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Generally, the low electron–hole separation efficiency of covalent organic frameworks (COFs) prevents their catalytic performance from reaching satisfactory results. For this reason, the creation of heterojunctions is considered an effective strategy but usually suffers from dimensional mismatch of the integrated material, even at the expense of its redox capacity. To overcome these difficulties, a novel 2D/2D S‐scheme heterojunction between H2N–Cu–MOF (NCM) and TpPa–1–COF (TP1C) is successfully constructed for efficient photocatalytic H2 production. The matching dimensions of two crystalline porous materials enables the integrated materials with abundant surface reactive sites, strong interaction and optimized electronic structure. Moreover, the combination of two crystalline porous materials can also form a S–scheme heterojunction, which can not only promote the separation of electron–hole pair, but also preserve the redox ability, thus remarkably boosting the catalytic competence. Consequently, the rate of optimal 20% NCM/TP1C in photocatalytic H2 production reaches 4.19 mmol g−1 h−1, which is 46.5 times higher than that of bare NCM, and 22.1 folds over that of pure TP1C. This research offers an innovative perspective for the formation of S–scheme heterojunctions based on porous crystal materials for efficient solar energy utilization. [ABSTRACT FROM AUTHOR]

Riemann surfaces inspired chemists to design and synthesize such multidimensional curved carbon architectures. It has been predicted that carbon nanosolenoid materials with Riemann surfaces have unique structures and novel physical properties. Here we report the first synthesis of a nitrogen-doped carbon nanosolenoid (N-CNS) using bottom-up approach with a well-defined structure. N-CNS was obtained by a rational Suzuki polymerization, followed by oxidative cyclodehydrogenation. The successful synthesis of N-CNS was fully characterized by GPC, FTIR, solid-state 13C NMR and Raman techniques. The intrinsic single-strand molecular structures of N-CNS helices can be clearly resolved using low-dose integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) technique. Possessing unique structural and physical properties, this long π-extended polymer N-CNS can provide new insight towards bottom-up syntheses of curved nanoribbons and potential applications as a metal-free photocatalyst for visible-light-driven H2 evolution and highly efficient photocatalyst for photoredox organic transformations. Carbon nanosolenoid materials with Riemann surfaces have unique structures and novel physical properties. Here, the authors report a nitrogen-doped carbon nanosolenoid heterojunction material with distinctive photocatalytic properties for light driven hydrogen production and organic transformations. [ABSTRACT FROM AUTHOR]

This study demonstrates the successfully fabrication of 2D/2D g-C 3 N 4 /TiO 2 (B) hierarchical microflowers via a hydrothermal in-situ exfoliation and assembled method. The structural and optical properties of g-C 3 N 4 /TiO 2 (B) are characterized by X-ray diffraction, transmission electron microscopy, as well as spectroscopic techniques. The recombination of g-C 3 N 4 with TiO 2 (B) significantly improves the photocatalytic performance in the photo-oxidation of benzyl alcohol to benzaldehyde using visible light (λ > 420 nm). Trapping experiments and electron spin resonance spectroscopy indicate the active radicals of ⋅O 2 −, ⋅OH and h+ are responsible for the enhanced activity. The heterojunction interface between g-C 3 N 4 sheets and TiO 2 (110) facets boosts separation efficiency of photogenerated charges, thus resulting into the high catalytic performance of g-C 3 N 4 /TiO 2 (B) composites. Density functional theory (DFT) calculations reveal that the charge transfer between the TiO 2 (B) and g-C 3 N 4 interface and the consequent formation of a built-in electric field at the interface, which are responsible for the high catalytic performance of g-C 3 N 4 /TiO 2 (B) composites. The study firstly reports a simple in-situ hydrothermal growth protocol to efficiently construct 2D/2D g-C 3 N 4 /TiO 2 (B) heterojunction composites and offer guidelines for design of a new synthetic strategy to prepare efficient photocatalysts. [Display omitted] • Novel 2D/2D TiO 2 (B)/g-C 3 N 4 hierarchical microflower was prepared by a hydrothermal in-situ exfoliation and assembled method. • The recombination of g-C 3 N 4 with TiO 2 (B) significantly improves the photocatalytic performance in the photo-oxidation. • The active radicals of ⋅O 2 − and h+ play an important role in the photo-oxidation. • DFT calculations reveal the built-in electric field at the TiO 2 (B)/g-C 3 N 4 interface is responsible for the superior activity. [ABSTRACT FROM AUTHOR]

In this work, an InVO4/TiO2 heterojunction composite catalyst was successfully synthesized through a facile hydrothermal method. The structural and optical characteristics of InVO4/TiO2 heterojunction composites are investigated using a variety of techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and spectroscopy techniques. The addition of InVO4 to TiO2 considerably enhanced the photocatalytic performance in selective photo-oxidation of benzyl alcohol (BA). The 10 wt% InVO4/TiO2 composite photocatalyst provided a decent 100% BA conversion with over 99% selectivity for benzaldehyde, and exhibited a maximum conversion rate of 3.03 mmol g−1 h−1, which is substantially higher than bare InVO4 and TiO2. The excellent catalytic activity of the InVO4/TiO2 photocatalyst is associated with the successful assembly of heterostructures, which promotes the charge separation and transfer between InVO4 and TiO2. [ABSTRACT FROM AUTHOR]

