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A series of reduced graphene (rGO) and AgBr composite heterojunction photocatalysts were fabricated through a facile solvothermal method. The rGO/AgBr heterostructures were characterized by XPS, XRD, UV–Vis DRS, SEM, TEM, photoluminescence (PL), and the transient photocurrent responses. The XRD, SEM, XPS, and TEM analyses indicated that the graphene and silver bromide were successfully compounded without other impurities. The UV–Vis DRS exhibited that the rGO/AgBr composites have better optical properties than pure silver bromide. The PL and the transient photocurrent responses demonstrated that the addition of graphene significantly promotes the separation of photogenerated electrons and holes. Subsequently, the photocatalytic activities of rGO/AgBr composites were studied by degrading Rhodamine B (RhB). It turned out that the degradation rate of RhB by the rGO/AgBr heterojunction photocatalysts was significantly higher than that by pure AgBr. Furthermore, to study the photocatalytic degradation mechanism of RhB by rGO/AgBr heterostructures, the trapping experiments were used to identify main active components. This work confirmed that the photocatalytic degradation performance of the catalyst was greatly improved after doping graphene, which provided certain data support for degradation of organic contaminants in water.

Controlling semiconductor photocatalysts by doping rare-earth ions is an effective strategy to improve photocatalytic performance. Simple solvothermal and calcination methods were used to prepare La

Heterojunction formation and morphology control have always been regarded as effective ways to improve the performance of visible-light-driven photocatalysts. In this study, a new facile strategy was applied to synthesize the Z-scheme GO/AgI/Bi2O3 heterojunction, where polyvinyl pyrrolidone (PVP) and γ-methacryloxypropyl trimethoxy silane (KH-570) were used to modulate the morphologies. Methyl orange and tetracycline hydrochloride were chosen as target contaminants to evaluate the photocatalytic properties of samples and the results revealed that 2% GO/AgI/Bi2O3 exhibited the best photocatalytic performance under visible-light irradiation. The enhanced photocatalytic activity can mainly attribute to Z-scheme heterojunction formed by the deposing of AgI and GO as well as the sufficient heterogeneous interfaces resulted from the improved morphology, which have effectively promoted the separation and transfer of electron-hole pairs. To deeply realize the enhanced performance of GO/AgI/Bi2O3 photocatalysts, the reaction kinetics, trapping experiments and photocatalytic mechanism were deduced.

Defect construction and rare earth doping are the linchpins to completing the target of partial electronic regulation. In Er

It is a useful strategy to use a solid electronic mediator with good conductivity to assist the separation of semiconductor photo-induced electron-hole pairs and the redox of semiconductor materials. In order to construct a photocatalyst for more efficient photocatalytic degradation of antibiotics, a simple hydrothermal and precipitation method was used to construct the Ag-AgBr/Bi

Recently, the photocatalytic oxidation technique for removing antibiotics and industrial dyes in wastewaters has attracted widespread concern. Herein, a Z-scheme Ag2MoO4/CuBi2O4 heterojunction was synthesized by utilizing a facile in situ precipitation medium and characterized by XRD, FT-IR, XPS, FE-SEM, EDS, TEM, UV–Vis DRS, PL and photoelectrochemical test for explaining the compositions, morphologies and optical natures of synthesized catalysts. Most importantly, the size of the Ag2MoO4 is significantly reduced after loading, due to the pre-adsorption of Ag ions on the CuBi2O4 rod and limiting its growth. The best photocatalytic degradation property was achieved when introducing ~ 50% moral of Ag2MoO4 in the Ag2MoO4/CuBi2O4 (AC-50), and the degradation efficiency of tetracycline (TC) and rhodamine B (RhB) was 1.84 times and 2.04 times than that of pristine CuBi2O4. Besides, the reduction of silver nanoparticles (NPs) on the surface of Ag2MoO4/CuBi2O4 during photodegradation contributes to the formation of the Z-scheme Ag2MoO4/Ag/CuBi2O4 charge transfer system. Tapping tests and ESR analysis had proved that superoxide radicals (·O2−) and holes (h+) were the governing active substances during the process of photodegradation. In view of characterization results and capture tests, a plasma Z-scheme Ag2MoO4/Ag/CuBi2O4 heterojunction mechanism is further described, which provides more redox species and contributes to water pollution repair treatments.

