Search

Abstract Z -Scheme Ag/TiO 2 /AgMIL-101(Cr) was prepared by co-doping Ag and TiO 2 with AgMIL-101(Cr) via solvothermal synthesis combined with sol-gel method. Ag and anatase TiO 2 nanoparticles were well dispersed on the surface of AgMIL-101(Cr) with octahedral structure. 5 wt% Ag and 50% TiO 2 co-doping on the AgMIL-101(Cr) (Ag 5 T 50 Ag 5 M) exhibited large specific surface area (346.5 m2·g−1) and narrow band gap 2.16 eV. Only 10 min of UV light irradiation resulted in the conversion of nitrate and nitrogen selectivity up to 100% over Ag 5 T 50 Ag 5 M. After 5 cycles of nitrate removal, the conversion of nitrate remained 90% indicating that catalyst had stable reusability. Moreover, instead of formic acid, ofloxacin (OFX) was used as a hole scavenger to evaluate the ability of Ag 5 T 50 Ag 5 M for the nitrate reduction. The result showed that the concentration of OFX was important factor to affect the conversion of nitrate. Based on the above discussion about the characterization and photocatalytic nitrate reduction, combined with the photoluminescence and electrochemical measurement results, the enhanced conversion of nitrate and nitrogen selectivity was reasonably explained. Finally, the route of electron transfer during the three constituents constructed Z -Scheme system and the mechanism of nitrate reduction to nitrogen was presumed. Highlights • First example of Z -Scheme Ag/TiO 2 /AgMIL-101(Cr) for NO 3 − reduction. • Ofloxacin instead of traditional formic acid as hole scavenger was investigated. • Z-Scheme mechanism over Ag/TiO 2 /AgMIL-101(Cr) for photoreduction nitrate was proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nitrogen-doped graphitized aminated cellulose and TiO 2 /NCC-EDA was fabricated. • The physical properties and chemical structure of the TiO 2 /NCC-EDA was studied. • Photocatalytic CO 2 reduction activity of TiO 2 /NCC-EDA was measured. • Photocatalytic CO 2 reduction mechanism of TiO 2 /NCC-EDA was discussed. Abstract For decades, researchers have been looking for a high-efficiency, low-cost, and environment-friendly photocatalyst for CO 2 reduction. In this work, we employed SOCl 2 chlorination and EDA passivation to decorate the surface of nanocellulose crystals (NCC), and obtained aminated cellulose crystal NCC-EDA. Next, using coordination and dispersion of amino, hydroxyl, and other functional groups at the NCC-EDA surface, the TiO 2 nanoparticles synthesized in-situ from Ti(OBu) 4 were coated by NCC-EDA via a hydrothermal synthesis approach. Subsequently, the composite photocatalyst TiO 2 /NCC-EDA with various NCC-EDA contents was fabricated. The structure, optical properties, and photocatalytic CO 2 reduction performance of the photocatalyst were measured. The results suggest that the NCC-EDA based composite catalyst has highly efficient electron-hole separation and electron transfer as well as excellent CO 2 adsorption ability. The TiO 2 /NCC-EDA exhibits outstanding photocatalytic CO 2 to HCOOCH 3 conversion performance. At reaction time of 6 h, the HCOOCH 3 yield is 372.85 µmol/g cat, which is 4.5 times the yield of pure TiO 2 photocatalyst. [ABSTRACT FROM AUTHOR]

