Photodegradation Of RhB Research Articles

Effect of calcination temperature on the structure and photocatalytic performance of BiVO 4 prepared via an improved solution combustion method

The bismuth vanadate (BiVO4) photocatalysts were synthesised via an improved solution combustion method. The effects of different calcine temperatures on microstructure and photocatalytic properties of BiVO4 were studied. The samples were characterised by X-ray diffraction, X-ray phototelectron spectroscopy, transmission electron microscope, ultraviolet–visible and photoluminescence analyses. Furthermore, the photocatalytic activity of the sample was evaluated by photocatalytic decomposition of rhodamine B (rhB). The results showed that all samples were monoclinic structures with high purity. Moreover, the calcination temperature had significant effects on both morphology and photocatalytic properties of BiVO4. The sample obtained at 500°C had the narrowest bandgap energy and presented the best photocatalytic activity for the rhB photodegradation rate reached up to 86.67% after 50 min under visible-light irradiation.

Synthesis and Photocatalytic Degradation Performance of g-C<sub>3</sub>N<sub>4</sub>/ CQDs/SAPO-5 Ternary Composite

Due to the fatal drawback of fast photoreduced electron-hole pair recombination rate of g-C3N4, g-C3N4/CQDs/SAPO-5 ternary composite were prepared. Both of carbon quantum dots and SAPO-5 can form heterojunction with g-C3N4to inhibit the recombination. Their properties were characterized by XRD, SEM, FT-IR, DRS and PL. Data of PL shows a much lower photoreduced electron-hole pair recombination rate of g-C3N4/CQDs/SAPO-5. The effect of CQDs amount loaded on ternary composite on the RhB photodegradation performance under visible light was discussed in detail. The observed RhB degradation performances indicate that the order of photocatalytic activity is: g-C3N4/CQDs/SAPO-5> g-C3N4/ SAPO-5 > g-C3N4. g-C3N4/CQDs/SAPO-5 with CQDs load ratio of 0.25 w.t.% shows the best photodegradation performance. The highest efficiency is about 24.43% higher than g-C3N4/ SAPO-5 and 47.15% higher than pristine g-C3N4, respectively. This work is promising for developing novel g-C3N4-based photocatalysts for environmental purification.

Cs2Ge3In6Se14: A Structure Transformation Driven by the Size Preference and Its Properties.

The new selenide Cs2Ge3In6Se14, featuring its own structure type with germanium in mixed-valence states, is discovered via a solid-state reaction at 1173 K. The compound crystallizes in the R3̅ m space group with a = 7.9951(6) Å and c = 41.726(4) Å. Two adjacent condensed layers of InSe4 tetrahedra are linked by a [Ge2+Se6] octahedron into a double slice that is further stacked along the c direction with a packing sequence of ··· abca··· through the [Ge3+2Se6] dimer via its Ge-Ge metallic bond. The coexistence of Ge2+/Ge3+ and Ge-Ge metallic bonding has been confirmed by XPS and ELF analyses, respectively. More interestingly, although sharing many structure similarities, Cs2Ge3In6Se14 and our previously reported Cs2Ge3In6Te14 reveal a R3̅ m to P3̅ m1 structure transformation with a tripled c parameter. Single-crystal diffraction data and a thorough structure survey of related compounds point out that such a transformation is driven by the size preference of the [Ge2Q6] dimer. The title compound possesses a band gap of 2.08 eV and shows photodegradation of RhB under visible light that is more efficient than that for the commercial P25.

Synthesis of novel elm branch-like hierarchical γ-Bi2MoO6 nanostructures with enhanced visible-light-driven photocatalytic performance

A novel elm branch-like hierarchical γ-Bi2MoO6 nanostructure was successfully synthesized via a combination of electrospinning and sintering technique. The construction and photocatalytic properties of the samples were spectroscopically and structurally characterized in detail (XRD, FT-IR, SEM, HRTEM, UV-vis DRS, BET, PL, TOC, HPLC, I-t and EIS). The distinctive nanostructures consist of ultrafine nanotubes and ultrathin nanoplates, which afford the large specific surface area and significantly improve the photocatalytic activity. The elm branch-like hierarchical γ-Bi2MoO6 nanostructures exhibit an enhanced performance for the photodegradation of RhB, compared with γ-Bi2MoO6 nanoparticles under visible light irradiation. The electronic structure calculations of photocatalysts were carried out based on density functional theory (DFT). Moreover, the relationship between the structures and photocatalytic activities is also discussed in detail.

