Efficient Visible-light Photocatalyst Research Articles

Mesoporous Dual-Semiconductor ZnS/CdS Nanocomposites as Efficient Visible Light Photocatalysts for Hydrogen Generation.

The development of functional catalysts for the photogeneration of hydrogen (H2) via water-splitting is crucial in the pursuit of sustainable energy solutions. To that end, metal-sulfide semiconductors, such as CdS and ZnS, can play a significant role in the process due to their interesting optoelectronic and catalytic properties. However, inefficient charge-carrier dissociation and poor photochemical stability remain significant limitations to photocatalytic efficiency. Herein, dual-semiconductor nanocomposites of ZnS/CdS nanocrystal assemblies (NCAs) are developed as efficient visible light photocatalysts for H2 generation. The resultant materials, synthesized via a polymer-templated self-polymerization method, comprise a unique combination of ~5-7 nm-sized metal-sulfide nanoparticles that are interlinked to form a 3D open-pore structure with large internal surface area (up to 285 m2 g-1) and uniform pores (circa 6-7 nm). By adjusting the ratio of constituent nanoparticles, the optimized ZnS/CdS catalyst with 50 wt.% ZnS content demonstrates a remarkable stability and visible light H2-evolution activity (~29 mmol g-1 h-1 mass activity) with an apparent quantum yield (AQY) of 60% at 420 nm. Photocatalytic evaluation experiments combined with electrochemical and spectroscopic studies suggest that the superior photocatalytic performance of these materials stems from the accessible 3D open-pore structure and the efficient defect-mediated charge transfer mechanism at the ZnS/CdS nanointerfaces. Overall, this work provides a new perspective for designing functional and stable photocatalytic materials for sustainable H2 production.

Synthesis of TiO2 nanotubes from ilmenite with CuS nanoparticles as efficient visible-light photocatalyst.

Titanium dioxide nanotube (TNT) is one of the most widely used photocatalysts. In this research, TNT was prepared by a facile method using ilmenite (FeTiO3) concentrate as the titanium source. For this purpose, iron was leached out from ilmenite using HCl in assistance with the iron powder as the reducing agent to produce pure TiO2, where consequently, TNT was produced through hydrothermal treatment of the prepared TiO2 in an alkaline solution. CuS quantum dots, using the L-cysteine as a linker, were coated on the TNT to improve TNTs' photocatalytic properties. Characterization was done using XRD, SEM, FESEM, HRTEM, FT-IR, nitrogen sorption, and band gap measurement. The results revealed the formation of TNT with a star-shaped macrostructure as well as, a good dispersion of uniform CuS quantum dots with an average diameter of a few nanometers on the TiO2 structure. A dye adsorption kinetics study of the TNT and CuS-dopped TNT showed that TNT carries a higher adsorption capacity compared to the CuS-dopped TNT, developed due to its higher surface area and pore volume. Next, the photocatalytic performance (under visible light) of the prepared composite was studied over the methylene blue (MB) and malachite green (MG) dyes, after the determination of the dye adsorption equilibrium point (where the adsorption stops). TNT showed almost no dye degradation while the prepared composite degraded almost 95 % of the dyes as the result of the reduced band gap from 3.21 to 2.67 eV. In this study, for the first time, the TNT was prepared using a mineral source and ilmenite, enhanced in photocatalytic properties, and presented a successful application.

Au nanoparticles dispersed chitosan/ZnO ternary nanocomposite as a highly efficient and reusable visible light photocatalyst