Process-based samples of VOCs were collected in three prebaked anode manufacturers to analyze the emission characteristics of calcining and baking process. Besides, the ratios of diagnostic VOCs were investigated, and the OH loss rate (LOH), ozone potential formations (OFP) and secondary organic aerosol formations potential (SOAFP) of VOCs were calculated to estimate environmental impact. Results shows that the VOCs concentrations emitted from calcining and baking were in the range of 213.5–1081.8 μg/m3, and 2530.1–26774.8 μg/m3, respectively. Aromatics accounted 51.8% and 68.7% and naphthalene accounted 22.6% and 30.7% for total VOCs in calcining or baking, respectively. VOCs emission factors of prebaked anode manufacturing industry were averaged 0.198 ± 0.153 kg/t, and at least 3.2 ± 2.5 kt and 5.6 ± 4.4 kt VOCs were released in China and global, respectively, in 2017. The measured diagnostic ratios of VOCs such as benzene, toluene, xylene, ethylbenzene, naphthalene, styrene, and CS2 were expected to be useful for source identification. VOCs emitted from baking had more adverse impact on environment than calcining, and whether in calcining or baking, aromatics were the largest contributor to LOH, OFP and SOAFP, means that should be controlled primarily.

A series of Z-scheme Ag2WO4/Bi2MoO6 composites were successfully synthesized by a solvothermal-precipitation method. The crystallization, optical property, morphology properties were studied by XRD, UV–Vis DRS, PL, PT, EIS, BET, and SEM, respectively. The photocatalytic properties of Z-scheme Ag2WO4/Bi2MoO6 photocatalyst were evaluated by the degradation of methylene blue (MB) under visible-light irradiation. The results have shown that 30%Ag2WO4/Bi2MoO6 samples possessed the highest photocatalytic activity and superior adsorption capability for methylene blue (MB) with almost complete degradation within 30 min, which was considerably better than pure Bi2MoO6 (70%) and Ag2WO4 (32%). The enhanced photocatalytic activity can be attributed to the synergistic effect in the Ag2WO4/Bi2MoO6 composites, lower electron–hole recombination rate, and higher electron–hole separation efficiency. Radical trapping experiments revealed that the •O2− and h+ were the main active species in catalysis. In addition, the potential photocatalytic mechanism also was discussed based on experimental and characterization results. This work provides a simple method for synthesizing photocatalysts with excellent photocatalytic performance, which has a good prospect in the field of water purification.

The series of novel visible-light-driven ZnMoO4/BiOI heterojunctions were successfully fabricated via in situ solvothermal directly growth of BiOI on the surface of ZnMoO4 plate-like, and the ratio of composite was optimized by increasing of ZnMoO4 loading. The phase, morphology and optical characteristics of obtained ZnMoO4/BiOI heterojunctions were systematically characterized using several analytical measures. The photocatalytic performance was assessed by degrading tetracycline (TC) under visible light irradiation. The results showed that the 30 wt% ZnMoO4/BiOI (ZB-30) composite exhibited highest photocatalytic performance than others. The enhanced photocatalytic efficiency could be attributed to the appropriate band gap of composites, strong visible light response, the formation of heterojunctions with close interface contact and generation and separation of photoinduced carriers. The trapping experiments indicated that ·O2−, h+ and ·OH radicals played distinct parts in the photodegradation process, and ·O2− radicals was the dominant specie. In addition, a probable photocatalytic mechanism of the fabricated composites was also put forward.

The series Ag-AgI/BiOI-Bi2O3 visible-light-driven photocataslyts were successfully synthesized by solvothermal method. The as-synthesized samples were systematically characterized by XRD, SEM, TEM, EDS, BET, XPS, FR-IR, UV–vis DRS, photoelectrochemical measurements and EPR. The formation mechanism of the new composite photocataslyts was investigated and the simulate formation process had been illustrated. The photocatalytic properties of the samples were evaluated by degradation of methyl orange under visible-light irradiation. The results shown that the 30% Ag-AgI/BiOI-Bi2O3 photocataslyts possessed the best photocatalytic activity and the kinetics reaction models were followed pseudo-first-order kinetics. The enhanced photocatalytic performance could be attributed to the effective separation and transfer of electron–hole pairs resulting by the deposing of Ag-AgI nanoparticles and Bi2O3. The photocatalytic mechanism was deduced by trapping experiments and EPR, and the results demonstrated that h+, OH, O2− radicals played different roles in the degradation. Furthermore, a new Z-scheme multi-heterojunction mechanism was proposed basing on the results of trapping experiments and EPR.

To investigate the formation of haze during the cold season, continuous ambient air measurements were taken at an urban site in Zhengzhou from October 10, 2016 through December 31, 2016 using a single particle aerosol mass spectrometer. In total, 4,099,800 particles were analyzed and classified into eight major particle types: elemental carbon (EC, 36.7%), organic carbon (OC, 30.0%), ECOC (8.6%), K-rich (13.0%), levoglucosan (1.2%), metal (2.2%), NH4-K (2.1%), and dust (6.2%). By combining these measurements with correlation analysis and wind data, particle sources were determined to be vehicles, industrial emissions, coal combustion, biomass burning, secondary aerosols, agriculture, and dust. Additionally, analysis of mixing states indicated that particles underwent substantial aging and secondary OC particles were dominant OC species. Temporal profiles of meteorological parameters, mixing states, and particle types during a typical haze episode revealed that EC and OC particles were dominant components during haze formation, and a northeastern transport route (Anyang-Zhengzhou and Puyang-Xuchang) for OC particles was identified by potential source contribution function and concentration weighted trajectory analysis. Relatively higher humidity and lower temperature favored the formation of secondary inorganic aerosol. Wind direction and speed determined the transport, formation, and elimination of stagnant weather conditions. In sum, heavy haze during the cold season in Zhengzhou was observed due to extensive aerosol aging under adverse weather conditions (i.e., northeastern wind direction, wind speed 60%, temperature inversion, and uniform pressure field).