Photocatalytic technology provides a new strategy for mitigating energy crisis. The development of photocatalytic materials with high efficiency and stable visible light response has always been the direction of researchers in the field of photocatalysis. Graphite carbon nitride (g-CN) has attracted ever increasing attention in the field of photocatalysis due to its special characteristics (such as visible light response, high stability, and low cost). However, the low separation efficiency of photogenerated electrons and holes limits its catalytic activity. In this paper, a novel g-CN-based intramolecular donor–acceptor (D–A) system was prepared to promote the separation efficiency of light-induced charge carriers. The catalyst is prepared from g-CN and 1,2-dibromobenzene (Bz) through a simple calcination method. Characterization results confirmed that Bz was successfully introduced into the g-CN (g-CN-Bz (x)) framework. The formation of the D–A structure leads to the spatial separation of electrons and holes pairs, which significantly accelerates the separation efficiency of charge carriers. Moreover, the D–A structure plays an important role in adjusting the width of band gap, which can increase the light absorption capacity of the catalyst. The D–A system also leads to the formation of a built-in electric field, which significantly accelerates the migration speed of electrons. Among the prepared catalysts, g-CN-Bz (0.01) has the best photocatalytic CO2 reduction performance, and the evolution rate of CO is 5.2 times higher than that of CN (3.64 μmol g−1). In addition, the reaction is carried out in water without any sacrificial agent, which makes it green and environmentally friendly. The charge carrier excitation-recombination process between donor and acceptor, and photocatalytic reduction of CO2 to CO over the CN based DA composites. [ABSTRACT FROM AUTHOR]

Photocatalytic technology provides a new strategy for mitigating energy crisis. The development of photocatalytic materials with high efficiency and stable visible light response has always been the direction of researchers in the field of photocatalysis. Graphite carbon nitride (g-CN) has attracted ever increasing attention in the field of photocatalysis due to its special characteristics (such as visible light response, high stability, and low cost). However, the low separation efficiency of photogenerated electrons and holes limits its catalytic activity. In this paper, a novel g-CN-based intramolecular donor–acceptor (D–A) system was prepared to promote the separation efficiency of light-induced charge carriers. The catalyst is prepared from g-CN and 1,2-dibromobenzene (Bz) through a simple calcination method. Characterization results confirmed that Bz was successfully introduced into the g-CN (g-CN-Bz (x)) framework. The formation of the D–A structure leads to the spatial separation of electrons and holes pairs, which significantly accelerates the separation efficiency of charge carriers. Moreover, the D–A structure plays an important role in adjusting the width of band gap, which can increase the light absorption capacity of the catalyst. The D–A system also leads to the formation of a built-in electric field, which significantly accelerates the migration speed of electrons. Among the prepared catalysts, g-CN-Bz (0.01) has the best photocatalytic CO2 reduction performance, and the evolution rate of CO is 5.2 times higher than that of CN (3.64 μmol g−1). In addition, the reaction is carried out in water without any sacrificial agent, which makes it green and environmentally friendly. The charge carrier excitation-recombination process between donor and acceptor, and photocatalytic reduction of CO2 to CO over the CN based DA composites. [ABSTRACT FROM AUTHOR]

Construction of g-C 3 N 4 and carbazole based D-A structure with enhanced charge carrier separation efficiency for efficient photoreduction of CO 2. [Display omitted] • A new D-A structure (g-CN-0.01Dbc) based on g-C 3 N 4 and carbazole was prepared. • The D-A structure led to enlarged the light response region and reduced bandgap. • The spatial separation of charge carrier resulted from D-A structure remarkably reduced the recombination of electron-hole pair. • The photoelectric properties and catalytic performance of g-CN-0.01Dbc were significantly improved. Photocatalytic conversion of CO 2 into hydrocarbon fuels is an ideal technology of mitigating greenhouse effect caused by excessive emission of CO 2. However, the high recombination rate of electron-hole pairs and limited charge carriers transport speed constrained the catalytic performance of many semiconductor catalysts. In this contribution, a series of carbon nitride (g-CN) samples with intramolecular donor-acceptor (D-A) system were successfully prepared by introducing organic donor into their structures. Characterization results confirmed that carbazole was successful connected to the structure of g-CN via chemical bond. The formation of intramolecular D-A system greatly enlarged the light response region of g-CN-xDbc. In addition, a new charge transfer transition mode was formed in g-CN-0.01Dbc due to the incorporation carbazole, which enable it to use light with energy lower than the intrinsic absorption of g-CN. Meanwhile, the D-A structure led to the spatial separation of electrons and holes in g-CN-xDbc and significantly decreased the recombination rate of electron-hole pairs. The g-CN-0.01Dbc presented the best catalytic performance and the CO evolution rate was 9.6 times higher than that of g-CN. Moreover, the reaction was performed in water without any additive, which made it green and sustainable. DFT simulation confirmed the D-A structure and charge carrier migration direction in the prepared samples. [ABSTRACT FROM AUTHOR]

