BiOI Nanoplates Research Articles

A novel method for preparing BiOI nanoplates and their use as precursors to synthesize porous BiVO4 water oxidation photocatalysts.

In this work, we report an innovative method for synthesizing BiOI nanoplate powder by a slow basification of an aqueous solution constituted of Bi(NO3)3 and KI. The basification was done with NH3 vapor which was naturally generated on top of an NH4OH solution kept in a closed space. The impact of the basification rate on the morphology and crystallinity of the BiOI product was investigated. Herein, we also report on the use of newly produced BiOI nanoplate powder together with the VO(acac)2 precursor for fabricating BiVO4 photoanodes for solar driven water splitting applications. We also discuss how the morphology of BiOI nanoplates and their orientation on a fluorine doped tin oxide substrate will affect the morphology, topology and photocatalytic performance of the electrode. The BiVO4 photoanode showed a photocatalytic current density of 0.55 mA cm-2 at 1.23 V vs. the Reversible Hydrogen Electrode (RHE) when assayed in a pH 7 phosphate buffer electrolyte and under 1 sun illumination.

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.

Double charge transfer mechanistic insights into the tailoring of BiOI nanoplates and boron-doped graphitic carbon nitride: a 2D/2D anchored p–n heterojunction nanocatalyst for improved photodegradation

The article highlights the synthesis of a nanocomposite BiOI/BCN-xthat aims to degrade toxic organic pollutants from wastewater bodies. Mechanistic insights incorporating dual charge transfer have been envisioned for boosted photoactivity.

Catechol exerts an in situ surface oxygen vacancy effect on BiOI: an innovative signal transduction mode for cathodic photoelectrochemistry.

Cathodic photoelectrochemistry, a research hotspot in state-of-art bioassays, is generally circumscribed by its monotonous signal transduction tactic of photoinduced electron transfer (PET) mechanism, which significantly narrows the scope of its applications. In this study, we reveal the surface oxygen vacancy (VO) formation elicited by the spontaneous coordination of catechol (CA) onto the surface of BiOI nanoplates for the innovative operation of the cathodic PEC signal transduction tactic. The in situ-generated VO functions as a carrier separation center to efficiently promote photocurrent generation. Taking tyrosinase (TYR) and Escherichia coli O157:H7 (E. coli O157:H7) as model targets, the established signal transduction tactic was validated as efficient and sensitive for the detection of the two targets with linear ranges from 1.0 × 10-4 to 1.0 U mL-1 and 5.0 to 1.0 × 106 CFU mL-1, respectively. Low-detection limits of 1.0 × 10-4 U mL-1 and 3.0 CFU mL-1 were achieved for TYR and E. coli O157:H7, respectively. This study opens up a new perspective of in situ generated surface VO on semiconductors, which underlies an innovative PEC signal transduction mechanism with convincing analytical performance. Hopefully, it might encourage more explorations of new methodologies for introducing surface vacancies with exquisite applications.

In-situ-construction of BiOI/UiO-66 heterostructure via nanoplate-on-octahedron: A novel p-n heterojunction photocatalyst for efficient sulfadiazine elimination

Sulfadiazine (SDZ), as a broad-spectrum pharmaceutical antibiotic, has drawn extensive attention owing to its wide application and persistence. Photocatalytic oxidation has been considered as a high-efficiency and environment-friendly technology for degrading organic contaminants. A novel BiOI/UiO-66 p-n heterojunction (BiU-x) was fabricated via the in-situ deposition of p-type BiOI nanoplates on n-type UiO-66 octahedrons with the aid of a controlled precipitation method. The optimizing BiU-9 heterojunction exhibited a remarkably enhanced photocatalytic efficiency in removing SDZ, in which the SDZ (5 mg/L) removal efficiency over BiU-9 (0.5 g/L) reached nearly 100 % within 90 min of visible light irradiation. The influence of some important environmental factors (e.g., photocatalyst dosage, pH, co-existing inorganic anions and real sunlight irradiation) were systematically investigated. Such improvement mechanism should be assigned to the following three factors. Firstly, the introduction of narrow gap semiconductor BiOI effectively improved photo adsorption capacity. Secondly, benefiting by the large specific surface area, the involvement of UiO-66 contributed to boost the surface active sites. Most importantly, an internal electric field at the contact interface between UiO-66 and BiOI accelerated the separation of photo-generated electrons and holes. Furthermore, ·O2− and photo-generated holes were identified as the dominating reactive species accounting for the SDZ removal. The decomposition pathways of SDZ and ecotoxicities of the intermediates were analyzed via combing with LC-MS/MS and T.E.S.T theoretical calculation. This work may provide an alternative way for enhanced photocatalytic performance of MOF-based materials through construction of p-n heterojunction with bismuth-based semiconductors.

