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Developing high-efficiency photocatalyst for the degradation of environmental pollutants under visible light is ideal. In this study, indium-doped zinc oxide with rich oxygen vacancy defects (In–OV–ZnO) was successfully fabricated by using a facile solution method followed by annealing process. The morphological, structural, and optical properties of the as-synthesized samples were studied. The X-ray diffraction measurements revealed the positions of the main peaks in the synthesized samples with In3+ ions and oxygen vacancies were slightly shifted. The analysis of SEM and TEM showed that the In–OV–ZnO samples were in the nanoscale regime (20-50 nm) with hexagonal crystalline morphology. The UV–vis DRS spectra showed that In–OV–ZnO samples had the band gap value of 3.14 eV. Based on photocurrent analysis and photoluminescence studies, the oxygen vacancy of In–OV–ZnO favored the electron–hole pairs' separation. Photocatalytic studies revealed that the In–OV–ZnO samples display better photocatalytic activities of methylene blue (MB) and methyl orange (MO) under visible light irradiation, which exhibited maximum degradations of 96.84% and 90.05%, respectively. The enhanced photocatalytic performance can be ascribed to the synergistic effect of the oxygen vacancy defects and the In3+ ions favoring efficient electron–hole separation, which provided several active sites. This work develops a study to enable an efficient and cost-effective design of novel photocatalysts and offers insight into the influence of surface defects in enhancing photocatalytic activity. Image 1074 • A oxygen defect-rich In-doped ZnO nanostructure was fabricated. • The prepared In-doped ZnO nanostructure exhibited excellent photocatalytic performance under visible light irradiation. • Oxygen vacancy and In3+ ions doping play an vital role in the improvement of photocatalytic performance. • Photodegradation mechanism of In–OV–ZnO photocatalysts is proposed. [ABSTRACT FROM AUTHOR]

It was found that the Na modification is beneficial to the synthesis of Ru single-atomic catalyst anchored on GO Na, which was prepared by one-step hydrothermal process. Importantly, the strong metal-support interaction facilitates the electron transfer from Ru SA to GO Na via d-π conjugation, thus lowering the electron density of Ru SA. Experimental results and DFT calculations confirmed that the low electron density of Ru SA can significantly weaken the absorption of H* intermediates and simultaneously accelerate the desorption of generated H 2 from catalyst surface. As a result, the Ru SA/GO Na displayed exceptional HER activity with an extremely low over-potential of 20 mV at 10 mA cm−2, outperforming the benchmark commercial Pt (21 mV over-potential) and Ru nanoparticles (212 mV over-potential) catalysts. When Eosin Y was employed as a light harvester, this Ru SA/GO Na achieves outstanding photocatalytic hydrogen production with a record-high apparent quantum efficiency of 65.2% at 520 nm. Moreover, single-atomic Pt, Pd, Au and Rh were also successfully anchored on the Na-functionalized GO support, suggesting the universality of Na-induced single-atomic synthesis. This work not only provides an effective method for the synthesis of single-atomic metal catalysts but also establishes the connection between the electronic structures of catalyst and performances. [ABSTRACT FROM AUTHOR]

The activity of photocatalytic CO 2 reduction (PCR) remains inadequate due to the thermodynamically stable CO 2 molecules and sluggish carrier kinetics. This work simultaneously adopts active site and heterojunction engineering to collaboratively enhance PCR. A heterojunction of g-C 3 N 4 microtube-supported Co 3 O 4 nanoparticle has been developed through the hydrothermal pretreatment and calcination processes. The g-C 3 N 4 microtubes play dual roles in enhancing PCR of Co 3 O 4 : (1) they act as a substrate to support Co 3 O 4 nanoparticles, thereby making small size and good dispersion of Co 3 O 4 nanoparticles. The Co active sites can be highly exposed to accept photogenerated electrons and capture CO 2 molecules; and (2) the p-type Co 3 O 4 nanoparticles and n-type g-C 3 N 4 microtubes build a p–n junction. An internal electric field is created to expedite the charge transfer. As a result, the g-C 3 N 4 microtube-supported Co 3 O 4 nanoparticle affords a significantly high turnover number (TON) of 24.72, which is 24-fold higher than that of the pure Co 3 O 4 and comparable to state-of-the-art photocatalysts. [Display omitted] • Active site and heterojunction engineering enable the enhanced CO 2 photoreduction. • A hollow tubular heterojunction of g-C 3 N 4 microtubes@Co 3 O 4 nanoparticles. • Photosensitizer/heterojunction hybrid systems with a high turnover number. • The strong CO 2 adsorption and rapid electron transfer. [ABSTRACT FROM AUTHOR]