Carbon nitride (CN) has attracted increasing attention in the field of photocatalysis due to its special properties such as visible light response, high stability, and low cost. However, the low separation efficiency of photogenerated electrons and holes limits its catalytic activity. Herein, a novel kind of CN based intramolecular donor–acceptor (DA) system was prepared to facilitate the separation efficiency of photoinduced charge carriers. The catalysts were prepared from CN and 4,7-dibromo-2,1,3-benzothiadiazole (Dbbt) by a simple calcination method. A series of characterization results confirmed that Dbbt is successfully introduced into the framework of CN (CN–Dbbt-x). It was found that the formation of the DA structure leads to the spatial separation of electrons and holes which significantly accelerate the separation efficiency of charge carriers. Moreover, the DA structure played an important role in regulating the bandgap structure, which can increase the optical absorption ability of the catalysts. Also, the DA system led to the formation of a built-in electric field, which remarkably accelerates the migration speed of electrons. CN–Dbbt-0.01 displayed the best photocatalytic CO2 reduction performance, and the CO evolution rate was 4.9 times higher than that of CN. Moreover, the reaction was carried out in water without any sacrificial agents, which makes it a green and environmentally friendly reaction. DFT simulation and experimental results showed that Dbbt and CN respectively serve as the donor and acceptor in CN–Dbbt-0.01. [ABSTRACT FROM AUTHOR]

Carbon nitride (CN) has attracted increasing attention in the field of photocatalysis due to its special properties such as visible light response, high stability, and low cost. However, the low separation efficiency of photogenerated electrons and holes limits its catalytic activity. Herein, a novel kind of CN based intramolecular donor–acceptor (DA) system was prepared to facilitate the separation efficiency of photoinduced charge carriers. The catalysts were prepared from CN and 4,7-dibromo-2,1,3-benzothiadiazole (Dbbt) by a simple calcination method. A series of characterization results confirmed that Dbbt is successfully introduced into the framework of CN (CN–Dbbt-x). It was found that the formation of the DA structure leads to the spatial separation of electrons and holes which significantly accelerate the separation efficiency of charge carriers. Moreover, the DA structure played an important role in regulating the bandgap structure, which can increase the optical absorption ability of the catalysts. Also, the DA system led to the formation of a built-in electric field, which remarkably accelerates the migration speed of electrons. CN–Dbbt-0.01 displayed the best photocatalytic CO2 reduction performance, and the CO evolution rate was 4.9 times higher than that of CN. Moreover, the reaction was carried out in water without any sacrificial agents, which makes it a green and environmentally friendly reaction. DFT simulation and experimental results showed that Dbbt and CN respectively serve as the donor and acceptor in CN–Dbbt-0.01. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using a non-toxic process to prepare biomass red and blue light emitting carbon quantum dots. • Red emitting carbon quantum dots exhibit excellent absorption performance for ultraviolet visible light. • The doping of carbon quantum dots significantly improves the band structure of C 3 N 4 /BiOBr. • The h+ and ·O 2 – of CQDs/C 3 N 4 /BiOBr are the main active species for photocatalytic degradation of RhB. The environmental crisis is an important factor that restricts human development. Biomass-derived carbon is an excellent material for the treatment of organic pollutants; however, realization of the energy band regulation of semiconductor photocatalysts remains challenging. Herein, we used green tea as a raw material to obtain different-colored carbon dots and hydrothermal carbon and introduced the C 3 N 4 /BiOBr Z-scheme heterostructure for enhancing electron transfer and band regulation. The experimental results show that the material exhibits good photocatalytic performance. 98.48% of rhodamine B (RhB) was degraded within 15 min by 20 wt% red light emitting carbon quantum dot doped C 3 N 4 /BiOBr, indicating that its performance is 4.07 times that of BiOBr. The electron spin resonance indicates that the composite material generates ·OH and ·O 2 − radicals and the reaction mechanisms of the catalyst and the intermediate from the RhB degradation. This study provides a new strategy for the development of biomass-derived carbon photocatalysis. [ABSTRACT FROM AUTHOR]

