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In this work, a facial synthesis of α-MoO 3 nanoparticles was done by chemical co-precipitation method. The synthesized α-MoO 3 nanomaterials have been reported for sensing and photocatalysis applications together. For sensing, the α-MoO 3 was coated on FTO based interdigitated electrodes, and the prepared sensor was tested for numerous concentrations of ammonia (100–600 ppm) under different relative humidity levels (11–33%−56–75% −95% RH). The response and recovery time of α-MoO 3 based sensor for 500 ppm of NH 3 were 8 s and 11 s under 95% RH, respectively. The prepared α-MoO 3 based sensor exhibits high selectivity and stability towards ammonia. To analyze the photocatalytic activity of prepared α-MoO 3 nanoparticles, the photodegradation of methylene blue (MB) and methyl orange (MO) under visible light irradiation was studied. The first-order reaction rate constant for MB dye is 0.02434 min−1, and for MO dye is 0.01111 min−1. Finally, the maximum degradation efficiency for MB and MO dyes was calculated to be 95% and 73%, respectively. The given data conclude that the synthesized α-MoO 3 nanoparticles can be used as an effective NH 3 sensor as well as an efficient photocatalyst in organic dye degradation. [Display omitted] • The chemical co-precipitation technique was used to synthesize the hierarchical α-MoO 3 nanoparticles. • The sensor's selectivity, sensitivity, repeatability, and stability towards NH 3 were studied. • The relative humidity enhanced the performance of the NH 3 sensor. • Fast and efficient removal of methylene blue (95%) and methyl orange (73%) were investigated under visible light irradiations. [ABSTRACT FROM AUTHOR]

In this work, a facial synthesis of α-MoO 3 nanoparticles was done by chemical co-precipitation method. The synthesized α-MoO 3 nanomaterials have been reported for sensing and photocatalysis applications together. For sensing, the α-MoO 3 was coated on FTO based interdigitated electrodes, and the prepared sensor was tested for numerous concentrations of ammonia (100–600 ppm) under different relative humidity levels (11–33%−56–75% −95% RH). The response and recovery time of α-MoO 3 based sensor for 500 ppm of NH 3 were 8 s and 11 s under 95% RH, respectively. The prepared α-MoO 3 based sensor exhibits high selectivity and stability towards ammonia. To analyze the photocatalytic activity of prepared α-MoO 3 nanoparticles, the photodegradation of methylene blue (MB) and methyl orange (MO) under visible light irradiation was studied. The first-order reaction rate constant for MB dye is 0.02434 min−1, and for MO dye is 0.01111 min−1. Finally, the maximum degradation efficiency for MB and MO dyes was calculated to be 95% and 73%, respectively. The given data conclude that the synthesized α-MoO 3 nanoparticles can be used as an effective NH 3 sensor as well as an efficient photocatalyst in organic dye degradation. [Display omitted] • The chemical co-precipitation technique was used to synthesize the hierarchical α-MoO 3 nanoparticles. • The sensor's selectivity, sensitivity, repeatability, and stability towards NH 3 were studied. • The relative humidity enhanced the performance of the NH 3 sensor. • Fast and efficient removal of methylene blue (95%) and methyl orange (73%) were investigated under visible light irradiations. [ABSTRACT FROM AUTHOR]

Graphical abstract The dyes removal performance for MG and RhB was effectively enhanced and the catalyst has a good potential in dye wastewater treatment. Abstract As a photocatalyst, bismuth vanadate coupled with reduced oxide graphene (BiVO 4 -rGO) has been reported for dye degradation. However, this catalyst faced the disadvantages of low catalytic efficiency and long catalytic time. In this paper, BiVO 4 -rGO composites were synthesized by a modified hydrothermal method, and characterization results showed the monoclinic BiVO 4 surface successfully coupled with a layer of rGO. The dye removal performance of BiVO 4 -rGO composites were evaluated by the degradation of malachite green and rhodamine B under visible light irradiation and photocatalytic results showed that the BiVO 4 with rGO modification could effectively enhance the dyes removal performance. In a specific photocatalytic experiment, BiVO 4 -rGO-300 could remove 99.5% MG in two hours and 99.84% RhB in four hours, which was superior to previous studies. Furthermore, application of catalyst in practical wastewater was also taken into account. MG and RhB were degraded by BiVO 4 -rGO in several kinds of actual wastewater and experimental results showed that this catalyst could efficiently remove dye in actual environment. This improvement could be ascribed to the increase of special surface area, efficient charge transfer and reduction of electron-hole pair recombination with the incorporation of rGO. The influences of pH, supporting electrolyte and mechanism of the dye degradation were also investigated in details. [ABSTRACT FROM AUTHOR]