The environmental pollution in particular contamination of surrounding and ground water are major concerns for regulation authorities and scientific community. In the current work, a novel visible light ternary photocatalytic structure based on mesoporous ZnO in combination with chitosan (CSN) and gold nanoparticles (AuNPs) was synthesized for serious water pollution issue. The Au@CSN/ZnO nanocomposite photocatalyst was developed through the sol-gel methodology followed by ultrasonication and photoreduction techniques. XRD investigation revealed the hexagonal wurtzite structure of ZnO, while XPS and FTIR measurements confirmed the formation of ternary nanocomposite among Au, CSN and ZnO. TEM analysis revealed the presence of AuNPs (5–15 nm), CSN sheets (micron size) and ZnO nanoparticles (20–120 nm) in designed ternary photocatalyst. Diffuse reflectance spectroscopy showed lowering in band gap energy from 3.1 to 2.87 eV as bare ZnO modified to Au@CSN/ZnO. The as-fabricated Au@CSN/ZnO nanocomposite was proven as a decidedly efficient photocatalyst when employed on colorless insecticide imidacloprid (IMD) and on colored methylene blue (MB) dye under visible-light illumination. Efficient photocatalytic performance with 93.21% removal of insecticide only in 20 min was achieved, representing 211% more efficient than bare mesoporous ZnO. In addition, Au@CSN/ZnO nanostructure showed rapid removal of MB with almost complete destruction of complicated structure just in 12 min under visible light. Furthermore, the current-developed photocatalyst exhibited adequate stability and recyclability, which is beneficial for the practical application in environmental remediation.

BiFeO3-PDMS hybrids: Development of visible-active floating photocatalysts with minimal catalyst loading.

Recent advances in photocatalysis include the development of floating catalysts since they assure efficient and rapid recollection of the catalysts from the purified liquid, besides enhancing the availability of photons at the catalytic surface. Bismuth ferrite (BiFeO3 and BFO) is a multifunctional perovskite material renowned for its excellent photocatalytic properties. Since bandgap of BFO falls in the visible spectrum, BFO nanoparticles could be combined with a suitable floating substrate to develop efficient visible light photocatalysts. Here, we report the synthesis of BFO-polydimethylsiloxane (PDMS) hybrids for photocatalytic applications, where sol-gel-synthesized BFO nanoparticles are immobilized on a floating porous PDMS sponge. The successful incorporation of the nanoparticles on PDMS is confirmed using Raman spectroscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The photocatalytic activity of the floating catalysts was studied by monitoring the degradation of malachite green dye under visible light irradiation. The effect of the amount of BFO immobilized, and the area and thickness of the PDMS sponge on the photocatalytic activity of the floating catalysts were investigated. An efficiency of 80.5% was obtained when the weight of BFO immobilized on the PDMS sponge was 5 mg. The method yields degradation efficiencies comparable with or higher than that of conventional BFO powder catalysts, even with 6-18 times less catalyst loading. The method introduces the fabrication of recyclable floating photocatalysts of notable efficiency using significantly less amount of BFO nanoparticles, which could be further modified by approaches such as doping, functionalization, or composite formation.

Fabrication of g-C3N4@N-doped Bi2MoO6 heterostructure for enhanced visible-light-driven photocatalytic degradation of tetracycline pollutant

An effective catalyst for the removal of antibiotic pollutants which severely impact water bodies and the environment is most favorable. In this study, g-C3N4 (gCN) and nitrogen-doped Bi2MoO6 (gCN-NBM) heterostructures are developed using a solvothermal process with enhanced photocatalytic degradation of tetracycline (TC) pollutants under visible-light irradiation. The experimental results confirm that nitrogen-doped Bi2MoO6 (NBM) nanomaterials were dispersed on the gCN surface, and a close combination of NBM and gCN leads to the efficient photocatalytic performance of TC. The photocatalytic efficiency of the heterostructure catalysts is four-fold higher than those of the pristine Bi2MoO6 catalysts owing to the excellent photogenerated charge separation and reduced recombination rate. Photocurrent measurements and electrochemical impedance spectra results disclose that the prepared heterostructure catalysts exhibit efficient photo-induced charge transfer. The electron spin resonance spectra and quenching experiments results reveal that superoxide radicals (.O2−) play a major role in TC degradation. This study presents a promising approach for designing efficient visible-light photocatalysts for environmental remediation applications.

