Simulated Solar Illumination Research Articles

ZnO/g-C3N4 Nanostructured Photocatalyst for Enhancement of Photodegradation of Antibiotic Pollutant in Wastewater under Simulated solar Light Illumination

ZnO/g-C3N4 Nanostructured Photocatalyst for Enhancement of Photodegradation of Antibiotic Pollutant in Wastewater under Simulated solar Light Illumination

Alkali Etching Induced CoAl‐Layered Double Oxides with Regulatable Cation and Oxygen Vacancy Defects to Promote the Photothermal Degradation of Methanol

AbstractBy controlling the alkali etching time, the cation and oxygen vacancies contents of CoAl‐LDHs were adjusted. Then CoAl‐layered double oxides catalysts (CoAl‐LDOs‐x) were prepared by calcination and applied to the photothermal catalytic degradation of methanol and acetone under the full spectrum simulated solar illumination. Compared with CoAl‐LDOs‐0 without alkali etching, CoAl‐LDOs‐9 with alkali etching for 9 h showed the most superior photothermal catalytic activity and excellent stability. A series of studies had suggested that the most superior activity of the catalyst could be ascribed to the cation vacancy produced by alkali etching, resulting in more Co3+ active sites on the surface. At the same time, alkali etching also produced oxygen vacancy, which accelerated the adsorption and conversion of surface reactive oxygen species (ROS). In addition, the activation effect of light on lattice oxygen and gas phase oxygen was proved by in‐situ DRIFTS, and the degradation path of methanol was clarified.

Self-assembly of hierarchical MXene@SnO2 nanostructure for enhancing the flame retardancy, solar de-icing, and mechanical property of polyurethane resin

Taking into consideration the frigid and thunderstorms, the flame retardancy and de-icing performance are simultaneously desiderated for some open-air key equipment, such as air fuselage and wind turbine blades. Here, inspired by the anti-reflection phenomenon of moth eyes and cicada wings, a multi-functionalized and biomimetic MXene@SnO2 hierarchical nanostructure is prepared to effectively impart flame retardancy and solar de-icing performance to thermoplastic polyurethane (TPU) resin used widely as the finishing coat of protective materials of open-air equipment. Based on the catalytic effect and barrier function, the addition of hierarchical MXene@SnO2 nanostructures also effectively decreases the release of heat and toxic smoke from PU resin, as confirmed by reductions of 50.5% and 33.1% in the peak heat release rate and smoke production rate, respectively. Due to the appropriate refractive index, the light reflection phenomenon is effectively suppressed, thus promoting solar absorption (∼90% at 0.4 mm film) and photo-thermal conversion (∼74.2 °C with simulated solar illumination of 1.0 kW/m2) in TPU-MXene@SnO2 nanocomposites. Within the environment of −20 °C, the surface temperature of TPU-MXene@SnO2 nanocomposites is still up to 32.7 °C and the surface ice pellet begins to melt at ∼40s, much earlier than 600s of pure TPU resin. In addition, the practical application of functionalized TPU nanocomposites is further improved by the higher mechanical properties, attributed to the strong interfacial interaction. Inspired by moth eyes and cicada wings, flame retardancy and solar de-icing performance are first integrated into polymer materials, thus effectively promoting their application in some extreme environments.

Hot-Casting-Assisted Liquid Additive Engineering for Efficient and Stable Perovskite Solar Cells.

High-performance inorganic-organic lead halide perovskite solar cells (PSCs) are often fabricated with a liquid additive such as dimethyl sulfoxide (DMSO), which retards crystallization and reduces roughness and pinholes in the perovskite layers. However, DMSO can be trapped during perovskite film formation and induce voids and undesired reaction byproducts upon later processing steps. Here, it is shown that the amount of residual DMSO can be reduced in as-spin-coated films significantly through use of preheated substrates, or a so-called hot-casting method. Hot casting increases the perovskite film thickness given the same concentration of solutions, which allows for reducing the perovskite solution concentration. By reducing the amount of DMSO in proportion to the concentration of perovskite precursors and using hot casting, it is possible to fabricate perovskite layers with improved perovskite-substrate interfaces by suppressing the formation of byproducts, which increase trap density and accelerate degradation of the perovskite layers. The best-performing PSCs exhibit a power conversion efficiency (PCE) of 23.4% (23.0% stabilized efficiency) under simulated solar illumination. Furthermore, encapsulated devices show considerably reduced post-burn-in decay, retaining 75% and 90% of their initial and post-burn-in efficiencies after 3000h of operation with maximum power point tracking (MPPT) under high power of ultraviolet (UV)-containing continuous light exposure.