[Display omitted] • A tree-inspired semiconductor-on-ceramic 2D/1D heterostructure. • Vertical alignment of silicate nanosheets on hydroxyapatite nanowires. • Hierarchical structure enhances CO 2 adsorption and charge transfer. • Highly efficient CO 2 photoreduction into CO. Two-dimension nanosheets are ideal photocatalysts for CO 2 reduction due to their high exposure of active sites and short charge transfer pathway. However, 2D photocatalysts have a tendency to agglomeration, thus compromising the performance of photocatalytic CO 2 reduction. Trees, one of the most important plants for photosynthesis, have a unique "leaf-on-branch" structure. This unique two-dimension/one-dimension (2D/1D) configuration maximizes the adsorption of CO 2 molecules and light harvesting. Herein, a tree-inspired semiconductor-on-ceramic 2D/1D heterostructure for efficient photocatalytic CO 2 reduction is reported. The cobalt silicate (CoSi) nanosheets (∼0.68 nm) are in situ grown on the surfaces of hydroxyapatite (HAP) nanowires, creating a well-defined 2D/1D hierarchical structure. The vertical alignment of ultrathin CoSi nanosheets on the HAP nanowires effectively suppresses their agglomeration, leading to a large BET surface area (106.45 m2/g) and excellent CO 2 adsorption (8.00 cm3 g−1). The results of photoelectrochemical characterization demonstrate that the 2D/1D hierarchical structure is powerful to expedite charge transfer. As a result, the gas generation rate of CO is as high as 28780 μmol g−1 h−1 over the CoSi-on-HAP 2D/1D heterostructure. In addition, the electron transfer mechanism and reaction pathways of CO 2 reduction are revealed by in situ irradiated XPS and in situ DRIFT spectra. [ABSTRACT FROM AUTHOR]

The nanocomposite material C@Pt/MoS 2 @CdS was prepared by a simple microwave-assisted hydrothermal method combined with photoreduction method. The crystal structure, microstructure, and surface physical chemistry properties of the material were analyzed by X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance absorption spectroscopy (UV–vis/DRS), X-ray photoelectron energy spectroscopy (XPS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), nitrogen adsorption–desorption measurement, photoluminescence spectroscopy (PL), and electrochemical tests. As a result, this material has full-spectrum light absorption property and the composited CdS presents a good hexagonal phase. Moreover, the composite material presents a nanorod-like multi-layer core-shell structure, wherein the rod-like MoS 2 @CdS surface is covered with Pt and C. The formation of the multi-layer core-shell structure increases the specific surface area of as-composite material and strengthens its light absorption performance. The electrochemical impedance and transient photocurrent test results show that C@Pt/MoS 2 @CdS has the highest charge separation efficiency and enhanced photocurrent density compared with other systems. Photogenerated charge carriers have higher separation efficiency, and photogenerated electrons and holes exhibit longer life. During the photocatalysis experiments, the nanocomposite C@Pt/MoS 2 @CdS shows enhanced photodegradation activity under multi-modal photocatalytic experiments and excellent stability under visible light irradiation. In addition, C@Pt/MoS 2 @CdS has a strong photocatalytic water splitting ability. Under the same experimental conditions, its hydrogen production is 60 times that of commercially available P25. Through capture experiments, the reactive species in the photocatalytic reaction process were determined, and the possible photocatalytic reaction mechanism of this multi-layer core-shell C@Pt/MoS 2 @CdS nanocomposite was inferred. • Constructed a multi-layer core-shell structure photocatalytic composite material. • Improved the photocatalytic activity and stability of CdS-based photocatalyst. • The hydrogen production of C@Pt/MoS 2 @CdS was approximately 60 times that of commercially available P25. • Recombination rate of photogenerated charge carriers was effectively restrained. [ABSTRACT FROM AUTHOR]

In this paper, bayberry-like BiOBr/AgBr/LaPO 4 nanocomposites were synthesized by microwave-assisted hydrothermal treatment. The composition, structure, and morphology of BiOBr/AgBr/LaPO 4 nanocomposites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV−visible diffuse reflectance (UV−vis/DRS), high-power transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), and N 2 adsorption−desorption measurements. The results show that the light absorption capacity of BiOBr/AgBr/LaPO 4 is clearly enhanced and that a bayberry-like structure is more likely to produce diffraction and reflection of light on the surfaces of composites. AgBr in the composite is capable of reducing to Ag0 after light irradiation. Ag0, acting as a charge-transfer mediator, can be the medium, thus forming a Z-scheme structure. At the same time, the surface plasmon resonance (SPR) effect of Ag0 exhibits higher activity in the simulated sunlight photocatalysis process in BiOBr/AgBr/LaPO 4. The photoelectrochemical methods further indicate that BiOBr/AgBr/LaPO 4 possesses the best electron−hole pair separation ability. Furthermore, two different interface electron transfer modes and multipathway photoelectron migration in the composite are determined. • A bayberry-like structure BiOBr/AgBr/LaPO 4 composite was synthesized. • AgBr in the composite is capable of reduction to form Ag0 after light irradiation. • The presence of Ag0 results in forming two different electron transport pathes. • Two electron transfer modes synergistically improve photocatalytic ability. [ABSTRACT FROM AUTHOR]

