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Graphitic carbon nitride (gCN) has shown great potential in photocatalysis. Developing suitable cocatalysts is a critical way to enhance gCN's photocatalytic performance. In this paper cobalt–nickel bimetallic phosphide (CoNiP) was used as a cocatalyst to modify gCN. A gCN/CoNiP composite was successfully prepared by a simple hydrothermal method. XRD, XPS, SEM, UV-vis DRS, and PL characterization studies showed that a Schottky junction-like structure was constructed between gCN and CoNiP, which intensified the visible light response, enhanced the charge transfer rate and prohibited the recombination of photogenerated carriers, thus significantly improving gCN photocatalytic activity. Under simulated sunlight, the removal efficiency of methylene blue (10 mg L−1) was 97.8% by 120 min of irradiation, 44.6% higher than that of gCN. The quenching experiment showed that ˙O2−, ˙OH and h+ were the main active species. Based on the above points, the possible mechanism of photocatalysis was deduced. [ABSTRACT FROM AUTHOR]

The heterojunction structure of semiconductor photocatalysts is significant for making full use of their capabilities for organic molecules and dye degradation. In this paper, we present a heterogeneous junction composite fabricated with hybrid phase TiO2 and g-C3N4 for methylene blue (MB) removal through adsorption and photocatalytic degradation. The heterogeneous junction system was prepared by hydrothermal treatment with a subsequent pyrolysis process. The variation of the proportion and lattice structure of hybrid phase TiO2 in the synthesized catalysts was analyzed by refinement. Adsorption experiments showed that the maximum adsorption capacity of TiO2/g-C3N4 (1 : 10) was 1667 mg g−1, which was 45.97 times and 63.78 times higher than that of TiO2 and g-C3N4, respectively. In the photodegradation process, the TiO2/g-C3N4 (1 : 10) photocatalyst shows a removal rate of MB of 100 mg L−1, which was as high as 96.262%, significantly higher than that of pure TiO2 and g-C3N4. Brunner–Emmett–Teller (BET) measurements and Fourier transform infrared spectroscopy (FTIR) showed that the adsorption of MB onto TiO2/g-C3N4(1 : 10) was chemical adsorption, and ˙OH, which acts as an active substance, was found to play a major role in the photocatalytic degradation process. Overall, the developed hybrid phase TiO2/g-C3N4 heterojunction composite may be beneficial for the treatment of water pollution. [ABSTRACT FROM AUTHOR]

In this paper, Eu/F co-doped bismuth vanadate photocatalysts with different doping ratios were prepared by a hydrothermal method, and their microscopic morphology, crystal structure, light absorption and photocatalytic performance were investigated. Part of the F in the Eu/F co-doped samples might be doped to replace O in the BiVO4 lattice, while Eu3+ ions replaced Bi3+ ions, which led to a difference in the morphology and internal structure. XRD and Raman spectroscopy characterization showed that the crystal structures of the samples were all monoclinic scheelite type, and contained a certain tetragonal scheelite type, and the crystallinity was good. The Eu/F co-doped samples exhibited better photoactivity under UV-Vis light. The recombination rate of the photogenerated carriers in the Eu/F co-doped samples was obviously reduced, but it showed a serious concentration dependence on the doping species. Under visible light irradiation, Eu/F co-doped samples (R = 0.75) had the best degradation effect on methylene blue (MB). In addition, the degradation mechanism of the photocatalyst was also explored. ˙O2− and h+ were the main active species affecting the degradation of MB by Eu/F–BiVO4. [ABSTRACT FROM AUTHOR]

A novel Fe–RGO/TiO2/PTFE photocatalytic composite membrane was developed for the purification of MB wastewater. The properties of the prepared membranes were characterized using XRD, SEM, FT-IR spectroscopy, the BET method, and water contact angle, membrane flux, and BSA adsorption measurements. The photocatalytic properties of the surface-modified membranes were investigated in filtration experiments using MB as a representative organic contaminant. The results of the experiments showed that the Fe–RGO/TiO2 particles were securely loaded onto the surface of the PTFE membrane, demonstrating excellent chemical stability of the composite membrane. The incorporation of Fe3+ inhibited the agglomeration of TiO2 particles and enhanced the photocatalytic reaction rate. The introduction of RGO could broaden the photoresponsive range of TiO2, increase the specific surface area of the photocatalyst, introduce a large number of hydrophilic groups to enhance the hydrophilicity of the composite membrane, and subsequently increase the membrane flux. The MB wastewater was treated with the Fe–RGO/TiO2/PTFE composite membrane system for 3 h and the removal rate of MB reached 95.8% and 60.1% under UV and visible light, respectively. Reaction kinetic analysis indicated that the removal process of MB wastewater by Fe–RGO/TiO2/PTFE involves an adsorption–degradation–filtration synergy mechanism. [ABSTRACT FROM AUTHOR]