A series of flower-like BiVO4/BiOI core/shell composites were synthesized by depositing BiOI irregular nanosheets on the surface of sphere-like BiVO4 particles via an in situ precipitation method. Tetracycline was selected to evaluate the photocatalytic activity under visible-light irradiation. The samples were characterized by series measurements, which the SEM and TEM results showed that the flower-like BiVO4/BiOI photocatalysts were fabricated. The BiVO4/BiOI (V: I = 0.1) composite exhibited the highest excellent photocatalytic activity and superior adsorption capability. The results could be ascribed to the p–n junction, close core/shell heterostructure and high specific surface area, which promoted the separation and transfer of photogenerated electron–hole pairs. In addition, the radical trapping experiments revealed that the ∙O2− and h+ were the main active species to the photodegradation of tetracycline in the system. This work provides a simple method to design the core/shell structure photocatalysts with excellent photocatalytic performance and adsorption capability for removal antibiotic pollutants.

Size-resolved samples were collected using a 14-stage impactor during four seasons in Zhengzhou and analyzed for 26 elements to calculate the health risks from atmospheric particle-bound metals. High concentrations of heavy metals were observed in ultrafine (10.2 (Ni)–66.9 (Cd) ng m−3) or submicrometer (11.4 (Ni)–134 (Pb) ng m−3) mode in winter. Two size-dependent models were used to estimate the deposition of inhaled toxic metals in various regions of the human respiratory system. Results show that heavy metals deposited in the alveolar region ranged from 7.6 (As)–375 (Al) ng m−3 and were almost concentrated in ultrafine and fine modes. Cd (2.2–8.6) may cause accumulative non-carcinogenic health effects on children, and Cr (1.0 × 10−4–2.2 × 10−4) may lead to carcinogenic health risks for nearby residents around the sampling site. The major sources by principal component analysis that contributed to Cr and Cd in ultrafine and fine particles were coal combustion, vehicular and industrial emissions. The atmospheric dry deposition fluxes of Cr and Cd were between 0.7 and 1.9 μg m−2 day−1 calculated by a multi-step method. From the environmental and public health perspective, environmental agencies must control the emission of heavy metals in the atmosphere.

The ZnFe2O4/BiOI hybrid photocatalysts were fabricated by the solvothermal method. The crystalline phase, morphologies composition and optical absorption property of the samples with different ZnFe2O4 contents were analyzed utilizing XRD, SEM, PL and UV–vis diffuse reflection spectrum, respectively. The photocatalytic activities of the as-prepared photocatalysts were evaluated by degrading methyl orange (MO) under visible light irradiation. Compared with pure BiOI and pure ZnFe2O4 catalyst, ZnFe2O4/BiOI hybrid photocatalysts could observably enhance photocatalytic activity and the 5% ZnFe2O4/BiOI composite performed the optimal degradation efficiency (81.2%) in 100 min. The kinetic studies indicated that the photo-degradation followed the first-order kinetic reaction model. Free radical trapping tests illustrated that ·O2− and h+ play the key roles in catalytic reaction. In consequence, the ZnFe2O4/BiOI composite can be widely used to treat organic pollutant in wastewater.

Heterojunction formation and morphology control have always been regarded as effective ways to improve the performance of visible-light-driven photocatalysts. In this study, a new facile strategy was applied to synthesize the Z-scheme GO/AgI/Bi

The Bi-Co0.5Zn0.5Fe2O4/AgBr photocatalyst was fabricated by facile sol–gel and hydrothermal methods. The crystal phase, microstructures, morphologies composition, chemical states and optical absorption property were studied by XRD, SEM, XPS and UV–Vis diffuse reflection spectroscopy, respectively. The degradation capability for methyl orange was evaluated under visible light irradiation. The results show that the hybrid photocatalyst exhibited higher photocatalytic activity than pure AgBr, among which 15% Bi-Co0.5Zn0.5Fe2O4/AgBr (Bi-Co0.5Zn0.5Fe2O4/AgBr, 15%) emerge the highest degradation efficiency (85.2%) in an hour. The enhanced photocatalytic activity could be attributed to the enhancement of the visible absorption range. Free radicals trapping experiments reveal that ·OH plays a key role in catalytic action. Furthermore, the introducing of Bi-Co0.5Zn0.5Fe2O4/AgBr provides the composite a good photocatalytic property, which is expected to widely applied in water purification.