Chlorophenols (CPs) have been considered as a kind of priority environmental pollutants for their potential detrimental effects, and photocatalytic reduction dechlorination tend to be a promising approach to CPs’ removal. In this work, 2,4-dichlorophenol (2,4-DCP) was adopted as the model pollutant of CPs, and a simple mixing and heating method was employed to prepare graphitic carbon nitride and bismuth tungstate (g-C 3 N 4 /Bi 2 WO 6 ) binary photocatalysts. Under UV–vis light irradiation and anoxic atmosphere, the g-C 3 N 4 /Bi 2 WO 6 samples exhibited enhanced photocatalytic activities. The optimal dechlorination rate constant of 2,4-DCP over g-C 3 N 4 /Bi 2 WO 6 (weight ratio 3:7) was 1.13 h −1 , 7.6 and 8.9 times higher than that of pristine g-C 3 N 4 and Bi 2 WO 6 respectively. The enhanced activities originated from the effective suppression of charge recombination and extended spectrum absorption range. Kinetic studies revealed that the dechlorination processes followed the pseudo-first-order model. The photocatalytic mechanism of 2,4-DCP over g-C 3 N 4 /Bi 2 WO 6 was discussed in detail, and based on which, a mediator-free Z-scheme mechanism was proposed. This work extends the application range of g-C 3 N 4 /Bi 2 WO 6 photocatalyst and provides a new insight into environmental remediation. [ABSTRACT FROM AUTHOR]

It was widely accepted that pristine CdS showed weak photocatalytic activity for reduction of 4-nitroaniline (4-NA) to p-phenylenediamine (PPD) because of its poor photogenerated carriers separation and transfer efficiency. Yet the influence of conduction band (CB) and valence band (VB) redox potentials on its photocatalytic reduction reaction efficiency was often neglected, especially the VB potential. Considering the above facts, in this work, we design a highly efficient carbon quantum dots (CQDs)/Zn 2+ ions doped-CdS nanowires (ZnCdS NWs) composite photocatalysts, where CQDs were acted as metal-free co-catalysts to promote the separation and transfer of photogenerated carriers and Zn 2+ ions doping was used to adjust the redox of CdS NWs. As a result, under visible light irradiation, 4-NA could be completely converted to PPD with near 100% selectivity over the as-synthesized CQDs/ZnCdS NWs within 6 min in the presence of ammonium formate. It was found that Zn 2+ ions doping increased VB potential of CdS rather than lowering its CB potential, which was responsible for its enhanced photocatalytic activity. The present strategy on the combination of co-catalyst and energy band engineering could open a new avenue to develop highly efficient visible-light-driven photocatalysts for green organic synthesis. [ABSTRACT FROM AUTHOR]

A series of Au-g-C 3 N 4 (Au-CN) catalysts were prepared through a NaBH 4 -reduction method using g-C 3 N 4 (CN) from pyrolysis of urea as precursor. The catalysts’ surface area, crystal structure, surface morphology, chemical state, functional group composition and optical properties were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible (UV–vis) diffuse reflectance spectra, fourier transform infrared, photoluminescence and transient photocurrent analysis. The carbon dioxide (CO 2 ) photoreduction activities under ultraviolet visible (UV–vis) light irradiation were significantly enhanced when gold (Au) was loaded on the surface of CN. 2Au-CN catalyst with Au to CN mole ratio of 2% showed the best catalytic activity. After 2 h UV–vis light irradiation, the methane (CH 4 ) yield over the 2Au-CN catalyst was 9.1 times higher than that over the pure CN. The CH 4 selectivity also greatly improved for the 2Au-CN compared to the CN. The deposited Au nanoparticles facilitated the separation of electron-hole pairs on the CN surface. Moreover, the surface plasmon resonance effect of Au further promoted the generation of hot electrons and visible light absorption. Therefore, Au loading significantly improved CO 2 photoreduction performance of CN under UV–vis light irradiation. [ABSTRACT FROM AUTHOR]

