Visible-light Photocatalytic Ability Research Articles

Effect of rGO content on enhanced Photo-Fenton degradation of Venlafaxine using rGO encapsulated magnetic hexagonal FeTiO3 nanosheets

In this work, we synthesized magnetic reduced graphene oxide (rGO) encapsulated hexagonal FeTiO3 (FTO@rGO) nanosheets with rGO loading amount of 0, 1, 5 and 10 wt%, with a primary objective of efficiently degrading venlafaxine (VLF) through photo-Fenton processes across a wide pH range of 3–11. The inherent visible-light photocatalytic ability of ilmenite FeTiO3 (FTO) and catalytic activation of H2O2 by Fe sites during the photo-Fenton process were established. Through the strategic integration of rGO, all FTO@rGO catalysts show higher VLF degradation rate than FTO in photo-Fenton evolution experiments and the FTO@rGO catalysts with rGO loading amount of 5 wt% presents the highest VLF degradation rate (100 % VLF degradation at 90 min), which attributed to the accelerated migration of photo-generated electrons and the efficient Fe2+/Fe3+ cycle. Furthermore, the encapsulation of rGO significantly mitigated Fe leaching throughout the reaction pH range, directing H2O2 activation to occur at the FTO@rGO interface instead of in solution. Through a comprehensive analysis, we identified 47 intermediate products of VLF and deduced the degradation pathway based on 12 representative intermediates. The degradation process was primarily driven by hydroxyl radicals as the dominant reactive oxygen species, complemented by the contribution of superoxide radicals, photogenerated electrons, and holes during the FTO@rGO-catalyzed photo-Fenton process. This study not only expands the application of ilmenite in the realm of advanced oxidation processes (AOPs) but also provides valuable insights for the future exploration and development of metal oxide/carbonaceous heterostructure catalysts.

Nitrogen-Doped Graphene Quantum Dot-Passivated δ-Phase CsPbI3: A Water-Stable Photocatalytic Adjuvant to Degrade Rhodamine B.

Inorganic halide perovskite CsPbI3 is highly promising in the photocatalytic field for its strong absorption of UV and visible light. Among the crystal phases of CsPbI3, the δ-phase as the most aqueous stability; however, directly using it in water is still not applicable, thus limiting its dye photodegradation applications in aqueous solutions. Via adopting nitrogen-doped graphene quantum dots (NGQDs) as surfactants to prepare δ-phase CsPbI3 nanocrystals, we obtained a water-stable material, NGQDs-CsPbI3. Such a material can be well dispersed in water for a month without obvious deterioration. High-resolution transmission electron microscopy and X-ray diffractometer characterizations showed that NGQDs-CsPbI3 is also a δ-phase CsPbI3 after NGQD coating. The ultraviolet-visible absorption spectra indicated that compared to δ-CsPbI3, NGQDs-CsPbI3 has an obvious absorption enhancement of visible light, especially near the wavelength around 521 nm. The good dispersity and improved visible-light absorption of NGQDs-CsPbI3 benefit their aqueous photocatalytic applications. NGQDs-CsPbI3 alone can photodegrade 67% rhodamine B (RhB) in water, while after compositing with TiO2, NGQDs-CsPbI3/TiO2 exhibits excellent visible-light photocatalytic ability, namely, it photodegraded 96% RhB in 4 h. The strong absorption of NGQDs-CsPbI3 in the visible region and effective transfer of photogenerated carriers from NGQDs-CsPbI3 to TiO2 play the key roles in dye photodegradation. We highlight NGQDs-CsPbI3 as a water-stable halide perovskite material and effective photocatalytic adjuvant.