The visible-light-driven Fe3O4/BiOI n-p heterojunction photocatalysts were successfully synthesized by a facile and economical solve-thermal method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, and vibrating sample magnetometer. The methyl orange and sulfadiazine sodium salt were taken as the model pollutants to estimate the photocatalytic activities of the Fe3O4/BiOI composites with different Fe3O4 contents. The results revealed that the photocatalytic properties of photocatalysts within the appropriate loading range were superior to pure BiOI. Among them 7 wt% Fe3O4/BiOI composite exhibited the highest photocatalytic activity both on degradation of MO and SD-Na. The increase in photodegradation activity may be attributed to the moderate loading of Fe3O4, which could promote the separation of electron–hole pairs effectively. Furthermore, the introducing of Fe3O4 provides the composite a good magnetic property, which greatly promotes the practical application of Fe3O4/BiOI composite photocatalysts in water purification.

The magnetic Co0.5Zn0.5Fe2O4 incorporated Ag3PO4 photocatalysts were fabricated by facile sol-gel and hydrothermal route. The resulting Co0.5Zn0.5Fe2O4/Ag3PO4 composites were characterized by XRD, 1 SEM, 2 UV–vis DRS, 3 FT-IR 4 and VSM. 5 The results indicated that the magnetically separable composites with good dispersity showed a strong absorption in the uv–vis region and the saturation magnetization was 85.25 emu g−1. Anionic dye methyl orange (MO) and tetracycline hydrochloride (TCH) were used to evaluate the activity of the photocatalysts. The result revealed that the magnetic composites exhibited enhanced photocatalytic activity and stability under the visible light irradiation. The ·OH and ·O2- radicals were found to be the major active species during the photodegradation of TCH, while·O2- played the important role in photodegrading MO. And a Z-scheme mechanism for the enhanced photocatalytic process was proposed.

To investigate the characteristics of elements in size-segregated atmospheric particulates, samples were collected using a 14-stage electrical low-pressure impactor (ELPI+) at an urban site in Zhengzhou from October 1 till 25, 2016, and analyzed for 25 elements. Results show that crustal elements were concentrated in coarse particles and toxic elements were concentrated in ultra-fine particles. The size distributions of Na, Mg, Al, Si, Ca, Fe, Ti, S and Cl were uni-modal with dominant peaks in the size range of 1.43–2.14 µm or 0.295–0.487 µm. K, P, Mn and Ba exhibited bimodal distributions, and the remaining elements showed multimodal distributions. Enrichment factor, correlation and principal component analyses indicated that vehicles were the dominant source of particles. Biomass burning, coal combustion and dust also contributed to the accumulation of particles. The elemental concentrations affected by different air masses are discussed to investigate the effects of regional transport. An increase in elemental concentrations related to vehicle and coal sources was observed when air masses came from eastern areas. Furthermore, air masses from the southeast could be a major factor in air pollution for Zhengzhou during special times, such as periods of biomass burning or naked cropland. When air masses came from the northwest, the majority of elements from dust and coal combustion were lower in concentration compared with clean days, while elements originating from vehicle emissions increased.

Co0.5Zn0.5Fe2O4/AgBr hybrids with p-n heterojunction were prepared by a facile sol-gel and hydrothermal method. And the samples with different AgBr contents were characterized by XRD, 1 SEM, 2 UV–vis DRS 3 and FT-IR. 4 The degradation capability of the photocatalysts were evaluated under visible light and used methyl orange (MO) as a target contaminant. All the composites possessed the magnetic properties of Co0.5Zn0.5Fe2O4 and also exhibited high photocatalytic activity of AgBr. Among the prepared photocatalysts, the hybrids prepared with 0.5 g AgNO3 exhibited the highest photocatalytic efficiency. The increase photocatalytic activity of Co0.5Zn0.5Fe2O4/AgBr hybrids might be associated with the formation of suitable internal structures between Co0.5Zn0.5Fe2O4 and AgBr. And a possible photocatalytic mechanism of the Co0.5Zn0.5Fe2O4/AgBr hybrids was proposed.

A dual Z-scheme carbon-bridged g-C3N4/BiOI-Bi2O3 photocatalyst were synthesized by simple solvothermal and calcination methods. The physical and chemical properties of prepared samples were explored via a series of characterization and Density Functional Theory (DFT) calculations. The formation mechanism of the composite photocatalyst was systematically studied and the formation process was simulated. Under the irradiation of visible light, 10% carbon-bridged g-C3N4/BiOI-Bi2O3 exhibited the best photocatalytic performance. And the kinetics reaction model was followed pseudo-first-order kinetics. Moreover, the possible TC degradation pathways were established based on LC-MS. The enhanced photocatalytic activity was mainly attributed to the dual Z-scheme heterojunction formed by carbon-bridged g-C3N4 deposition on the surface of Bi2O3 and BiOI and a higher charge transfer rate of carbon-bridged g-C3N4, which effectively promoted the separation and transfer of electron-hole pairs. The trapping experiments were carried out to further explore its photocatalytic mechanism. This work provided an in-depth understanding of g-C3N4 and bismuth-based catalysts.

