared via in-situ crystallization method with different calcining temperatures. All samples were characterized by XRD, SEM, UV–vis, PL to explore the effect of internal electric field (IEF) among different dimensions. B-200 (calcinated under 200 °C) with the optimized IEF attained the most superior photocatalytic oxidation capacity in removing gas-phase Hg0. Also, the formed 2D mixed 3D dimension changes the inter-atomic spacing to make the band bend upward, then moves the electrons and holes in the horizontally opposite direction. In combination with the above factors, the optimized IEF and dimension effectively intensify the separation of charge carriers and make the photocatalytic performance greatly improved.

Based on the density functional theory (DFT) combined thermodynamics method, the flue gas arsenic forms from the coal-fired power plants were successfully confirmed at different temperature ranges, and the interaction mechanism of the fly ash unburned carbon (UBC) components on different gaseous arsenic species were also investigated. The content of trivalent arsenic (As3+) is the highest in flue gas, and its morphological distribution is significantly affected by the flue gas temperature. When the flue gas temperature is lower than 900 K, the As2O3 molecules are dominant in the trigonal bipyramid type. While when the temperature exceeds 900 K, the priority structure of As2O3 is chain type > horn type > trigonal bipyramid type in turn. This paper has verified the feasibility for the adsorption of flue gas arsenic via the unburned carbon in fly ash, and the performance of the zigzag carbon surface is always better than the armchair surface. This paper provides theoretical support for arsenic removal in coal-fired power plants, and also provides some new ideas for the secondary utilization of fly ash and the development of carbon-based arsenic removal adsorbent.

The effective capture or conversion of elemental mercury (Hg0), is the key scientific problem for controlling total mercury pollution in coal-fired power plants. In this work, the cerium chloride (CeCl3) modified carbon aerogel (CA) was successfully synthesized via impregnation method. The as-prepared samples maintained the large specific surface area and excellent pore structure of CA, and the CeCl3 was evenly dispersed, which can play a synergistic role in chemical adsorption and thermal catalysis to capture and oxidize the Hg0 effectively, and the Hg0 removal efficiency was greatly improved, up to 98% at 120 °C. The enhanced Hg0 removal performance could be attributed to the surface active chlorine and cerium oxide (CeO2) particle generated in the preparation process. Based on density functional theory (DFT), the mechanism of mercury removal was discussed in detail. This work would give a new insight for mercury and other heavy metal pollution control in coal-fired power plants.

Bismuth-based nanomaterials exhibiting unique structures, which endow them with fascinating physicochemical properties, have received more and more interests as promising photocatalysts. Fabrication of BiOIO 3 photocatalysts by calcination method was investigated for the first time. XRD patterns showed that the crystallinity of BiOIO 3 photocatalysts could be controlled by calcination temperature. TGA demonstrated that calcining the precursor at a specific temperature range was appropriate for preparing BiOIO 3 photocatalysts. XPS and FT-IR characterization revealed that the BiOIO 3 photocatalysts prepared by calcination method possessed oxygen vacancies, which acted as the positive charge centers to trap the electron easily, inhibiting the recombination of photo electron-hole pairs. Furthermore, PL spectra confirmed the oxygen vacancies can favor for the separation of the electron-hole pairs and in turn enhance the photocatalytic performance. From the above analysis, the mechanism of preparing BiOIO 3 photocatalysts by calcination method was proposed. Meanwhile, the effect of oxygen vacancies on the photocatalytic activity of BiOIO 3 photocatalysts was investigated. The BiOIO 3 photocatalysts with oxygen vacancies were found to be efficiently photocatalytically remove gaseous Hg 0 and the relative photocatalysis mechanism was investigated.

The titanium dioxide phase junction nanorods with Ti3+ and oxygen vacancies (Ov) were successfully prepared by in-situ growth method and vacuum freeze-drying, which was used for photocatalytic removal of gas phase mercury. Experimental results and characterization data indicate that the phase junction, Ti3+ and Ov synergistically promote photogenerated electron-hole separation and transfer efficiency and photocatalytic activity. The efficiency of the most efficient sample reaches 63.77 %, which is about 3.6 times that of commercial P25. Finally, we proposed the reaction mechanism that the phase junction, Ti3 + and Ov in TiO2 nanorods form an effective charge transport channel. This work provides new ideas for the effective utilization of solar energy and the design of photocatalysts.