Engineering of tunable Au-Ag2S heterostructures: A study of morphology-induced visible-light photocatalytic performance by SERS

Efficient visible-light photocatalysts are essential for energy and environmental sustainability. Many efforts have been devoted to designing diverse heterostructures in the pursuit of high-performance photocatalysts. However, the effect of morphology of the heterostructures on the photocatalytic performance still needs to be further explored. Here, tunable Au-Ag2S heterostructures were synthesized to investigate the morphology-induced photocatalytic performance by surface-enhanced Raman scattering (SERS) spectroscopy. All the Au-Ag2S heterostructures possess remarkable visible-light photocatalytic and SERS activity compared with Au or Ag2S. Moreover, with increasing exposure of the Au component, the Janus heterostructures display better photocatalytic performance than the heterostructures with other morphologies. The possible mechanism is that the axially separated structure enhances the plasmon-induced electron-hole separation and facilitates interfacial charge transfer in the anisotropic heterostructures, owing to a stronger plasmon-enhanced near field. The photocatalytic degradation efficiency of methylene blue by the Au-Ag2S Janus heterostructures reached 93.9% within only 60 s. The photocatalytic degradation rate is 2.38, 1.53 and 1.48 times higher than that of the core–shell, eccentric core–shell-I and eccentric core–shell-II heterostructures. Our work demonstrates that the morphology of the Au-Ag2S heterostructures exhibits a significant effect on the visible-light photocatalytic performance, which opens a new pathway toward the design of heterostructures for high-performance photocatalysis.

Microwave-assisted synthesis of nanostructured tin sulfide as a highly efficient visible-light active photocatalyst: Characterization, applications, and theoretical studies

In this study, nanostructured tin sulfide was synthesized using a facile microwave-assisted method. The as-prepared sample was further characterized via X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), UV–Visible Diffuse Reflectance Spectroscopy (DRS), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH) and Mott-Schottky analyses. Based on the results, the synthesized SnS is an n-type semiconductor and has a direct band gap of 1.32 eV. Photocatalytic activity of nanostructured SnS was then evaluated through degrading methylene blue (MB) under visible light in a cylindrical batch reactor. The results show that this highly efficient photocatalyst can degrade almost up to 83.06% of 14 mg/L pollutant within 10 min, which can be attributed to its relatively high specific surface area of 52.819 m2/g. In addition, the photocatalyst performance was studied from the isothermic, thermodynamic, and kinetic points of view. The results suggest that Fritz-Schlunder along with Baudu are the most appropriate models to describe the adsorption process (the first step of photochemical reactions), as they have the lowest error functions and highest correlation coefficients. Based on kinetic studies results, there is a good agreement between the pseudo-second-order adsorption kinetic model and our experimental data. Additionally, the corresponding structural parameters of SnS were compared by size-strain plot (SSP), and Williamson-Hall methods. Furthermore, a density functional theory (DFT) approach was conducted to get more insight into the electronic and structural properties of the SnS. In terms of the band structure, 1.35 eV of band gap energy (Eg) is obtained, which perfectly matches with the results of characterization tests (1.32 eV). Finally, the partial density of states curves indicate that the valence band maximum (VBM) is mainly generated from 3pS, 5sSn, and 5pSn states while the conduction band minimum (CBM) is made of 5pSn states. Consequently, the spin-up and spin-down curves are found to be highly symmetric, indicating the non-magnetic property of tin sulfide.

One-Step Hydrothermal Synthesis of Cu2ZnSnS4 Nanoparticles as an Efficient Visible Light Photocatalyst for the Degradation of Congo Red Azo Dye.

A hydrothermal method was successfully employed to synthesize kesterite Cu2ZnSnS4 (CZTS) nanoparticles. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and optical ultraviolet-visible (UV-vis) spectroscopy were used for characterization of structural, chemical, morphological, and optical properties. XRD results confirmed that a nanocrystalline CZTS phase corresponding to the kesterite structure was formed. Raman analysis confirmed the existence of single pure phase CZTS. XPS results revealed the oxidation states as Cu+, Zn2+, Sn4+, and S2-. FESEM and TEM micrograph images revealed the presence of nanoparticles with average sizes between 7 nm to 60 nm. The synthesized CZTS nanoparticles bandgap was found to be 1.5 eV which is optimal for solar photocatalytic degradation applications. The properties as a semiconductor material were evaluated through the Mott-Schottky analysis. The photocatalytic activity of CZTS has been investigated through photodegradation of Congo red azo dye solution under solar simulation light irradiation, proving to be an excellent photo-catalyst for CR where 90.2% degradation could be achieved in just 60 min. Furthermore, the prepared CZTS was reusable and can be repeatedly used to remove Congo red dye from aqueous solutions.

