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Graphical abstract Bismuth sulfide (Bi 2 S 3) has been synthesized in the morphology of hierarchical nanostructures by facile hydrothermal method. The photocatalytic efficiency of Bi 2 S 3 nanostructures has been checked for the degradation of MB, RhB single dye solution and their binary mixture and compared with commercial TiO 2 (Degussa P25) sample under visible light illumination. The degradation rate of RhB and MB is enhanced by ∼8 times and ∼3 times in their binary solution as compared to that in single dye solution and increased by ∼14 times than that of Degussa P25 for both RhB and MB degradation in the binary solution, respectively. This remarkable improvement in the photocatalytic activity of Bi 2 S 3 is attributed to the faster separation of charge carriers at the interface due to the favourable LUMO and HOMO alignment of RhB and MB with band levels of Bi 2 S 3 in the RhB-MB-Bi 2 S 3 trio system. The photocatalytic degradation study of colourless contaminants, p-chlorophenol (CP), p-nitrophenol (NP) and their mixture (CP-NP) is also investigated. The degradation rate of NP is observed to be highest in the single solution, whereas, the degradation rate of both CP and NP is found to decrease in binary mixture solution in comparison to their individual solution. Highlights • Hierarchical nanostructures of Bi 2 S 3 have been synthesized by hydrothermal method. • Utilized Bi 2 S 3 for the photodegradation of MB, RhB and their binary solution. • Demonstrated the enhanced photocatalytic activity in RhB-MB-Bi 2 S 3 trio system. • Degradation of p-chlorophenol (CP), p-nitrophenol (NP) and CP-NP over Bi 2 S 3. • Achieved highest degradation rate of NP among all phenolic compounds. Abstract Hierarchical nanostructures of bismuth sulfide (Bi 2 S 3) have been synthesized by a facile hydrothermal method. The potentiality of Bi 2 S 3 hierarchical nanostructures for the photocatalytic degradation of Rhodamine B (RhB), Methylene blue (MB) and the mixture of RhB-MB organic dyes have been demonstrated and compared with commercial TiO 2 (Degussa P25) sample under visible light illumination. The degradation efficiency of Bi 2 S 3 and Degussa P25 is found to be higher in the single as well as in the binary dye solution for MB degradation as compared to RhB degradation. Furthermore, the degradation rate of RhB and MB is enhanced by ∼8 times and ∼3 times in their binary solution as compared to that in single dye solution. Whereas, Bi 2 S 3 has demonstrated ∼14 times higher degradation rate of both RhB and MB in their binary solution than that of Degussa P25 for RhB and MB degradation in the binary solution under visible light exposure, respectively. Interestingly, Bi 2 S 3 nanostructures has exhibited larger improvement in the degradation efficiency for RhB in its binary solution which is attributed to the faster separation of photogenerated charge carriers due to the proper alignments between the molecular orbits of dyes and band level positions of Bi 2 S 3 in RhB-MB-Bi 2 S 3 heterogenous system. The photocatalytic degradation study of colourless contaminants, p-chlorophenol (CP), p-nitrophenol (NP) and their mixture (CP-NP) is also investigated in the presence of Bi 2 S 3 nanoflowers. Among the phenolic compounds, the degradation rate of NP is observed to be highest in the single solution. However, the degradation rate of both CP and NP is found to decrease in binary mixture solution in comparison to their individual solution. A possible mechanism for the enhanced photodegradation of RhB-MB dye mixture based on the active species trapping experiment has been proposed. [ABSTRACT FROM AUTHOR]

CdS nanorods decorated with CoFe 2 O 4 (CFO) nanoparticles have been synthesized by using a facile soft chemical method. The surface of the nanorods was carefully functionalized with citrate ions to attach the CFO nanoparticles. The CFO nanoparticles decorated CdS nanorods were found to exhibit enhanced visible light driven photocatalytic activity for the degradation of methylene blue dye as compared to CdS and CFO nanostructures. The enhancement in the photocatalytic activity is attributed to the formation of heterojunction between the CdS and CFO which significantly suppresses the recombination of the photogenerated charge carriers. Also, due to the magnetic behavior of CFO this coupled nanostructure can be easily separable from the aqueous solution by applying an external magnetic field. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO) coupled CdS/ZnO core/shell nanorods have been synthesized using a soft chemical route. The photocatalytic activity of CdS/ZnO/RGO nanostructure has been examined for the degradation of methylene blue dye under solar irradiation at room temperature. The CdS/ZnO/RGO nanostructure exhibits five times enhanced photocatalytic activity as compared to CdS nanostructures which is attributed to the formation of heterojunction between the CdS and ZnO and its coupling with the reduced graphene oxide which facilitates the efficient transport of photogenerated charge carriers. Also, CdS/ZnO core/shell nanostructure exhibits very good photostability due to the presence of stable ZnO as cap layer. [ABSTRACT FROM AUTHOR]