α-Fe2O3/Bi2O3 nanocomposites with a p–n heterojunction were synthesized via an anodization strategy and the hydrothermal method for photocatalytic applications. By changing the hydrothermal treatment time, Bi2O3 nanosheets were deposited on the surface of α-Fe2O3 nanotube arrays (NTAs). The morphologies and photochemical performance of the as-prepared α-Fe2O3/Bi2O3 nanocomposites were investigated in detail. The presence of Bi2O3 nanosheets resulted in an obvious red-shift in the UV-Vis diffuse reflectance spectrum, indicating that the α-Fe2O3/Bi2O3 nanocomposites had an expanded visible light photo-response range. The α-Fe2O3/Bi2O3 nanocomposites displayed excellent photocatalytic activity, stability and recyclability toward the decomposition of methylene blue under visible light illumination. The photocurrent and electrochemical impedance spectra also testified efficient electron transport and charge separation in the α-Fe2O3/Bi2O3 nanocomposites. The enhanced photocatalytic performance can be ascribed to a high light harvesting ability, fast separation of photogenerated electron–hole pairs and the presence of an efficient interfacial electric field from the p–n heterojunction. The photogenerated holes and superoxide radicals played crucial roles in the photocatalytic process. The photocatalytic mechanism was discussed. [ABSTRACT FROM AUTHOR]

Due to their carcinogenic, mutagenic and poisonous nature, industrial wastes such as metals, dyes, polycyclic aromatic hydrocarbons, surfactants and pharmaceutical waste have become a major worldwide issue for human health. In this context, we are reporting the synthesis, characterization and application of copper-immobilized nanocomposites NiAlFeO4@Cu for catalytic reduction of hazardous and carcinogenic nitrophenols and photocatalytic degradation of different dyes (rhodamine B (RhB), methyl orange (MO) and methylene blue (MB)), individually as well as their mixture under visible light irradiation. Magnetically separable mesoporous composites of NiAlFeO4 and copper nanoparticles in the molar ratios of 2 : 1 (NAFO2@Cu), 5 : 1 (NAFO5@Cu) and 10 : 1 (NAFO10@Cu) were prepared through a simple reduction method with pure water as the solvent. The structural, morphological and physicochemical features of the prepared nanocatalysts were examined using PXRD, FE-SEM, PL, DRS, VSM and BET. The nanocomposites were found to be very porous and spherical with an average crystallite size between 4 and 8 nm. Magnetic measurements were carried out using a vibrating sample magnetometer, which reveal the ferromagnetic nature of our samples, making them magnetically separable. A UV/Vis study was used to analyse the reduction of nitrophenols by employing sodium borohydride as a reducing agent. Furthermore, the band gap energy values of the nanocomposites were found to be in the visible range (1.63–1.66 eV) making them suitable for photocatalysis. Rhodamine B was used as a model dye pollutant for estimation of the photocatalytic deterioration of the synthesized nanocatalysts. Among all the prepared nanocomposites, NAFO2@Cu exhibited the highest catalytic efficiency for the reduction of nitrophenols, while the maximum degradation efficiency was shown by NAFO10@Cu for the photodegradation of different dyes individually as well as in their ternary solution. [ABSTRACT FROM AUTHOR]