Gaseous zero-valent mercury (Hg0) emitted from coal-fired power plants results in serious environmental problems, therefore, it is important to remove Hg0 emitted from the power plants. Herein, a novel material with a flower-shaped spherical appearance was used for the removal of Hg0. A BiOBr0.5I0.5/WS2 solid solution with {1 1 0} exposed facets of BiOBr0.5I0.5 and {1 0 4} exposed WS2 facets was synthesised through a simple self-assembly method. BiOBr0.5I0.5/WS2 exhibited excellent photoactivity under visible light, which is attributed to the synergetic effects of the exposed low facets, high surface area, and optimized band structure. Particularly, a 40- wt%-WS2-coated BiOBr0.5I0.5 photocatalyst exhibited the highest Hg0 removal of 87.52% via photocatalytic oxidation. These Z-scheme heterojunction with facets exposed can efficient separate electron-hole pairs and improve the visible light absorption performance. Further analysis indicate that BiOBr0.5I0.5/WS2 is an effective photocatalyst for solar energy utilization and environmental remediation.

A series of BiOI doped with lanthanide metals (lanthanide metals = La, Ce, Eu) were synthesized by solvothermal method and calcination method. The physical and chemical state of the as-prepared BiOI doped with lanthanide metals were characterize by characterization methods. The Hg0 photocatalytic oxidation was performed under visible light to further evaluate the photocatalytic activity. The experimental results indicate that the introduction of lanthanide ions into the BiOI lattice has an important effect on the photocatalytic activity. Moreover, it was found that BiOI doped with different lanthanide ions have different effects on the separation efficiency of charge carriers and the prevention of photo-corrosion. Compared with BiOI doped with La and Eu ions, the results identified that the incorporation of Ce was of a significant role in promoting the photocatalytic activity BiOI. It is proposed that the incorporation of La and Eu ions could induce excessive electrons on the BiOI surface under visible light, which leads to photo-corrosion of the catalyst in contact with the surface H2O. More importantly, the enhanced photocatalytic activity of Ce–BiOI is attributable to the oxygen storage capacity of the Ce3+/Ce4+redox pairs and surface defects that promote molecular oxygen activation to facilitate the photocatalytic oxidation reaction. This work can provide theoretical support for the future use of lanthanide metal substitution doped modified photocatalysts.

To explore the effect of pH on the photocatalytic oxidation activities of BiOCl catalysts, the BiOCl catalysts under different pH values were prepared via a facile hydrothermal method. The as-prepared catalysts were characterized by BET, XRD, HRSEM, SEM and UV–vis to find out the impact of pH values. Photocatalytic ability of BiOCl catalysts were evaluated by oxidation of gaseous elemental mercury under UV light irradiation. It was found that BiOCl catalysts prepared under alkaline condition exhibited the best photocatalytic oxidation activities. The difference of photocatalytic activity among the as-prepared catalysts can be attribute to the growth orientation of the crystal BiOCl catalyst and the adsorption capacity of elemental mercury.

A one-pot synthetic approach to prepare self-assembled BiOI/BiOCl microflowers by a template-free coprecipitation method at room temperature has been developed. The physicochemical structure of BiOI/BiOCl microflowers were characterized using transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning electron microscopy (SEM). The composition information and bonding energy structure of the BiOI/BiOCl microflowers were studied by X-ray diffraction (XRD) and high-resolution X-ray photoelectron spectra (XPS), Fourier Transform Infrared Spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (DRS) analysis and photoluminescence (PL) spectra. The photocatalytic performance of as-prepared BiOI/BiOCl microflowers was tested through photocatalytic oxidation of gas-phase mercury, as a useful catalyst (or additive) in wet electrostatistic precipitator (WESP) to capture heavy metals including mercury. The results show that the prepared BiOI/BiOCl samples demonstrate higher photocatalytic efficiency than pure BiOI or BiOCl. By optimizing the component ratio of the BiOI and BiOCl, up to 72.2% oxidation efficiency can be achieved in BiOI/BiOCl microflowers. Finally, the photocatalytic influence of BiOI/BiOCl microflowers on gas-phase mercury oxidation had been proposed.