Ternary oxide semiconductor could effectively adjust the energy band gap and location by changing the elemental ratio, which remarkably benefits the electron transfer and photoelectrocatalytic H 2 generation. In this paper, hydrangea-like CuBi 2 O 4 sensitizers were prepared on TiO 2 nanotube arrays (TiO 2 NTAs) by one-pot solvothermal deposition. The alkali kind showed vital influences on the microstructure and photoelectrocatalytic performance of CuBi 2 O 4 /TiO 2 NTAs, and the excellent pollutant remediation, photoelectric conversion and photoelectrocatalytic water splitting were achieved by the sample prepared by C 6 H 12 N 4. Under visible light irradiation, the optimized sample displayed the higher photoelectrocatalytic H 2 generation rate (87.42 μmol·cm−2·h−1) than that of samples prepared using other alkali kinds. Moreover, the CuBi 2 O 4 /TiO 2 NTAs also exhibited high organic dye and Cr(VI) removal performance, and the outstanding photoelectrocatalytic activity indicates the novel strategy for the construction of CuBi 2 O 4 /TiO 2 NTAs photocatalyst for H 2 generation by effective photocatalytic water splitting. [Display omitted] • Hydrangea-like CuBi 2 O 4 sensitizers were synthesized on TiO 2 NTAs. • The CuBi 2 O 4 /TiO 2 NTAs photocatalyst showed the high H 2 evolution capacity. • The preparation and photocatalytic mechanisms were explored. [ABSTRACT FROM AUTHOR]