CeO 2 /Bi 2 MoO 6 heterostructured microspheres with excellent and stable catalytic activity for CO 2 photoreduction were successfully synthesized via a solvothermal route. The morphology, porosity, phase, chemical structure, optical and electronic properties of the as-prepared samples are characterized. It is observed that the CeO 2 /Bi 2 MoO 6 nanocomposites with heterojunction showed greatly increased specific surface area, enhanced response to visible light, promoted charge carrier separation and transfer efficiency. Furthermore, the mechanism of CO 2 photoreduction was also investigated. It demonstrates that the CO 3 2− and HCO 3 − would be the reactive species, proving the thermodynamic feasibility of CO 2 photoreduction. Notably, the presence of basic CeO 2 on Bi 2 MoO 6 surface dramatically enhances the adsorption ability of CO 2 , which could be further transferred into b-CO 3 2− and b-HCO 3 − species as reactive intermediates for the photoreduction reaction. Consequently, introduction of CeO 2 could significantly enhance the CO 2 photoreduction performance of CeO 2 /Bi 2 MoO 6 nanocomposites, attributing to the synergistic role of CeO 2 as photosensitizer and CO 2 adsorbent. The maximum total yield of CH 3 OH and C 2 H 5 OH was 58.4 μmol gcat −1 obtained over 5C-BM, which was about 1.9 and 4.1 times higher than that over pure Bi 2 MoO 6 and pure CeO 2 . Moreover, the CeO 2 /Bi 2 MoO 6 nanocomposites exhibit excellent chemical stability and recyclability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ru doped Ag@TiO 2 core–shell nanophotocatalyst was prepared by an impregnation method. • The Ru in the TiO 2 shell significantly improves the absorption of visible light. • The Ag NPs as core effectively reduced the recombination of electron-hole pairs. • Ag@Ru/TiO 2 efficiently reduced the 4-NP, 2,4-DNP and 2,4,6-TNP within 2, 3 and 4 min. In the present study, a novel Ag@Ru/TiO 2 core–shell nanophotocatalyst with silver metal cores and ruthenium-doped TiO 2 semiconductor shells has been fabricated via an impregnation method and was characterized by XRD, Raman spectroscopy, XPS, UV–vis DRS, STEM, EDX, photoluminescence (PL) spectroscopy, FTIR, and BET analysis. In Ag@Ru/TiO 2 , the Ag NPs core serves as electron traps to prevent the electron-hole pairs recombination, and Ru doping significantly increases the absorption of visible light of the TiO 2. The photocatalytic efficiency of Ag@Ru/TiO 2 was assessed by the reduction of 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,4,6-trinitrophenol (2,4,6-TNP) in presence of visible light. Ag@Ru/TiO 2 demonstrated superior photocatalytic performance and attained 100% photocatalytic reduction of 4-NP in 2 min, 2,4-DNP in 3 min, and 2,4,6-TNP in 4 min to their corresponding aminophenols, which was almost 58 and 2.35 times higher than TiO 2 and Ag@TiO 2. Different experimental parameters including the NaH 4 concentration, and the catalyst quantity were also explored. The order of reduction rate constant has been found to be: 4-NP (2.33 min−1) > 2,4-DNP (1.99 min−1) > 2,4,6-TNP (1.4 min−1). Reusability studies revealed the high stability and excellent photocatalytic efficiency of Ag@Ru/TiO 2. This novel and highly efficient nanophotocatalyst is a good material for photoreduction of aromatic nitro compounds. [ABSTRACT FROM AUTHOR]

Ternary zero-valent iron/phos photungstic acid/g-C 3 N 4 composite (Fe 0 @PTA/g-C 3 N 4 ) was synthesized via photoreduction of iron (II) ions assisted by phosphotungstic acid (PTA) over g-C 3 N 4 flakes. The as-prepared Fe 0 @PTA/g-C 3 N 4 was investigated for removal of As(III) and As(V) species from water. The result showed that Fe 0 @PTA/g-C 3 N 4 exhibited a better performance for As(V) removal than As(III) species from water, and the maximum adsorption capacity for As(V) was 70.3 mg/g, much higher than most of the reported adsorbents. As(V) removal by the Fe 0 @PTA/g-C 3 N 4 adsorbent is mainly via a chemical process, synergistically occurring of reduction of As(V) and oxidation of Fe 0 . Moreover, the Fe 0 @PTA/g-C 3 N 4 adsorbent showed effective As(V) removal from the simulated industrial wastewater and underground water. This study demonstrates that Fe 0 @PTA/g-C 3 N 4 can be a potential adsorbent for As(V) removal due to its high performance, and simple one-pot synthesis process. [ABSTRACT FROM AUTHOR]