Fe-doped TiO2 hollow microspheres were prepared by the hydrothermal method and characterized by the X-ray diffraction (XRD), the Scanning Electronic Microscopy (SEM), the Energy Dispersive X-Ray (EDX), the Brunauer-Emmett-Teller (BET), and the UV–visible diffuse-reflectance spectrum (UV–Vis). The as-prepared samples were evaluated for photocatalytic removal of Hg0 under ultraviolet light irradiation. The results showed that the sample had a good photocatalytic performance. When M* (the molar ratio of Fe/Ti) was 0.05, the mercury removal efficiency reached up to 100%. It was found that the incorporation of iron narrowed the energy band gap of TiO2 (from 3.11 eV to 2.58 eV) and the absorbing boundary increased from 398 nm to 480 nm. While too much Fe3+ may occupy the capture sites of electrons and holes, which leads to a decrease of photocatalytic efficiency.

Construction of Z-scheme heterojunctions is an effective means to promote electron-hole separation leading to enhanced catalytic efficiency. In this study, a simple deposition method is used to load gray particles of TiO2 onto flower microsphere of Bi7O9I3 to form a direct Z-scheme heterojunction. The surface morphology, energy bands, structural properties, and optic1dal properties of the prepared composites are characterized through several techniques. The results indicate that by controlling the concentration of TiO2 particles, the properties such as electron-hole separation efficiency, band gap energy, photoresponse range, and specific surface area can be adjusted, and the mass percentage of TiO2 in the best Bi7O9I3/TiO2 composite is obtained as 30%. The obtained composite exhibited an absorption range of 700 nm and Hg0 removal efficiency of 92.5% under visible light irradiation, which is a great improvement over the characteristics of pure Bi7O9I3. Further, the Hg0 removal efficiency of the composite is evaluated in simulated flue gas. Finally, based on the characterization results, a reasonable reaction mechanism and electron transport mechanism are proposed.

Effective charge-carrier separation and molecular oxygen activation are crucial factors for photocatalytic environmental purification. Herein, an efficient Fe-doped Bi7O9I3 microflowers photocatalyst was synthesized. It was discovered that Fe doping could not only tune the concentration of oxygen vacancies of Bi7O9I3 to optimize the dissociation of excitons, but also promote the separation of charge-carriers and the activation of oxygen molecules. Meanwhile, the inducing of surface oxygen vacancies and Fe3+/Fe2+ by Fe optimal doping can act as the activation center for catalytic reactions, which also significantly enhances the photocatalytic activity. Benefiting from the optimized properties, the photocatalytic activity of Fe-doped Bi7O9I3 photocatalyst has been significantly improved by more than 4 times. Finally, we proposed that a highly efficient catalytic oxidation reaction mechanism can be achieved via modulating Fe doping to induce oxygen vacancies to promote charge separation and molecular oxygen activation. This work provides a novel approach for designing efficient photocatalysts.

In the present study, to insert the Cu nanoparticles (NPs) into mesoporous carbon aerogels and first applied it to remove H2S efficiently. This desulfurizer was made based on the dimensional policy by inserting the Cu NPs on mesoporous carbon aerogels to overcome the sintering problem and improve the activity, which has potential performance at high-temperature catalysis. The obtained desulfurizer was employed for H2S removal at middle temperature conditions (optimal H2S adsorption at 550 °C). We explored the optimum doping amount of CuOx, optimum temperature conditions, and the influence of textural parameters of carbon aerogels. The desulfurizers were characterized by means of field-emission scanning electron microscopy (FESEM), N2-adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), and Raman spectra techniques. The results confirmed that the presence of H2 was unfavorable for sulfidation and obviously shortened the breakthrough time. However, the existence of CO had little impact on the desulfurization and sulfur capacity. In a nutshell, this work could provide a new synthetic route to prepare Cu NPs deep into the lattice of carbon aerogels structure of desulfurizers and understand the desulfurization mechanism.