1D Bi2S3 nanorods modified 2D BiOI nanoplates for highly efficient photocatalytic activity: Pivotal roles of oxygen vacancies and Z-scheme heterojunction

• Novel Bi 2 S 3 /Bi 5 O 7 I porous hierarchical network-like Z-scheme heterojunctions with abundant OVs were prepared via an in-situ ion exchange etching method. • BSBI NHs were consisted of internal BiOI nanoplates and outside networks orderly interwoven by Bi 2 S 3 nanorods. • BSBI NHs displayed a significantly improved visible-light photocatalytic ability. • The construction of Z-scheme heterojunction and massive OVs resulted in the efficient separation of photogenerated charge carriers. • ∙OH, ⋅O 2 − and h + played primary roles during the photocatalytic process. In this study, a novel Bi 2 S 3 /BiOI Z-scheme photocatalyst with 3D porous hierarchical network-like heterostructure (BSBI NHs) and rich oxygen vacancies (OVs) was fabricated by a facile ion exchange method followed by the in-situ growth process. A possible formation mechanism of BSBI NHs was studied, showing the self-assembled process of in-situ interwoven growth of 1D Bi 2 S 3 nanorods (NRs) on the surface of 2D BiOI disk-like nanoplates (NPs), which followed the Ostwald ripening and epitaxial growth. The modification of BiOI NPs by Bi 2 S 3 NRs brought about the formation of Z-scheme heterojunction and massive OVs, which improved the visible-light response property and promoted the separation of photoexcited charge carriers of BSBI NHs. BSBI NHs exhibited a significantly enhanced photocatalytic activity compared with Bi 2 S 3 and BiOI, and BSBI-1 can remove almost all bacteria and Rhodamine B (RhB) after 60 min visible light illumination. In addition, the photocatalytic mechanism was studied and speculated based on the tests of active species capture, electron spin resonance (ESR), and density functional theory (DFT) simulation calculation, proving the primary roles of ∙OH, ·O 2 – , and h + during the photocatalytic reaction. This work provides new insights into the design and exploitation of novel heterojunctions with highly efficient photocatalytic performances for environmental remediation applications.

Effective CO2 Capture and Selective Photocatalytic Conversion into CH3OH by Hierarchical Nanostructured GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg.

The attenuation of greenhouse gases, especially CO2, as one of the main causes of global warming and their conversion into valuable materials are among the challenges that must be met in the 21st century. For this purpose, hierarchical ternary and quaternary hybrid photocatalysts based on graphene oxide, TiO2, Ag2O, and arginine have been developed for combined CO2 capture and photocatalytic reductive conversion to methanol under visible and UV light irradiation. The material's band gap energy was estimated from the diffuse reflectance spectroscopy (DRS) Tauc analysis algorithm. Structural and morphological properties of the synthesized photocatalysts were studied using various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The calculated band gaps for GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg were 3.18 and 2.62 eV, respectively. This reduction in the band gap showed that GO-TiO2-Ag2O-Arg has a significant visible light photocatalytic ability. The investigation of CO2 capture for the designed catalyst showed that GO-TiO2-Ag2O-Arg and GO-TiO2-Ag2O have high CO2 absorption capacities (1250 and 1185 mmol g-1, respectively, at 10 bar and 273 K under visible light irradiation). The amounts of methanol produced by GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg were 8.154 and 5.1 μmol·gcat1·h-1 respectively. The main advantages of this study are the high efficiencies and selectivity of catalysts toward methanol formation. The reaction mechanism to understand the role of hybrid photocatalysts for CO2 conversion is deliberated. In addition, these catalysts remain stable during the photocatalytic process and can be used repeatedly, proving to be enlightening for environmental research.

Trash to treasure: Green synthesis of novel Ag2O/Ag2CO3 Z-scheme heterojunctions with highly efficient photocatalytic activities derived from waste mussel shells

