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Cu2O nanoparticles and MoS2 nanoflowers decorated with ZnO nanospheres were successfully co-deposited on Cu mesh via a mild electrodeposition method to build a dual direct Z-scheme heterostructure. The prepared materials can effectively synthesize ammonia with N2 and H2O in the liquid membrane reactor under simulated visible light. The results indicate that 3D nanomaterials exhibit better performance compared to a pure semiconductor due to the synergistic effect of enhanced visible light absorption, longer photogenerated carrier lifetime and the specific charge transfer path of dual direct Z-scheme structure. Meanwhile, the hydrophilicity of Cu2O/MoS2/ZnO rapidly makes the surface of the catalyst wet when it participates in the photo reaction, which promotes the contact between the reactant and exciton. This work proposes the electron transfer and possible reaction mechanism corresponding to the designed catalyst, which can provide a reference for other photocatalytic applications using a semiconductor heterojunction as a catalyst. [ABSTRACT FROM AUTHOR]

• Micro-nanosheet oxygen vacancy modified Bi 2 O 2 CO 3 were synthesized. • Highly efficient photocatalytic nitrogen fixation activity and recycle stability. • N 2 activation by joint effects of surface effect and surface oxygen vacancies. • Band gaps were consecutively tuned by artificial control of the content of surface oxygen vacancies. As a promising ammonia synthesis approach to replace the industrial Harber method, the biggest problem restricting photocatalytic nitrogen fixation is the suboptimal efficiency. Herein, novel surface oxygen vacancies modified micro-nanosheet structure Bi 2 O 2 CO 3 (namely BOC/OV) were successfully synthesized via facile formation under room temperature. These defects-rich nanosheets exhibit outstanding performance for photocatalytic nitrogen fixation under visible light. The surface oxygen vacancies provide abundant active sites for molecular N 2 activation, and the effect of scattered nanometer-size could facilitate the separation of photo-generated charges. Moreover, the energy band can be consecutively tuned with the accumulation of surface oxygen vacancies by lowering the conduction band position. Among all as-prepared samples, BOC/OV3 exhibited the highest NH 4 + yield, reaching 1178 μmol·L−1·g−1·h−1, which is 10 times than that of pristine Bi 2 O 2 CO 3. In this work, all samples synthesis and defects formation were conducted without requiring any secondary energy, which is of great significance for realizing green and efficient artificial ammonia synthesis. [ABSTRACT FROM AUTHOR]

CuO/CNT/Bi2WO6 composites were synthesized with a solvothermal and impregnation-calcination method. This material combines the advantages of CuO, carbon nanotubes (CNTs) and Bi2WO6. The photocatalytic activity of the catalyst was evaluated by degrading phenolic organic pollutants such as p-nitrophenol and phenol under visible light. Compared with pure Bi2WO6, the photocatalytic activity of CuO/CNT/Bi2WO6 composites is significantly increased by a factor of 3.52. The main reason for the increased activity is that the doped CNTs and CuO promote the separation of photogenerated hole and electron pairs. In addition, the coupling of π-π electrons on the CNT surface with the pollutants promotes the adsorption of the pollutants on the photocatalyst surface. The degradation rate of pure photocatalytic degradation of phenol can reach 60%. Under the synergistic effect of H2O2, the degradation rate of phenol can reach 94%, which is 1.56 times higher than that of pure photocatalysis. The UV–vis absorption spectrum shows that CuO/CNT/Bi2WO6 has stronger light absorption ability in both visible and ultraviolet light regions. The trapping experiments of active species show that h + and • OH are the main active substances for photocatalytic degradation of phenol. This paper proposes a Z scheme mechanism to improve the photocatalytic performance. [ABSTRACT FROM AUTHOR]

Due to the powerful functions of photocatalytic technology in degrading organic pollutants by using sunlight, the development of photocatalytic materials with visible light response has received great attention in order to meet the requirements of energy saving and emission reduction. Herein, we synthesize a new type of composite photocatalyst composed of graphite-like C3N4 and ZnO by co-melting-recrystallizing the precursors of two pure catalysts at 600 °C under air atmosphere. The composites present an enhanced photocatalytic activity under visible light irradiation, the kinetic constant of Methyl Orange (MO) degradation with g-C3N4/ZnO is 2.89 and 8.23 times those of the pure g-C3N4 and ZnO, respectively. Moreover, the high stability of the photocatalyst was reflected in the photodegradation of MO. The ZnO was successfully incorporated into the lattice of g-C3N4, and a Zn–N bond was formed, which resulted in an enhanced charge transfer efficiency in composites. Therefore, the low separation efficiency of photogenerated electrons–hole pairs existed in a single catalyst was well solved after g-C3N4 was combined with ZnO. The adjustment of raw material ratio shows great influence on the photocatalytic activity, and the optimum synergetic effect of the composite catalyst was found at a weight ratio of 1/30 of ZnO precursor to g-C3N4 precursor. We concluded that the photocatalytic system formed by g-C3N4 and ZnO should be the Z-scheme heterojunction with an improved transfer efficiency of photogenerated electron–hole pairs and strong redox capacity, which can be confirmed by radical trapping experiments, DMPO-ESR technique and valence band XPS spectra measurements. [ABSTRACT FROM AUTHOR]