Synthesis of g-C3N4/SmFeO3 nanosheets Z-scheme based nanocomposites as efficient visible light photocatalysts for CO2 reduction and Congo red degradation

Synthesis of g-C3N4/SmFeO3 nanosheets Z-scheme based nanocomposites as efficient visible light photocatalysts for CO2 reduction and Congo red degradation

Multifunctional CdS Nanoparticle-Decorated CeO2 as Efficient Visible Light Photocatalysts and Toxic Cr(VI) Sensors.

Several one-dimensional and three-dimensional CdS@CeO2 nanocomposites were synthesized by a solvothermal route. A nanoflower-shaped CdS@CeO2 nanocomposite (CdS-NF@CeO2) was selected as the model catalyst after various characterizations. It was, then, employed directly as a luminescent sensor for Cr(VI) detection in an aqueous medium. A good linear quenching was observed in the range of 0-0.5 μM with a detection limit of 0.04 μM. The quantum yield of the catalyst was found to be 73%. Moreover, our catalyst is highly selective toward Cr(VI) and can be applied as an efficient sensor for real water analysis. The efficiency of the catalyst was also tested in controlling the photocatalytic activity for oxidation of benzylamine to N-benzylidenebenzylamine under a domestic LED bulb with molecular O2 as a sole, green oxidant. Conversion (>99.9%) and selectivity as high as 100% were observed for the CdS-NF@CeO2 photocatalyst. These results show the potential applications of CdS-NF@CeO2 nanocomposites as an efficient photocatalyst for organic transformation and environmental remediation.

A robust rationally designed multinarydouble perovskites microplates as an efficient visible-light photocatalyst

Rationally designed perovskite structured, multinary oxides having two or more different cations combinations diversify its photocatalytic applications. In current study Rhombohedral structured rationally designed visible light-responsive double perovskites (DPOs) were produced by hydrothermal method. The synthesized perovskites were confirmed by various characterizations techniques. The average crystallite size of the DPOs was found 25 nm calculated from XRD data using Scherer's equation. The EDX images confirmed the elemental composition of the synthesized material. The morphology of the DPOs was smooth, uniform and well organized as regular microplate form as seen in the SEM images. The average length of DPOs was 5.52 μm and the band gap was 2.03 eV, lies in the visible range. The BET results showed that the DPOs had a high specific surface area of 389 m²/g . The point of zero charge of the synthesized materials lies in the basic region at pH 8. The DPOs microplates showed 97% degradation of crystal violet (CV) at optimum conditions of pH 12, 50 ppm initial dye concentration, 0.6 g/L DPOs dosage within 20 min of irradiation contact time, following 2nd order kinetics with 0.9822, R2 value. The ANOVA confirmed that the polynomial quadratic model is best fitted model having high R2, R2 adj, and R2 pred values. In conclusion, the DPOs (Na2FeCoSeNaO6) are the most suitable and efficient entrant as a photocatalyst for dyes eradications.

Engineering of efficient visible light photocatalysts: Ti1–x+yCuxLayO2 (x = 0.03; y = 0, 0.005, 0.01) compositions

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers (electrons–holes pairs) are of paramount significance. In the current study, we report the photocatalytic characteristics of four compositions composed of TiO2, Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders for two harmful dyes (Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO2 and Ti0.97Cu0.03O2 powders while Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO2 confirm the substitution of Ti4+ sites by Cu2+ and La3+ ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO2 (3.13 eV) through insertion of La3+ plus Cu2+ ions. Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 samples exhibit a visible light band gap of 2.3 and 2.7 eV, respectively. Based on SEM images, incorporation of Cu2+ and La3+ ions influences the surface morphology of TiO2. The resulting Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti0.96Cu0.03La0.01O2 catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm MB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti0.96Cu0.03La0.01O2 catalyst can be clarified in terms of higher charge carriers’ separation (Cu2+ + e– → Cu+, La3+ + e– → La2+), oxygen vacancies, full anatase phase structure as well as the wide range of visible light absorption.

One-pot Preparation of Porphyrin-Sensitized ZIF-8 as a Visible Light Photocatalyst

Tetraaminoporphyrin (TAPP) sensitized ZIF-8 was successfully prepared by one-pot method as an efficient visible light photocatalyst. The prepared photocatalyst TAPP/ZIF-8 was characterized by XRD and SEM. The combination of TAPP and ZIF-8 enhances the absorption of visible light, effectively improves the electron-hole separation, and improves the photocatalytic activity under visible light. In the photocatalytic experiment, TAPP/ZIF-8 showed good photocatalytic performance for the removal of Rhodamine B (RhB) under visible light. Therefore, our work provides an efficient green photocatalyst for water treatment.