In this work, a novel flower-shaped NV-g-C3N5@VS2 heterojunction was prepared by hydrothermal in situ synthesis using NV-g-C3N5 as the matrix and thioacetamide as the precursor. The prepared heterojunction showed a flower-like and layered structure, which widened the visible light absorption range and facilitated the usage of visible light. Under visible light irradiation, the NV-g-C3N5@VS2 heterojunction exhibited excellent photoelectrocatalytic nitrogen reduction activity with an ammonia yield of 49.26 μg h−1 mg−1 in an electrolyte solution saturated with N2. Moreover, the NV-g-C3N5@VS2 heterojunction achieved outstanding photocatalytic degradation activity. The photocatalytic degradation rate of Rhodamine (RhB) reached 95% in 35 min under visible light irradiation. More importantly, the catalyst displayed good reusability and stability after four cycling runs for the photodegradation of MB. The prepared catalyst showed excellent photocatalytic universality and was also applied to efficiently degrade organic pollutants such as methyl orange (MO) and methylene blue (MB). Therefore, solar light-driven photocatalytic and photoelectrocatalytic applications based on the NV-g-C3N5@VS2 heterojunction are expected to pave a new way for fertilizers, energy utilization, and environmental remediation. [ABSTRACT FROM AUTHOR]

We demonstrate a low-cost, simple-operation, and environmentally friendly magnetic grinding synthetic process to prepare nontoxic copper sulfide-based composites with photocatalytic activity. Using this efficient approach, CuS/ZnS and CuS/CdS composites were successfully synthesized from elemental powders without using any other additives or solvents. The formation of metal sulfides was confirmed using a series of characterizations. The photocatalytic activities of the as-prepared materials were evaluated by the degradation of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) dyes in the presence of hydrogen peroxide (H2O2), which served as an oxidant under visible irradiation. The degradation efficiencies of MB and RhB by CuS/ZnS and CuS/CdS composites were more than 95% in 30 min and the degradation efficiency of MO was more than 85% in 90 min. The photocatalytic activities of the CuS/ZnS and CuS/CdS composites were better than those of pure metal sulfides. In addition, the CuS/ZnS and CuS/CdS composites showed good stability toward photocatalytic degradation and their main reactive species for degrading organic dyes are photogenerated hydroxyl radical (˙OH). Reasonable photocatalytic reaction mechanisms are proposed to explain the photocatalytic processes of the CuS/ZnS and CuS/CdS composites. [ABSTRACT FROM AUTHOR]

The effects of Zn precursors, S precursors and hydrothermal temperatures on the morphologies and structures of ZnS microspheres were investigated by a facile hydrothermal method. The results showed that the mixed phase ZnS microspheres prepared with ZnCl2 and L -cysteine at 180 °C exhibited a visible light response. The as-prepared ZnS microspheres were used for photodegradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB). The photodegradation rates of ZnS microspheres to these azo dyes were 87.5% (RhB), 84.3% (MB), and 65.3% (MO), respectively. In addition, ZnS microspheres maintained good photodegradation activity after four cycles. In this work, ˙O2− was the major active species and the possible photocatalytic mechanism of ZnS microspheres was also illustrated. [ABSTRACT FROM AUTHOR]

The development of low-cost, efficient and sustainable technology is considered to be of paramount for the efficient degradation of toxic pollutants. The research in this report constructs an S-scheme heterojunction CoO/ZnFe2O4 nanocomposite (NCs) with outstanding photocatalytic performance on methylene blue (MB) dye degradation under visible light illumination. Several techniques were used for nanoparticles (NPs) and NCs to determine their morphological, structural, and optical properties. The CoO/ZnFe2O4 NCs (88.5%) exhibited excellent photocatalytic activity compared to the pristine CoO (66.8%) and ZnFe2O4 (64.3%). The total organic carbon (TOC) analysis confirmed that the MB dye was completely mineralised by the as-prepared NCs. From the results of the GC-MS/MS analysis, a possible intermediate formation and degradation pathway was identified. The h+ and ˙OH are the free radicals which primarily dominate the photocatalytic process. A recyclability study performed on the CoO/ZnFe2O4 NCs revealed that it was an extremely stable catalyst, even after six cycles, without substantial decreases in its degradation activity. The intermediate toxicity was predicted using ECOSAR software and the results confirmed the non-toxicity of the end product formed during the degradation of the MB dye. [ABSTRACT FROM AUTHOR]