The midgap states and amino groups resulted from bulk phase N defects and surface C defects synergistically catalyze the photocatalytic reduction of CO 2 to hydrocarbon fuels. Defect structure is one of the crucial factors for enhancing the catalytic activities of photocatalysts. However, rational design and construction of defect structures in catalysts to meet the aim of enhancing photocatalytic performance in a simple and cost-effective way is still a challenge. In this contribution, we report a strategy to construct defect structures in graphitic carbon nitride (g-CN) by simple copolymerizing of urea with polyethyleneimine (PEI). Among the prepared catalysts, u-0.05PEI presents the best photocatalytic activity for CO 2 reduction, with CO and CH 4 yields of 32.86 and 1.68 μmol g−1 in 4 h, which is about 3.2 and 2.5 times higher than that of g-CN, respectively. Characterization results show that both C and N defects are formed in the newly prepared catalysts. The C defects on the surface of u-xPEI result in the formation of more amino groups which are beneficial for CO 2 adsorption. Meanwhile, the N defects inside the samples lead to the generation of midgap states between the valance band and conduction band of u-xPEI. The midgap states greatly enlarge the light absorption extent, and enable the use of light with energy lower than the intrinsic absorption of g-CN in the photoreduction of CO 2. As confirmed by DRS, EPR, PL analysis, the excellent catalytic activity of u-0.05PEI is mainly attributed to the remarkably improved light utilization efficiency and fast charge transfer. Moreover, the reaction is performed in water without any additive or organic solvent, which makes it environmentally friendly. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The 0D/2D anatase/graphene composites are synthetized by a facile hydrothemal method. • Graphene modification results in the changes in the structure of the anatase and red shift. • Graphene modification leads to obvious increase of the Ti3+ ions content. • Graphene modification can effectively trap electrons to enhance the separation of charges. • Anatase/graphene exhibit excellent synergistic photocatalytic activity for Cr(VI) and RhB. Abstract In this study, a novel anatase/graphene (0D/2D)-based composite photocatalyst is synthesized through a facile hydrothemal method using graphene oxide (GO), titanium sulfate (Ti(SO 4) 2) and hydrazine hydrate (N 2 H 4 ·H 2 O) as precursors. The study reveals that the surface-dispersed anatase nanoparticles adhere well to the flake-like graphene. Compared with pure anatase nanoparticles, the anatase/graphene composite showed a significantly modified crystal structure in the crystallinity of the anatase phase and surface area. The involvement of graphene also dramatically enhanced the absorption of visible light and provided a shift in the absorption edge towards red wavelengths. From the analysis of the fluorescence spectra, it is demonstrated that the recombination dynamics of the photogenerated charge (electron-hole) pairs can be effectively inhibited by the compounded graphene and hence improve the efficiency of the charge carrier separation. The dramatically improved reduction of Cr(VI) is achieved through the visible light photocatalytic activity provided by the anatase/graphene composite. The rate of the reaction measured for the composite is 4.83-fold and 9.78-fold greater than that of the pure anatase under ultraviolet and visible light irradiation, respectively. Moreover, the synergism of the RhB degradation with the reduction of Cr(VI) also dramatically improves the latter. Additionally, we present an analysis of a potential alternate system for the improvement of photocatalytic activity. [ABSTRACT FROM AUTHOR]