A novel ternary composite (Ag/CQDs/MIL-53(Fe)) with full-spectrum absorption and high photocatalytic activity was successfully synthesized for the first time. The combination between up-conversion effects of the carbon quantum dots (CQDs) and the surface plasmon resonance (SPR) effects of the Ag NPs synergistically boosts the absorption over the full solar spectrum of the Ag/CQD/MIL-53(Fe) composite. The synergistic effects of Ag NPs, CQDs and MIL-53(Fe) can effectively increase the charge separation and transfer rates. 15-Ag/CQDs/MIL-53(Fe) displayed the best photocatalytic activity, for which could degrade methylene blue at a rate of up to 93.05% within 120 min under simulated sunlight. In addition, 15-Ag/CQDs/MIL-53(Fe) has 75.75%, 76.42% and 41.48% degradation rates for MB under UV light, visible light and infrared light, respectively. The above experimental results show that Ag/CQDs/MIL-53(Fe) composite has high photocatalytic degradation efficiency over the whole solar spectrum. In addition, the charge transfer processes in the Ag/CQDs/MIL-53(Fe) degradation of organic pollutants were also deduced. [ABSTRACT FROM AUTHOR]

Visible-light photocatalytic hydrogen evolution is a key step towards utilizing solar energy. Here we constructed covalently bonded oxidized graphitic C 3 N 4 /TiO 2 (O-g-C 3 N 4 /TiO 2 ) heterostructure with high surface area via an in-situ solvothermal synthetic strategy. The edge-anchoring of two-dimensional (2D) TiO 2 on 2D O-g-C 3 N 4 was evidenced by the HAADF-STEM EDS mapping, EELS and XPS analysis. Density functional theory computations suggest strong affinity between TiO 2 and O-g-C 3 N 4 2D structures through N O Ti covalent bonding, which drastically enhances the synergetic effect of the light absorption of O-g-C 3 N 4 and high surface area of TiO 2 . The as-formed heterojunction can remarkably boost the visible-light photocatalytic activity for H 2 evolution by 6.1 times compared to physical mixture of TiO 2 nanosheets (NS) and O-g-C 3 N 4 . [ABSTRACT FROM AUTHOR]

As two effective approaches to increase the visible light-absorption capacities of photocatalysts, ion doping and metallic nanoparticles loading are compared in this work. Palladium was selected to modify Bi2O2CO3. Compared to dispersing palladium nanoparticles on the photocatalyst surface, it was more effective for the method of doping with palladium to shift the energy level within the bandgap of Bi2O2CO3 in improving its photocatalytic activity under visible light. This might be because doping with Pd2+ narrows the band gap of Bi2O2CO3 so as to increase the absorption capacity of visible light photons. Pd nanoparticles on the other hand can absorb photons to produce electrons which are then utilized by Bi2O2CO3 for photocatalytic reactions. Different mechanisms resulted in significant differences, and this work provides solid evidence that ion doping may be a more effective method to improve the photocatalytic activity of Bi2O2CO3. [ABSTRACT FROM AUTHOR]

Ag 2 O-Bi 2 MoO 6 p-n heterojunction photocatalysts were prepared via simple precipitation and photosynthesis processes. The prepared composites exhibited excellent photocatalytic activity in the removal of organic pollutants (Rhodamine B and phenol) from wastewater. The improved visible-light driven photocatalytic activity can be attributed to the existence of silver nanoparticles on the surface and to the establishment of p-n heterojunctions between Ag 2 O ( p -type semiconductor) and Bi 2 MoO 6 ( n -type semiconductor). This work sheds light on the importance of considering the semiconductor type (p/n- type) when forming composite photocatalysts and utilization of the SPR effect of nanoparticles on the photocatalysts surface. [ABSTRACT FROM AUTHOR]

Pd-doped Bi 2 MoO 6 was prepared and investigated for the first time. The prepared samples were characterized by their crystal structures, chemical states, atomic compositions, optical properties and morphologies. The photocatalytic activities of prepared samples under visible light irradiation were determined by degradation of phenol, which is widely found in wastewater from many industrial processes and is difficult to destroy. The sample exhibiting the highest removal efficiency with respect to the degradation of phenol contained 2% Pd. The enhancement effect can be interpreted as the integrated effects of a reduction in the rate of electron-hole recombination, surface plasmon resonance, and production of Cl 0 . This work sheds light on the potential applications of noble metal nanoparticles in visible light-driven photocatalysis. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic activity of graphitic carbon nitride (g-C 3 N 4 ), surface hydroxylation was employed as an efficient modification method. Characterizations were conducted to examine the formation of surface hydroxyl groups, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and diffuse-reflection spectroscopy (DRS). The improvement of photocatalytic activity brought by the surface hydroxylation modification was examined by measuring the degradation of Rhodamine B under visible light irradiation. Both theoretical and experimental explanations were given concerning the formation of photo-generated active radicals. This study sheds light on the benefits of surface hydroxylation modification, as well as on the differences in the roles of active radical species. [ABSTRACT FROM AUTHOR]