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag3PO4/AgBr composite photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of cetyltrimethyl ammonium bromide (CTAB). CTAB was served as surfactant and the source of bromide ions. The as-prepared Ag3PO4/AgBr microspheres were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that the Ag3PO4/AgBr sample (synthesized with CTAB, 0.8 g) exhibited the highest photocatalytic activity to the photodegradation rate of 96.36%. Moreover, mechanism detection experiment indicated that h+ was the major active species in the degradation process. So the enhanced photocatalytic activity of Ag3PO4/AgBr composites is attributed to its excellent separation of photogenerated electron-hole pairs through Ag3PO4/AgBr heterojunction. Also, Ag3PO4/AgBr heterojunction has a lower band gap compared to pure Ag3PO4 and pure AgBr, so higher efficiency of light harvesting is equipped.

The AgBr/Ag3PO4 obtained under the condition of pH 7.0, 453 K and reaction of 12 h was a visible-light response catalyst and the absorption spectrum ranges from 200 to 560 nm.The as-fabricated samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy. Compared with bare Ag3PO4 or AgBr, it displayed much higher photocatalytic property for tetracycline hydrochloride (TC) degradation under visible light. The main element nitrogen ions were changed into NO3 − and NH4 +, and chloridion ion presumably formed AgCl precipitation or some oxidation state of chloridion during the photodegradation process, the rate of TC photodegradation and mineralization can reach 96.1 and 60.1%, respectively.

The metal defect engineering is the crux to accomplish the goal of local electronic regulation, which is an important factor for visible light to drive photocatalyst performance. In this paper, the solvothermal-precipitation method was used to reduce Bi in situ via the reducer glucose to construct Ag-AgI/Bi-Bi2O2CO3-OVs heterojunction. The Ag-AgI/Bi-Bi2O2CO3-OVs composite photocatalyst has excellent photoresponse ability and fast charge carrier separation. In addition, the powerful S-scheme heterojunction retains the original redox capability of the components. The unique lawn-like structure exhibits favorable surface scattering and reflection, which promotes efficient separation of photoinduced charge carriers. Especially, 30% Ag-AgI/Bi-Bi2O2CO3-OVs exhibits brilliant photocatalytic performance for the degradation of tetracycline, which is 4.85 times and 1.15 times higher than the original Bi2O2CO3 and AgI, respectively. The enhanced photocatalytic activity mainly attributes to the presence of oxygen vacancies, the sensitization of Ag-AgI, the double surface plasmon resonance (SPR) effect, and the heterogeneous interface due to the improved morphology, which effectively inhibits the recombination of electron-hole pairs. This work provides a new perspective for the reasonable construction and simple synthesis of high-performance Bi-based semiconductor photocatalysts.

The nano-scale Ag3PO4 was successfully synthesized by the silver ammonia complexing precipitation method at room temperature. And the Graphene oxide (GO)/Ag3PO4 nanocomposites with different contents of GO were successfully synthesized using the electrostatic driving method. The as-prepared GO/Ag3PO4 nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), confirming that Ag3PO4 were highly dispersed to GO sheet. The photocatalytic properties of GO/Ag3PO4 were evaluated by the degradation of Methyl Orange (MO) under visible light irradiation and solar irradiation respectively. The results showed that the photocatalytic efficiencies of GO/Ag3PO4 nanocomposites had enhanced largely and the kinetics reaction models were followed first-order. Furthermore, 5% GO/Ag3PO4 exhibited the highest photocatalytic activity on degradation of MO under visible-light irradiation. The improved photocatalytic performances of the GO/Ag3PO4 nanocomposites mainly attributed to the introducing of GO, which benefit for electron transfer and inhibit the recombination of electron–hole pairs, promoting the practical application of Ag3PO4 in water purification.

The CuFe2O4 and CuFe2O4/AgBr composites with different CuFe2O4 contents were prepared by a facile sol-gel and hydrothermal method, respectively. The as-synthesized photocatalysts were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectrum (UV–vis DRS). Their magnetic properties, photocatalytic degradation activities on methyl orange (MO) and tetracycline hydrochloride (TC) solution and photocatalytic mechanism were investigated in detail. The results revealed that the CuFe2O4/AgBr composites exhibited significantly higher photocatalytic activities than the pure CuFe2O4. The enhanced photocatalytic activity could be attributed to the matched band structure of two components and more effective charge transportation and separations. In addition, the quenching investigation of different scavengers demonstrated that h+, OH, O2− reactive species played different roles in the decolorization of MO and degradation of TC.