Synthesis and Visible-Light-Driven Photocatalytic Activity of Ta4+ Self-Doped Gray Ta2O5 Nanoparticles

C-impregnated/Ta4+ self-doped ultrafine Ta2O5 nanoparticles (NPs) were prepared by a one-step solvothermal method through reaction of Ta(V) chloride with benzyl alcohol. These NPs showed a large specific surface area of 253.4 m2 g–1, mean diameter of 2–3 nm, and superior photocatalytic activity in the photodegradation of Rhodamine B dye (RhB), compared to TiO2 (P25) and Ta2O5 commercial NPs. The obtained materials were annealed at different temperatures and their structure, morphology and optical and photocatalytic properties were investigated in detail. The C-impregnated Ta4+ self-doped Ta2O5 NPs presented enhanced and extended absorption in the visible range of the solar spectrum, increasing significantly their photocatalytic activity. The best photocatalyst could completely remove RhB after only 12 min of UV irradiation and yielded 68% and 43% of RhB photodegradation after 120 min of simulated sunlight and visible irradiation, respectively, with an apparent quantum efficiency of 3.6% at 447 nm. This en...

Enhanced photocatalytic degradation and hydrogen production activity of in situ grown TiO2 coupled NiTiO3 nanocomposites

A UV and visible light responsive binary phase TiO2 coupled NiTiO3 nanocomposites were prepared by a facile co-precipitation method followed by calcination at elevated temperatures. The phase structure, morphology and optical properties of the nanocomposite were characterized by XRD, FE-SEM, HRTEM, UV–vis DRS, EIS and Raman spectra. XRD and Raman spectrum shows that between 650 °C and 850 °C, a phase transition takes place. FE-SEM and TEM analysis revealed that during the synthesis, growth of cylindrical shaped amorphous NiTiO3 took place and upon calcinations; it transforms into highly crystalline interlinked chain type morphology. A noticeable three distinct optical transitions corresponding to 3.1, 2.5 and 2.27 eV were observed by UV–vis diffuse reflection spectroscopy (DRS). The TiO2/NiTiO3 nanocomposite was used for Tetracycline and RhB photodegradation, and photocatalytic water splitting activity under UV–vis light irradiation. The results of this study showed that the nanocomposites calcined at 750 °C exhibit significantly higher photocatalytic degradation and water splitting activity. Based on the experimental results, an n-n heterojunction charge carrier transfer and separation mechanism is proposed.

Visible light photocatalytic property and mechanism of peroxy bond incorporated layered H4Nb6O17 niobate

The layered niobium oxide H4Nb6O17 (HNO) crystal has an open layered structure. The H2O2 molecules can enter rapidly into the interlayers of HNO crystal, and coordinate with Nb within NbO6 octahedron to form the peroxy bond intercalated HNO crystal (P-HNO). The introduction of peroxy bond causes the positive shift of the CB minimum of HNO crystal from −0.39 eV to 0.42 eV, resulting in its band gap narrowing from 3.49 eV to 2.68 eV and the improvement of visible light absorption. The photocatalytic investigation indicates that such P-HNO crystal has the visible light photocatalytic performance for RhB dye degradation. Moreover, the trapping experiment indicates that h+ and ▪ are the main active species during the visible light photocatalytic degradation of RhB dye. And the study of photocatalytic degradation mechanism shows that there is a synergy between P-HNO crystal and RhB during the photodegradation of RhB.

Two anthracene-based metal–organic frameworks for highly effective photodegradation and luminescent detection in water

Two anthracene-based MOFs (Eu-ADBA and In-ADBA) with fcu and acs topologies have been successfully designed and synthesized. Eu-ADBA displays highly efficient photodegradation of MB, RhB and TC in water. In-ADBA shows excellent detection towards nitrofurans (NFZ and NFT) and nitrophenols (TNP, 2,4-DNP and 4-NP) in water.

Facile synthesis of Bi/BiVO4 composite ellipsoids with high photocatalytic activity.