A composite material of CQDs@CdIn 2 S 4 /CdS modified by carbon quantum dots (CQDs) with up-conversion property was prepared by the microwave assisted method. CQDs@CdIn 2 S 4 /CdS composites consisting of hexagonal phase CdS and cubic phase CdIn 2 S 4 show a uniform flower spherical-like morphology and a significant increase in specific surface area. Moreover, the prepared CQDs with up-converted photoluminescence property can convert long wavelength light (λ > 600 nm) into short wavelength light (λ < 600 nm), which can match the light absorption range of the composite CdIn 2 S 4 /CdS reasonably, broaden its light response range and improve its utilization of sunlight. At the same time, the photocatalytic activity of CQDs@CdIn 2 S 4 /CdS series composites under different light sources was studied with methyl orange as the model molecule, and 1% CQDs@CdIn 2 S 4 /CdS was determined as one of the best photocatalytic material. The composite material 1% CQDs@CdIn 2 S 4 /CdS not only had high photohydrogen production capacity (3177.8 μmol/g, 8 h), but also had a very stable effect on the ultraviolet photocatalytic degradation rate and the final hydrogen evolution yield of photolyzed water after four cycles. • Flower spherical-like CQDs@CdIn 2 S 4 /CdS was prepared by microwave-assisted method. • CQDs with up-conversion property can convert long wavelength light into short wavelength. • The light absorption range of CQDs and CdIn 2 S 4 /CdS was reasonably matched. • 1%CQDs@CdIn 2 S 4 /CdS had high photodegradation and photohydrogen production capacity. • CQDs act as spectral converters, electron transport mediators and acceptors. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel catalyst comprising hydrophobic NaY zeolite decorated with TiO 2 , TiO 2 @HYZ, has been successfully constructed. • Hydrophobic NaY zeolite could facilitate the adsorption of toluene by hindering the water diffusion. • TiO 2 @HYZ showed excellent anti-deactivation performance with effective toluene removal. • The possible anti-deactivation mechanism of TiO 2 @HYZ was proposed. Photocatalysis is regarded as a promising in situ air purification technology for the removal of volatile organic compounds. However, the deactivation of photocatalysts remains a serious issue that needs to be addressed. Herein, we report a novel dual-functional photocatalyst (TiO 2 @HYZ) with spatially separated catalytic sites and adsorption sites, which has been obtained by combining hydrophilic {0 0 1} TiO 2 nanosheets with hydrophobic NaY zeolite. TiO 2 @HYZ showed excellent photocatalytic activity for the degradation of gaseous toluene under UV irradiation in humid air. The optimized TiO 2 @HYZ-2 (containing 45.7 wt% TiO 2) achieved 96.6% toluene removal and 87.4% mineralization within 120 min. The specific reaction rate constant of TiO 2 @HYZ-2, pristine TiO 2 and P25 normalized by the unit amount of TiO 2 during the photocatalytic degradation process were calculated to be 0.481, 0.230 and 0.250 min−1 g−1, respectively. Moreover, TiO 2 @HYZ-2 showed superior durability, maintaining stable performance over repeated toluene degradation processes, even at high toluene concentration, whereas pristine TiO 2 incurred severe deactivation with increasing number of photocatalysis cycles. The significantly enhanced activity and anti-deactivation property was attributed to a synergistic effect between HYZ and TiO 2 in the catalyst structure, which strengthened the adsorption of toluene on HYZ and facilitated effective separation of photoexcited charge carriers on TiO 2 , thus avoiding the deposition of degradation intermediates on the active sites and simultaneously improving mineralization. This work provided a new perspective for the design of efficient and deactivation-resistant photocatalysts for air pollution remediation. [ABSTRACT FROM AUTHOR]