A novel composite material, MoS 2 /Bi 2 WO 6 , has been fabricated via a facile two-step approach. The few layered MoS 2 as a cocatalyst has intimate interactions with the hierarchical flower-like Bi 2 WO 6 microspheres, which boosts the visible light harvesting and charge transferring, and promotes the separation of electron-hole pairs, thus leading to the superior photocatalytic activity. It was found that the as-synthesized MoS 2 /Bi 2 WO 6 nanocomposites exhibited significantly enhanced performance for the photoreduction of CO 2 into hydrocarbons, i.e. methanol and ethanol, as compared with pure Bi 2 WO 6 . The yields of methanol and ethanol obtained over the composite with optimal content of MoS 2 (0.4 wt%) were 36.7 and 36.6 μmol gcat −1 after 4 h of visible light irradiation, respectively, which were 1.94 times higher than that over pure Bi 2 WO 6 . Furthermore, the mechanism of CO 2 photoreduction was also investigated. It indicates that the CO 3 2− , HCO 3 − and H 2 CO 3 generated in CO 2 aqueous solution would be the reactive substrates during the photoreduction reaction, proving the thermodynamic feasibility of CO 2 photoreduction. This work demonstrated that MoS 2 is a very promising candidate for development of highly active photocatalysts, and supplied a facile and simple strategy for designing environmentally benign, cheap non-noble metal, and highly efficient semiconductor composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • A one-dimensional hierarchical Bi 2 O 2 CO 3 is developed as high-performance photocatalyst. • The hierarchical Bi 2 O 2 CO 3 displays efficient photocatalytic reduction of Cr(Ⅵ) and bisphenol A under solar light. • Surface-assembly forms one-dimensional hierarchical structure along one-dimensional direction. • One-dimensional hierarchical structure enhances light harvesting and accelerates surface reaction kinetics. High-performance photocatalysts are highly needed for removing pollutants from water under solar light. A one-dimensional (1D) hierarchical Bi 2 O 2 CO 3 is developed through a self-assembly route by using ordered nanosheets. During reaction process, sodium citrate decomposes and releases CO 3 2– which in-situ reacts with Bi 2 O 3 to form Bi 2 O 2 CO 3 nanosheets exposed with (0 0 1) crystal facets. Each non-decomposed citrate ion (Cit3-) with tree carboxylate groups adsorb on some (0 0 1) crystal facets and compel the Bi 2 O 2 CO 3 nanosheets parallelly grow up, finally the 1D hierarchical Bi 2 O 2 CO 3 structure self-assembled by ordered nanosheets is obtained. The presented Bi 2 O 2 CO 3 exhibits an outstanding photocatalytic activity including 100 mg/L of Cr(VI) solution can be completely reduced in 10 min under solar light. Moreover, bisphenol A is also degraded efficiently. It is ascribed to special hierarchical structure of Bi 2 O 2 CO 3 which can not only increases the surface area, but also enhances light utilization, improving the photocatalytic performance. [ABSTRACT FROM AUTHOR]

The increased concentration of CO 2 in the atmosphere, originating from the burning of fossil fuels in stationary and mobile sources, is referred as the “Anthropogenic Greenhouse Effect” and constitutes a major environmental concern. The scientific community is highly concerned about the resulting enhancement of the mean atmospheric temperature, so a vast diversity of methods has been applied. Thermochemical, electrochemical, photocatalytic, photoelectrochemical processes, as well as combination of solar electricity generation and water splitting processes have been performed in order to lower the CO 2 atmospheric levels. Photocatalytic methods are environmental friendly and succeed in reducing the atmospheric CO 2 concentration and producing fuels or/and useful organic compounds at the same time. The most common photocatalysts for the CO 2 reduction are the inorganic, the carbon based semiconductors and the hybrids based on semiconductors, which combine stability, low cost and appropriate structure in order to accomplish redox reactions. In this review, inorganic semiconductors such as single-metal oxide, mixed-metal oxides, metal oxide composites, layered double hydroxides (LDHs), salt composites, carbon based semiconductors such as graphene based composites, CNT composites, g-C 3 N 4 composites and hybrid organic-inorganic materials (ZIFs) were studied. TiO 2 and Ti based photocatalysts are extensively studied and therefore in this review they are not mentioned. [ABSTRACT FROM AUTHOR]