A new mononuclear Fe3+ metalloligand MC1 [FeLN3(H2O)], developed by using the N2O2 donor Schiff base ligand H2L, has been successfully used to detect and remove Hg2+ and Cd2+ from several transition metal ions with the formation of two unusual hetero metallic μ-oxo Fe3+–Hg2+/Cd2+ clusters, [(Fe23+)(μ-O)L2Cl4(Hg22+)] (MC2) and [(Fe23+)(μ-O)L2I4Cd22+] (MC3) [(where H2L is 6, 6′-(1E, 1′E) (ethane-1, 2 diylbis(azaneylidene))bis(methaneylylidene))bis(2-ethoxyphenol)]. All three complexes were identified by X-ray single-crystal data analysis along with a range of spectral studies. In MC1, the Fe3+ is coordinated with deprotonated H2L, one water molecule, and one azide ion as a secondary anionic residue, forming an octahedral geometry. Interestingly, MC2 and MC3 are isostructural, where each asymmetric unit contains deprotonated H2L, one Fe3+ and Hg2+/Cd2+ metal center, two Cl−/I− and two Fe3+ centers are connected by a μ-O bridge to form tetranuclear complexes. As the band gap energy values of MC1, MC2, and MC3 (3.07 eV, 2.69 eV, and 2.55 eV, respectively) are in the visible region so all the three complexes are exposed to investigate their potentiality to be effective Schottky devices and at the same time a thorough inspection has been carried out to check their catalytic behaviour in aqueous medium in terms of methylene blue (MEB) dye degradation under visible light irradiation. A thorough inspection reveals the better MB dye degradation potentiality of MC3 in comparison to MC2 in the presence of H2O2. At the same time, the investigation of the device performances, conductivity, and device parameters disclose more effectiveness of MC3 in comparison to MC2 in a better Schottky device. The effectiveness of MC3 in both applications may be attributed to its lower band gap value. [ABSTRACT FROM AUTHOR]

A cable-like photocatalyst, TiBs@MCN, based on TiO2 belts and mesoporous g-C3N4 nanosheets, is fabricated by an in situ hydrothermal self-assembly approach. The mesoporous g-C3N4 nanosheets (MCN) are prepared by a chemical etching method and the TiO2 belts (TiBs) by a hydrothermal method. Several characterization analyses such as SEM, TEM, XRD, FTIR, BET, XPS, DRS, PL, EIS and the photocurrent test are employed to study the morphology and optical properties of the as-prepared photocatalysts. The photocatalytic activities of the catalysts are evaluated by the degradation of methylene blue (MB) and methyl orange (MO) solutions under visible light (μ > 420 nm). The results show that the as-prepared TiBs@MCN (with the ratio of TiBs to MCN of 1 : 7) photocatalyst has a large specific surface area (374.7 m2 g−1), good visible-light photocatalytic activity and excellent stability. In addition, the main reactive species in the degradation of MB are identified by adding different inhibitors and a possible photocatalytic mechanism is proposed and discussed. [ABSTRACT FROM AUTHOR]

A new porphyrinic vanadium-based metal–organic framework (MOF), namely V-MOF-10 [V2(OH)2(H2TCPP)], constructed from {V(OH)O4}∞ chains and 4-tetracarboxyphenylporphyrin linkers, was synthesized by a solvothermal procedure. Structural analysis indicated that V-MOF-10 possesses orthorhombic symmetry featuring two types of pores (5.2 × 11.9 Å and 3.5 × 11.9 Å). Full characterization of V-MOF-10 was performed by powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and elemental analysis (EA). The N2 isotherm of V-MOF-10 at 77 K shows a reversible uptake and permanent porosity with a high BET (Langmuir) surface area of 1477 m2 g−1 (1553 m2 g−1). The optical band gap of V-MOF-10, measured by UV-vis diffuse reflectance spectroscopy, is calculated to be 1.71 eV, resulting in a shift of absorption wavelength to the visible light region. Furthermore, our density functional theory (DFT) calculations confirm an acceptable correspondence of the band gap value with the mentioned experimental investigation, similar to the incorporated experimental and theoretical observations in the previous literature. Remarkably, V-MOF-10 exhibits an excellent photocatalytic property of organic dyes with the degradation efficiency of 100% for methylene blue (MB) and 89% for methylene orange (MB) after 120 min under illumination by visible light. These results suggest that V-MOF-10 could be used as a promising candidate in further photocatalytic studies. [ABSTRACT FROM AUTHOR]