Current heterojunction photocatalysts suffer from sluggish charge transfer due to the discontinuous interfaces at an atomic level. Herein, we report a NiO–Co 3 O 4 ultrathin lateral heterojunction using NiCo-based bimetal–organic layers as precursors. The atomic-resolution images display a unique continuous semi-coherent interface between NiO and Co 3 O 4. The experimental results confirm that the continuous semi-coherent interfaces effectively expedite the electron transfer from NiO to Co 3 O 4. Concomitantly, the electron transfer raises d -band center of Co 3 O 4 in NiO–Co 3 O 4 toward Fermi level, as revealed by the density functional theory calculations. As a result, the *COOH intermediate can be strongly bound on cobalt reactive centers. The successful modulation of charge transfer and intermediate binding by continuous semi-coherent interfaces leads to a remarkable gas yield of 22.67 mmol h−1 from photocatalytic CO 2 reduction over NiO–Co 3 O 4. This work highlights the crucial roles of interface engineering in regulating carrier kinetics and surface reactions. [Display omitted] • Bimetal–organic layer-derived NiO–Co 3 O 4 ultrathin lateral heterojunction. • A unique continuous semi-coherent interface at an atomic level. • The continuous interface accelerates electron transfer from NiO to Co 3 O 4. • The continuous interface raises d -band center toward Fermi level. [ABSTRACT FROM AUTHOR]

MgO/TiO 2 (Degussa P25 TiO 2 ) composites were prepared and were used as visible-light-driven photocatalysts for the oxidation of aniline to nitrosobenzene under oxygen atmosphere. The typical sample with 5 wt% MgO loaded P25 (MP5) shows comparable photocatalytic activity with 2 wt% Pt/P25. The analyzed results of XPS indicate that the lattice oxygen in the MP5 possess higher electron density than those in P25. The electron-rich lattice oxygen, formed as a result of MgO loaded, would facilitate the deprontonation of aniline. A new peak at 3310 cm −1 was observed in in-situ FTIR spectrum for aniline adsorbed on the sample MP5, suggesting that anilino species were formed. These species may be produced via the deprontonation of aniline and result in the formation of the surface complexes. Further XPS studies for aniline adsorbed on the catalysts also indicate the existence of the surface complexes. Under visible light irradiation, the electrons may excite from the surface complexes and initiate the oxidation processes. Finally, speculated photocatalytic processes for the oxidation of aniline to nitrosobenzene were proposed at molecular level. [ABSTRACT FROM AUTHOR]

Monolayer H 1.4 Ti 1.65 O 4 ·H 2 O nanosheet (denoted as NST) has been prepared as a photocatalyst for the oxidation of furfuryl alcohol (denoted as FA) to furaldehyde under visible light irradiation. The photocatalytic activity of NST is over 10 times higher than that of its layered counterpart. This enhanced activity may be attributed to the high percentage of exposed Lewis acid sites in NST. The in-situ FTIR result suggests that FA are efficiently chemosorbed on the exposed Lewis acid sites forming the surface coordination species via C O groups, resulting in the activation of FA. The surface coordination species would respond to visible light absorption. Furthermore, The XAFS result shows that the signals for Ti O and Ti–Ti in NST are weaker dramatically and the signals positions are shifted by 0.03 Å in the higher R direction as compared with those in layered counterpart, suggesting the more exposed Ti and O defects in NST. The oxygen molecules absorbed on these surface defects are activated forming O 2 − by photo-electrons under visible light irradiation. Finally, a possible mechanism has been proposed at a molecular level. [ABSTRACT FROM AUTHOR]

Halide perovskites and derivatives have been used as emerging photocatalysts due to their unique optoelectronic and structural diversity. However, compared with the well-explored photophysical processes for light-driven more energetic carriers to trigger redox reactions, catalytic effects on the surface of halide perovskite or their derivatives for chemical transformations between reactive species are seldom addressed, which is equally important for improving the efficiency for halide perovskite-based photocatalysts. Here, we demonstrate that Cs 3 Bi 2 Br 9 sites in the Cs 3 Bi 2 Br 9 /CdS heterojunction, not only participate in light-driven processes, but also play a vital role for the activation and conversion of key intermediates during C(sp3)-H bond transformation, via a more thermodynamically and kinetically favorable surface reaction pathway. Besides, various aromatic hydrocarbons can be effectively photocatalytic converted to corresponding aldehydes/ketones as major products. This work highlights the importance of surface catalysis mechanism in photocatalysis not only for halide perovskites but also for other semiconductors. [Display omitted] • Synergistic surface activation for chemical conversion on halide perovskite sites is proposed for the first time. • Focusing on surface catalytic effects of halide perovskites, except for usual photoelectrical functions in photocatalysis. • Providing a new perspective for designing halide perovskite-based photocatalyst based on the surface catalytic properties. • C(sp3)-H bonds of aromatic hydrocarbons can be effectively converted with high activity and selectivity. • Emphasizing the importance of surface catalysis in photocatalysis for both halide perovskites and other photocatalysts. [ABSTRACT FROM AUTHOR]