A novel beta iron oxyhydroxide (β-FeOOH) supported graphitic carbon nitride hybrid was synthesized for the first time by a facile adsorption-hydrolysis method. The g-C 3 N 4 was surface-modified with oxygen-containing functional groups such as hydroxyl and carbonyl groups, by ultrasonic treatment of pristine g-C 3 N 4 with hydrogen peroxide. Due to the formation of these groups, the β-FeOOH was able to grow directly on the surface of g-C 3 N 4 through strong electrostatic interactions. The as-prepared hybrid showed enhanced light absorption in the visible light region compared to pure g-C 3 N 4 , and possessed a type-II heterojunction structure. The photocatalytic properties of these hybrids were evaluated through the photocatalytic degradation of RhB under visible light irradiation. It was found that a loading quantity of 4% β-FeOOH exhibited the best performance. The reported β-FeOOH/g-C 3 N 4 hybrid is a highly efficient visible light photocatalyst. [ABSTRACT FROM AUTHOR]

Hierarchical flower-like Bi2WO6 was successfully synthesized by facile hydrothermal method at low pH. And Ag/AgCl was loaded by photoreduction on its surface. As-prepared photocatalysts were characterized by various techniques. Bi2WO6 was successfully synthesized at a size of 2-3 μm. Depositing Ag/AgCl did not destroy the crystal structure, and both Ag+ and metallic Ag0 were found. The band gap of the composite was 2.57 eV, which indicates that visible light could be the activating irradiation. In the photocatalytic activity test, the composite with 10 wt% Ag/AgCl boasted the highest removal efficiency (almost 100%) in 45 min. The significant enhancement can be attributed to the surface plasmon resonance (SPR) effect and the establishment of heterostructures between Ag/AgCl and Bi2WO6. A possible mechanism of photocatalytic oxidation in the presence of Ag/AgCl-Bi2WO6 was proposed. This work sheds light on the potential applications of plasmonic metals in photocatalysis to enhance their activities. [ABSTRACT FROM AUTHOR]

Monoclinic BiVO4 powders were synthesized via a novel route using potassium metavanadate (KVO3) prepared by calcination of K2CO3 and V2O5 as a starting material and followed by hydrothermal treatment and were investigated for the degradation of Rhodamine B (RhB) under visible light irradiation. The synthesized BiVO4 particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Visible (UV-Vis) light diffuse reflectance spectrophotometry. The synthesis produced pure monoclinic BiVO4 particles with multimorphological features containing flower-like, flake-ball, flake, cuboid-like, and plate-like shapes and exhibited strong absorption in the visible light range. The BiVO4 prepared via KVO3 possessed excellent photocatalytic activity for the degradation of RhB under visible light. The performance of this catalyst was found to be superior to other BiVO4 photocatalysts prepared via ammonium metavanadate (NH4VO3) using coprecipitation, combustion, and calcination methods reported in literature, respectively. [ABSTRACT FROM AUTHOR]

A novel oxygen vacancy (OVs) modified Bi 2 MoO 6 /WO 3 hybrid electrode based on the ITO glass was successfully fabricated by a facile two-step hydrothermal and solvothermal method with one calcination process between two reactions. The result exhibited an enhanced optical harvesting and photogenerated electron migration capability. In the degradation process of rhodamine B (RhB), the hybrid electrode showed a better photoelectrocatalytic removal ratio of 80.1% within 4 h under visible light irradiation and 2.0 V bias, which is mainly ascribed to the synergistic promotion of surface OVs, heterostructure and external bias. The optical features and band structures of the composite catalyst were analyzed to give out the possible electrode system mechanism of the PEC degradation process. This work not only constructs a newly designed OVs Bi 2 MoO 6 /WO 3 photoelectrode but also provides some investigations in fabricating and controlling process of photoelectrodes. [ABSTRACT FROM AUTHOR]