BiVO4-based composites have been extensively investigated as promising photocatalysts due to their strong visible-light absorption. In this work, novel Bi/BiVO4 composites with excellent photocatalytic performance were firstly fabricated via a simple hydrothermal method, using BiVO4 as a self-sacrificing template and N2H4·H2O as a reductant. In the hydrothermal process, partial BiVO4 was reduced to form metallic Bi nanoparticles, which were deposited on the surface of BiVO4. The Bi content in the Bi/BiVO4 composites could be easily tuned by controlling the concentration of the N2H4·H2O solution. The photocatalytic performance of the Bi/BiVO4 composites was examined by studying the photodecomposition of RhB under visible-light illumination. The experimental results revealed that the Bi/BiVO4 composites exhibit high visible-light photocatalytic activity for the photodegradation of RhB compared with that of pure BiVO4. This enhanced photocatalytic activity likely originates from the strong visible-light absorption and high separation efficiency of photogenerated electron-hole pairs by Bi nanoparticles. This work presents a new approach for the development of Bi/BiVO4 composite photocatalysts with high activity and stability.

A new sandwich type transition metal complex based on tungstobismuthates and 1-methylimidazole ligands exhibiting photocatalytic properties

A new sandwich-type transition metal complex based on tungstobismuthates and 1-methylimidazole ligands Na7(mim)2[{Na(H2O)2}3{CoII(mim)}3(BiIIIWVI9O33)2]·9H2O (1) (mim = 1-methylimidazole) has been successfully isolated in aqueous solution. The composition and structure were established by the single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy. Single-crystal X-ray diffraction and TG analyses indicate that compound 1 consists of two tri-vacant [α-B-BiIIIWVI9O33]9- units linked through three cobalt ions. All the CoII ions were sandwiched in the middle and bonded with terminal oxo atoms from [α-B-BiIIIWVI9O33]9- units as well as 1-methylimidazoles. Photocatalytic experiment indicates that compound 1 exhibit good catalytic activities for photodegradation of RhB under UV irradiation.

Oxygen self-doped g-C3N4 with tunable electronic band structure for unprecedentedly enhanced photocatalytic performance.

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has attracted much attention for solving the worldwide energy shortage and environmental pollution. In this work, for the first time we report oxygen self-doping of solvothermally synthesized g-C3N4 nanospheres with tunable electronic band structure via ambient air exposure for unprecedentedly enhanced photocatalytic performance. Various measurements, such as XPS, Mott-Schottky plots, and density functional theory (DFT) calculations reveal that such oxygen doping can tune the intrinsic electronic state and band structure of g-C3N4via the formation of C-O-C bond. Our results show that the oxygen doping content can be controlled by the copolymerization of the precursors. As a consequence, the oxygen doped g-C3N4 shows excellent photocatalytic performance, with an RhB photodegradation rate of 0.249 min-1 and a hydrogen evolution rate of 3174 μmol h-1 g-1, >35 times and ∼4 times higher than that of conventional thermally made pure g-C3N4 (0.007 min-1 and 846 μmol h-1 g-1, respectively) under visible light. Our work introduces a new route for the rational design and fabrication of doping modified g-C3N4 photocatalyst for efficient degradation of organic pollutants and H2 production.

Photodegradation behavior of ZnO nanorods on various types of organic dyes

In this paper, the effectiveness of ZnO nanorods in degrading various types of organic dyes under UV irradiation was studied. ZnO nanorods were synthesized by solution precipitation method using zinc nitrate tetrahydrate and hexamethylenetetramine as precursors. The nanorods were hexagonal wurtzite ZnO as shown in XRD analysis. The sample displayed strong UV absorption attributed to its wide energy bandgap, i.e. 3.37 eV. The room temperature PL spectrum showed low UV emission with relatively strong visible emission, indicating the presence of large amount of defects in the ZnO nanorods. Three organic dyes, i.e. RhB, MB and MO, were degraded by ZnO nanorods via cycloreversion. The removal efficiencies of ZnO nanorods were 99.3, 96.6 and 74.1% for RhB, MB and MO dyes, respectively after 30 min of UV light (λ = 352 nm) irradiation. The photodegradation of RhB, MB and MO by ZnO nanorods followed the pseudo first-order kinetic reaction. It was proposed that the variation of photodegradation efficiencies by ZnO nanorods was due to the different types of bonding in various organic dyes.