Abstract In the present work, nanostructures comprising of plasmonic silver (Ag) nanoparticles (NPs) decorated on the hydrothermally grown bismuth sulfide nanorods (Bi 2 S 3 –NR) and hierarchical nanoflowers (Bi 2 S 3 NF) have been successfully synthesized by chemical route. We have fabricated the nanostructured photoanodes and demonstrated their enhanced photoelectrochemical (PEC) performance for water splitting applications. Bismuth sulfide nanoflowers have shown appreciable increased PEC activity due to its hierarchical structure as compared to the nanorods facilitated by the faster charge transport due to the availability of more interfacial sites. Among all, Ag/Bi 2 S 3 NF photoanode has exhibited highest photocurrent density (12.34 mA/cm2 at 2 V vs. Ag/AgCl) which is ∼2 fold higher as compared to Bi 2 S 3 nanoflowers. A ∼3 fold enhancement in the incident photon-to-current conversion efficiency is achieved by Ag/Bi 2 S 3 NF photoanode as compared to Bi 2 S 3 NF photoanode. The remarkable enhancement in the photocurrent density of Bi 2 S 3 after grafting metal plasmons is attributed to its enhanced photoresponse, faster transfer of plasmon mediated hot electrons from excited state of Ag NPs to Bi 2 S 3 surface and higher separation efficiency of photogenerated charge carriers facilitated by the metal-semiconductor interface. A plausible mechanism is also proposed for the improved PEC water splitting over Ag/Bi 2 S 3 NF photoanode. Graphical abstract Plasmonic silver (Ag) NPs have been successfully grafted on the hydrothermally grown bismuth sulfide nanorods (Bi 2 S 3 –NR) and hierarchical nanoflowers (Bi 2 S 3 NF) via chemical method. The Ag NPs coupled Bi 2 S 3 photoanode (Ag/Bi 2 S 3 NF) has demonstrated ∼2 and ∼3 fold enhancement in the photocurrent density and incident photon-to-current conversion efficiency (IPCE), respectively as compared to Bi 2 S 3 NF photoanode. The observed enhancement in the PEC activity for Ag/Bi 2 S 3 NF photoanode is attributed to the faster transport of plasmon mediated hot electrons from excited state of Ag NPs to the conduction band of Bi 2 S 3 nanoflowers and the slower recombination rate of photogenerated charge carriers facilitated by the metal-semiconductor interface. Image 1 Highlights • Bi 2 S 3 has been synthesized in the form of nanorods and hierarchical nanoflowers by hydrothermal method. • Plasmonic Ag NPs have been grafted on the Bi 2 S 3 nanostructures by chemical route. • A ∼2 and ∼3 fold enhancement in the photocurrent density and IPCE is achieved by Ag/Bi 2 S 3 NF as compared to Bi 2 S 3 photoanode. • The improvement is due to the enhanced photoresponse and surface plasmonic effect. [ABSTRACT FROM AUTHOR]

A noble metal-free photocatalyst, consisting of graphitic carbon nitride (g-C 3 N 4 ), TiO 2 and carbon nanotubes (CNT) was synthesized by a facile hydrothermal method and its application for the photocatalytic decolouration of methylene blue (MB) dye under visible light irradiation has been demonstrated. The microstructure, morphology, structural and optical properties of the synthesized nanocomposites was systematically studied using TEM, SEM, XRD, RAMAN, FTIR and UV–Vis DRS techniques. The g-C 3 N 4 /TiO 2 /CNT ternary nanocomposite exhibits five times higher photocatalytic activity compared to bare g-C 3 N 4 under visible light irradiation. Enhanced photocatalytic performance of the ternary nanocomposite has been attributed to the synergistic effects of three components: Multistep charge transfer between heterojunction formation at g-C 3 N 4 /TiO 2 interface and CNT, enhanced visible-light absorption and effective charge separation. A possible reaction mechanism has been proposed and scavenger experiment has been carried out to find the role of active radical species responsible for the dye decolouration. Additionally, the g-C 3 N 4 /TiO 2 /CNT photocatalyst retained excellent stability even after several cycles. This study offers a promising way of developing a highly efficient, noble metal-free, stable and visible-light-driven photocatalyst to promote the utilization of solar energy for environmental purification. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) coupled Zinc oxide (ZnO) nanocomposite has been synthesized by the chemisorption method and demonstrated its potential applications for photocatalytic degradation of methylene blue dye and photoelectrochemical (PEC) water splitting. A ∼7 fold enhancement in the photodegradation activity and ∼3 fold enhancement in the incident photon-to-electron conversion efficiency is observed for PANI/ZnO nanocomposite as compared to bare ZnO nanorods. The observed enhancement in the photocatalytic and photoelectrochemical activity is attributed to the photosensitization effect of visible light responsive PANI and the formation of type-II heterojunction between ZnO and PANI leading to the efficient separation and faster transfer of photoinduced charge carriers at the interface. A possible mechanism for the enhanced photocatalytic activity and photoelectrochemical water splitting for PANI/ZnO nanocomposite has been proposed. [ABSTRACT FROM AUTHOR]