G-C3N4/BiOI S‑scheme heterojunction: A 2D/2D model platform for visible-light-driven photocatalytic CO2 reduction and pollutant degradation

Photo-degradation of pollutant and photo-reduction of CO2 are efficient ways to address challenges of water pollution, the greenhouse effect and energy crisis, respectively. In our work, via fastening two-dimensional (2D) BiOI nanoplates on 2D g-C3N4 nanosheets, a BiOI/g-C3N4 (BI/CN) S-scheme photocatalyst with closely stacked structure were prepared though a self-assembly process. The prepared BI/CN S-scheme heterojunction could improve the transfer and separation efficiency of photo-generated electron-hole pairs by facilitating the electrons transfer from BiOI to g-C3N4. Under visible light exposure, the photo-degradation efficiencies of tetracycline hydrochloride (TC) and p-chlorophenol (4-PC) by BI/CN-50% reached nearly 100% and 46%, respectively, which were more excellent in comparison with other samples. And BI/CN-50% sample exhibited the best CO production (12.45 μmol∙g−1) with visible-light irradiation of 4 h. This value was approximately 4.37 and 5.41 times higher than that of BI (2.85 μmol∙g−1) and CN materials (2.30 μmol∙g−1), respectively. Moreover, the excellent photocatalytic performance had no visible decay during five cycles. Meanwhile, an S-scheme charge transfer process was confirmed by species trapping experiments and electron spin-trap analysis. This study offers new insights into the activity, kinetics, and mechanism over BiOI-based materials for photocatalysis technology.

Novel TiO2/Bi4Ti3O12 nanorod arrays decorated with Co-Pi for boosted solar photoelectrochemical water splitting

We present a simple methodology to construct novel Co-Pi decorated TiO 2 /Bi 4 Ti 3 O 12 nanorod (TiO 2 /BTO@Co-Pi NR) arrays as photoanode for enhanced water splitting. By using successive ionic layer adsorption and reaction (SILAR) method, controllable amounts of BiOI nanoplates were uniformly immobilized on the hydrothermal grown TiO 2 NR arrays on Fluorine-doped tin oxide (FTO) substrate. TiO 2 /BTO NR heterojunction was conveniently obtained by partial conversion of TiO 2 to high crystallized Bi 4 Ti 3 O 12 through a solid-state reaction with BiOI nanoplates at high temperature. Afterwards, Co-Pi nanoparticles were deposited on TiO 2 /BTO by photoelectrical deposition to generate TiO 2 /BTO@Co-Pi composites. Photoelectrochemical (PEC) measurements have demonstrated that the prepared TiO 2 /BTO photoanode exhibits extremely enhanced performance than pristine TiO 2 for PEC water splitting thanks to the increased visible light absorption and photogenerated charge separation efficiency. Moreover, both the photocurrent density and incident photo-to-current conversion efficiency (IPCE) were further improved after the decoration of Co-Pi. This work provides a feasible and low-cost strategy to establish TiO 2 /Bi 4 Ti 3 O 12 based photoelectrode, therefore, is suitable for practical applications. • Novel TiO 2 /Bi 4 Ti 3 O 12 nanorod arrays were easily constructed by simple SILAR and solid-state reaction. • Controllable Bi 4 Ti 3 O 12 could be formed by adjusting the SILAR cycles to achieve a optimium photocurrent. • BTO can largely enhance the IPCE and photocurrent density, which were further improved by Co-Pi nanoparticles.

Direct Z‐Scheme Structure g‐C3N4‐BiOI with Highly Efficient Visible‐Light‐Driven Photocatalytic Activity for Bacteria Inactivation

AbstractA series of direct Z‐scheme g‐C3N4‐BiOI photocatalysts with different BiOI contents were constructed by in‐situ depositing BiOI nanoplates on the surface of g‐C3N4 nanosheets. Light absorption results indicated that the introduction of BiOI can improve the visible‐light absorption of g‐C3N4. By analyzing the transient photocurrent responses, electrochemical impedance and photoluminescence (PL) emission spectra, it was disclosed that g‐C3N4‐BiOI Z‐scheme structure not only decreases the recombination rate of photogenerated charge carriers but also remains the electrons with higher reduction ability and holes with higher oxidizing ability. The results of photocatalytic disinfection of Escherichia coli (E. coli) under visible light irradiation indicated that g‐C3N4‐BiOI exhibits dramatically enhanced photocatalytic activity when compared to single g‐C3N4 and BiOI. And the optimal loading amount of BiOI corresponding to the highest photocatalytic performance of g‐C3N4‐BiOI is 20 %. In addition, the radical trapping experiments indicated that .O2− and h+ are the main reactive species responsible for the disinfection of E. coli.