The construction of a 2D–2D heterostructured composite is an efficient method to improve the photocatalytic hydrogen generation capability under visible light. In this work, simple heat treatment of a mixture of g‐C3N4 and delaminated Ti3C2 was used to prepare a series of d‐Ti3C2/TiO2/g‐C3N4 nanocomposites. The d‐Ti3C2 not only acted as the support layer and resource to glue the anatase TiO2 particles and g‐C3N4 layers together but also served as the fast electron transfer channel to improve the photogenerated charge carriers' separation efficiency. By tuning the g‐C3N4/d‐Ti3C2 mass ratio, heating temperature and soaking time, the d‐Ti3C2/TiO2/g‐C3N4 nanocomposite 4‐1‐350‐1 achieved an excellent H2 evolution rate of 1.62 mmol h−1 g−1 driven by a 300 W Xe lamp with a 420 nm cutoff filter. The heterostructured composite photocatalyst was stable even after 3 cycles, representing excellent potential for the practical application in solar energy conversion. Heterostructured d‐Ti3C2/TiO2/g‐C3N4! The photocatalytic activities of Ti3C2 and g‐C3N4 are critically dependent on the microstructure. A facile heating treatment of the Ti3C2 and g‐C3N4 mixture is used to obtain heterostructured d‐Ti3C2/TiO2/g‐C3N4 nanocomposites (see image). The TiO2 particles and g‐C3N4 nanosheets are glued together by the delaminated Ti3C2 layers, demonstrating excellent performance in visible‐light photocatalytic H2 evolution. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is regarded as an ideal method for use in solving the energy shortage and environmental issues by converting solar energy to chemical energy. Herein, we have designed a facile synthetic methodology to obtain a ternary co‐modified g‐C3N4 composite via WS2 and carbon‐doped TiO2 (C‐TiO2) nanorods with highly efficient photocatalytic activity for hydrogen production from deionized (DI) water and a natural seawater system under visible‐light illumination. This composite exhibits enhanced photocatalytic activity compared to the pristine g‐C3N4, WS2, C‐TiO2 nanorods, and the reference‐modified g‐C3N4 composite with individual WS2 or C‐TiO2 nanorods. Co‐modified g‐C3N4 composite shows a great photostability in both DI water and seawater. Under λ=420 nm monochromatic light illumination, the apparent quantum efficiency of the co‐modified g‐C3N4 composite in seawater solution is 13.08 %, which is higher than pure g‐C3N4 (5.06 %). WS2, TiO2, and g‐C3N4 constitute a ternary heterojunction boosting the fast separation of photoinduced electron–hole pairs, which plays a crucial role in enhancing photocatalytic activity. Therefore, the WS2 and C‐TiO2 nanorod co‐modified g‐C3N4 composite with high photocatalytic performance provides a promising candidate for rationally utilizing the seawater resource to produce clean chemical energy. A ternary co‐modified g‐C3N4 composite with WS2 and C‐TiO2 nanorods has been designed and synthesized to split seawater to give clean hydrogen energy. WS2 and C‐TiO2 nanorods act as effective charge separators, resulting in the enhanced photocatalytic performance on co‐modified g‐C3N4 compared with pristine g‐C3N4 and the individual modified g‐C3N4 with WS2 or C‐TiO2 (see figure). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Red phosphorus modified ZnIn 2 S 4 was synthesized via a facile hydrothermal method. • The P- ZnIn 2 S 4 hollow microspheres exhibited excellent photoactivity and stability. • A volcano-type variation of photocatalytic activity with increase of P. • The mechanism for enhancing photocatalytic activity was proposed. Abstract Amorphous red phosphorus modified ZnIn 2 S 4 (ZIS) hollow spheres were synthesized via a simple one-step hydrothermal method. The P-modified ZIS exhibited enhanced photocatalytic activity under visible light (λ > 420 nm) irradiation, and 1 wt% P-ZIS were found to be the optimal performance for both the H 2 evolution and X 3 B degradation. Moreover, the reason for the enhancement of photocatalytic activity was discussed in detail, which is the addition of P not only can broaden the response range of the catalyst in the visible light wavelength range, but also promotes the separation and transfer of photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2 ) has been widely investigated as a photocatalyst material because of its stability and hypotoxicity. However, the photocatalytic activity of TiO 2 is suppressed by the large band gap and the high recombination rate of the charge carrier, which leads to confined application. Moreover, how to improve photocatalytic H 2 production without any co-catalyst remains a big challenge. Here, we report a conceptual strategy in a core–shell nanostructure of simultaneously reducing the band gap and the charge carrier recombination rate by introducing a carbon-doped porous TiO 2 layer onto a metallic TiC nanostructure using a facile in situ thermal growth method. TiC@C-TiO 2 core–shell nanostructure materials have higher photocatalytic activity in methanol aqueous solution than those of pure P25 and carbon-doped TiO 2 , which results from enhanced visible light absorption, drastic charge transfer, and the large surface area. Notably, the novel core–shell nanostructures still exhibit excellent photocatalytic H 2 production without Pt co-catalyst. The results demonstrate that TiC is an ideal support for TiO 2 photocatalysts, and this novel core–shell nanostructure can significantly shift the position of the band edge of the obtained material. This study presents a design principle for photocatalytic materials as highly efficient visible light photocatalysts. [ABSTRACT FROM AUTHOR]

In this work, ZnO microspheres-reduced graphene oxide (rGO) nanocomposites were synthesized via a simple solution method and used for the photodegradation of methylene blue (MB) dye from water under UV light. The SEM and TEM observations demonstrate that the microsphere morphologies of the ZnO microspheres-rGO nanocomposite is composed of ZnO microspheres anchored on rGO sheets, confirming the formation of ZnO microspheres-rGO composites. Raman spectra and X-ray photoelectron spectroscopy reveal that both of the reduction of GO tight contact between ZnO and rGO are achieved during the high temperature calcination process. During the photocatalytic test, in comparison with ZnO microspheres and P25 TiO2, the ZnO microspheres-rGO nanocomposite shows improved photodegradation of MB dye, because the rGO sheets could reduce the charge recombination in electron-transfer processes. According to the scavenger experiments, the possible MB degradation mechanism is contributed mainly to the generation of active species induced by the photogenerated holes (h + ) and superoxide radicals ( O 2 − ). [ABSTRACT FROM AUTHOR]

A stable liquid paraffin/water Pickering emulsion with amphiphilic graphitic carbon nitride (g-C 3 N 4) to provide photocatalytic activity is prepared for the rapid treatment of rhodamine B (RhB) dye wastewater. The results show that the decolorization rate of RhB by liquid paraffin extraction alone is 50.9%; that by g-C 3 N 4 adsorption alone is 51.4%. When liquid paraffin and g-C 3 N 4 are combined to form a Pickering emulsion for treating RhB solutions, the decolorization rate increases to 78.8% in the dark. Under visible light irradiation, the decolorization rate reaches almost 100% in 25 min because of the addition of in situ photodegradation. The used Pickering emulsion can be easily recycled without performance degradation. The combination of adsorption, extraction, and photodegradation in the process intensifies the dye treatment, which does not require the separation and recovery of nano-photocatalysts or the secondary treatment of the eluent in adsorption and extraction. This work provides a convenient and promising method to form a functional and reusable Pickering emulsion for highly efficient wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)–ZnO nanorods composites were successfully synthesized by a facile room-temperature approach using the colloidal coagulation effect. The samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and UV–vis spectroscopy. The photodegradation of methylene blue (MB) has been investigated in the presence of composites. It is observed that the absorption capacity and photocatalytic effect could be enhanced by adding graphene oxide. [ABSTRACT FROM AUTHOR]