The present research investigates the photocatalytic activity of pyrrole and polypyrrole (PPy) under visible light for the treatment of contaminated water with the organic dye methylene blue (MB). Pyrrole is inert for photo-catalytic activities, because of its large HOMO-LUMO gap. However, when PPy was synthesized, the electronic structure changes, making PPy an active photo-catalyst. PPy can be utilized to produce photo-excited charges on any type of light source (UV or visible) since it has broad absorbance spectra. The UV-Vis spectroscopy shows absorbance bands in the UV and visible region, which correspond to absorption maxima at 380 nm, 470 nm and 525 nm. Additionally, a broad tail near the IR region was observed which corresponds to polaronic and bipolaronic transitions. These charges actively contribute to the breakdown of dye during the degradation phenomenon. The presence of polaron was confirmed by electron spin resonance (ESR) having g value of 1.99, and its intensity decreases on light exposure. The interaction between PPy and MB through polaron-bipolaron was explained by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). N 1s and C 1s XPS results show the shift in the B.E. of –N–H+·, =N–H+, –C N+ and =C–N+·when PPy interacts with MB which gives the signature of charge transfer. Furthermore, the interactions within the system were analyzed by ultraviolet photoelectron spectroscopy (UPS) data which provided descriptive information on the molecular orbital level and also gave an indication of charge transfer state formation between PPy and MB at − 7.83 eV. [Display omitted] • Photocatalytic activity of pyrrole and PPy nanoparticles with methylene blue under visible light. • By introducing polaronic-bipolaronic levels within HOMO-LUMO gap of PPy, increases its absorption efficiency in vis-range. • Polarons-bipolarons are interacting charge mediators among PPy and MB, contributing to dye degradation. • Molecular orbital interaction between PPy and MB has been explained by UV photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is a visible light active photo-catalyst, but its photo-catalytic efficiency is hampered by rapid recombination of the photo-induced charge carriers in g-C 3 N 4. This adverse charge recombination of g-C 3 N 4 is efficiently retarded by compositing g-C 3 N 4 with cadmium selenide (CdSe). The energy band gap of CdSe is narrower than that of g-C 3 N 4, and also its band positions are compatible with g-C 3 N 4 in order to carry out the lateral intersystem crossing of the photo-induced electrons from the conduction band of g-C 3 N 4 to that of CdSe. In this work, g-C 3 N 4 /CdSe nanocomposites with four different CdSe mass loading (1%, 2.5%, 5%, and 10%) were synthesized by pulsed laser induced method, where laser fragmentation (LFL), and laser defect engineering (LDL) are the underlying processes. The structural, morphological, and elemental characterizations using XRD, TEM, FE-SEM, and EDX confirmed the proper anchoring of CdSe nanoparticles on the g-C 3 N 4 polymeric surface. The modified band structure in the g-C 3 N 4 /CdSe nanocomposite not only enhanced the visible light absorption, but also effectively retarded the photo-induced charge recombination, which are reflected in the optical absorption spectra, and the photoluminescence spectra respectively. Photo-catalytic degradations of Rhodamine B (RhB), and methylene blue (MB) dyes under visible light in the presence of four different variants of g-C 3 N 4 /CdSe nanocomposites were estimated, and bench marked with pure g-C 3 N 4. As anticipated, the photo-catalytic degradation efficiency of all the variants of g-C 3 N 4 /CdSe nanocomposites is significantly higher than that with pure g-C 3 N 4. The highest photo-catalytic degradation rate constant of 0.0222 min−1, 0.0178 min−1 respectively for MB and RhB were achieved using g-C 3 N 4 /CdSe nanocomposite with 2.5% CdSe mass content. As a second application, g-C 3 N 4 /CdSe nanocomposite was also used in the electrocatalytic hydrogen evolution process in the acidic medium. Thin this study, the observed over potential recorded was lower for g-C 3 N 4 /CdSe nanocomposite than that with pure g-C 3 N 4, indicating the higher hydrogen evolution capability of this nanocomposite as the electro-catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Rational design of photoelectrode with high visible light utilization rate and separation efficiency of electron-hole pairs is the key step in photoelectrocatalytic technology. In this work, Z-Scheme photoelectrocatalyst (ZTO/rGO/Ag/AgBr) was synthesized by hydrothermal and photo-reduction process. Comparing with pure Zn 2 SnO 4 (ZTO), adding reduced graphene oxide (rGO) effectively improved electrons transfer efficiency. Notably, the addition of Ag/AgBr not only broaden the visible light response range of ZTO, but also accelerated the separation of photo-generated electron-hole pairs, and constructed all-solid-state Z-Scheme heterojunction. Meanwhile, DFT calculation showed that Ag metal on rGO surface could act as active site for organic dyes degradation. Moreover, the addition of extra bias potential during photoelectrochemical process not only accelerate the migration of carriers, but also inhibit the recombination of photo-generated electron-hole pairs. Methylene blue (MB) could be effectively removed during photoelectrochemical reaction process, which was attributed to hydroxyl radical (•OH) and superoxide radical (•O 2 -). In this work, Z-Scheme transfer pathway, assisted photoelectrocatalytic technology, is a feasible strategy for improving catalytic performance. [Display omitted] • All-solid-state Z-Scheme heterjunction was confirmed by in-situ XPS and DFT calculation. • Z-Scheme transfer pathway assisted electrocatalysis accelerated carrier separation. • Adding rGO effectively improved the electrical conductivity of photo-anode. • Ag metal on rGO surface could act as active site for anionic group. [ABSTRACT FROM AUTHOR]