Fabrication of hierarchical flower-like BiOI/MoS2 heterostructures with highly enhanced visible-light photocatalytic activities

In the paper, a novel BiOI/MoS2 (BMS) heterojunction was prepared by a facile hydrothermal method. BiOI nanoplates grew in-situ on the surface of exfoliated MoS2 nanosheets, followed by anisotropic growth and self-assembly, forming a hierarchical flower-like heterostructure finally. Experimental results illustrated that MoS2 as well as the BiOI amounts play a vital role in influencing the morphology and photocatalytic activity of BMS heterojunctions. Among the obtained photocatalysts, BMS-8 displayed the strongest photocatalytic performance under visible light irradiation towards the degradation of rhodamine B (RhB) and disinfection of Pseudomonas aeruginosa (P. aeruginosa). The highly enhanced photocatalytic activity can be attributed to the synergistic effect and formation of a type II heterostructure between BiOI and MoS2, boosting the catalytic active sites, enhancing visible light harvesting, and promoting the efficient separation of photoinduced charge carriers. Moreover, BMS-8 composite showed a good stability in photocatalytic reaction, which favored a long-term use. The active species trapping experiments validated the dominating role of photogenerated holes (h+) and ⋅O2− radicals in the photocatalytic process for BMS-8 heterojunction. It is anticipated that this work can promote further interest in constructing novel heterostructures with controllable morphology and highly efficient photocatalytic activity for potential environmental purification and energy conversion.

Enhancement of Solar-Driven Photocatalytic Activity of BiOI Nanosheets through Predominant Exposed High Energy Facets and Vacancy Engineering.

The increasing application of exposed high energy facet is an effective strategy to improve the photocatalytic performance of photocatalysts because the vacancies are beneficial to photocatalytic reaction. Vacancy dominates numerous distinct properties of semiconductor materials and thus plays a conclusive role in the photocatalysis applications. In this work, two kinds of BiOI nanomaterials with different vacancies are synthesized via a facile solvothermal method. The positron annihilation analysis shows that the thinner BiOI nanosheets possess larger-sized vacancy than BiOI nanoplates. Thus, BiOI nanosheets show the enhanced separation efficiency of electron-hole pairs and adsorption ability for contaminants under visible light. The results are also validated with the first-principle computation. Therefore, higher photocatalytic activity to the photodegradation of tetracycline is observed from the nanosheets than that obtained from BiOI nanoplates. This work not only arouses attention to vacancies, but also opens up an avenue for precision design of vacancies to prepare novel photocatalytic materials driven under solar light.

Visible-light-driven, hierarchically heterostructured, and flexible silver/bismuth oxyiodide/titania nanofibrous membranes for highly efficient water disinfection

Constructing a flexible inorganic membrane photocatalyst for efficient visible-light-driven water disinfection is highly desired but remains a great challenge. Herein, we fabricated a flexible and heterostructured silver/bismuth oxyiodide/titania (Ag/BiOI/TiO2) nanofibrous membrane by combining the electrospinning technique with simple successive ionic layer adsorption and reaction (SILAR) and photodeposition process. In this ternary nanocomposite, ultrathin BiOI nanoplates were firmly anchored onto TiO2 nanofibers, while Ag nanoparticles were uniformly decorated on the surface of both BiOI and TiO2. Benefiting from the large surface area, improved visible-light absorption, and the effective interfacial charge transfer induced by multi-heterojunctions, the resultant Ag/BiOI/TiO2 membrane exhibited superior photocatalytic disinfection activity (7.5 log inactivation of E. coli within 1 h) under visible light illumination. Moreover, the plasmonic Z-scheme charge transfer mode was also proposed for Ag/BiOI/TiO2 system according to the band structure and reactive species analysis. More significantly, the Ag/BiOI/TiO2 membrane-based photoreactor could be facilely constructed for high-efficiency disinfection of high volume contaminated water, and the membrane still maintained good structural integrity and mechanical flexibility after utilization. This work may open up new avenues for designing and constructing flexible high-performance photocatalytic membranes for environmental applications.