The series Ag-AgI/BiOI-Bi

Interfacial charge transfer acts as a linchpin role in the research of photogenerated carrier recombination and photocatalysis. In this work, AgBr/Bi2O2CO3 was constructed to explore the structure-activity relationship between heterostructure and catalytic mechanism. The excellent photosensitizer silver bromide nanoparticles were immobilized on the surface of the Bi2O2CO3 hollow pineal-like via a simple hydrothermal method and deliberated the formation mechanism of the heterostructure. The heterostructures were characterized through XRD, BET, XPS, SEM, TEM, EDX, UV–Vis DRS, EIS, PT and TOC. Research demonstrates that owing to the distinct layered structure exhibits fine surface scattering and reflection. It has excellent degradation performance for dyes and PPCPs wastewater and can be completely degraded in a short time. Simultaneously, the introduction of the Z-type mechanism into the p-n type heterojunction photocatalyst, together with the joint contribution of the Schottky barrier, extremely facilitates the charge separation, illustrating brilliant photocatalysis active. Furthermore, Free radical capture experiments certificate that •O2− and h+ are the chief active species in the decomposition of organic pollutants, and the potential photocatalytic mechanism is considered. The consequences of this work will furnish a fresh perspective for the configuration of high-performance visible light-responsive photocatalysts.

The three-dimensional (3D) flower-shaped layered Bi5O7I nanosheets exhibited tremendous potential in wiping out hazardous organics of sewage due to appropriate band structure and rich surface for attachment of reactants, modified with CuBi2O4 (CBO) and reduced graphene oxide (rGO) further enhancing its photocatalytic effects. Herein, a novel, stabilized and efficient CBO/Bi5O7I@rGO photocatalyst was constructed via sequential hydrothermal process, and the microstructures, physicochemical and optical properties were further researched by serial means such as XRD, XPS, FESEM-EDS, TEM, UV–vis DRS, PT, EIS and physical absorption. SEM and TEM manifested that the composite was successfully prepared and gossamer rGO as a co-catalyst, which is not only conducive to the separation of photo-generated carrier but also facilitates photocatalytic removal pollutants. Furthermore, the photodegradation tests indicated that CBO/Bi5O7I@1.5% rGO sample displayed the highest removal rates towards contaminations such as tetracycline hydrochloride (91%), Rhodamine B (77%) and ciprofloxacin (92%) under visible-light, respectively. Besides, the addition of higher initial concentrations and certain anions inhibited photocatalytic efficiency, which perhaps was due to greater competition with contaminations towards active radicals. Finally, the capture experiment and electron spin resonance (ESR) test certified that superoxide radicals ( · O 2 - ) are the direct active group, whereas the holes (h+) and hydroxyl radicals ( · OH) exert a supporting role. This work could offer an actual and doable design for constructing of efficient Z-scheme system using rGO as an auxiliary catalyst to sewage remediation.

Ion-doped semiconductor photocatalysts were considered to be an important strategy to improve photocatalytic performance. A simple one-step solvothermal method was used to prepare flower ball-shaped Bi4O5I2 nanomaterials modified by Nickel. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra, photocurrent response and EIS Nyquist plots were used to explore its structural composition and photoelectrochemical properties. The photocatalytic activity was studied by simulating the degradation of tetracycline under visible light. The degradation results showed that photocatalytic effect of 5 wt% Ni-doped Bi4O5I2 was the best among the samples, and the degradation rate was 91%. The capture experiment shown that the vital active radical is O2–. The final results shown that Ni-doping improved the charge separation efficiency and the specific surface area of the material, and it is proved by Raman that Ni-doping formed shallow traps on the surface of Bi4O5I2, which promoted the separation and transfer of carriers and improved the photocatalytic activity. This work can provide a reference for the subsequent development of bismuth-based photocatalysts.

In this work, a series of 3D hierarchical γ-AgI/Bi2WO6 (AB) Z-scheme heterojunctions with intimate interface contact was synthesized by facile hydrothermal and precipitation method. The optimal proportion of γ-AgI/Bi2WO6 exhibited superior photocatalytic property during the removal of Rhodamine B (RhB), tetracycline (TC) and ciprofloxacin (CIP). The outstanding photocatalytic capability was probably responsible for the intimate contact among Bi2WO6 flake ball-shaped and γ-AgI nanoparticle, which could heighten the responsive range of visible-light, promote the separation of photo-generated carriers and fully utilize the strong redox ability of composites. Additionally, the function of active species in the photodegradation was also researched through exploiting trapping tests and electron spin resonance experiments to reveal the vital effect of holes (h+) and superoxide anion radicals ( O2−). Moreover, the possible Z-scheme photocatalytic mechanism with an internal electric field was also proposed. This study spreads an effective strategy for reasonably devising the Bi2WO6-based photocatalytic system to decontaminate multiple pollutants.