A new Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) sandwich nanosphere with Ag nanoparticles as an interim layer is fabricated, and they shows excellent photocatalytic Cr(VI) reduction performance and stability in cyclic use and harsh environment. [Display omitted] • A novel Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) sandwich nanosphere with Ag nanoparticles as an interim layer is developed. • Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) shows excellent photocatalytic Cr(VI) reduction performance. • Outmost mesoporous TiO 2 -ZrO 2 shell enhances the stability of Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) in cyclic use and harsh environment. • Mechanisms for Cr(VI) reduction are proposed. A sandwich structured Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) magnetic nanosphere with Ag nanoparticles as an interim layer was fabricated with in situ deposition of Ag nanoparticles onto Fe 3 O 4 nanospheres and subsequent coating an outmost shell of mesoporous TiO 2 -ZrO 2. As compared to Fe 3 O 4 /m(TiO 2 -ZrO 2)/Ag with Ag nanoparticles as the outmost layer, unique Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) sandwich nanospheres possess higher efficient charge migration and larger specific surface area disclosed by the BET and photoelectrochemical characterizations, so they present improved photocatalytic activity toward Cr(VI) reduction. In addition, they have high thermal stability because mesoporous TiO 2 -ZrO 2 outmost shell could protect the interim Ag nanoparticles from damage and agglomeration at high temperature. Results showed reduction efficiency of Cr(VI) of Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) reached 98.4 % in 30 min, as 1.6 times as that of Fe 3 O 4 /m(TiO 2 -ZrO 2)/Ag. The Fe 3 O 4 /Ag/m(TiO 2 -ZrO 2) still obtained 91.3 % and 87.9 % reduction ratio after calcination at 500 ℃ and recycling 5 times, respectively. The photocatalytic mechanism was also revealed by scavenger experiments and ERP analysis. This work provided a good example for further design and preparation of magnetic photocatalysts with high performance for the remediation of heavy metal pollutants. [ABSTRACT FROM AUTHOR]

α-Fe 2 O 3 /g-C 3 N 4 composites were fabricated by a facile hydrothermal method. The prepared composites were characterized by XRD, XPS, TEM, DRS, PL and photoelectrochemical measurement. Under visible light irradiation, α-Fe 2 O 3 /g-C 3 N 4 composite displays higher photocatalytic activity than pure g-C 3 N 4 and α-Fe 2 O 3 for Cr(VI) reduction. The enhanced photocatalytic activity should be attributed to the well-matched band structure and intimate contact interfaces between g-C 3 N 4 and α-Fe 2 O 3 , which lead to the effective transfer and separation of the photogenerated charge carriers. The decoration of α-Fe 2 O 3 does not affect the morphology and size of g-C 3 N 4 . The lower photoluminescence intensity and higher photocurrent density indicate the effective transfer and separation of photogenerated charge carriers. α-Fe 2 O 3 /g-C 3 N 4 composite shows more intense optical absorption compared with pure g-C 3 N 4 . The addition of hole scavengers can greatly facilitate the photocatalytic reduction of Cr(VI) and the α-Fe 2 O 3 /g-C 3 N 4 composite shows excellent stability during the photocatalytic reduction of Cr(VI). [ABSTRACT FROM AUTHOR]