A novel particle-nanosheet CeO2/BiOIO3 composites with Ce4+/Ce3+ redox centers and oxygen vacancies were successfully prepared via hydrothermal and calcination schemes. Then the as-prepared samples were analyzed with SEM, TEM, XRD, EPR and other characterizations for the morphology, elemental composition and chemical state. Photocatalytic performance of the CeO2/BiOIO3 composites was evaluated by the removal ability of gas-phase Hg0. It is clearly illustrated that the conjunction of CeO2 with BiOIO3 regulatory band structure effectively reduced the band gap, which can promote the utilization of visible solar light. Furthermore, abundant Ce4+/Ce3+ redox centers and oxygen vacancies on the catalyst surface can promote carrier separation and transfer efficiency. Therefore, combining the above advantages, the best photocatalytic mercury removal efficiency of CeO2/BiOIO3 reached 86.53%, which is 1.3 times higher than that of the pure BiOIO3. Based on the experimental results, the photocatalytic mechanism of CeO2/BiOIO3 heterostructure has been proposed. The catalyst design scheme in this work can provide new ideas for catalyst modification, which can be widely used in solar energy utilization and environmental restoration.

In this work, a high performance photocatalyst by integrating iodine vacancy of bismuth oxyiodide (BiOI) was designed, having rich iodine vacancy and superior photocatalytic activity. Specifically, the mechanisms for the formation of iodine vacancy and reaction process were investigated. Further, a novel iodine vacancy flower-like BiOI1-x photocatalyst were successfully fabricated, in which the Bi5O7I nanoparticles were in-situ crystallized by using pristine BiOI and calcination method. The morphology and microstructure, physicochemical, and photoelectrochemical properties of photocatalyst were fully characterized. The photocatalytic performance of iodine vacancy flower-like BiOI1-x photocatalyst was evaluated with removal mercury, which the gaseous mercury is difficult to be removed. The iodine vacancy flower-like BiOI1-x photocatalyst possessed excellently enhanced photocatalytic efficiency for the removal of gaseous mercury under visible light irradiation. The results show that the defective flower-like Bi-410 °C photocatalyst exhibits excellent photocatalytic performance, which manifests a mercury removal efficiency of 68.89% under visible light. Further, the photocatalyst showed favourable stability. Combined with theoretical simulation, the density function theory calculations (DFT) demonstrate that the iodine vacancy BiOI photocatalyst possess a positive VBM position due to calcination process. This work promises good prospect for the design of defect engineering materials for use in energy and environmental restoration.

Plant growth-promoting bacteria (PGPB) that inhabit hyperaccumulating plants assist cadmium (Cd) absorption, but the underlying mechanism has not been comprehensively studied. For this reason, we combined the fluorescence imaging, and transcriptomic and metabolomic methods in a Cd hyperaccumulator, Sedum alfredii, inoculated or not with PGPB Pseudomonas fluorescens. The results showed that the newly emerged lateral roots, that were heavily colonized by P. fluorescens, are the main entry for Cd influx in S. alfredii. Inoculation with P. fluorescens promoted a lateral root formation of its host plant, leading to a higher Cd phytoremediation efficiency. Furthermore, the plant transcriptome revealed that 146 plant hormone related genes were significantly up-regulated by the bacterial inoculation, with 119 of them showing a complex interaction, which suggests that a hormonal crosstalk participated root development. The targeted metabolomics analysis showed that P. fluorescens inoculation significantly increased indole acetic acid concentration and significantly decreased concentrations of abscisic acid, brassinolide, trans-zeatin, ethylene and jasmonic acid in S. alfredii roots, thereby inducing lateral root emergence. Altogether, our results highlight the importance of PGPB-induced lateral root formation for the increased Cd uptake in a hyperaccumulating plant.

