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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.

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.

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.

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.

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.

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.