The present work demonstrates a facile hydrothermal synthesis of Plasmonic Au–TiO 2 nanocatalyst followed by its successful application for complete photocatalytic dye degradation (oxidation) in batch and continuous flow process under natural sunlight as well as visible and UV light. The Au-TiO 2 nanocatalyst was synthesized by a hydrothermal method at basic pH conditions. It was meticulously analyzed by a variety of spectroscopic (UV-Vis, Raman, FTIR, PL, Powder XRD, ED-XRF, XPS), microscopic (FE-SEM with elemental mapping, TEM), and thermal (DSC) techniques. The characterization results showed that monodisperse Plasmonic Au(0) nanoparticles with a mean diameter of 12 ± 1 nm are homogeneously deposited on Anatase TiO 2 crystals. The nanocatalyst showed complete photocatalytic degradation of various dye compounds (Eosin Yellowish, Indigo Carmine, Methyl Orange, Methylene Blue, and Rhodamine B) under visible light or sunlight as confirmed through UV-Vis spectra, mass spectral study, and TOC analysis of dye solutions. A continuous flow process using a specially designed photoreactor was accomplished with a long catalyst lifespan, easy processibility, and low cost. Easy synthesis of the catalyst, its very detailed characterization, and its efficient catalytic studies to completely degrade various dye molecules under visible light source in the absence of any added oxidizer (O 2 , H 2 O 2 , KMnO 4 , Organic peroxides) and the demonstration of continuous flow process are significant highlights of the present work. A plausible mechanistic pathway is also presented in line with the previous literature reports and presently observed phenomenon. [Display omitted] [ABSTRACT FROM AUTHOR]

Adopting a facile one-step solvothermal method, CN/MgAl 0.80 Ce 0.20 -LDH, a lamellate composite of graphitic carbon nitride (g-C 3 N 4 , CN) and Ce-doped MgAl-layered double hydroxide (LDH), was synthesized. Profiting from the combined effect of Ce-doping and CN-LDH composition, CN/MgAl 0.80 Ce 0.20 -LDH possesses large specific surface area (52.71 m2 g−1) and high separation efficiency of photogenerated charge. When used to remove organic dye Congo red (CR), the composite exhibits enhanced efficiency which can be attributed to the synergetic performance of adsorption and photocatalysis. As a result, ~49% CR (50 mg L−1) can be adsorbed by CN/MgAl 0.80 Ce 0.20 -LDH and the CR degradation efficiency exceeds 90% within 180 min under light-emitting diode (LED) visible light irradiation, which is much higher than that of pristine CN (48.77%). The augmented surface area and proliferated active sites benefit the increase of adsorption capacity. The enhanced photocatalytic performance can be attributed to the efficient transmission of photogenerated electrons and holes between CN and MgAl 0.80 Ce 0.20 -LDH. Electrochemical impedance spectroscopy (EIS) analysis and photoluminescence (PL) analyses confirmed the effective separation of photogenerated electron-hole pairs in CN/MgAl 0.80 Ce 0.20 -LDH, while electron spin resonance (ESR) results verified the derivation of superoxide radicals (·O 2 -) species amid CR photocatalytic degradation. [Display omitted] [ABSTRACT FROM AUTHOR]

The synergy of oxygen excess defects, hierarchical structure and strong dye adsorption capacity gives the oxygen-rich Ti-based composite microspheres a high visible-light photocatalytic activity. • The doping-free ORTCs display high visible-light response. • ORTCs have oxygen excess defects, hierarchical structure and strong adsorption capacity. • ORTCs show an excellent visible-light photocatalytic performance without annealing. • The reported method is simple, mild and dopant-free. The oxygen-rich Ti-based composite (ORTC) microspheres with high visible-light photoactivity were successfully synthesized by a facile and dopant-free hydrothermal method. The as-synthesized urchin-like microspheres possess a controllable hierarchical structure that is strongly dependent on the concentration of H 2 O 2 and NH 4 Cl, and displayed an excellent visible light photoactivity without annealing activation, which is attributed to the formation of the oxygen excess defects. The ORTC prepared in optimal conditions gave the narrowest band gap of 2.31 eV due to its highest oxygen excess defects content, and showed a stable and high-efficiency visible-light photocatalytic performance for organic dyes degradation, exhibiting three-fold as that of the control sample. The synergistic effect of oxygen excess defects, hierarchical structure and strong adsorption capacity was identified as the key factor responsible for the prominent performance. Based on the obtained results, a plausible mechanism for fabricating urchin-like ORTC microspheres with nanofiber branches was proposed and discussed in detail. [ABSTRACT FROM AUTHOR]