Shells, valuable renewable natural resources with particular mechanical properties and structures, are mostly abandoned as waste and accumulated in environment, leading to serious pollution and resource waste. To realize the high value reutilization and environmental protection, here, novel Ag-based photocatalysts were in-situ fabricated via a facile ball milling method using waste mussel shells as precursors for the first time. The composition, structure and photocatalytic activity of the obtained Ag-based photocatalysts can be regulated by the alkalinity of the reaction system caused by different treatments towards mussel shells. Among the obtained products, the Ag2O/Ag2CO3 Z-scheme heterojunctions with massive oxygen vacancies displayed the strongest visible-light photocatalytic ability and superior reusability in degrading sulfadiazine, which can be attributed to the wider light response region and faster separation of photoinduced charge carriers. Besides, the photocatalytic mechanism was speculated according to the tests of radicals trapping, electron spin resonance and simulation calculations, verifying the charge transfer direction and chief roles of ·O2− and h+ during the photocatalytic reaction. Above all, this study not only provides a convenient in-situ solid-state strategy to construct novel Ag-based photocatalysts with excellent photocatalytic activity, but also opens up a new perspective towards high value reutilization of waste shells in environmental remediation, “One Stone Two Birds” realizing the “control of waste by waste” and “trash to treasure”.

Fabricating effective heterojunction in metal-organic framework-derived self-cleanable and dark/visible-light dual mode antimicrobial CuO/AgX (X = Cl, Br, or I) nanocomposites

Owing to the alarming consequences of antimicrobial resistance, the requirements for effective antimicrobial materials working under dark and visible-light conditions are on the high rise. On a different note, heterojunctions between semiconductors are highly desirable to enhance the photocatalytic activity of the individual components in a synergistic way. In this work, we address these two aspects in a single material composition through a rationally designed synthetic strategy. Among several candidates, silver and copper are known to exhibit high antimicrobial characteristics in the dark. Besides, CuO and silver halides are known for their visible-light photocatalytic activity. Hence, a copper-based porous metal organic framework, Cu-BTC, has been deposited with a silver halide followed by calcination to yield CuO/AgX (X = Cl, Br, or I) nanocomposites. The initial deposition of the silver halide over the MOF is envisaged to provide a high dispersion of the halide in the CuO matrix through numerous anchoring pods and thereby result in a tight and effective heterojunction. The nanocomposites obtained through this approach have been characterized structurally and morphologically using various techniques. The nanocomposites have been studied for their visible-light photocatalytic and self-cleaning ability via photodegradation of methylene blue and 4-chlorophenol as model systems. Further, their antimicrobial efficacy has been studied against E. coli and S. aureus both under dark and visible-light conditions. In addition to revealing the high potential of the CuO/AgX nanocomposites towards environmental applications, the synthetic approach presented herein can potentially be extrapolated to fabricate exotic compositions possessing enhanced efficacy.

UiO-66 with confined dyes for adsorption and visible-light photocatalytic reduction of aqueous Cr(VI)

• Dye molecules confined in MOFs for continuous and stable photosensitization in a photocatalytic reaction. • Photocatalytic reduction of Cr(VI) in water at neutral pH without any sacrificial reagent. • Adjustment on surface electrostatic properties of UiO-66 by dye confinement and loading of Pt nanoparticles. • A simple and feasible method to enhance the visible-light photocatalytic ability of a MOF. Dye sensitization is an important method to improve the visible-light response of a photocatalyst. In order to obtain stable dye-sensitized MOF photocatalysts, UiO-66 with confined rhodamine B (RhB) and eosin Y (EY) dye were prepared by simply adding dyes in the synthetic process in this work. In comparison with pristine UiO-66, the obtained RhB@UiO-66 and EY@UiO-66 can not only adsorb Cr(VI) from water more effectively, but also enhance the photocatalytic reduction of Cr(VI) to Cr(III) at a neutral pH under visible-light without adding any sacrificial agent. Thus, they both achieved an overall Cr(VI) removal rate of about 99%. The loading of Pt nanoparticles can further improve the photocatalytic abilities of RhB@UiO-66 and EY@UiO-66. The highest photocatalytic removal rate of Cr(VI) over Pt/RhB@UiO-66 is 66.4%. The confinement of the dyes and the loading of Pt nanoparticles largely changed the surface electrostatic properties of UiO-66. The adsorption process of Cr(VI) was therefore affected. Meanwhile, Pt nanoparticles greatly improved the utilization efficiency of photogenerated electrons.