Fe2(MoO4)3 photocatalysts were synthesized by a simple hydrothermal method. Fe2(MoO4)3 photocatalysts showed lower photocatalytic activity for the degradation of methylene blue under visible light irradiation. After compositing with g-C3N4, the photocatalytic activity of Fe2(MoO4)3 was enhanced obviously. The enhanced photocatalytic activity of the g-C3N4/Fe2(MoO4)3 photocatalysts could be attributed to the effective separation of the photogenerated e−/h+ pairs. In order to further enhance the degradation efficiency of g-C3N4/Fe2(MoO4)3, g-C3N4/Fe2(MoO4)3 was used to double activate peroxymonosulfate to degrade methylene blue. The influences of peroxymonosulfate dosage, pH value, inorganic anions and methylene blue concentration on double activating peroxymonosulfate to degrade methylene blue were investigated in detail. The mechanism of g-C3N4/Fe2(MoO4)3 double activating peroxymonosulfate was proved by radical quenching experiments, which proved that SO4˙− dominated the degradation of methylene blue. [ABSTRACT FROM AUTHOR]

The development of advanced compositions to remove contamination from water resources has become a global challenge in the last decades. Herein, nanofibrous membranes of polycaprolactone (PCL) incorporated with hydroxyapatite (HAP) that was modified with different amounts of Cu(II) ions have been fabricated. The structures, morphologies, and surface roughnesses of the constructed (Cu–HAP@PCL) membranes were characterized via a wide range of spectroscopic, microscopic, and surface science tools. Probing the surface morphology revealed that these membranes exist as networked fibers with various diameters ranging from 0.45–1.5 to 0.2–0.9 μm, along with maximum height roughnesses (Rt) of 266.2 to 463 nm for compositions having increased amounts of Cu(II) ions, respectively. The mechanical behavior results attested that the elasticity of the membranes was enhanced upon the addition of Cu(II) dopants, and the maximum strain before break reached nearly 125.59 ± 6.5% for the sample containing the highest Cu(II) content. As for biological applications, the fabricated Cu–HAP@PCL membranes showed powerful antibacterial potency, with activity areas of 14.5 ± 1.7 and 14.7 ± 1.6 mm achieved against E. coli and S. aureus, respectively. Further, the degradation efficiency of methylene blue (MB) dye indicated that the highest degradations of 88.6%, 89.4%, 91.0%, 91.1%, and 94.3% were accomplished after 70 min of irradiation under visible light using the fabricated Cu–HAP@PCL membranes. The efficient performance of the fabricated Cu–HAP@PCL membranes in biologically and environmentally related persistent problems encourages their potential utilization in wastewater management and microbial treatments. [ABSTRACT FROM AUTHOR]

The microstructure design and construction of a heterojunction are major strategies for enhancing the photocatalytic activity of semiconductors. Herein, Bi2WO6 flower spheres were synthesized and acted as a porous template for depositing BiOCl to fabricate a Bi2WO6/BiOCl composite photocatalyst. Through changing the concentrations of the Bi3+ and Cl− precursors, a hydrangea-like Bi2WO6/BiOCl composite with a porous nanostructure was synthesized. Rhodamine B (RhB), methylene blue (MB) and tetracycline hydrochloride (TCH) were selected as simulated pollutants for degradation by the photocatalyst. Under the irradiation of visible light, the optimized Bi2WO6/BiOCl composite removes almost 100% of RhB from solution in 60 min, 88% of MB in 75 min, and 90% of TCH in 90 min, much better than the performances of pure Bi2WO6 or BiOCl. The excellent photocatalytic activity of the Bi2WO6/BiOCl composite can be attributed to its hydrangea-like nanostructure and Bi2WO6/BiOCl heterojunction. On the one hand, the hydrangea-like structure promotes the physical adsorption of organic molecules on the photocatalyst. On the other hand, the Bi2WO6/BiOCl heterojunction broadens the light absorption range, accelerates the separation of photogenerated electrons and holes, and decreases charge transfer resistance, further improving the photocatalytic activity of the material. ˙O2− and ˙OH reactive species were generated under visible light irradiation, which promoted the fast degradation of organic pollutants. Based on the reactive species and the position of its conduction/valence band, the photocatalytic mechanism of the Bi2WO6/BiOCl composite was proposed as a Z-scheme heterojunction transfer mode. [ABSTRACT FROM AUTHOR]