Thin silica shell on Ag3PO4 nanoparticles augments stability and photocatalytic reusability.

Semiconductor photocatalysts are promising cost-effective materials for degrading hazardous organic contaminants in water. Ag3PO4 is an efficient visible-light photocatalyst for the oxidation of water and dye degradation. The excited Ag3PO4 photocatalyst uses a hole to oxidise water or organic contaminants except the electron, which reduces Ag+ to Ag0. In the present study, the inherited disadvantage was overcome by a thin silica shell overcoating on Ag3PO4 nanoparticles. The silica-coated Ag3PO4 nanoparticles retain the photocatalytic activity even after five cycles of photodegradation, while the bare Ag3PO4 nanoparticles show a photocatalytic activity declined to half. The study demonstrates that the thin silica shell enhances the photostability, keeping the photocatalytic activity unaffected, even after several cycles of photodegradation of dyes. XPS analysis showed that the Ag0 formation on the surface of bare Ag3PO4 is greater than that on silica-coated Ag3PO4, which declines the photocatalytic activity of Ag3PO4 after five cycles of photodegradation. Electrochemical studies identified that the intermediates, such as OH˙ and O2-, formed during water oxidation play a crucial role in the photodegradation of dyes. This study can provide insights into the design of core-shell semiconductor nanostructures for reusable photocatalytic applications.

Pd nanoparticle-modified TiO2-x composites as efficient visible-light active photocatalysts for tetracycline degradation and microbial disinfection

In the present work, Ti3+-self-doped TiO2 heterostructure photocatalysts were prepared by coupling with different additions of palladium quantum dots by means of deposition-reduction methodology. The electron paramagnetic resonance (EPR) analysis indicated the existence of Ti3+ in synthesized samples. The transmission electron microscopy (TEM) images presented the modification of TiO2-x nanoparticles by coupling with nano palladium. Photoluminescence (PL) results demonstrated the lowest charge carrier recombination rate in 5% Pd/TiO2-x composites. Photocatalytic performances of photocatalysts were evaluated by degrading Tetracycline (TC) and inactivating Escherichia coli (E. coli) and Fusarium oxysporum f. sp. Vasinfectum (Fov) with the presence of visible light, in which an enhanced photocatalytic degradation and inactivation activity was found in all Pd coupled composites with the highest efficiency in 5% Pd/TiO2-x. The improved photocatalytic activity of Pd/TiO2-x was associated to the generation of more hydroxyl radicals (•OH) and superoxide anions radicals (•O2-) during photocatalytic process which were demonstrated by the electron spin-resonance spectroscopy (ESR) technique. Moreover, 5% Pd/TiO2-x composites were found to remain high photocatalytic properties in a circulating photo-disinfection system.

Straightforward synthesis and mechanism insight of TiO2/α′-AgVO3 heterostructure with enhanced photocatalytic activity

With the deterioration of our environment, it is imperative to develop high-performance photocatalysts for ‘green’ environmental protection. In this work, a novel TiO2/α′-AgVO3 heterostructure has been successfully synthesized by a straightforward hydrothermal method for the photodegradation of Rhodamine B (RhB). Specifically, TiO2/α′-AgVO3 with a molar ratio of 4:1 displays excellent stability and outstanding photodegradation efficiency, which can remove 94% RhB within 120 min visible light irradiation. The free radical capture experiments demonstrate that h+ and ·OH act as pivotal parts in the photodegradation of RhB. Additionally, the enhanced photocatalytic performance of TiO2/α′-AgVO3 heterostructure is mainly attributed to the appropriate surface areas, broadened range of light adsorption, more photocarrier generation, and effective charge separation. This research reveals that TiO2/α′-AgVO3 heterostructure is an efficient visible light photocatalyst and is expected to be applied in organic sewage degradation.