Cadmium sulfide nanoflowers (CdS-NF), nanorods (CdS-NR), and its nanocomposites with polyaniline (PANI) were successfully synthesized using facile chemical methods. Transmission electron microscopy (TEM) images confirmed the growth of CdS as nanoflowers and nanorods. High-resolution transmission electron microscopy (HRTEM) images showed clear lattice fringes, indicating good crystallinity of the CdS nanostructures and the formation of interface between PANI and CdS. The photocatalytic activity of CdS nanostructures and its composites was demonstrated for the degradation of methylene blue (MB) dye under visible light irradiation. The PANI/CdS nanocomposites showed enhancement in the photocatalytic activity as compared to bare CdS nanostructures, and it is attributed to efficient charge transfer between CdS and PANI. Photoluminescence study confirmed the enhancement in photogenerated electron-hole pairs separation in CdS nanostructures after the addition of PANI. The composite of PANI with CdS-NF exhibited larger improvement in the photodegradation efficiency over CdS-NF as compared to the improvement observed in PANI/CdS-NR over CdS-NR, which is attributed to the formation of more interfacial sites between PANI and CdS nanoflowers as compared to PANI and CdS nanorods. Our present work indicates that by carefully designing the semiconductor nanomaterial composites, the photocatalytic activity can be significantly enhanced. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of ZnO/MWCNT nanocomposite, and their potential application in photoelectrochemical (PEC) water splitting for hydrogen generation and photocatalytic degradation of methylene blue dye. For the synthesis of nanocomposite, ZnO nanoparticles were grown on the MWCNT surface by a simple chemical route. Microscopic studies showed that ZnO nanoparticles were well dispersed on the MWCNT surface and Raman study confirmed the intimate integration between ZnO and MWCNT. The nanocomposite exhibit higher photocatalytic degradation of methylene blue dye as compared to bare ZnO. The ZnO/MWCNT photoanode shows ∼5 times increase in photocurrent density in comparison to pure ZnO, at an applied potential of +1 V vs. Ag/AgCl. The enhanced photocurrent density of ZnO/MWCNT photoanode is attributed to the decrease in band-bending and effective interfacial electron transfer due to the conducting CNT scaffold, which facilitates the charge collection and charge transport in the ZnO/MWCNT nanocomposite. The Electrochemical impedance spectroscopy measurements confirmed the faster charge transfer at the interface in the case of nanocomposite. These results suggest substantial potential of ZnO/MWCNT nanocomposite in dye degradation and PEC water splitting applications. [ABSTRACT FROM AUTHOR]

Highly dispersible, uniform size (∼7 nm) single-phase Cu 2 ZnSnS 4 nanoparticles have been synthesized by hydrothermal method using non-toxic surfactant (oleic acid). High resolution transmission electron microscopy image indicates good crystallinity of the Cu 2 ZnSnS 4 nanoparticles with the growth along (1 1 2) plane. X-ray photoelectron spectroscopy analyses suggested that the formation of with Cu, Zn, and Sn in +1, +2 and +4 oxidation states. The optical absorption spectrum of Cu 2 ZnSnS 4 nanoparticles exhibits an absorption in the visible region and its optical band gap was found to be ∼1.72 eV, which could be much more appropriate for photocatalytic application under visible light irradiation. These Cu 2 ZnSnS 4 nanoparticles have been shown high photocatalytic degradation activity of methylene blue (MB) dye in the presence of visible light irradiation. The rate constant ( k ) value of Cu 2 ZnSnS 4 nanoparticles is found to be 0.0144 min −1 . We have discussed the mechanism of dye degradation process that drives the photocatalytic degradation process. The reusability of the Cu 2 ZnSnS 4 nanoparticles for the dye degradation is also demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • V 2 O 5 and V 2 O 5 /rGO nanocomposites were successfully synthesized by hydrothermal method. • V 2 O 5 /rGO nanocomposites shows enhanced photocatalytic activity and higher Photoelectrochemical (PEC) performance. • The higher performance of V 2 O 5 /rGO nanocomposites was achieved during PEC and photocatalytic activity due to higher charge transfer rate. In this work, we have synthesized reduced graphene oxide (rGO) coupled vanadium oxide (V 2 O 5 /rGO) nanocomposite by the simple hydrothermal route and validated its potentiality for the photodegradation of methylene blue (MB) dye and photoelectrochemical (PEC) water splitting activities. The reduction in the bandgap value of V 2 O 5 /rGO nanocomposite after coupling rGO with V 2 O 5 increases the visible light absorption property withreduced recombination rate of photogenerated charge carriers in comparison to bare V 2 O 5, which result in ∼3 fold enrichment in the photocatalytic activity. Moremore, the PEC performance of fabricated V 2 O 5 /rGO photoanode has been investigated where a ∼3.5 fold higher value of current density (1.4 mA/cm2 at 0.8 V vs. Ag/AgCl)is achieved compared to V 2 O 5 photoanode. These observations are also evident by the decreased value of charge transfer resistance at the V 2 O 5 /rGO photoanode/electrolyte interface and higher value of donor density (N d) in electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) measurements. The possible enhanced charge transfer process in V 2 O 5 /rGO nanocomposite has been proposed responsible for the improved photodegradation of methylene blue (MB) dye and enhanced PEC water splitting activity. [ABSTRACT FROM AUTHOR]