Abstract: La2O3/Ti1−x B x O2 nanocrystals are prepared under supercritical conditions in which the La2O3 is present in a separate phase adsorbed by TiO2 while B-dopants are incorporated into TiO2 lattice via Tih name="sbnd" />B bond. During degradation of methylene blue under visible irradiation, the as-prepared photocatalyst exhibits higher activity than the undoped TiO2, the La2O3/TiO2, the Ti1−x B x O2, and even the La2O3/Ti1−x B x O2 obtained via direct calcinations, showing synergetic promoting effects from the supercritical treatment, the La2O3 and the B-dopant. The B-doping extends light absorbance to visible region while the La2O3 could enhance the surface area and also capture the photoelectrons, leading to the lower recombination between photoelectrons and holes. Supercritical treatment results in well-crystallized anatase and high surface area, which facilitate the light absorbance, the adsorption of organic substrate, and the separation of photoelectrons from holes, leading to the enhanced quantum yield. Meanwhile, supercritical treatment may strengthen the interactions of the La2O3 and the B-dopants with TiO2, leading to enhanced promoting effects. [Copyright &y& Elsevier]

[Display omitted] • Hollow tubular In 2 O 3 /AgI photocatalysts with oxygen vacancies were synthesized. • A BIEF with e- flowing from AgI to In 2 O 3 helps the formation of Z-scheme structure. • In 2 O 3 /AgI (2:1, molar) performed well as a photocatalyst for tetracycline degradation. • 1O 2 , h+, •O 2 −, and •OH were the key reactive species in the photocatalytic system. • In 2 O 3 /AgI photocatalysts exhibited excellent structural stability and reusability. A novel In 2 O 3 /AgI heterojunction, which has a hollow tubular structure with AgI particles distributed evenly on the outer and inner surfaces of In 2 O 3 microtubes, was fabricated from annealing of AgI adhered to MIL-68(In). The as-prepared heterojunction exhibited much higher photocatalytic activity towards tetracycline degradation compared to In 2 O 3 and AgI. The presence of InAg-1 (1.0 g/L), which has a In 2 O 3 :AgI mole ratio of 2:1, could achieve 98.4% removal of tetracycline (20 mg/L) from the solution phase under visible light illumination in 10 min, and it had excellent reusability and stability. The In 2 O 3 /AgI heterojunction also exhibited excellent performance in photocatalytic degradation of tetracycline in different types of water matrices and under natural sunlight illumination, demonstrating its potential in practical application. The superior photocatalytic activity of InAg-1 is attributed to the heterojunction formation and generation of oxygen vacancies (OVs), which improve the separation efficiency of photoinduced e−-h+ pairs. Meanwhile, the built-in electric field (BIEF) formed with e- flowing from AgI to In 2 O 3 , which is confirmed by density functional theory calculations, helps the formation of a Z-scheme, instead of type II, heterojunction between In 2 O 3 and AgI. Results of radical trapping experiments and electron spin resonance spectra reveal that 1O 2 , h+, •O 2 −, and •OH were the key reactive species involved in the photocatalytic degradation process. These findings indicate that Z-scheme photocatalysts with OVs could efficiently activate molecular oxygen and thus have excellent photocatalytic activity towards degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Vertically-aligned ZnO nanorod arrays on a fluorine-doped tin oxide glass substrate were homogeneously coated with visible light active CuInS 2 quantum dots by using a controllable electrophoretic deposition strategy. Compared with the pure ZnO nanorod arrays, the formation of high-quality ZnO/CuInS 2 heterojunction with well-matched band energy alignment expanded the light absorption from ultraviolet to visible region and facilitated efficient charge separation and transportation, thus yielding remarkable enhanced photoelectrochemical performance and photocatalytic activities for methyl orange and 4-chlorophenol degradation. The ZnO/CuInS 2 film with the deposition duration of 80 min showed the highest degradation rate and photocurrent density (0.95 mA/cm 2 ), which was almost 6.33 times higher than that of the pure ZnO nanorod arrays film. The CuInS 2 QDs sensitized ZnO nanorod arrays film was proved to be a superior structure for photoelectrochemical and photocatalytic applications due to the optimized CuInS 2 loading and well-maintained one-dimensional nanostructure. [ABSTRACT FROM AUTHOR]