A sheet-on-sheet and metal-free graphene/C 3 N 4 /carbon dots (GR/C 3 N 4 /CDots) ternary heterostructure with efficient visible-light photocatalysis for pollutants degradation has been reported. Via a convenient and hydrothermal method, large-sized GR nanosheets can serve as substrate for monodispersed dispersion of C 3 N 4 nanosheets. A subsequent loading of very small amount of CDots (1 wt%, 2–5 nm) onto sheet-on-sheet heterostructure significantly enhance visible-light-driven photoredox performances of catalysts, including oxidation of organics pollutant (RhB, 96.0%) and reduction of heavy metals [Cr(VI), 83.6%]. Excellent catalytic properties of GR/C 3 N 4 /CDots heterostructure can be predominantly ascribed to the intimate interfacial contact among constructing ingredients, increased specific surface area and enhanced light adsorption derived from GR and CDots carbon materials. Particularly, the synergistic sheet-on-sheet interaction between C 3 N 4 and carbon materials (GR and CDots) remarkably accelerate the electrons/holes separation, giving rise to significantly enhanced photoredox performances of GR/C 3 N 4 /CDots in comparison with other counterparts. The synergism effect between organic contaminants and heavy metals also contributed to the efficient performance of GR/C 3 N 4 /CDots, wherein the O 2− and OH were the main active species in the photoredox reactions. This metals-free heterostructure shows favorable photostability in cyclic experiments. We anticipate that our work could provide a classical paradigm for rational design of efficient and visible-light-driven photocatalysts for their sustainable applications in wastewater treatment. [ABSTRACT FROM AUTHOR]

With the help of polystyrene template, the indium oxide-titanium dioxide (In 2 O 3 -TiO 2) composite with a three-dimensional ordered macroporous (3DOM) structure was synthesized first, then cadmium sulfide (CdS) was loaded on the surface, and eventually 3DOM CdS/In 2 O 3 -TiO 2 composites were prepared. 3DOM CdS/In 2 O 3 -TiO 2 mainly presents the anatase structure of TiO 2 , while CdS and In 2 O 3 exist in the composite with low crystallinity. Compared with the monomer, the light absorption performance of the composite is significantly improved. The regular and well-organized three-dimensional ordered macroporous structure broadens the absorption of visible light, optimizes the charge transfer efficiency, and extends the photogenerated carrier life. The presence of heterojunctions in 3DOM CdS/In 2 O 3 -TiO 2 leads to enhanced performance of photodegradation and photolysis of water for hydrogen production. In particular, the hydrogen production of 3DOM CdS/In 2 O 3 -TiO 2 is 40.7 times that of the commercially available P25. Through the capture experiments, the possible photocatalytic reaction mechanism was speculated. [Display omitted] • 3DOM CdS/In 2 O 3 -TiO 2 was prepared by using polystyrene (PS) spheres as templates. • By combining CdS, In 2 O 3 and TiO 2 , a type II heterostructure was constructed inside the composite material. • The transmission path of light inside the catalyst was extended, resulting in the enhancement of light absorption capacity. • CdS/In 2 O 3 -TiO 2 composite showed well open 3DOM structures, which can enhance its photodegradation and water splitting. [ABSTRACT FROM AUTHOR]