• Oxygen vacancy modified Bi 2 MoO 6 /MIL-88B(Fe) heterostructure hexagonal microrods were fabricated. • The synergistic effect between heterostructure and oxygen vacancy led to enhanced charge separation at the bulk & interface. • The Bi 2 MoO 6 /MIL-88B(Fe) exhibited enhanced photocatalytic activity under visible light irradiation. • Oxygen vacancy assisted Type II heterojunction mechanism was presented. The development of efficient strategies to promote spatial charge separation is a promising way for the improvement of photocatalytic performance. Herein, a novel surface oxygen vacancy (OVs) modified Bi 2 MoO 6 /MIL-88B(Fe) heterostructure (BMO/M88) was exemplified by a facile two steps solvothermal method to demonstrate synergistic promotion of bulk & interface charge separation. Due to the existence of OVs and the construction of heterostructure, the Bi 2 MoO 6 /MIL-88B(Fe) composites exhibited significant enhancement of visible-light responsive range and possessed more efficient bulk & interface charge separation. This novel Bi 2 MoO 6 /MIL-88B(Fe) composites exhibited high visible light photocatalytic performance toward dye pollutant rhodamine B (RhB) and model colorless pollutant bisphenol A (BPA) photodegradation, and the possible Type II heterojunction mechanism of photocatalysis process was investigated. This work not only provides a novel pathway for design of MOFs-based heterojunction with surface OVs defect modification but also offers a strategy for significantly enhanced bulk & interface charge carriers separation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NaNbO 3 /Bi 2 WO 6 type-II heterostructures were successfully prepared. • Various experimental factors on photoactivity were studied. • Mechanism of the enhancement in photocatalysis was explored. Abstract In this study, a series novel N a N b O 3 / B i 2 W O 6 heterojunction composites with a type-II alignment were fabricated via a facile wet impregnation method. The as-prepared photocatalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-Vis spectroscopy (DRS), photocurrent (PC) and electrochemical impedance spectroscopy (EIS) analyses. The 30 wt% N a N b O 3 / B i 2 W O 6 composite exhibited the best performance in the case of degrading rhodamine B (RhB) aqueous solution under visible light irradiation (λ > 410 nm), which was ∼2.5 times and ∼40 times that of pure B i 2 W O 6 and N a N b O 3 , respectively. The improved photocatalytic performance was further demonstrated by 2-chlorophenol under the same reaction conditions. This may be attributed to the enhanced electron-hole separation efficiency in B i 2 W O 6 with the assistance of N a N b O 3 , as well as the dye-sensitization effect of RhB dye itself. Intermediates produced during the reaction and RhB degradation pathway were investigated as well. Radical quenching experiments revealed h + played the predominant role; O 2 · - functioned as well to some degree. Based on experimental results, the potential functioning mechanism was proposed, which is different from previously reported type-II heterostructure systems when B i 2 W O 6 works as the electron reservoir and O 2 · - is one of the dominant active species. The as-prepared photocatalyst composite exhibited excellent stability after repetitively running five times. Effects of several operating parameters on the catalyst performance including initial RhB concentration, catalyst dosage, reaction temperature and initial pH were also discussed. This study provides solid evidence for N a N b O 3 to be a promising candidate for photocatalysis and gives out a novel photocatalytic mechanism of B i 2 W O 6 -based heterostructures. [ABSTRACT FROM AUTHOR]

A bismuth-based compound, Bi 2 WO 6 , was successfully synthesized using a facile hydrothermal method. Aiming to improve its photocatalytic activity under visible light irradiation, Pd/PdCl 2 was first doped onto the surface of Bi 2 WO 6 via a photo-reduction method. The prepared Pd/PdCl 2 -Bi 2 WO 6 samples were characterized based on crystal structures, chemical states, atomic compositions, and morphologies as well as photoabsorption properties. In the screening tests for photocatalytic activity, the 4% Pd-Bi 2 WO 6 sample performed with the highest removal efficiency with respect to the degradation of phenol in wastewater. This sample exhibited better in complete degradation of phenol under visible light irradiation, compared to TiO 2 under ultraviolet irradiation. A possible mechanism for the enhanced visible light-driven photocatalytic activity by means of loading Bi 2 WO 6 with Pd was also suggested. This work sheds light on the potential applications of noble metal nanoparticles in visible light-driven photocatalysis. [ABSTRACT FROM AUTHOR]

Porous, peanut-shaped BiVO 4 was prepared and further decorated with palladium nanoparticles on its surface using a photodeposition approach. The well-dispersed palladium nanoparticles were found to suppress photogenerated charge carriers, and may also improve the capacity of BiVO 4 to harvest visible light photons due to a local surface plasmon resonance effect. The prepared Pd–BiVO 4 composites exhibited excellent photocatalytic activity in the degradation of phenol under visible light irradiation. This performance rivaled that of TiO 2 under UV light. However, the active oxidants in Pd–BiVO 4 and TiO 2 processes are different, with photogenerated holes in BiVO 4 photocatalysis and OH radicals in TiO 2 photocatalysis. Furthermore, different mechanisms and different pathways for the degradation of phenol under the effects of different oxidants were proposed. This work not only opens up new possibilities for the efficient removal of phenolic compounds in wastewater via visible-light-driven photocatalysis in the presence of a Pd–BiVO 4 composite, but also suggests that OH radicals may not be the most important oxidants in all photocatalysis processes. [ABSTRACT FROM AUTHOR]