Fabricating 2D CN and COF based all organic van der Waals heterojunction catalyst for efficient transformation of CO 2 to hydrocarbon fuels. • 2D CN and COF based all organic heterojunction catalyst 2D CN-COF was successfully prepared. • The heterojunction arose from the interface van der Waals interaction between 2D CN and COF-TD. • The photoelectrical properties of 2D CN-COF was significantly enhanced due to the formation of heterojunction. • The CO evolution rate over 2D CN-COF is 9.2 times and 3.3 times higher than that of 2D CN and COF-TD, respectively. • The reaction was performed in the absence of any solvent and sacrificial agent. Two dimensional carbon nitride (2D CN) has attracted extensive attention due to its potential application in the field of photocatalysis. However, the poor electron-hole separation efficiency and low charge carrier migration speed confine the photocatalytic performance of 2D CN. In this work all organic van der Waals heterojunction (vdWH) catalyst (2D CN-COF) was prepared from 2D CN and triazine-based covalent organic framework (COF-TD) to efficiently enhance the catalytic activity of 2D CN. Characterization and simulation results verified the successful preparation of the catalyst. The heterojunction was originated from the intense interface van der Waals force interaction between the molecules of 2D CN and COF-TD. Furthermore, the intense π-π interaction between 2D CN and COF-TD led to the morphology transformation of COF-TD from sphere of isolated sample to elliptic sheet in 2D CN-COF. The intimate interface contact of vdWH has led to reduce bandgap, which remarkably enlarged the visible light responding region of the samples. Meanwhile, the charge carrier recombination was significantly reduced because of the formation of vdWH. The evolution rate of CO over 2D CN-COF was 9.2 times and 3.3 times higher than that of 2D CN and COF-TD, respectively. Moreover, the reaction was performed in the absence of any solvent and sacrificial agent, matching well with the idea of sustainable development. This work not only provides a new and simple strategy to fabricate 2D CN based all organic heterojunction catalyst for efficient photoreduction of CO 2 to CO and CH 4 , but also serves as a reference for other researchers to design organic heterojunction, which is based on 2D CN and COFs. [ABSTRACT FROM AUTHOR]

The development of a simple, low-cost strategy is highly desirable to greatly enhance photocatalytic efficiency. Herein, a simple, inexpensive surface halogenation method is developed to improve the photocatalytic activity of Bi 2 O 2 CO 3 (BOC) nanotubes. It is found that halogen atoms (F, Br) mainly chemically adsorb on the BOC surface rather than substitute/dope into crystal lattice (X-BOC). Importantly, halogenation modification has tuned the energy band structure and improved charge separation efficiency. The catalytic activity is estimated by the photo-degradation reaction of rhodamine B (RhB). Under UV light irradiation (λ < 400 nm), the activity of Br–BOC has increased by 3.25 times than BOC. The enhanced activity of X-BOC is mainly attributed to the boosted charge separation efficiency by surface halogen modification. In the RhB degradation reaction, holes and •O 2 − play the crucial role more than •OH. The simple approach is low cost, which can be applied to the other photocatalyst system. [Display omitted] • The electrons gathered and accumulated around the surface Br on Bi 2 O 2 CO 3 (BOC). • The Br greatly enhanced the adsorptions of O 2 and H 2 O, as well charge separation. • •O 2 − and hole play more crucial roles than •OH in the degradation reaction of RhB. • The degradation efficiency of RhB is increased by 3.25 times by surface Br • This simple method could be extended to the other photocatalysts. [ABSTRACT FROM AUTHOR]

Synthesis of carbon nitride based catalysts containing donor-acceptor systems for photocatalytic reduction of CO 2 to CO. • Carbon nitride with donor-acceptor (D-A) systems was fabricated by C and O co-doping. • The D-A systems optimize the optical absorption and bandgap structures of carbon nitride. • The spatial separation of charge in D-A systems enhances the charge separation efficiency. • The catalyst displayed efficient CO 2 photoreduction activity and catalytic durability. Photocatalytic reduction of CO 2 to hydrocarbon fuels is an ultimate and utmost strategy to resolve the ever-increasing environmental problems and energy crisis. Our study aimed to develop a specific type of photocatalysts with increasing light utilization efficiency, reducing electron-hole recombination rate and enhancing photocatalytic activity by integrating unique donor-acceptor systems into the polymeric network of graphitic carbon nitride (g-CN). The results of the characterization showed that C and O are successfully integrated into the framework of g-CN. The O-containing and C-containing section of the as-prepared catalysts (OCCNx) play the role of donor and acceptor, respectively. The donor-acceptor systems of OCCN x offer an extra electron transfer transition mode, which dramatically extends the optical absorption range, and narrows down the bandgap of g-CN from 2.74 to 2.03 eV. Also, the donor-acceptor systems significantly improve the delocalized ability of the photoinduced charge carriers, which efficiently prolongs the lifetime of the charge carriers and reduces the electron-hole recombination rate, as all of these are all beneficial for boosting the photocatalytic activity of the catalysts. Experimental results show that OCCN 0.25 displays the best photocatalytic CO 2 reduction performance with a CO production rate of 34.97 μmol g−1 in 4 h, which is 4.3-fold higher than that obtained in the case of bulk g-CN. Moreover, the reaction is performed in water without any co-catalyst and sacrificial agent, which makes it a green and environmentally friendly reaction. Results obtained from DFT simulation agree well with the empirical results, and a possible reaction mechanism is suggested based on these calculations. [ABSTRACT FROM AUTHOR]

The ZnO/g-C 3 N 4 nanocomposites were synthesized by a single-step and scalable synthesis method through calcining the mixture of zinc acetate and urea. Two-dimensional shape, porous and carbon-doped microstructure were demonstrated by the SEM, TEM, N 2 adsorption and XPS. ZnO/g-C 3 N 4 nanocomposites were used as a photocatalyst for photodegradation of MB and MO under visible light irradiation. The photocatalytic performance of the porous sheet-like carbon-doped ZnO/g-C 3 N 4 nanocomposites was higher than those of commercial P25, ZnO and g-C 3 N 4 . [ABSTRACT FROM AUTHOR]