The construction of heterostructures is considered as an excellent strategy to achieve efficient charge separation and enhance photocatalytic activity. In this paper, CoZnAl-LDH was first prepared by a temperature-programmed hydrothermal method. Then g-C 3 N 4 /CoZnAl-LDH composite was synthesized by loading g-C 3 N 4 in situ, followed by supporting In 2 S 3 on the surface of composite g-C 3 N 4 /CoZnAl-LDH. Finally, a novel dual S-scheme lamellar photocatalyst In 2 S 3 /g-C 3 N 4 /CoZnAl-LDH with ternary heterojunction was prepared. The crystal structure, morphology, composition and surface physicochemical properties of as-prepared photocatalysts were characterized by various testing methods. The results show that the lamellar In 2 S 3 /g-C 3 N 4 /CoZnAl-LDH composite mainly presents the characteristic structure of CoZnAl-LDH hydrotalcite compounds, and In 2 S 3 and g-C 3 N 4 are attached to the surface of CoZnAl-LDH. Compared with CoZnAl-LDH, the light absorption range of In 2 S 3 /g-C 3 N 4 /CoZnAl-LDH composite material is obviously broadened, and the specific surface area is increased. The results of multi-mode photocatalytic degradation of pollutants show that the photocatalytic degradation activity of In 2 S 3 /g-C 3 N 4 /CoZnAl-LDH composite with In 2 S 3 loading weight ratio of 40% is significantly higher than that of a single CoZnAl-LDH or g-C 3 N 4 /CoZnAl-LDH composite material. In addition, the composite exhibits enhanced photocatalytic hydrogen production capacity (404.78 μmol/g hydrogen production in 8 h, which is more than 6 times that of the monomer CoZnAl-LDH). Moreover, the photocatalytic activity remains stable after 3 cycles of experiments. The introduction of g-C 3 N 4 and In 2 S 3 on the CoZnAl-LDH matrix to form a dual S-scheme heterostructure is one of the main reasons for the enhanced photocatalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphite-like carbon nitride (g-C 3 N 4 ) displays strong potential applications in visible-light photocatalytic for water treatment, but its applications are greatly restricted by high recombination probability of photo-generated electron-hole pairs, as well as a weak reduction ability toward the heavy metals. In this work, we reported the synthesis of nZVI-g-C 3 N 4 nano-hybrid with highly efficiency toward the photodegradation of RhB and Cr(VI) under the visible light irradiation. The nZVI nanoparticles can well be immobilized and dispersed on the surface of g-C 3 N 4 nanosheets by a facile borohydride-reduction method. As-synthesized nZVI-g-C 3 N 4 has an improved photocatalytic activity much better than that of the pure g-C 3 N 4 , wherein over 92.9% of Cr(VI) and 99.9% of RhB can be removed by using nZVI-g-C 3 N 4 . The nZVI particles not only contributes to the reduction and immobilization of Cr(VI), but also accelerates the photocatalytic degradation efficiency of RhB due to a lower recombination rate of photoexcited holes and electrons. Moreover, nZVI-g-C 3 N 4 preserves superior photodegradation efficiency after five experimental cycles. It can be attributed that nZVI-g-C 3 N 4 photocatalyst is chemically stable, and part of nZVI can be recovered by g-C 3 N 4 . We believe that, the composite of nZVI-g-C 3 N 4 reported here could provide guidance for the design of efficient and reusable materials to remove both the organic compounds and heavy metal ions from waste waters. [ABSTRACT FROM AUTHOR]

The nano-TiO 2 samples with different morphologies were prepared for visible-light-driven photocatalytic selective oxidation of benzylamine and the role of active sites between morphologies and photocatalytic performances was discussed. [Display omitted] • Three types of anatase nano-TiO 2 with different morphologies were prepared for visible-light-driven photocatalytic selective oxidation of benzylamine. • The surface properties of the samples were systematically studied by various characterization techniques. • Coordinatively unsaturated Ti atoms can chemisorb and activate benzylamine molecules via forming H-N ... Ti coordination species. • Oxygen vacancies can chemisorb and activate oxygen molecules to form reactive oxygen species. • The role of active sites between morphologies and photocatalytic performances was discussed. Enormous efforts have been devoted to exploring the influence of the materials' morphology on photocatalytic performance, while the role of active site between them attracts less attention. Herein, three types of anatase nano-TiO 2 with different morphologies were successfully prepared for visible-light-driven photocatalytic selective oxidation of benzylamine. The material properties of the samples were systematically studied by various characterization techniques such as XRD, SEM, TEM, AFM, XPS, UV–vis DRS, ESR and in situ FTIR. Due to possessing clear advantages especially for having more active sites (coordinatively unsaturated Ti atoms and oxygen vacancies), the TiO 2 with porous structure shows more excellent photocatalytic performance than the other samples. Coordinatively unsaturated Ti atoms can chemisorb and activate benzylamine molecules via forming H-N ... Ti coordination species, whose absorption property of visible light guarantees that TiO 2 samples can achieve the photocatalytic process under visible light. Oxygen vacancies can chemisorb and activate oxygen molecules to form reactive oxygen species (superoxide radical) by the reduction of photogenerated electrons. Finally, a possible synergetic mechanism based on the interaction of reactants and catalyst interfaces was proposed at the molecular level to illustrate the photocatalytic process. [ABSTRACT FROM AUTHOR]

• CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2 composite was prepared by PS microspheres as the template. • The composite modified by CdS QDs has a good light absorption range. • Three-dimensional ordered hollow spherical structure enhances the charge transfer. • As-hollow structure offers more suitable transport channels for reactive molecules. • A rate of hydrogen evolution of CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2 is 300 times of TiO 2. Three-dimensional ordered hollow spherical ZnTiO 3 -ZnO-TiO 2 composite (3DOH ZnTiO 3 -ZnO-TiO 2) was prepared by vacuum impregnation combined with calcination method using polystyrene (PS) colloidal microspheres as the template, and the CdS QDs were modified into 3DOH ZnTiO 3 -ZnO-TiO 2 by water bath method. The crystal structure, chemical composition, surface morphology, optical absorption and surface physicochemical properties of CdS QDs modified 3DOH ZnTiO 3 -ZnO-TiO 2 (CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2) composite were well characterized. The results show that the three-dimensional ordered hollow spherical CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2 composite mainly composes of anatase phase TiO 2 , rutile phase TiO 2 , and hexagonal phase ZnTiO 3 and hexagonal phase ZnO. Among them, a homojunction is formed between the mixed crystal phase of TiO 2 (anatase–rutile), and a heterojunction is found between hexagonal phase ZnTiO 3 and hexagonal phase ZnO. In addition, the composite treated by the polystyrene (PS) colloidal microspheres template has formed the three-dimensional ordered hollow sphere structure, the hollow spheres are arranged neatly and orderly, and the sphere wall is formed by stacking nanoparticles. At the same time, the three-dimensional ordered hollow spherical structure of CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2 composite provides more transfer paths for material transport and promotes repeated light absorption, prolonging the lifetime of photogenerated charge carriers. Moreover, due to the close connection between CdS QDs, ZnTiO 3 , ZnO and TiO 2 , the separation of electrons and hole pairs is facilitated, and the recombination of electron and hole pairs is effectively suppressed, so that CdS QDs 3DOH ZnTiO 3 -ZnO-TiO 2 composite exhibits extremely high photocatalytic activity. Its hydrogen production is more than 300 times that of pure TiO 2 , moreover, of which cycle stability also shows better. [ABSTRACT FROM AUTHOR]

A novel direct dual Z-scheme 3DOM (three-dimensional ordered macropores) SnS 2 –ZnS/ZrO 2 composite was prepared by the template method combined with the in situ sulfur replacement technology. The composition, structure, morphology, and surface physicochemical properties of the composites were well characterized. The results indicate that it possesses a uniform and periodical macroporous structure, a large surface area (121.1 m2 g−1), broad visible light absorption, and high separation ability of photoinduced electron/hole pairs. 3DOM SnS 2 –ZnS/ZrO 2 composite removed 96.8% of methyl orange within 210 min of simulated sunlight irradiation. Moreover, photocatalytic hydrogen production achieved the rate of 928.1 μmol g−1, which was 66.3 times as high as that of the commercial P25 after 8 h simulated sunlight irradiation. The enhanced photocatalytic performance mainly attributed to the direct dual Z-scheme system, which improves the charge separation efficiency and optimizes the charge transfer pathway. The charge transfer mechanism over the 3DOM SnS 2 –ZnS/ZrO 2 is discussed in detail based on the results of radical trapping experiments. Our work paves a new way to design 3DOM materials with direct dual Z-scheme structure. [Display omitted] • 3DOM SnS 2 –ZnS/ZrO 2 was obtained by in suit sulfur replacement technology. • Polystyrene microspheres served as templates for the regular 3DOM structure. • It has large specific surface area and wide visible light absorption. • The unique dual Z-scheme system contributes to the excellent photocatalytic ability.. [ABSTRACT FROM AUTHOR]

[Display omitted] • Upcycling of waste adsorbents into CO 2 -reduction photocatalysts. • Harmful heavy metals are removed and transformed into valuable photocatalysts. • In situ formation of metal sulfides semiconductors through sulfurization treatment. • An ideal adsorbent of one-unit-cell calcium silicate hydrate ultrathin nanosheets. Although adsorption is regarded as a facile and efficient method to remove heavy metals from polluted water, the disposal of the spent adsorbents remains a great challenge. Here, an "adsorbent-to-photocatalyst" conversion strategy is reported. One-unit-cell calcium silicate hydrate (CSH) nanosheets (~2.8 nm) are used as an ideal adsorbent, and four typical heavy metals including Cu2+, Zn2+, Co2+, and Cd2+ ions are selected for studies. CSH nanosheets show superiority in the ultrahigh specific surface area (577.8 m2 g−1) and chemical stability. After the heavy metal removal, the CSH nanosheets containing heavy metal ions are transformed into metal sulfides through in situ sulfurization treatment. Interestingly, in the case of Cd2+ ions, CdS nanoparticles are produced and well dispersed on the surface of CSH nanosheets. CSH-CdS has a narrow bandgap of 2.34 eV and shows the photoabsorption edge up to visible light (550 nm). Besides, CSH-CdS also possesses a suitable energy band structure, making itself an ideal photocatalyst for CO 2 reduction under visible light (λ > 420 nm). The "adsorbent-to-photocatalyst" conversion strategy demonstrated here not only ameliorates the water and air pollution but also produces the valuable chemical feedstock (CO and H 2). [ABSTRACT FROM AUTHOR]