Recoverable magnetic CoFe2O4/BiOI nanofibers for efficient visible light photocatalysis

A facile methodology for fabricating novel magnetic fibrous visible light photocatalysts CoFe2O4/BiOI (CFO/BiOI) is presented. The fabrication procedure involves production of electrospun CoFe2O4 nanofibers and subsequent controllable decoration of BiOI nanoplates by both the successive ionic layer adsorption and reaction (SILAR) and solvothermal methods on CoFe2O4 nanofiber surface. The BiOI nanoplates on the fiber surface obtained by two methods are highly crystallized with lamellae morphology. The resulting CFO/BiOI fibers exhibit strongly magnetic response to external magnetic field and can be quickly collected. All the CFO/BiOI fiber samples exhibit excellent visible light photocatalytic performance towards degrading RhB regardless of the preparation methods, in which h+ and O2− play the major roles examined by the trapping experiment. Above 80% RhB dyes can be degraded within 2 h after 3 cycles under visible light irradiation, suggesting the good reusability of the photocatalysts. This work demonstrates that the CFO/BiOI is characteristic with high visible light photocatalysis performance and magnetic response, hence is promising for photocatalysis.

BiOI/BiVO4 Two-Dimensional Heteronanostructures for Visible-Light Photocatalytic Degradation of Rhodamine B

By virtue of the facile anion-exchange technique, smart BiOI/BiVO4 two-dimensional (2D) heteronanostructure (HNS) photocatalysts targeted for the degradation of organic pollutants have been developed by the in situ growth of BiVO4 on the scaffolds of BiOI nanoplates. The as-obtained BiOI/BiVO4 HNSs exhibited excellent 2D structure as templates of BiOI nanoplates and well structure stability due to the in situ growth pattern of BiVO4 on BiOI. The 2D HNSs exhibited superior photocatalytic activities, especially the V/I8 2D HNSs (V:I = 80%), exhibited the highest Rhodamine B (RhB) and salicylic acid (SA) degradation rates, which are 29.8 times (RhB) and 15.7 times (SA) those of the individual BiVO4 and 6.4 times (RhB) and 10 times (SA) those of BiOI, respectively. Such excellent photocatalytic activities should be attributed to the organic combination of the 2D structure and heterojunction, as verified by the detailed morphology and composition characterizations. The well-known unique advantages of 2D nanost...

Sonochemical synthesis and characterization of BiOI nanoplates for using as visible-light-driven photocatalyst

BiOI nanoplates were successfully synthesized by a simple sonochemical method. X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS) revealed the presence of pure tetragonal BiOI nanoplates in the solutions with the pH of 8–12. The photocatalytic activities of the BiOI nanoplates were evaluated through the degradation of rhodamine B (RhB) under xenon visible-light irradiation. Obviously, the pH of precursor solutions played an important role in the photocatalytic activities. In this research, the BiOI nanoplates synthesized in the solution with the pH of 12 showed the highest efficiency of 81.19% within 180 min.

Microwave-assisted solvothermal synthesis of novel hierarchical BiOI/rGO composites for efficient photocatalytic degardation of organic pollutants

In the present paper, a novel composite of BiOI/rGO with excellent visible-light photocatalytic activity was successfully fabricated via very different simple, fast and mild rapid microwave hydrothermal method. The BiOI/rGO −1(BG-1) was donated as a simple chemical mechanical and the BiOI/rGO −2(BG-2) was donated as one-step rapid microwave hydrothermal method. The BG-1 were composed of the BiOI microspheres with a diameter of about 1μm and mixed heterogeneously with graphene. While, the BG-2 were consist of the BiOI nanoplates with the thickness of approximately 20nm dispersed heterogeneously on the surface of rGO. The degradation of 40mg/L methylene blue (MB) and 20mg/L levofloxacin (LEV) under visible light irradiation can reach about 11 and 3 times than that of P25, respectively. Furthermore, the reactive species of hole was determined to dominant the photodegradation process. The intensive photocatlytic could ascribe to more effective electron transportation and separations, this conclusion was different with other studies. A possible photocatalytic mechanism of BG-2 was also proposed.