A facile, environmental-friendly Ag3PO4-PN photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of ammonia and polyvinyl pyrrolidone (PVP). As-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The enhancement of photocatalytic efficiency of Ag3PO4-PN is strongly dependent on the excellent photo-absorption capacity, sharp edges and corners, and synergistic effect of PVP and NH3·H2O. The effects of catalyst dosage, TC concentration and solution pH were explored with tetracycline hydrochloride (TC) as target contamination. The mineralization was evaluated by total organic carbon (TOC) analysis and determination of the concentration of inorganic ions such as NO3 (-) and Cl(-). Radical detection experiment indicated the h(+) and ·O(2-) are major active species in the degradation of TC by Ag3PO4-PN. Moreover, photocatalyst stability and regeneration experiments exhibited the favorable stability and rejuvenation ability, suggesting a promising prospect of practical application of Ag3PO4 in the wastewater treatment.

A series of hierarchical AgIO3/BiVO4-GO photocatalysts was synthesized using a solvothermal-precipitation method. The composition, structure, morphology, optical and photoelectrochemical performance of as-obtained photocatalysts were systematically characterized by XPS, XRD, TEM, SEM, EDS, PL, UV–Vis DRS, PT, and EIS, respectively. The photocatalytic activity was evaluated by the degradation of tetracycline hydrochloride (TC) and Rhodamine B (RhB) under visible light irradiation. Experimental results exhibited the photocatalytic degradation activity of AgIO3/BiVO4 was significantly improved compared with pure AgIO3 and BiVO4. This may be due to the heterojunction formation of AgIO3 and BiVO4 and the introduction of GO, which accelerates the separation and migration of electron-hole pairs and reduce recombination. The h+ and •O2− was the key active species in the photocatalytic degradation process according to the trapping experiment. Furthermore, a potential photocatalytic mechanism was predicted based on experimental results.

The emission factors (EFs) and source profiles of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM10 and PM2.5) from the prebaked anode industry were studied to fill the knowledge gap and provide data for emission inventory and source resolution. In 2018, three prebaked anode plants were selected in Central China, each having one calcining chimney as well as one baking chimney, and then 92 samples were collected from the stack gas of the six chimneys. The results of the study are as follows. (1) PM10 and PM2.5 from the prebaked anode industry contained 37–42% water-soluble ions, 16–20% elements, 11–17% organic carbon, and 9.2–14% elemental carbon. (2) The EFs for PAHs of PM10 and PM2.5 were 1146.1 ± 899.7 and 866.2 ± 1179.8 mg/(t aluminum produced), respectively. The EF for BaP was seven times lower than that given by the European Environment Agency (EEA), whereas those of BbF, BkF, and IcdP were 2–13 times higher than those given by the EEA. (3) Seven diagnostic ratios for PAHs, including Ant/(Ant+Phe), Flua/(Flua+Pyr), BaA/(BaA + Chr), IcdP/(IcdP+BghiP), Flu/(Flu+Pyr), Phe/Ant and BaA/Chr were discussed. Just by diagnostic ratio, it is hard to precisely distinguish between calcining and baking in prebaked industry. (4) The toxic equivalence of PMs in the baking stack gas in the prebaked anode industry was five times higher than that in the calcining stack gas, and PM2.5 showed higher potential toxicity risk than PM10.

This study aimed to investigate the characteristics of the water-soluble ions concentrations in atmospheric particulates. Highly time-resolved measurements of inorganic ions associated with PM2.5 were conducted from December 1, 2017 to February 28, 2018 in Zhengzhou. The hourly mean and standard deviation of PM2.5 concentration during the observation episodes were 108.2 ± 80.7 μg/m3. The hourly mass concentration of PM2.5 increased from 8 μg/m3 to 438 μg/m3 throughout the entire observation. The proportion of water-soluble inorganic ions in PM2.5 was 52.5% throughout the entire observation period. The ions existed mainly in the form of (NH4)2SO4 and NH4NO3. The average mass concentration ratio of NO3− to SO42− was 1.9 ± 0.8 throughout the entire observation period, which initially increased and then decreased with the increased pollution level. The average ratio of the molar equivalent concentration of [NH4+] to that of [NO3− + SO42−] was 1.14 ± 0.27, which decreased with the increased pollution level. Homogeneous reactions played an important role in the formation of nitrate, while, the heterogeneous reactions were important in the formation of sulfate. Both of the values of sulfur oxidation ratios (SOR) and nitrogen oxidation ratios increased with relative high humidity (RH) condition; especially, the SOR values sharply increased when the RH was above 50%. The results of potential source contribution function model demonstrated that the western and northeastern regions of Zhengzhou had a greater influence on PM2.5 pollution in Zhengzhou. All these results suggested that reducing the emission of precursors of secondary inorganic ions was highly important in controlling PM2.5 pollution in Zhengzhou.