Bi 2 WO 6 hierarchical hollow microspheres (HHMS) modified with different conducting polymers (polyaniline, polypyrrole, and polythiophene) were successfully synthesized by ‘in situ’ deposition oxidative polymerization method, and evaluated as photocatalysts for the photocatalytic reduction of CO 2 with H 2 O to methanol and ethanol. It was found that the introduction of conducting polymers obviously decreased the recombination of photogenerated electron–hole pairs, thus promoting the photocatalytic activity of Bi 2 WO 6 . Among the as-fabricated photocatalysts, polythiophene modified Bi 2 WO 6 (PTh/Bi 2 WO 6 ) exhibited the best photoelectronic and photocatalytic performance, due to the narrow band gap and good charge mobility of polythiophene. The results demonstrate that the methanol and ethanol yield over PTh/Bi 2 WO 6 was 56.5 and 20.5 μmol g cat −1 in 4 h, respectively. The total yield of hydrocarbons is 2.8 times higher than that over pure Bi 2 WO 6 . It is noted that the catalyst exhibits good recyclability and stability. After five consecutive runs, the PTh/Bi 2 WO 6 catalyst shows no significant loss of photocatalytic activity. The possible photocatalytic mechanism was proposed which is beneficial for further improving the activity of photocatalysts. The approach described in this study provides a simple and reliable strategy for the rational design of efficient visible light-driven photocatalysts for photoreduction of CO 2 to hydrocarbons. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photocatalyst of CaTiO 3 was synthesized by a one-pot facile solvothermal method. • CaTiO 3 exhibited efficient photocatalytic reduction performance of Cr(VI) at low pH. • The surface reduced Cr(III) species could be conducive to the removal of Cr(VI). Pollution of the environment with hexavalent chromium (Cr(VI)) has attracted a lot of concern recently as the high toxicity and mobility of Cr(VI). Hence, the removal of Cr(VI) from aquatic systems has become an urgent issue. In this study, we synthesized an efficient photocatalyst of cubic CaTiO 3 particles via a facile solvothermal method, and investigated it removal performance towards Cr(VI). Under low pH condition, we found that the photogenerated electrons played a significant role in photocatalytic reduction of Cr(VI) verified through trapping experiment. Moreover, the more positive zeta potential of CaTiO 3 after the completion of photocatalytic experiment was due to the existing trivalent chromium (Cr(III)) species. It could benefit the electrostatic attraction between anionic Cr(VI) species and the surface of CaTiO 3. Meanwhile, the X-ray photoelectron spectroscopy (XPS) revealed that the Cr 2p peak of the photocatalytic treated sample was more apparent than that of the adsorption treated sample, indicating that large numbers of Cr species were loaded on CaTiO 3 surface after the photocatalytic treatment. Herein, the surface reduced Cr(III) species on CaTiO 3 played a positive role in the loading of Cr(VI) on CaTiO 3 surface under low pH. [ABSTRACT FROM AUTHOR]

Highlights: [•] The CdIn2S4 with strong absorption in the visible light region was prepared from l-cysteine. [•] The CdIn2S4 synthesized by different sulfur sources was compared. [•] The l-cysteine sample collaborated to the high evolution rates of DMM and MF on photocatalytic reduction of CO2 in methanol. [•] The mechanism of the photocatalytic reaction was studied. [Copyright &y& Elsevier]

Ce2S3 photocatalysts were synthesized by a co-precipitation method using cerium nitrate and thioacetamide as raw materials. The samples were characterized by X-ray powder diffraction analysis, UV–visible diffuse reflectance spectroscopy, scanning electron microscopy, and differential thermal analysis. Photocatalytic reduction of nitrobenzene (NB) under UV or visible light illumination was used to evaluate the photocatalytic activity of the Ce2S3 samples. The result indicated that the sample prepared at 300°C for 12h exhibited the highest activity. For 140mL 8.13×10−4 mol/L of NB in methanol solvent, after illumination for 5h, about 43.9% and 34.7% of NB were reduced to aniline over the sample under UV and visible light irradiation, respectively. The effects of the catalyst amount, illumination time, and sorts of solvent on the photocatalytic performance were investigated specifically. The reduction process of NB over Ce2S3 was finally discussed. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to investigate the photocatalytic (PC) reduction of potassium chromate by Zn-doped TiO2/Ti film catalysts. The film catalyst was prepared by plasma electrolytic oxidation method in H2SO4 solution with different dosages of ZnSO4. The composition and structure of the film catalysts was studied by XRD, SEM and EPMA. The removal rate of potassium chromate was investigated under the conditions of the different dosages of ZnSO4 and the initial concentration of chromate potassium, and the reductive product during the PC reduction process was analyzed. The results showed that the film catalyst was composed of anatase TiO2 and rutile TiO2 with the porous structure. When the dosage of ZnSO4 was 0.2g/L, the film catalyst presented the highest catalytic activity, which related to the amount and the crystal grain size of anatase TiO2 in the film. The PC reduction of potassium chromate by the film catalyst obeyed the pseudo-first-order kinetic equation. The UV–vis spectrum and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III), which existed in the form of insoluble Cr(OH)3. [Copyright &y& Elsevier]