Sonochemical synthesis and characterization of Cu2HgI4 nanostructures photocatalyst with enhanced visible light photocatalytic ability

These days, an important concern in water contamination is the remaining dyes from various sources (for instance, dye and dye intermediates industries, pulp and paper industries, textile industries, craft bleaching industries, tannery, and pharmaceutical industries, etc.), and a broad range of persistent organic contamination has been entered to the wastewater treatment systems or natural water supplies. Indeed, it is extremely hazardous and toxic to the living organism. Therefore, it is necessary to remove these organic pollutants before releasing them into the environment. Photocatalysis is a quickly growing technology for sewage procedures. For this purpose, Cu2HgI4 nanostructures were prepared via facile, and cost-effective sonochemical method. The effect of varied circumstances, such as various surfactants, sonication power, and sonication time was considered on the crystallinity, structure, shape, and particle size of products. Cu2HgI4 possesses a suitable bandgap (2.2 eV) in the visible area. The photocatalytic performance of the Cu2HgI4 was surveyed for the elimination of various organic dyes under visible radiation and exposed that this compound could degrade and remove methyl orange about 94.2% in an acidic medium after 160 min under visible light. Besides, the result showed that various parameters, including, pH, dye concentration, types of dyes, catalyst dosages, and time of irradiation affected the photocatalytic efficiency.

N-C3n4/Bioclxi1-X S-Type Heterojunction with Enhance Internal Electric Field and Stretching Spatial Charge Separation for Visible Light Photocatalytic Ability

N-C3n4/Bioclxi1-X S-Type Heterojunction with Enhance Internal Electric Field and Stretching Spatial Charge Separation for Visible Light Photocatalytic Ability

Study of N-doping in (Bi2MoO6, MoO3)/SnOx:N photocatalys in the degradation of RhB using visible light

Novel composites operating in visible light (VL) energy are an important issue in photon excited system. The (Bi2MoO6, MoO3)/SnO[Formula: see text]:N composite photocatalysts were prepared by the one-step spray pyrolysis method. The effect of N-doping in SnO[Formula: see text] layer with controlled N/Sn ratio in precursor to the photocatalystic ability of the composite was studied. The photocatalytic ability of the composites was evaluated by photodegradation of Rhodamine B (RhB) under visible-light emitting diode illumination. The composites were characterized by film optical absorption analysis, X-ray diffraction and scanning electron microscopy. Film with suitable N-doping shows the improved visible-light photocatalytic ability with rate constant 0.019 min[Formula: see text]. With the electrical property of SnO[Formula: see text]:N films and the scavenger analysis of the composites, the photocatalytic mechanism was discussed.

Zr-Porphyrin Metal–Organic Framework-Based Photocatalytic Self-Cleaning Membranes for Efficient Dye Removal

The self-cleaning ability and reusability of a membrane are critical in practical applications because they can severely affect the lifespan and the separation efficiency of the membranes. In this work, hydrophilic Zr-porphyrin metal–organic frameworks (MOFs) with different dimensions (2D or 3D) were embedded in the polyamide active layer to develop a self-cleaning membrane with enhanced separation performance. Zr-porphyrin MOF (3D) with excellent photocatalytic activity and uniform 1D open triangular channels can not only endow this membrane with visible-light photocatalytic ability for the degradation of organic dyes deposited on the membrane surface but also provide additional transport channels leading to a high membrane permeate flux. The optimum membrane exhibits a superior water permeate flux of 110.4 L m–² h–¹ (threefold higher than the pristine thin-film composite membrane) while maintaining very high dye rejection (close to 100%) for five dyes (anionic dyes: Congo red, Direct red 23, and Reactive Black 5 and cationic dyes: methylene blue and rhodamine B) and an outstanding photocatalytic degradation self-cleaning ability (the recovery of water permeate flux exceeds 97% after 4 cycles). Overall, this study may offer new inspiration for designing and tuning Zr-porphyrin MOF-based self-cleaning membranes with excellent dye removal ability.