Two dimensional visible-light-active Pt-BiOI photoelectrocatalyst for efficient ethanol oxidation reaction in alkaline media

Two dimensional (2D) BiOI nanoplates were synthesized and used as support for the deposition of Pt nanoparticles. Owing to broad visible light absorption (up to 660nm), the as-obtained Pt–BiOI electrode was used as effective photoelectrocatalyst in the application of catalytic ethanol oxidation in alkaline media under visible light irradiation. Compared to dark condition, the Pt–BiOI modified electrode displayed 3 times improved catalytic activity towards ethanol oxidation under visible light irradiation. The synergistic effect of electrocatalytic and photocatalytic, and the unique of 2D structures contribute to the improvement of catalytic activity. The mechanism of enhanced photoelectrocatalytic process is proposed. The present results suggest that 2D visible-light-activated BiOI can be served as promising support for the decoration of Pt and applied in the fields of photoelectrochemical and photo–assisted fuel cell applications

Facile synthesis of p-n heterojunction of phosphorus doped TiO2 and BiOI with enhanced visible-light photocatalytic activity

TiO2/BiOI heterostructures were prepared with BiOI nanosheets and phosphorus-doped TiO2 nanoparticles by a facile method at a low temperature. X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectra and X-Ray Photoelectron spectroscopy were employed to characterize the phase structures, morphologies and optical absorption properties of TiO2/BiOI p-n heterojunction. The experimental results show that BiOI nanoplates and TiO2 nanoparticles bind through chemical bonds rather than a simple mixture of the two materials. The optical absorption edge of TiO2/BiOI heterostructures was extended to more than 650nm in visible-light region. The samples exhibited higher photocatalytic activity than pure BiOI and TiO2 for the degradation of Rhodamine B under the irradiation of visible light. In addition, the photocatalytic mechanism of TiO2/BiOI heterostructures has also has been investigated in the presence of active species scavengers. The photocatalytic activity enhancement of TiO2/BiOI heterostructures could be attributed to the synergistic effect of the strong absorption in the visible region and low recombination rate of the electron-hole pairs because of the p-n heterojunction of BiOI naosheets and P-doped TiO2 nanoparticles.

Facile synthesis of 3D nanoplate-built CdWO4/BiOI heterostructures with highly enhanced photocatalytic performance under visible-light irradiation

Three-dimension (3D) nanoplate-built CdWO4/BiOI heterostructural composites were fabricated by a facile chemical bath method at low temperature. The samples were characterized by XRD, SEM, EDS, TEM, BJH, XPS, DRS and photoluminescence (PL) spectroscopy. The results showed that n-type CdWO4 was successfully combined with p-type BiOI. The TEM and SEM morphologies indicated the self-assembly of low-dimensional BiOI nanoplates and CdWO4 nanorods built the 3D CdWO4/BiOI composites. The photodegradation experiment demonstrated that the photocatalytic activities of CdWO4/BiOI samples were enhanced significantly compared to pure BiOI and CdWO4, and the CB-0.07 sample showed the highest degradation rate with almost 95.1% removal of RhB under visible-light irradiation for 150min. This enhancement should be attributed to the unique 3D nanostructures, high specific surface area, high separation efficiency of charge carriers and the synergistic effect between BiOI and CdWO4.

SILAR BiOI-Sensitized TiO2 Films for Visible-Light Photocatalytic Degradation of Rhodamine B and 4-Chlorophenol.

BiOI nanoplates were deposited upon a film of TiO2 nanoparticles derived from a commercial source using a simple room temperature sequential ionic layer adsorption and reaction (SILAR) method. X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopies have been used to confirm the crystal phase, chemical states of key elements and morphology of the BiOI nanoplate-TiO2 composites. Using both valence band X-ray photoelectron spectroscopy and UV/Vis diffuse reflectance measurements the band structure of the composites is determined to be that of a type II heterojunction. Through initial screening of the photocatalytic activity of the SILAR-modified films it was determined that five SILAR cycles are optimal in the photocatalytic degradation of rhodamine B. The visible-light sensitisation effect of BiOI was then proven by examination of the photocatalytic degradation of the colourless organic pollutant 4-chlorophenol, showing a large enhancement over an equivalent TiO2 film.

Promotion of phenol photodegradation based on novel self-assembled magnetic bismuth oxyiodide core–shell microspheres

A novel visible-light driven “plates-over-nanospheres” (PONs) photocatalyst with BiOI nanoplates grown on the surface of Fe3O4 nanospheres was prepared using a facile method.