Construction of group III nitride van der Waals heterostructures for highly efficient photocatalyst

Photocatalytic water splitting is an effective way to solve the energy crisis and environmental problems. Here, we propose a series of heterostructures constructed by two-dimensional (2D) group III nitrides (AlN, GaN, InN) to filter out high-performance and environment-friendly materials that can work as promising photocatalysts. Using first-principles calculations, we mainly focus on the type-II van der Waals (vdW) heterostructures with high charge transfer and optical absorption properties. Through step-by-step screening, the stacking-V GaN/InN with a direct type-II band gap is found to be the best candidate. The overall water splitting reaction is then investigated for this selected heterostructure. The Gibbs free energy for the hydrogen evolution reaction process is found to be as low as −0.355 eV, which can be further optimized to −0.163 eV under a −2 % compressive strain. Besides, the overpotential for the oxygen evolution reaction process is as low as 0.853 V. All these properties confirm the stacking-V GaN/InN to be a highly efficient visible-light photocatalyst for the water-splitting reaction. This work could provide guidelines on solar energy applications of the group III nitrides heterostructures and contribute to developing the relevant photocatalysis systems.

Fabrication, characterization and application of single-phase hollow BiFeO3 nanofibers as an efficient visible-light photocatalyst for degradation of Rhodamine B in wastewater

In this paper, we conducted a study on the structural modulation and photocatalytic performance of single-phase hollow BiFeO3 nanofibers (SPH–BFO NFs) photocatalysts, investigated the effect of heat treatment temperature on the structure of BFO NFs and the formation mechanism of a hollow structure. The SPH-BFO NFs consist of BiFeO3 nanocrystals without other heterogeneous phases, with diameters of 400–600 ​nm and extraordinary flexibility, allowing easy separation of the catalyst from the solution. As a result, the SPH-BFO NFs possess outstanding photocatalytic performance and higher photocatalytic efficiency compared with other forms of BiFeO3. In addition, the effects of different environments and water quality on RhB degradation were investigated. It was found that the vacancies (h+) and superoxide radicals (·O2−) as active substances were less environment-dependent, making the SPH-BFO NFs more resistant to environmental interference. The RhB degradation efficiency of BFO NFs was about 99% in 10 ​mg/L of RhB dye solution at pH ​= ​6. This work provides valuable insights into the application of SPH-BFO NFs in photocatalysis and the design of nanofiber photocatalysts.

Development of a new high-performance visible-light photocatalyst by modifying tin disulfide with cyclized polyacrylonitrile

Tin disulfide (SnS2) coupled with cyclized polyacrylonitrile (CPAN) was prepared via a hydrothermal synthesis-mixing in the solution-solvent evaporation-thermal cyclization method from inexpensive SnCl4·5H2O, thioacetamide and polyacrylonitrile (PAN). The as-synthesized SnS2/CPAN exhibited not only a substantially increased photocatalytic activity (2.1 times that of bare SnS2), but also a fair stability in the visible-light (λ > 420 nm)-induced reduction of aqueous Cr(VI). The modification with CPAN is capable of enlarging the specific surface area, enhancing the transfer and separation of photogenerated charge carriers, and increasing the Cr(VI)-adsorbing capacity of SnS2, leading to the improved photocatalytic activity of SnS2/CPAN. This study is instructive to exploit PAN to make SnS2-based and other semiconductor-based new efficient visible-light photocatalysts. Moreover, the method employed for preparing SnS2/CPAN nanocomposite is simple, economical, and practical for producing various semiconductor/CPAN composite materials for photocatalytic and even other applications.

Double-shelled CeO2 coupled CdZnS nanoparticles as an efficient heterojunction visible light photocatalyst for hydrogen evolution

Designing of novel semiconductor photocatalysts toward high-efficient catalytic H2 generation has played a potential role in developing sustainable energy. Here, nanostructured CeO2/CdZnS/ZnO composite material has been synthesized through simple hydrothermal process. The present photocatalyst exhibits high photocatalytic activity for H2 generation under visible light irradiation (λ > 420 nm). It can be possibly explained: First, the ZnO layer formed on double-shelled CeO2 hollow spheres (D-CeO2) by the priority adsorption of Zn2+ exhibits both efficient hole consumption and photo-corrosion inhibition. Second, superior charge separation and charge transfer efficiency originates from the Z-scheme CeO2/CdZnS heterojunction.