• A high-specific-surface-area MIL-100(Fe)-based photocatalytic material with abundant photo-generated electrons was successfully synthesized by a hydrothermal method. • The Bi 2 Sn 2 O 7 @MIL-100(Fe) heterojunction exhibits excellent superoxide-radical-dominated photocatalytic activity for CIP. • The •O 2 − radicals are the predominant reactive species in the photocatalytic process and h+ radicals are also responsible for CIP degradation. A novel Bi 2 Sn 2 O 7 @MIL-100(Fe) composite photocatalyst was fabricated by loading Bi 2 Sn 2 O 7 nanoparticles on the surface of mesoporous MIL-100(Fe). The structure-property relationships of such composite photocatalyst were studied. The results exhibit that the formed Bi 2 Sn 2 O 7 @MIL-100(Fe) heterojunction promote the separation of photo-generated carriers, leading to the enrichment of photo-generated electrons on MIL-100(Fe). Meanwhile, MIL-100(Fe) can provide more active sites for photocatalytic reaction due to its extraordinary specific surface area. Therefore, the Bi 2 Sn 2 O 7 @MIL-100(Fe) composite photocatalyst exhibits excellent superoxide-radical-dominated photocatalytic activity and is more propitious to degrading the contaminants such as ciprofloxacin, which can be efficiently degraded in the absence of superoxide radicals. The Bi 2 Sn 2 O 7 @MIL-100(Fe) composite reveals enhanced photocatalytic activity for degrading ciprofloxacin with rate constant (0.0143 min−1) 1.96 and 3.86 times higher than that of pure MIL-100(Fe) (0.0073 min−1) and pure Bi 2 Sn 2 O 7 (0.0037 min−1), respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, Bi 2 GeO 5 /Ag 3 PO 4 nano-composites were synthesized by simple two-step approach. Then, Bi 2 GeO 5 /Ag@Ag 3 PO 4 Z-scheme heterojunction was assembled by subsequent photocatalytic processes. It was characterized using XRD, SEM, TEM, HR-TEM, EDX, SAED, XPS, PL, UV–Vis DRS, photoelectrochemical and photodegradation experiments. Results illustrated that the catalytic activity of Bi 2 GeO 5 /Ag 3 PO 4 nano-composites is remarkably superior to those of Bi 2 GeO 5 and Ag 3 PO 4. The influence of Bi 2 GeO 5 amount on the performance of the composites was also studied. Results showed that 0.1Bi 2 GeO 5 /Ag 3 PO 4 composite exhibited the best photocatalytic efficiency for rhodamine B (RhB) degradation, and gave rise to a 96% degradation of RhB after 30 ​min visible-light irradiation. In the degradation of RhB, the apparent rate constant of 0.1Bi 2 GeO 5 /Ag 3 PO 4 is the largest, which is 0.06836min−1. After 4 cycles, RhB degradation by 0.1Bi 2 GeO 5 /Ag 3 PO 4 still maintained 84%, equivalent to 1.7-fold higher than that of Ag 3 PO 4. The trapping experiments revealed that holes (h+) and superoxide anions (O- 2 ·) were the primary species responsible for the decomposition of RhB in 0.1Bi 2 GeO 5 /Ag 3 PO 4. Furthermore, the mechanism of improving photocatalytic activity was proposed relied on the experiments and characterization results. The formation of Bi 2 GeO 5 /Ag@Ag 3 PO 4 Z-scheme heterojunction by photocatalytic processes dramatically increased its photocatalytic activity and stability. Based on the aforesaid analysis, a Z-scheme reaction mechanism was proposed for the Bi 2 GeO 5 /Ag 3 PO 4 photocatalytic degradation process. [Display omitted] • Bi 2 GeO 5 /Ag@Ag 3 PO 4 Z-scheme heterojunction was assembled by photocatalytic processes. • The formation of Ag particles during photocatalysis enhances the catalytic activity. • The formation of Z-scheme heterojunction can be extended to other catalysts. [ABSTRACT FROM AUTHOR]

A series of hierarchical AgIO 3 /BiVO 4 -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 AgIO 3 /BiVO 4 was significantly improved compared with pure AgIO 3 and BiVO 4. This may be due to the heterojunction formation of AgIO 3 and BiVO 4 and the introduction of GO, which accelerates the separation and migration of electron-hole pairs and reduce recombination. The h+ and •O 2 − 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. Image 1 • The AgIO 3 /BiVO 4 -GO photocatalysts was formed by self-assembly. • The AgIO 3 /BiVO 4 -GO composites show outstanding photocatalytic activity. • The mainly active species and the mechanism of charge separation and transfer was discussed. • The cycle-stability of the AgIO 3 /BiVO 4 -1% GO photocatalysts was examined. [ABSTRACT FROM AUTHOR]