The g-C3N4/Bi4O5I2 bionic flower-like structure was facilely synthesized by one step calcination method, and the as-prepared samples were characterized by XRD, UV-vis DRS, photoelectron chemical analysis etc. There obviously exists the phenomenon of a certain right shift for absorption edge of bionic composites according to UV-Vis DRS tests. The mercury removal efficiency of NB-1 (the doping content of g-C3N4 is 1 mmol) can be improved by 76%, which is higher than that of g-C3N4 and Bi4O5I2. Electrochemistry confirms that the bionic structure is beneficial to facilitate the migration efficiency and suppress the surface charge recombination, in turn improve the photocatalytic performance. In addition, the heterostructure between g-C3N4 and Bi4O5I2 are built for efficient modulating the charge transfer channels in the interface/surface to enhance photocatalytic efficiency of Hg0. On the basis of experiment and characterization, a reasonable and convincing mechanism of charge transfer and photocatalytic reaction on Hg0 was proposed.

An amorphous phase TiO2 was fabricated via a fast and simple hydrolysis method and it was characterized with XRD, TEM, BET, UV–Vis, XPS and EPR. The as-prepared amorphous TiO2 has a specific surface area record-breaking 100 times that of crystal TiO2. The results show that the as-samples had better photocatalytic property, which was evaluated for gas-phase Hg0 oxidation under LED light, and photocatalytic efficiency reached up to 40%, which is 1.4 times that of commercial P25. It can be mainly attributed to the large specific surface area of amorphous TiO2 providing more reactive sites and its surface oxygen vacancies as carriers transport channels.

Bismuth oxide iodate (BiOIO3) was used to remove elemental mercury (Hg0) in recent years, due to its suitable position of valence band. While its low response to visible light and high recombination rate of electron-hole pairs limit the industrial application. In this work, the BiOIO3/graphene heterostructures were prepared successfully via the hydrothermal method, and series of characterization analysis were implemented. The prepared BiOIO3/GR composite have enhanced photocatalytic properties than pure BiOIO3. The density functional theoretical (DFT) calculation of the interfacial heterojunction between BiOIO3 (010) facet and graphene sheet further verifies the internal mechanism of improving photocatalytic performance. This work will give some help for mercury pollution control in coal-fired power plant and other similar pollutant control areas.

The BiOI/MoS2 heterojunction photocatalysts were fabricated by the hydrothermal method and calcination method, and the photocatalytic oxidation performance of the samples was evaluated by the removal gas-phase Hg0 under visible light irradiation. In this study, the BiOI/MoS2 heterojunction photocatalysts were adopted to explore the physical and chemical properties by characterization methods. The results show that BiOI/MoS2 with calcination method has an excellent photocatalytic performance for mercury removal reaching up to 58%. The enhanced photocatalytic performance can be due to the interfacial heterojunction between BiOI and MoS2, which inhibits the recombination of electrons and holes. Meanwhile, the Electron spin resonance (ESR) characterization indicated that the surface-active oxygen existed in BiOI/MoS2 heterojunction photocatalysts by calcination method. The synergistic effect of the above two factors makes BiOI/MoS2 be of higher activity under visible light. A plausible reaction mechanism and charge transfer were also proposed. In addition, this work provides a new prospect into hydrolysis of hydrogen production, CO2 reduction, degradation of organic pollutants and electrochemistry.

Coal is found in huge amounts throughout the world and has lower cost as compared to other fossil fuels, it represents at present about 70% of the world’s proven fossil fuel resources; therefore, coal is probably to remain one of the most important sources of primary energy for a long time, playing a strategic role in the medium–long-term energy production systems. However, coal utilization has a few negative impacts on the environment and atmosphere; the critical issue in promoting coal utilization is environmental pollution control without reducing the energy efficiency. Coal is a complex chemical mixture composed of carbon, hydrogen, and dozens of trace elements. When coal is severed as a fuel source, some of these elements would convert to gaseous emissions, such as sulfur dioxide (SO2) or hydrogen sulfide (H2S), nitrogen oxides (NO x ), mercury, and other chemical by-products via the coal combustion or thermal decomposition. These emissions have been established to possess detrimental effects on the environment and human health, which contributes to acid rain, lung cancer, and cardiovascular disease.