Synthesis and enhanced photocatalytic activity of g- $$\hbox {C}_{3}\mathrm{N}_{4}$$ C 3 N 4 hybridized CdS nanoparticles

The highly effective g- $$\hbox {C}_{3}\hbox {N}_{4}$$ hybridized CdS photocatalysts were synthesized via a successive calcination and hydrothermal process. The as-prepared photocatalysts were characterized by X-ray powder diffraction, transmission electron microscopy and UV–Vis diffuse reflectance spectroscopy. The photocatalytic performance of the $$\hbox {C}_{3}\hbox {N}_{4}$$ /CdS nanocomposites was evaluated by the photodegradation of RhB under visible light irradiation. The results showed that photocatalytic ability of the $$\hbox {C}_{3}\hbox {N}_{4}$$ /CdS nanocomposites was higher than that of pure $$\hbox {C}_{3}\hbox {N}_{4}$$ and CdS. The enhanced photocatalytic activity could be attributed to the high separation efficiency of the photo-excited electron-hole pairs. A possible mechanism of the photocatalytic degradation of RhB on $$\hbox {C}_{3}\hbox {N}_{4}/$$ CdS nanocomposites was also proposed.

Atomic layer deposited TiO2 ultrathin layer on Ag_ZnO nanorods for stable and efficient photocatalytic degradation of RhB

Highly stable and active TiO2-coated Ag-modified ZnO nanorods supported on stainless steel mesh (xTi@Ag_ZnO-SS) were successfully synthesized in this work. A low-temperature one-pot hydrothermal method was used to grow Ag_ZnO on stainless steel mesh, and subsequently, an atomic layer deposition (ALD) technique was applied to deposit a TiO2 layer on the surface of Ag_ZnO-SS. The addition of Ag-enhanced photoactivity via favored charge carrier transfer and the TiO2 layer improved stability through suppressed corrosion under UV irradiation, which was demonstrated by cycling performance for RhB photodegradation in two aspects: morphology and photoactivity. After 10 cycles (2 h/cycle) RhB degradation tests under UV irradiation, all the TiO2-protected ZnO materials maintained more intact nanorods structure and more than 80% of the initial photoactivity in the 1st cycle, whereas the ZnO materials without TiO2 coating were drastically deconstructed and only had 56% of initial photodegradation ability. Comprehensive study indicated that thicker TiO2 layers resulted in higher stability but lower photoactivity due to the inhibited charge transfer. The developed TiO2@Ag_ZnO nanorods immobilized on stainless steel mesh demonstrated a promising strategy for the design of highly stable and active photocatalysts endowed with great industrial scalability and practicality.

Facile synthesis of graphitic C3N4 nanoporous-tube with high enhancement of visible-light photocatalytic activity

A simple and convenient method was used to synthesize a graphitic carbon nitride (g-C3N4) nanoporous-tube by using SiO2 nanoparticles as pore formers. The structure of the g-C3N4 nanoporous-tube was characterized by the SEM and TEM images. Taking photodegradation of RhB as an example, the photocatalytic activity of the as-prepared g-C3N4 nanoporous-tube was investigated. It can photodegrade 90% RhB in 40 min under visible-light irradiation and obtain a k value of 0.04491 min−1, which is 8.16 times that of bulk g-C3N4, 3.09 times that of tubular g-C3N4 and 1.48 times that of tubular g-C3N4-SiO2. The significant enhancement in photocatalytic efficiency is due to the edge effect of the pores and the special structure of the tubes. In addition, the possible mechanism of photocatalytic degradation of RhB was also proposed based on the trapping experiment of active species, which indicated that the superoxide radicals () and the holes (h+) were the main reactive species in this photocatalyst. This work may open up a new idea of innovation in g-C3N4 structure and inspire its follow-up study.

Conjugated microporous polymers bearing metallophthalocyanine moieties with enhanced visible-light photocatalytic activity

A series of metallophthalocyanine-based conjugated microporous polymers (MPc-CMPs, M = Co, Cu, Zn) were synthesized and used for the photodegradation of organic pollutants for the first time. The as-obtained MPc-CMPs were characterized by UV-vis spectroscopy, Fourier transform infrared spectra (FTIR), scanning electron microscope (SEM). Their photocatalytic activities were assessed by the photodegradation of RhB in the presence of H2O2 under visible light irradiation. Moreover, the possible mechanism to predict this reaction pattern was proposed. As a result, the as-obtained MPc-CMPs, especially CoPc-CMP, exhibit excellent photocatalytic efficiency, recyclability and stability. These results indicate that the MPc-CMPs are potentially applicable in the environmental purification of organic pollutants in the industrial wastewater.