The low efficiency of photocatalytic nitrogen fixation to ammonia is determined by the low quantum efficiency photocatalyst and the configuration of the reactor.Therefore, a new method was adopted to introduce a gas-liquid-solid optofluidic microreactor with gas-liquid two-chambers into the photocatalytic nitrogen fixation reaction, and a novel and efficient TiO 2−x -Ag@HKUST-1/ carbon paper composite membrane was successfully synthesized. The porous structure of HKUST-1/carbon paper can well adsorb N 2 , and the uniformly dispersed Ag and Ti3+ in the TiO 2−x are bridged by O vacancies to form the Ti3+-Ov-Ag active center. These together improve the activity of photocatalytic nitrogen fixation to ammonia. The experimental results show that the TiO 2−x -Ag@HKUST-1/carbon paper composite membrane can continuously reduce N 2 to ammonia under visible light, and the yield can reach 10.62 mg.h-1.g cat -1and the corresponding apparent quantum yield (AQY) under 450 nm illumination reaches 2.08%, which is much higher than that of commercial TiO 2 (P25), HKUST-1, and also higher than most of the reported TiO 2 -based photocatalysts. This shows the superiority of the gas-liquid two-chambers gas-liquid-solid optofluidic microreactor in photocatalytic nitrogen fixation.This work can also be seen as a step towards the development of high-efficiency continuous photocatalytic nitrogen fixation to ammonia technology. [Display omitted] • The gas-liquid-solid optofluidic microreactor with gas-liquid two-chambers was introduced into the photocatalytic nitrogen fixation reaction. • The uniformly dispersed Ag and Ti3+ in the TiO 2−x are bridged by O vacancies to form the Ti3+-Ov-Ag active center. • The TiO 2−x -Ag@HKUST-1/carbon paper composite membrane can continuously reduce N 2 to ammonia, and the yield can reach 10.62 mg.h-1.gcat-1. [ABSTRACT FROM AUTHOR]

A series of graphene oxide-modified, multi-phase Ag 2 O/Ag 3 VO 4 /AgVO 3 composites were synthesized via simple procedures at room temperature. Compared to those of pure Ag 2 O/Ag 3 VO 4 /AgVO 3 , these GO-modified composites exhibited enhanced activities during photocatalytic degradation of rhodamine B and methyl orange under visible light illumination. A study of the effect of graphene oxide (GO) addition on photocatalytic performance indicated that 1.2 wt% GO was the optimum quantity. The increased photocatalytic activities of as-prepared GO-modified composites may be attributed to the large surface area possessed by GO as well as its interactions with other species in the multi-phase Ag 2 O/Ag 3 VO 4 /AgVO 3 composites during photocatalytic reactions under visible light illumination. From the enhancement in photocatalytic activity, it may be inferred that GO could improve the adsorption and absorption capabilities of the Ag 2 O/Ag 3 VO 4 /AgVO 3 composites and promote the separation of electron-hole (e-h) pairs during photocatalytic reactions compared to those of composites without GO addition. Moreover, GO as a modifier was able to partially protect silver species composites from photocorrosion. A possible mechanism was proposed for the photocatalytic degradation of organic dyes on the surface of GO-modified Ag 2 O/Ag 3 VO 4 /AgVO 3 . [ABSTRACT FROM AUTHOR]

A novel Ag 2 O/Ag 3 VO 4 /Ag 4 V 2 O 7 photocatalyst was synthesized by adjusting the molar ratio of silver–vanadium (Ag–V) in a facile hydrothermal method to obtain multi-phase Ag 2 O/Ag 3 VO 4 /Ag 4 V 2 O 7 photocatalyst. The photocatalytic activity of the prepared samples was quantified by the degradation of Rhodamine B (RhB) model organic pollutant under visible light irradiation. Compared to pure Ag 3 VO 4 , Ag 4 V 2 O 7 and P25 TiO 2 , respectively, the as-synthesized multi-phase Ag 2 O/Ag 3 VO 4 /Ag 4 V 2 O 7 powders gave rise to a significantly higher photocatalytic activity, achieving up to 99% degradation of RhB in 2 h under visible light. This enhanced photocatalytic performance was attributed to the effect of the multi-phase Ag 2 O/Ag 3 VO 4 /Ag 4 V 2 O 7 photocatalyst and the surface plasmon resonance (SPR) of the incorporated metallic silver (Ag 0 ) nanoparticles (NPs) generated during the photocatalysis, as evidenced by post-use characterization, resulting in improved visible light absorption and electron-hole (e − -h + ) separation. A mechanism was proposed for the photocatalytic degradation of RhB on the surface of Ag 2 O/Ag 3 VO 4 /Ag 4 V 2 O 7 . [ABSTRACT FROM AUTHOR]