A reduced graphene oxide supported g-C 3 N 4 /NiMgAl layered triple hydroxide (LTH) hybrid novel photocatalyst was synthesized by hydrothermal process, and its photocatalytic degradation activity was assessed against the methylene blue (MB) dye. The obtained experimental outcomes show that the as-prepared LTH are anchored on the surfaces of negatively charged g-C 3 N 4 and r-GO nanosheets. The dye degradation capacity of as-prepared samples was examined under visible-light irradiation and the r-GO supported g-C 3 N 4 /LTH hybrid formation shows significantly improved visible-light-driven photocatalytic activity along with good reusability. The electrochemical performances of as-prepared samples were investigated by cyclic voltammetry (CV), Nyquist plots and photocurrent measurement by three-electrode based system. As compared to other samples the r-GO/g-C 3 N 4 /LTH hybrid photocatalyst shows better electrochemical and photocatalytic activity. The improved catalytic performance may be due to the synergistic effect among the photocatalyst and high charge-carrier separation efficiency. The r-GO acted an agent to enhance the charge carrier separation in heterojunction, which consequently enhanced the photocatalytic activity. The current effort could open a new way for the preparation of visible-light-driven LTH based nanomaterials for effectual photocatalytic decomposition of organic pollutants. [ABSTRACT FROM AUTHOR]

A series of novel Fe(III) clusters modified Bi 12 O 17 Cl 2 (Fe/Bi 12 O 17 Cl 2) photocatalysts have successfully fabricated. Their chemical structure, element composition, surface feature, light response ability and photocatalytic activity were measured. The results revealed that Fe(III) clusters uniformly loaded on Bi 12 O 17 Cl 2 nanosheets surface, which resulted Fe/Bi 12 O 17 Cl 2 possessing improved visible light harvesting efficiency and introduced interfacial charge transfer effect in Fe/Bi 12 O 17 Cl 2 photocatalyst, conducing to photoinduced charge efficiently separation. Its photocatalytic ability was performed by degrading organic dye (Rhodamine b). Comparing with the degradation rate of Bi 12 O 17 Cl 2 (0.0743 min−1), that of Fe/Bi 12 O 17 Cl 2 photocatalyst was obviously enhanced (0.157 min−1). Clearly, Fe/Bi 12 O 17 Cl 2 photocatalyst had the improvement of photoproperty. Then, the results of trapping experiments revealed the key active species were O 2 − and h+. Lastly, a reasonable photocatalytic mechanism over Fe/Bi 12 O 17 Cl 2 photocatalyst was shown. [ABSTRACT FROM AUTHOR]