Acidification of potassium bismuthate for enhanced visible-light photocatalytic degradation ability: An effective strategy for regulating the abilities of adsorption, oxidation, and photocatalysis

In this work, a facile and effective strategy for improving the degradation ability of potassium bismuthate (KBiO3) was first proposed by using HNO3 acidification. The degradation ability of methylene blue (MB) by untreated and acidified KBiO3 was systematically investigated under both dark and light conditions. Under light condition, KBiO3 exhibited physical adsorption, chemical oxidation, and photocatalysis abilities during the MB degradation. Compared with KBiO3-0, the apparent reaction rate constant of KBiO3-1.0 (c(HNO3)/c(KBiO3) = 1.0) increased by 7.04 times. The specific surface area increased by 2.94 times. In-situ EPR demonstrated that the generation of singlet oxygen (1O2) was gradually increased with increasing acid addition, which promoted the oxidation degradation of MB. Moreover, according to the photocurrent, EIS, and PL spectra measurements, the separation efficiency of photogenerated electrons and holes was significantly enhanced, indicating the improved photocatalysis ability of KBiO3. This work provides a deep understanding into the regulation of adsorption, oxidation, and photocatalysis abilities of bismuthate.

Integration of oxygen vacancy rich-TiO2 with BiOI and Ag6Si2O7: Ternary p-n-n photocatalysts with greatly increased performances for degradation of organic contaminants

Photocatalysis process is a prominent approach for the degradation of organic contaminants. However, the swift recombination of charge carriers commonly limits the photoactivity. Hence, to create a suitable nanocomposite for removal of pollutants, BiOI and Ag6Si2O7 particles were anchored on the oxygen vacancy rich-TiO2 (abbreviated as OVs-TO) through a simple approach to construct the OVs-TO/BiOI/Ag6Si2O7 nanocomposites. Then, various structural features of the systems were assayed with different characterization tools. It was found that the photocatalyst with 20 wt% and 30 wt% of BiOI and Ag6Si2O7 exhibits the excellent performance in removal of RhB, which are about 194, 18.1, and 9.59-times higher than the TiO2 (abbreviated as TO), OVs-TO, and OVs-TO/BiOI (20 %) nanomaterials, respectively. This supreme improved photodegradation activity was allocated to the formed p-n-n heterojunctions between the semiconductors, impressive segregation of charges, significant visible-light absorption of OVs-TO, BiOI, and Ag6Si2O7, and textural enhancement. A suitable mechanism was also offered through the outcomes of Mott-Schottky and the quenching experiments. This research work illustrated that the ternary p-n-n photocatalyst could be efficacious for ameliorating the visible-light photocatalytic ability for environmental and energy applications.

Novel strategy for membrane biofouling control in MBR with CdS/MIL-101 modified PVDF membrane by in situ visible light irradiation

Novel control strategies for membrane biofouling with eco-friendly photocatalytic technology are critically needed in practical operation of membrane bioreactors (MBRs). In this study, a metal-organic frameworks (MOF) based photocatalytic membrane was firstly applied in an anammox MBR for a long-term biofouling control, where bacteria were inactivated and foulants were degraded simultaneously, with environmentally friendly and renewable visible light energy. By physicochemical characterization, the synthesized photocatalyst of CdS/MIL-101 showed superior visible-light photocatalytic ability, and the 1 wt% CdS/MIL-101 modified membrane C2 showed enhanced hydrophilicity and water permeability compared with the pristine membrane C0. In the long-term operation of anammox MBRs under waterproof lights irradiation, the filtration cycles of C2 (25–26 d) were obviously extended compared with C0 (10–14 d), while their average total nitrogen removal efficiencies were comparable up to 84%, indicating an excellent biofouling alleviation effect by using C2 with a satisfactory nitrogen removal performance maintained. By analysis of the biofilm on the fouled membranes, the organic foulants (especially extracellular polymeric substances) were degraded, and the live bacteria were inactivated effectively by the photocatalytic reactions of CdS/MIL-101 on C2. In the antimicrobial tests against model bacteria, C2 exhibited remarkable antimicrobial effect against both Gram-negative and Gram-positive bacteria with visible light irradiation by destruction of cell integrity with the inhibition rate of 92% for Escherichia coli and 95% for Staphylococcus aureus, respectively. In the model foulants (bovine serum albumin, sodium alginate, and humic acid) filtration tests, C2 showed higher antifouling capabilities, lower flux declining rates, and higher foulants rejection rates under visible light irradiation compared with C0. The reactive species of ·OH, e– and h+ generated on C2 were verified to play the predominant role in the anti-biofouling processes by simultaneous bacteria inactivation and foulants degradation. The findings offer a novel insight into the biofouling controlling in MBRs by simultaneous bacteria inactivation and foulants degradation with an eco-friendly method.