Highlights: [•] Ag/AgCl–AC composites were synthesized by deposition-precipitation-photoreduction. [•] The composites were photocatalytically active for MO and phenol degradation under visible light. [•] A mechanism was proposed based on the roles of Ag, AgCl, and AC. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-doping of TiO2 was performed to improve the visible light response and photocatalytic activity of this catalyst. In this work, the high temperature annealing of TiC was studied and the anatase–rutile doped TiO2 mixtures created were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible light absorption spectrophotometry (UV–Vis). It was found that the TiC fully reacts at 400°C. Transformation of the anatase to rutile phase was observed since the latter form is more heat stable. XPS analysis revealed that the carbon in the sample was present as carbonate species. The UV–Vis spectrum of the doped powders were red shifted compared to P25 TiO2, and a band gap narrowing of 0.2eV was observed. The photocatalytic activity of the powders was quantified by the degradation of methylene blue under visible light irradiation. Langmuir–Hinshelwood kinetics were applied, and the maximum pseudo-first order degradation rate observed was 0.015min−1 for the powder annealed at 400°C for 8h. Disinfection of Escherichia coli K12 was performed using the catalyst in an immobilized configuration under visible light, and up to 80% inactivation was observed, compared to negligible inactivation with P25. The modified Hom disinfection kinetic model was used to describe the data. [Copyright &y& Elsevier]

A facile and feasible interfacial self-assembly approach was developed to synthesize flower-like Cu 2 O/Bi 2 O 2 CO 3 micro-composites. Degradation of methylene blue (MB) was used to evaluate the photocatalytic activity of composite under visible light. When compared to Bi 2 O 2 CO 3 , the flower-like Cu 2 O/Bi 2 O 2 CO 3 micro-composites show higher photocatalytic activity. Additionally, our results indicate that the photocatalytic activity of Cu 2 O/Bi 2 O 2 CO 3 composites is dependent on Cu 2 O loading. The highest photocatalytic performance of Cu 2 O/Bi 2 O 2 CO 3 micro-composites is 94% after irradiation for 20 min, which is 3–5 times that of pure Cu 2 O (calculated based on the equivalent Cu 2 O content in Cu 2 O/Bi 2 O 2 CO 3 ) and pure Bi 2 O 2 CO 3 respectively. Photocatalytic mechanism for the degradation of MB over Cu 2 O/Bi 2 O 2 CO 3 was proposed based on the above. Our results provide an invaluable methodology for designing high visible-responsive photocatalysts based on Cu 2 O/bismuth and related functional materials, which is promising for semiconductor composites and new energy applications. [ABSTRACT FROM AUTHOR]

MoS 2 Quantum dots-interspersed Bi 2 WO 6 heterostructure is fabricated for photocatalytic applications for the first time. It exhibits enhanced visible light-driven photocatalytic detoxification and disinfection in wastewater compared to bare Bi 2 WO 6 and MoS 2 . MoS 2 quantum dots as a co-catalyst applied in photocatalysis oxidation possesses multiple merits: (1) noble-metal-free; (2) high mobility of photogenerated charge carriers; (3) high adsorption capacity and (4) improved capture capacity of visible light photons. Electron-hole separation rate which is critical for an efficient photocatalysis is greatly improved via the built-in electric field of p - n heterostructure and the quantum dots interspersed on the surface. This work shed a light on loading MoS 2 quantum dots as a co-catalyst on a support aiming to significantly improve its photocatalytic performance in organic pollutants degradation and bacteria inactivation. [ABSTRACT FROM AUTHOR]

Owing to its nontoxic property, low cost and narrow band gap, alpha-iron(III) oxide (α-Fe 2 O 3 ) is a promising material as photocatalyst. However, it has shortcomings such as quick recombination and a short lifetime of the electron-hole pairs, which directly reduce the photocatalytic efficiency of α-Fe 2 O 3 and hinder its wide applications. In this study, a facile hydrothermal method was used to incorporate BiOBr with α-Fe 2 O 3 in an attempt to overcome the previously mentioned limitations of α-Fe 2 O 3 , and the synthesized composites were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse-reflection spectroscopy (DRS). The BiOBr/α-Fe 2 O 3 composite showed much higher visible-light-driven photocatalytic activity than the pure α-Fe 2 O 3 and BiOBr for Rhodamine B (RhB) degradation. Specifically, the composite synthesized at 100 °C for 18 h with a mass ratio of BiOBr to α-Fe 2 O 3 5:10 performed the best. This work also explored the chemical mechanism and pathway of RhB degradation, and the roles of the oxidative species with the presence of BiOBr/α-Fe 2 O 3 composites in the photocatalytic oxidation process, including holes (h + ), hydroxyl radicals ( OH), and superoxide radicals ( O 2 − ). [ABSTRACT FROM AUTHOR]