• A novel double heterojunction of CdS-SnS-SnS 2 supported on rGO was synthesized. • CdS-SnS-SnS 2 /rGO showed enhanced photocatalytic activity and durability. • rGO as an electron carrier facilitated the migration of photogenerated charge. • The double heterojunction efficiently suppressed fast electron-hole recombination. In this work, a novel CdS-SnS-SnS 2 /rGO photocatalyst with two tin valence states (Ⅱ and IV) was successfully synthesized by a one-pot solvothermal method. For comparison, CdS-SnS 2 /rGO (GCS2) with tin in only the IV valence state was made by the same method. Based on a series of characterizations, CdS, SnS and SnS 2 were shown to be successfully loaded onto the rGO surface. The introduction of rGO may increase charge carrier separation. The degradation efficiency increased gradually with increasing rGO loading content, and the optimum photocatalytic activity was observed at 6.0 wt% rGO loading content (GCS1), which achieved the efficient removal (84.46%) of ibuprofen over 60 min. Compared with GCS2, the CdS-SnS-SnS 2 /rGO composite exhibited significantly improved photocatalytic performance, which can be ascribed to the formation of a double heterostructure. rGO worked as a transfer mediator to transfer electrons from the conduction band (CB) of SnS to the CB of SnS 2 at the heterointerface, which then flowed to the CB of CdS because of another heterojunction, further enhancing the separation efficiency of photogenerated carriers. Therefore, this study highlights a novel double heterojunction system with a facial preparation method, visible light response and good recyclability, which is beneficial for environmental remediation. [ABSTRACT FROM AUTHOR]

In this work, CdS@ZnS–ZnO composites were prepared by the temperature-programmed hydrothermal method combined with the microwave-assisted hydrothermal method. The composite consisted mainly of cubic phase ZnS, hexagonal phase CdS and hexagonal phase ZnO, and presented a spherical structure with relatively uniform size and shape. There were heterostructures between CdS, ZnS and ZnO in the spherical structure. At the same time, the grain size, specific surface area, average pore diameter and pore volume of the composited material changed significantly, and its light absorption performance in the visible light region was obviously enhanced, and the photocatalytic activity was also greatly improved. Under ultraviolet light, CdS@ZnS–ZnO can degrade simulated pollutants by more than 90% within 20 min. In addition, the results of hydrogen evolution from photolysis of water showed that the ternary composite CdS@ZnS–ZnO had excellent hydrogen evolution capacity compared with pure CdS, ZnS and ZnO, whose hydrogen evolution amount can reach 3647 μmol g−1 in 8 h, was 298 times than that of P25. Moreover, it still maintained a high hydrogen evolution capacity after 4 cycles. Image 1 • Established spherical structure ternary photocatalyst CdS@ZnS–ZnO. • Discussing type II heterojunction and the Z-scheme charge transfer process in CdS@ZnS–ZnO. • Within 20 min, simulated pollutants can be degraded more than 90%. • The hydrogen evolution amount of CdS@ZnS–ZnO can reach 3647 μmol g−1. [ABSTRACT FROM AUTHOR]

• ZnTi-LDH nanosheets were prepared for the oxidation of benzyl alcohol. • Benzyl alcohol would be chemisorbed on ZnTi-LDH forming surface coordination species. • Surface coordination species harvest visible light and induce the photocatalysis. • Oxygen vacancies would be induced in ZnTi-LDHs after the adsorption of BA. • Oxygen vacancies would benefit the oxidation of Benzyl alcohol. ZnTi-LDH nanosheets have been synthesized as photocatalysts for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation. Based on UV–vis DRS, in-situ FTIR and XPS results, it was revealed that BA would be efficiently chemisorbed and activated on ZnTi-LDH forming the surface coordination species, which contributed to harvesting visible light and induced the photocatalytic reaction. The ESR spectra suggested that oxygen vacancies would be produced in ZnTi-LDHs after the adsorption of BA molecules. More exposed surface OH groups would induce more oxygen vacancies, which would serve as the centers for capturing photoelectrons from the photoexcited surface coordination species and act as active sites for enhanced O 2 adsorption and activation, resulting outstanding photocatalytic activity. Finally, a possible mechanism was proposed to illustrate the photocatalytic process which mediated by surface coordination species formed by the interaction between ZnTi-LDH and BA. [ABSTRACT FROM AUTHOR]