Episodic haze is frequently observed in Zhengzhou, China. Such haze typically contains secondary inorganic aerosols. In this paper, we explore the formation mechanisms of sulfate, nitrate, and ammonium (SNA) in Zhengzhou from January 3 to 25, 2018 based on the results of a series of online instruments and a size-segregated filter sampler. Our results document the remarkable contributions of SNA to winter haze episodes in Zhengzhou, where they account for about 50% of PM2.5 mass concentration. SNA were mainly concentrated in droplet-mode particles, which increased remarkably with the aggravation of the haze episode. In addition, KNO3 and NaNO3 were formed in droplet-mode particles and coarse-mode particles respectively with increasing PM2.5 concentration. The atmosphere during the observation period was ammonia-rich, and the aerosol was acidic under high PM2.5 concentration. Homogeneous reactions dominated the formation of nitrate. HONO photolysis played a more important role in the origin of OH radicals when O3 decreased during haze episode. Under high relative humidity (RH), nitrate formation was influenced by heterogeneous hydrolysis reactions of N2O5. Sulfates were mainly formed through aqueous-phase reactions, especially when the RH was higher than 60%. Under these conditions, there were amounts of liquid water content existed in aerosols. Finally, we observed enhanced conversion of SO2 and NO2 during snowfall periods. This effect may be attributable to the higher RH and O3 levels despite the unfavorable effects of wet deposition and low concentrations of gaseous precursors.

A novel β-Ag2MoO4/BiVO4 heterojunction photocatalyst was synthesized via a simple precipitation method. The photocatalytic activity of photocatalysts was assessed by RhB (Rhodamine B) and TC (tetracycline hydrochloride) degradation. Furthermore, the Ag nanoparticles were produced during the photocatalytic degradation process facilitates the construction of Z-scheme system. The XRD, XPS, SEM, EDX, TEM, HR-TEM and BET measurements revealed the structure and morphology properties and the UV–Vis DRS, PL, PT and EIS were used to investigate the optical properties. The results exhibited that the β-Ag2MoO4/BiVO4 heterojunction photocatalyst possess higher photocatalytic activity than individual BiVO4 and β-Ag2MoO4. Furthermore, h+ was the most crucial active species in the β-Ag2MoO4/Ag/BiVO4 Z-scheme system according to the reactive species trapping experiments. The potential Z-scheme photocatalytic mechanism also was discussed based on experimental and characterization results. This work shows a simple method to construct Z-scheme heterojunction photocatalyst by self-assembly and demonstrates that photocatalytic technology has great application prospects for water purification.

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag

Bi7O9I3, a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi7O9I3. The result of SEM observation shows that the as-synthesized Bi7O9I3 consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi7O9I3 at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO3− and SO42– of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi7O9I3. The as-synthesized Bi7O9I3 exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.

A visible light-induced BiOI photocatalytic process was used to degrade sulfadimethoxine (SDM). The highest degradation efficiency of SDM was 96% after 2 h of visible light irradiation. The chemical oxygen demand (COD) of the solution decreased substantially and the high COD removal achieved 88%. During this time, the organic sulfur was recovered in the form of sulfate and the organic nitrogen was retrieved in the form of nitrate. Moreover, the high photodegradation efficiency and the less toxic photodegradation products suggest BiOI is a likely photocatalyst for the degradation of SDM under visible light.

a b s t r a c t To achieve high-performance, hierarchical plasmonic Ag/AgCl photocatalysts, a freeze-drying route was developed to form porous PVP-Ag + hybrid compounds, which were then transformed to hierarchical Ag/AgCl nanocrystals through a liquid-solid precipitation reaction followed by a partially photoreduction under ambient conditions. The PVP-Ag+ hybrid precursors and their final Ag/AgCl nanocrystals obtained were characterized by various techniques. The hierarchical Ag/AgCl nanocrystals obtained had an appar- ent size range of 156 ± 50 nm, and the surfaces of the large particles were covered with small nanocrystals with sizes of 33 ± 12 nm. The photocatalytic performance of the hierarchical Ag/AgCl nanocrystals was estimated by degradating organic dyes (i.e., RhB, MO, and MB) and alcohols (i.e., methanol and iso- propanol) under visible light (� ≥ 420 nm) and sunlight. The results indicated that the hierarchical Ag/AgCl nanocrystals obtained were efficient visible-light-driven photocatalysts in decomposing organic dyes, and their RhB photodegradation rates (∼0.97 min −1 ) was ∼54 times higher than that (∼0.018 min −1

Bi₇O₉I₃, a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi₇O₉I₃. The result of SEM observation shows that the as-synthesized Bi₇O₉I₃ consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi₇O₉I₃ at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO(3)(-) and SO(4)(2-) of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi₇O₉I₃. The as-synthesized Bi₇O₉I₃exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.