A series of Zr doped g-C 3 N 4 /Nb 2 O 5 photocatalysts with high visible light response and strong redox properties were synthesized for wastewater treatment under visible light, which achieved the synergistic effect of transition metal doping and semiconductor compounding. The doping of Zr promoted charge transfer due to the formation of Schottky barrier. As an electronic medium, Zr was devoted to formating the Z-scheme heterojunction between g-C 3 N 4 and Nb 2 O 5 , which effectively improved the redox ability of the catalyst as well as promoted the separation of photogenerated electrons and holes in semiconductors. The morphology, chemical structure, optical and electronic properties of Zr/g-C 3 N 4 /Nb 2 O 5 photocatalysts were well characterized. Compared with monomeric g-C 3 N 4 , the as-prepared Zr/g-C 3 N 4 /Nb 2 O 5 exhibited improved visible light response and enhanced separation efficiency of photogenerated carriers as a result of the synergistic effect of ion doping and semiconductor compounding. Subsequently, the activity of organic pollutant degradation were tested using as-prepared Zr/g-C 3 N 4 /Nb 2 O 5 under the representative organic pollutants methylene blue (MB) and levofloxacin (LF) as the targets. The Zr/g-C 3 N 4 /Nb 2 O 5 showed efficient photocatalytic activity toward degrading dye wastewater and pharmaceutical wastewater under visible light irradiation (λ＞410 nm) comparing with bare g-C 3 N 4 and Zr/g-C 3 N 4. The content of Zr and Nb 2 O 5 has a crucial effect on catalyst activity, and the Zr/g-C 3 N 4 /Nb 2 O 5 with 5 at% Zr and 4 wt% Nb 2 O 5 was of the best photocatalytic activity, which degraded 98.5% of MB in 120 min for visible light irradiation. The excellent performance of Zr/g-C 3 N 4 /Nb 2 O 5 is mainly due to the Z-scheme charge transfer mode. [Display omitted] [ABSTRACT FROM AUTHOR]

Regarding the shortcomings of CdS as photocatalyst for photocatalytic N 2 fixation, namely, inadequate visible-light response, fast recombination of the photogenerated charges, and poor adsorption of N 2 on the surface, a trinity strategy made up of shape control, element doping and etching is proposed to enhance the photocatalytic performance. Etched Ag-doped PVP modified CdS (Ag/PM-CdS(e)) is fabricated for photocatalytic N 2 fixation by problem oriented method. The morphology, chemical structure, optical and electronic properties of as-prepared photocatalysts are well characterized. The results show that PVP is an excellent surface modification agent, promoting the optical performance of CdS and avoiding particle agglomeration. The strong interaction between Ag and CdS enhances the separation and transfer of photogenerated electron-hole pairs. Importantly, etching induces a larger specific surface area, resulting in improved N 2 adsorption on catalyst surface. Under the synergistic effect of trinity strategy, the visible light response performance of photocatalyst is greatly improved, and the transient photocurrent density of the Ag/PM-CdS(e) sample reaches 3.5 times that of pristine CdS. Unsurprisingly, Ag/PM-CdS(e) exhibits improved photocatalytic NH 3 production (0.343 μg h−1 mg−1) under visible light irradiation by a factor of 4.97, 2.18 and 1.56 times compared with the pristine CdS, PM-CdS and Ag/PM-CdS, respectively. Meanwhile, Ag/PM-CdS(e) shows good stability in the process of NH 3 production for four successive cycles, NH4+ production with a rate of 0.269 μg h−1 mg−1 can be observed after 960 min of reaction. Finally, an anticipated mechanism for the meaningful N 2 photofixation enhancement is provided. • A trinity strategy is proposed regarding the shortcomings of CdS. • PVP modification significantly improved optical properties of CdS. • Ag doping enhances photogenerated electron-hole pairs separation. • Etching improves N 2 adsorption on CdS surface. • Ag/PM-CdS(e) exhibits outstanding NH 3 production rate. [ABSTRACT FROM AUTHOR]

Black Ti3+ self-doping TiO 2 nanotubes (BTNT) have attracted widespread attention due to their abilities to enhance visible light response and photo-generated electron-hole separation without introducing impurity particles. However, due to the poor stability of Ti3+, the doping of a large amount of Ti3+ is a huge challenge. In this work, we have taken a different approach, and the black Ti3+ self-doping TNT-Ag-WO 3 (BAW) photocatalyst was prepared. The BAW Z-scheme photocatalytic (PC) system was successfully constructed. Compared with TNT's PC system (degrade 40.56%), BAW Z-scheme PC system can degrade 97.67% with 20 mg/L MB wastewater after 120 min. By introducing a large number of Ti3+ and O vacancies, the inherent active group is mainly converted from the holes and.OH on the WO 3 valence band and.O 2 − on the TiO 2 conduction band, which improved the stability of O vacancies.Before and after the reaction, the reduction of Ti3+ in BTNT is about 30 times that of Ti3+ in BAW. This work provides a reference and basis for constructing Z-scheme heterojunction on BTNT, and also provides new ideas for improving the stability of Ti3+and O vacancies in self-doped TiO 2. [Display omitted] • the Z-scheme heterojunction BAW using an external electric field on the black Ti3+ self-doping TNT was constructed. • Before and after the reaction, the reduction of Ti3+ in BTNT is about 30 times that of Ti3+ in BAW. • Compared with TNT's PC system (degrade 40.56%), BAW PEC system can degrade 97.67% with 20 mg/L MB wastewater in 120 min. • The photocurrent density of BAW is about 4 times that of pure TNT, about 1.8 times that of BTNT. • The band gap of TNT changes from 3.22 eV to the band gap of BAW 2.59 eV. [ABSTRACT FROM AUTHOR]