Novel Au@C modified g-C3N4 (Au@C/g-C3N4) as efficient visible-light photocatalyst for toxic organic pollutant degradation: Synthesis, performance and mechanism insight

Tailoring economical g-C3N4-based composites with efficient visible-light photocatalytic degradation ability have received great attention. In this study, a novel and efficient visible-light photocatalyst, Au nanoparticles doped porous carbon modified g-C3N4 (Au@C/g-C3N4), was synthesized using thermal polycondensation method. The crystal, morphological and photoelectrical characterizations verified the successful synthesis of Au@C/g-C3N4 hybrid and it had larger specific area and narrower band gap than that of pure g-C3N4. The optimal Rhodamine B (RhB) photocatalytic oxidation performance (94.3%) and mineralization rate (50.7%) were obtained by Au@C/g-C3N4-2 composite at 1.0 g L−1 catalyst dosage and pH of 5.0, which was 3.23 and 2.96 times, respectively than that of g-C3N4 at the same conditions. Au@C/g-C3N4-2 also maintained satisfactory RhB degradation efficiency (70.7%) after 4 consecutive photocatalytic cycles. Mechanism analyses indicated that the significantly improved photocatalytic activity of Au@C/g-C3N4 composite mainly attributed to the rapid separation and migration of charge carriers via the interfacial interaction between the Au@C and g-C3N4, which resulted in the accelerated O2− generation for organic pollutants oxidation. In general, this study supplied a novel strategy for efficient g-C3N4 visible-light photocatalysts construction, and further clarified its plausible visible-light photocatalytic mechanism.

A novel ternary Pd-GO/N-doped TiO2 hierarchical visible-light sensitive photocatalyst for nanocomposite membrane

We investigated the visible-light sensitive photocatalytic ability of a designed ternary Pd-GO/TiON nano-composite for use as an effective photocatalyst in membranes. We succeeded in synthesizing the TiO2-based photocata-lyst for Suzuki coupling reaction and application of this photocatalyst for fabricating high performance photocatalytic membrane. In this regard, palladium metal as a complementary metal in combination with N-doped TiO2 (TiON) and graphene oxide (GO) nanosheets was utilized to synthesize the upgraded version of the visible light sensitive nanocom-posite photocatalyst. The synthesis of Pd-GO/TiON hierarchical nanostructure was confirmed by detecting Ti, Pd, C, O and N elements by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and EDX mapping analysis. Then, a series of PVDF-based photocatalytic nanocomposite membranes (PhNMs) filled with Pd-GO/TiON was fabricated. Evaluating the yield of Pd-GO/TiON photocatalyst was around 99% and 70% for heterogeneous system and the prepared PhNM containing 3% Pd-GO/TiON, respectively. Although, yield of Pd-GO/TiON photocatalyst in membrane is not comparable with the high yield reported by other researchers in heterogeneous system; however, it can be considered as a valuable result because of the importance of photocatalytic reactions and the environmental advantages of membrane technology. Furthermore, various analyses were also performed to study the synthesized photocata-lysts and the prepared photocatalytic membranes, including thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and diffuse reflectance spectrophotometry (DRS).