Ultrathin graphene oxide encapsulated in uniform MIL-88A(Fe) for enhanced visible light-driven photodegradation of RhB

It is very important to design excellent heterojunction structure for the improvement of the photocatalytic performance. In this study, we report a facile approach of polymerizing the ultrathin graphene oxide on the surface of the MIL-88A(Fe) to form MIL-88A(Fe)/grapheme oxide composite for enhancing the photocatalytic efficiency of organic molecules degradation. The optical grapheme oxide doping content in MIL-88A(Fe)/grapheme oxide hybrid is determined to be 9.0 wt%，which increases the surface area of the MOFs from 15.9m2g−1 to 408.9m2g−1 due to the emerging micropores, and the corresponding photocatalytic rate for RhB is 8.4 times higher than that of pure MIL-88A(Fe). Meanwhile, DMF-free MOF-based heterostructure could avoid secondary contamination in the photocatalytic application process, and the degree of RhB removal is maintained at about 100% after the five cycles of the reaction. Integrating the related electrochemical analysis and the active species trapping experiments, the decisive factors for the improved photocatalytic efficiency of MIL-88A(Fe)/grapheme oxide may be the unique structural advantages of ultrathin grapheme oxide sheets, compact and uniform interface contact, more adsorption sites and more reaction sites. This work provides a novel sight for preparing high-efficient and environment-stable photocatalysts by designing the surface heterojunction structure.

Hydrothermal synthesis of Sm-doped Bi2MoO6 and its high photocatalytic performance for the degradation of Rhodamine B

Serials Sm doped Bi2MoO6 photocatalyts with different Sm contents (xSm-Bi2MoO6, x% = 0.0%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%) were prepared via hydrothermal method to improve the photocatalytic performance of pure Bi2MoO6. The samples are characterized by XRD, XPS, SEM, TEM, HRTEM, and PL techniques. It indicates that Sm3+ ions were successfully doped into Bi2MoO6, and the band gap value was gradually decreased with Sm dopant concentration increasing. The photocatalytic activity of Sm-doped Bi2MoO6 photocatalyst was significantly affected by the Sm doping content. Compared to pure Bi2MoO6, the Sm-doped Bi2MoO6 samples exhibited much higher photocatalytic activity and 0.8% Sm-doped Bi2MoO6 shows the highest RhB photodegradation rate, being 89% in 50 min under visible light irradiation. The improved photocatalytic activity of Sm-doped Bi2MoO6 could be attributed to the enhanced visible light absorption, narrower band gaps and higher separation rate of electron-hole pairs derived from Sm trapping photogenerated electrons. But the phase structure, special surface areas and morphology have little effects on the higher photocatalytic activity of Sm-doped Bi2MoO6.

Bismuth terephthalate induced Bi(0) for enhanced RhB photodegradation and 4-nitrophenol reduction

A facile reductive method was used to prepare the semimetal Bi(0) through reacting Bi(NO3)3 with NaI. The Bi(0) incorporated bismuth terephthalate hybrids were prepared from two different strategies with enhanced visible light photodegradation of RhB and reduction of 4-nitrophenol. The synergistic interaction between layered bismuth terephthalate and Bi(0) with SPR effects could induce the effective separation of photogenerated electrons and holes that leading to the enhancement of their oxidation performance. In the reduction of 4-nitrophenol, bismuth terephthalate may act as an excellent supporter and as a precursor which in situ produces the semimetal Bi(0). The Bi(0) incorporated bismuth terephthalate reported in this work can be potentially applied in visible light photooxidation and reduction of organic compounds.

Hydrothermal synthesis of g-C3N4/Ag2MoO4 nanocomposites for improved visible light photocatalytic performance

Novel graphitic carbon nitride/silver molybdat (g-C3N4/Ag2MoO4) nanocomposites with different weight contents of g-C3N4 have been successfully synthesized by a hydrothermal synthesis method. The as-obtained nanocomposites were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic performance of g-C3N4/Ag2MoO4 nanocomposites for the photodegradation of RhB was better than that of the pristine g-C3N4 and Ag2MoO4 under visible light irradiation. The experiment results showed that the 80% g-C3N4/Ag2MoO4 nanocomposites exhibited the optimal photocatalytic performance. The probable mechanism of the improved photocatalytic performance by synergy effect between g-C3N4 and Ag2MoO4 was investigated systematically.