Highlights: [•] Escherichia coli K-12 inactivated using Ag/AgCl–activated carbon photocatalyst. [•] Up to 97% of bacteria inactivated in 60min under visible light irradiation. [•] Mechanism of photocatalytic inactivation due to action of radicals on cell wall. [ABSTRACT FROM AUTHOR]

Abstract: A series of cadmium sulfide (CdS)-sensitized layered perovskite-type compound (K2La2Ti3O10) composites (hereafter designated as CdS/K2La2Ti3O10) photocatalysts were synthesized by loading CdS particles on K2La2Ti3O10 via a facile precipitation method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet–visible (UV–vis) diffuse reflection spectra. The photocatalytic activities of these catalysts for H2 production were investigated in the presence of a Na2S sacrificial reagent under visible light irradiation. The results revealed that the CdS/K2La2Ti3O10 samples displayed a strong light absorption in the visible region, and the UV–vis diffuse reflectance spectra changed with the proportion of CdS present. The composite photocatalysts exhibited enhanced photocatalytic hydrogen evolution, and the highest activity of 50.53μmol was achieved using 5wt.% CdS/K2La2Ti3O10. This enhanced photocatalytic activity can be attributed to the efficient separation of electron–hole pairs and prevention of their recombination under the joint effects of the electric field established at the heterojunction and the layered space of K2La2Ti3O10. [Copyright &y& Elsevier]

Monomeric graphitic carbon nitride (g-C 3 N 4) with abundant pores and suitable energy band structure was prepared by calcining the mixture precursor at high temperature. Meanwhile, Zr/g-C 3 N 4 and g-C 3 N 4 /ZnO photocatalysts were fabricated by doping the transition metal and constructing heterojunctions respectively, thereby overcoming the defects of monomeric carbon nitride and improving photocatalytic activity. Sample morphology and structure were characterized by TEM, BET, XRD, XPS, PL, and UV–vis DRS techniques, and the photocatalytic performance was evaluated by degradation of methylene blue (MB) under visible light irradiation. The results indicated that the different energy band structures of g-C 3 N 4 from various precursors promoted the transfer and separation of photogenerated electron-hole pairs, thus improving the photocatalytic performance. Furthermore, Zr/g-C 3 N 4 presented an outstanding photocatalytic activity for MB degradation, which was mainly due to the adjustment of band gap and the rapid movement of charge caused by the introduction of Zr. The g-C 3 N 4 /ZnO photocatalyst synthesized by co-melting and recrystallizing the composite precursors of two semiconductors performed well on the aspects of structure and performance, degrading 98.07% MB after 180 min of irradiation, 29% higher than that of g-C 3 N 4 -MU. The Z-scheme charge transfer route in g-C 3 N 4 /ZnO system integral to improving the separation of photocarriers and enhancing the oxidation of photocatalyst. Based on the radical scavenging experiment, the main oxidation species in the photocatalytic process was determined, and the photocatalytic mechanism was further speculated, which provided a future direction in highly efficient g-C 3 N 4 photocatalyst design. [ABSTRACT FROM AUTHOR]

Photocatalytic technology is a new technique for environmental purification and solar energy conversions. The development of new and efficient photocatalysts has been a research hotspot for several years and the fabrication of composite photocatalyst has attracted wide attention. Herein, g-C 3 N 4 /TiO 2 photocatalyst with a special bilayer structure has been synthesized under mild solvothermal conditions with TiO 2 flake as the substrate material. The combination of TiO 2 and g-C 3 N 4 effectively increased the specific surface area of the composite and was conducive to the synergistic effect. The time of solvothermal reaction influences the binding mode of g-C 3 N 4 and TiO 2 , which in turn affects the photocatalytic activity. The photodegradation rate of methylene blue (MB) by g-C 3 N 4 /TiO 2 composite reached 97.61 % under visible light irradiation, which was 1.46 and 1.98 times higher than those of pure g-C 3 N 4 and TiO 2 , respectively. The improvement of photocatalytic performance is mainly attributed to the enhanced separation efficiency of photogenerated electron-hole pairs caused by the construction of heterojunctions, which has been confirmed by electrochemical impedance spectroscopy and optical transient current spectrum. Furthermore, the main active species in photocatalytic system were determined by radical trapping experiments and the photocatalytic mechanism of the composite photocatalytic system was further speculated. [ABSTRACT FROM AUTHOR]