G–C3N4– and polyaniline-co-modified TiO2 nanotube arrays for significantly enhanced photocatalytic degradation of tetrabromobisphenol A under visible light

An ordered g–C3N4– and polyaniline-modified titanium oxide nanotube array (g–C3N4– and PANI-co-modified TiO2 NTAs) was successfully synthesized and used as a photocatalyst. Polyaniline (PANI) was coated onto TiO2 NTAs by electrochemical polycondensation, and g-C3N4 was deposited via the soaking adsorption method. The photocatalysts were examined by several technologies. The experiments demonstrated that the amount of g-C3N4 and PANI, as well as the initial pH value, had significant effects on the photocatalytic efficiency. The resulting photocatalysts exhibited high visible light photocatalytic ability for tetrabromobisphenol A (TBBPA) for two reasons. First, PANI expanded the light absorption into the visible region. Second, rapid and efficient separation of photoinduced charges from the photogenerated potential difference were produced at the contact interface of g-C3N4 and PANI-co-modified TiO2 NTAs. The •OH, •O2− and h+ were dominant components for the photocatalytic degradation of TBBPA. In addition, the g-C3N4 and PANI-co-modified TiO2 NTAs have excellent long-term stability.

Synthesis of 1D Bi12O17ClxBr2−x nanotube solid solutions with rich oxygen vacancies for highly efficient removal of organic pollutants under visible light

With a view to balancing light absorption and redox capabilities, narrowing band gap and adjusting bandgap structure, a novel tubular Bi12O17ClxBr2−x (BCxB2−x) solid solution structure was fabricated using a facile polyvinylpyrrolidone K30 assisted solvothermal strategy. Photocatalytic degradation experiments were conducted under visible light, utilizing tetrachlorobiphenyl A (TCBPA) as the target pollutant. Within 120 min of irradiation, the Bi12O17ClBr (BCB) solid solution nanotubes exhibited approximately 92.8 % TCBPA degradation efficiency. Moreover, the active radical trapping experiments and electron spin resonance measurements show that superoxide and hydroxyl radicals play important roles. Importantly, BCB solid solution photocatalysts have a stable crystal structure and good recycling ability after five cycles of photodegradation. The work presents a feasible synthesis method for the design of solid solution materials and introduction of oxygen vacancies to improve visible-light photocatalytic ability for the treatment of environmentally refractory organic pollutants.

Facile preparation of a novel Bi24O31Br10/nano-ZnO composite photocatalyst with enhanced visible light photocatalytic ability

In this wok, a novel Bi24O31Br10/nano-ZnO composite photocatalyst has been synthesized with solvothermal method. The photocatalytic ability of the composite photocatalyst is estimated through degrading Rhodomine B (RhB) under visible light. The RhB degradation rate exceeds 90% in 40 min for the Bi24O31Br10/nano-ZnO (5%) composite, showing the most remarkable photocatalytic abilities. The excellent photocatalytic performance can be explained by the successful detachment and motion of photo-induced electrons (e−) and holes (h+) in the composite photocatalyst. Additionally, a probable photo-catalytic principle of the Bi24O31Br10/nano-ZnO composite for RhB degradation is discussed. This study could provide an original visible light driven photocatalyst on efficiently purifying dye wastewaters.

First-principles study on the optical spectra of ZrO2 crystal with oxygen vacancy

In this paper, we present the optical spectra of the ZrO2 crystal containing oxygen vacancy based on the Density Functional Theory (DFT). The finite-size correction scheme (FNV) is employed to eliminate the artificial interactions and correct the defect formation energy of oxygen vacancies with three different charges (0, +1, +2). Besides, we use hybrid density functionals to relieve the band edge problem. Finally, we obtain the optical spectra for the F center and F[Formula: see text] center containing the electron–phonon coupling. The absorption peak of F center of threefold coordinate oxygen vacancy (V[Formula: see text]) near 446 nm (2.78 eV) agrees well with the experimental value (2.83 eV), which can enhance the visible light photocatalytic ability of ZrO2. The luminescence peak of the F[Formula: see text] center of fourfold coordinate oxygen vacancy (V[Formula: see text]) is 561 nm (2.21 eV), which is close to the experimental value (2.5 eV).