[Display omitted] • Cr (VI) can be efficiently removed by SPF via synergistic adsorption and photocatalytic reduction. • SPF has shown good applicability in Cr (VI) containing industrial wastewater. • Mechanism validated by characterization and theoretical calculations. Conventional photocatalytic removal of hexavalent chromium (Cr (VI)) suffers from low metal uptake capacity, expensive photocatalysts, and slow desorption of trivalent chromium from the catalyst surface. In this study, calcium chloride and iron(III) nitrate were used to cross-link with polyethyleneimine grafted sodium alginate (SA) to acquire two materials, named as SPC and SPF, respectively, for the efficient removal of Cr (VI) from aqueous solutions via adsorption and photocatalytic reduction. FT-IR, DFT, and XPS results indicated that polyethyleneimine was successfully grafted onto the SA matrix and could electrostatically attractted hexavalent chromium anions in solution. Fe (III) cross-linking forms a highly porous structure at ambient temperature, which could overcome the polysaccharide collapse in the dehydration process. The UV–vis DRS, EIS, and photocurrent density characterizations of SA, SPC, and SPF suggested that SPF has smaller charge transfer resistance and is conducive to the separation of photogenerated charges, thus SPF exhibited superior performance in the photocatalytic reduction of Cr (VI). As a result, SPF is an efficient photocatalyst for the removal of Cr (VI) and provides new sights on polysaccharide-based photocatalysts applications. [ABSTRACT FROM AUTHOR]

• Cs x WO 3 /g-C 3 N 4 catalyst shows full spectrum CO 2 photoreduction activity. • Improved charge separation efficiency is realized on Cs x WO 3 /g-C 3 N 4 catalyst. • LSPR effect is responsible for the NIR photocatalytic activity. Full spectrum-driven Cs x WO 3 /g-C 3 N 4 catalyst was successfully synthesized by the combination of solvothermal and ultrasonication methods and used in CO 2 photocatalytic reduction. The experimental results suggested that 20 wt% Cs x WO 3 /g-C 3 N 4 catalyst possessed the best yield of CH 4 under NIR and full spectrum light irradiation, which were 1.72 and 6.79 μmol·g−1·h−1, respectively. This outstanding photocatalytic activity could be attributed to the localized surface plasmonic resonance effect and the formation of heterojunction structure, which led to the improved charge separation efficiency, good light-harvesting ability and broadened light response. [ABSTRACT FROM AUTHOR]

• Hydroxyl-modified g-C 3 N 4 is successfully prepared by base-hydrolyzing treatment. • HUCN exhibits excellent simulated sunlight photocatalytic reduction activity. • Presence of C OH groups at the edges of HUCN facilitates charge separation. • More negative CB edge potential of HUCN promotes the photocatalytic reduction ability. • The catalyst also possesses excellent reusability. Hydroxyl-modified graphitic carbon nitride (HUCN) with interconnected open-framework is fabricated by hydrolysis of urea-derived graphitic carbon nitride (UCN) in an aqueous NaOH solution followed by a self-assembly in dialysis process. Compared with bulk graphitic carbon nitride (UCN), HUCN possesses more advantages such as plentiful exposed active sites, fast photogenerated charge carrier separation rate and more negative conduction band edge potential. These advantages bestow the HUCN remarkably higher simulated sunlight photocatalytic reduction ability towards an aqueous Cr(VI) as compared with UCN. By the combination of the experimental results including photoelectrochemistry and electron scavenger with the DFT calculated electrostatic potential (ESP) distribution, a possible reaction mechanism for the simulated sunlight photocatalytic reduction of highly toxic and carcinogenic Cr(VI) to non-toxic Cr(III) is put forward tentatively. [ABSTRACT FROM AUTHOR]