The possible photocatalytic mechanism schematic of the binary type-I CdIn 2 S 4 /g-C 3 N 4 heterojunctions and H 2 O 2 for photodegrading RB19 under visible light irradiation. A visible-light-driven photocatalyst CdIn 2 S 4 /g-C 3 N 4 was firstly synthesized via a facile and green wet-impregnation method. The crystal phases, particle morphologies, chemical structures and optical properties of the prepared pure g-C 3 N 4 , bare CdIn 2 S 4 and binary CdIn 2 S 4 /g-C 3 N 4 heterojunctions were measured in detail by various standard characterization techniques, such as XRD, SEM, TEM, FT-IR, DRS, and PL. And then, a novel and high-efficiency visible-light-driven photocatalytic system comprised of binary CdIn 2 S 4 /g-C 3 N 4 heterojunctions and H 2 O 2 has been successfully constructed and exhibited superior photocatalytic degradation of Reactive Blue 19 (RB19). The following results can be obtained by photochemical characterizations and photocatalysis experiments: Compared with the pristine g-C 3 N 4 , the addition of CdIn 2 S 4 to form a type-I CdIn 2 S 4 /g-C 3 N 4 heterojunction effectively increases the visible light absorption range and reduces the recombination rate of photogenerated electron-hole pairs. After 100 min visible light irradiation, the photocatalytic degradation rate of RB19 by CdIn 2 S 4 /g-C 3 N 4 was approximately 8.30 times and 2.68 times higher than that of monomer g-C 3 N 4 and CdIn 2 S 4 , respectively. After 60 min visible light irradiation, the photodegradation efficiency of the novel photocatalytic system (CdIn 2 S 4 /g-C 3 N 4 and H 2 O 2) is 1.99 times higher than that of CdIn 2 S 4 /g-C 3 N 4 for RB19. Furthermore, the photocatalytic mechanism of the novel visible-light-driven photocatalytic system was proposed and elaborated. These findings emphasize the main role of g-C 3 N 4 in the degradation of organic dyes and provide a reasonable and effective method for rational design of a high-efficiency and low-cost visible light-driven photocatalytic system. [ABSTRACT FROM AUTHOR]

Different amount (3, 5, 7 and 9 mol%) of the Tantalum (Ta) doped CdS nanoparticles have been synthesized by hydrothermal approach for the photocatalytic degradation of the organic pollutant removals. The physicochemical properties of the synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), and photoluminescence (PL). The UV-DRS samples suggest that all the Ta-doped samples showed the redshift due to the lattice deformation in the CdS. The PL results indicate that the 7 mol % Ta-doped CdS shows the highly hindered charge carrier recombination, which can increase the charge carrier lifetime. The photocatalytic activity of as prepared photocatalyst was examined by monitoring the degradation of methylene blue under visible light irradiation for the time period of 120 min. The photocatalytic tests revealed that the 7 mol% of Ta-doped CdS nanoparticle exhibited much higher photocatalytic activity compared with pure, 3 and 5 mol% of Ta-doped CdS. The presence of Ta5+ generates electron and holes prolonged the recombination rate by introducing the temporary trapping sites, which essentially causes to improve the photocatalytic efficiency. Further, the experimental data were fitted well with the pseudo-first-order kinetic model. Therefore, the proposed Ta-doped CdS efficient photocatalyst applicable to future research. [ABSTRACT FROM AUTHOR]

Novel CuInS 2 /m-BiVO 4 composites with different mass ratios (CuInS 2 to m-BiVO 4 = 1:3, 1:1, and 3:1) were synthesized and their potential visible-light photocatalytic applications for photodegradation of some organic dyes (methylene blue, rhodamine B, and methyl orange) and inactivation of bacteria (Pseudomonas aeruginosa) were investigated. CuInS 2 /m-BiVO 4 with a mass ratio of 1:3 exhibited better photocatalytic degradation of methylene blue and antibacterial activity than those of either pure CuInS 2 or m-BiVO 4. Moreover, this composite photocatalyst showed different photocatalytic selectivity in terms of the organic dye degradation. Salicylic acid was also used to test the photocatalytic activity of this composite to clarify the dye sensitization effect. The photoelectrochemical (PEC) properties of the CuInS 2 /m-BiVO 4 photoelectrode, evaluated by linear sweep voltammetry (LSV) measurement, revealed that the composite photoelectrode exhibited higher current density and onset potential in comparison with the m-BiVO 4 photoelectrode. In addition, the electrochemical impedance spectroscopy (EIS) measurement also proved a faster rate of charge transfer at the electrode/electrolyte interface. The enhancement of photocatalytic and PEC activities of the CuInS 2 /m-BiVO 4 composite was revealed not only that the CuInS 2 /m-BiVO 4 composite extended light absorption in the visible light region, but also that the formation of a p-n heterojunction could promote photogenerated charges as well as facilitate effective charge separation and transportation between the CuInS 2 and m-BiVO 4 contact interface. [ABSTRACT FROM AUTHOR]