Creation of SnxNb1−xO2 solid solution through heavy Nb-doping in SnO2 to boost its photocatalytic CO2 reduction to C2+ products under simulated solar illumination

Photocatalytic CO2 reduction driven by green solar energy could be a promising approach for the carbon neutral practice. In this work, a novel defect engineering approach was developed to form the SnxNb1−xO2 solid solution by the heavy substitutional Nb-doping of SnO2 through a robust hydrothermal process. The detailed analysis demonstrated that the heavy substitution of Sn4+ by a higher valence Nb5+ created a more suitable band structure, a better photogenerated charge carrier separation and transfer, and stronger CO2 adsorption due to the presence of abundant acid centers and excess electrons on its surface. Thus, the SnxNb1−xO2 solid solution sample demonstrated a much better photocatalytic CO2 reduction performance compared to the pristine SnO2 sample without the need for sacrificial agent. Its photocatalytic CO2 reduction efficiency reached ∼292.47 µmol/(g·h), which was 19 times that of the pristine SnO2 sample. Furthermore, its main photocatalytic CO2 reduction product was a more preferred multi-carbon (C2+) compound of C2H5OH, while that of the pristine SnO2 sample was a one-carbon (C1) compound of CH3OH. This work demonstrated that, the heavy doping of high valence cations in metal oxides to form solid solution may enhance the photocatalytic CO2 reduction and modulate its reduction process, to produce more C2+ products. This material design strategy could be readily applied to various material systems for the exploration of high-performance photocatalysts for the solar-driven CO2 reduction.

Facile in-situ construction of Z-scheme Bi6O5(OH)3(NO3)5·3H2O/Bi5O7I binary heterojunction composites for superior photocatalytic degradation of diverse persistent organic pollutants in water

Constructing efficient heterojunction photocatalysts via facile synthetic strategies is attractive from the viewpoints of improving photocatalytic efficiency and energy saving. Herein, a series of novel Bi6O5(OH)3(NO3)5·3H2O/Bi5O7I (BBN/BOI) Z-scheme binary heterojunction composites were successfully prepared by a facile in-situ growth of Bi6O5(OH)3(NO3)5·3H2O nanoplates on the surface of Bi5O7I as substrate material. The structural features, morphology and optical properties of the fabricated samples were investigated by various physicochemical methods. The BBN/BOI composites exhibited enhanced photocatalytic superiority in comparison with Bi6O5(OH)3(NO3)5·3H2O and Bi5O7I. The sample BBN/BOI-1 prepared with a Bi(NO3)3·5H2O/Bi5O7I feeding molar ratio of 1:1 displayed the best photocatalytic performance for 2-sec-butyl-4,6-dinitrophenol (DNBP) and Rhodamine B (RhB) degradation under simulated solar light illumination with good recycling characteristics. The Z-scheme charge transfer mechanism in BBN/BOI composites can not only facilitate the separation and migration of photoinduced electron-hole pairs but also retain strong redox reaction capacity, which contributes to promote the generation of h+ and •O2− as major active species responsible for the photocatalytic degradation of organic pollutants. The structural stability and photocatalytic activity of BBN/BOI system verifies its great potential for applicability in wastewater treatment.

Photoanode Interface and Surface Treatment Effect in Dye-Sensitized Photo Electrochemical Systems on Oxidative Cleavage of Lignin

Traditionally, Dye-sensitized photo electrochemical cells (DSPECs) have been targeted for solar-driven water splitting as production of fuels in aqueous media. Recently, hydrogen atom transfer incorporated dye-sensitized photo electrochemical cell (HAT-DSPEC) which used photocatalyst and homogeneous catalysts incorporating system was suggested for the decomposition process of lignin. This HAT-DSPEC system representing conversion efficiencies over 90% resulted in the formation of the oxidized ketone product from model compounds under simulated solar illumination with an applied bias 0.4 V vs Ag/Ag+ for 24 hrs. However, they have several issues such as long reaction time, low stability and high bias potential.To overcome these problems, in this study, dye-sensitized photovoltaics’ advanced technic is applied. In HAT-DSPEC system, photo-anode (TiO2@Dye) has important role to produce oxoammonium species by oxidizing HAT mediator. And these oxidized HAT do a catalytic reaction with target materials: lignin model compounds (LMCs). However, in photo-anode, lots of charge recombination and electron back transfer occurs on the FTO and TiO2 surface. So, for effectively producing oxoammonium species from photoelectrode, using blocking layer to passivate FTO surface from electrolytes and applying TiCl4 post-treatment enhances charge transport in TiO2. The photocurrent response of the m-TiO2@Ru470 photoelectrode in a nonaqueous electrolyte was examined with increasing mediators concentration during light on/off cycles under AM 1.5G illumination (100 mW/cm−2), with an applied bias 0.4 V vs Ag/Ag+. Comparing three kinds of condition such as m-TiO2, BL/m-TiO2, BL/m-TiO2/TiCl4 post treatment, showed a significant increase in maximum photocurrent up to approximately 49.3, 101.3, 231.6 μA/cm−2 with 5 mM NHPI/2,6-Lutidine mediator. This result indicates that the blocking layer and TiCl4 post treatment enhanced electron life time and collection efficiency in the photoelectrode, as well as enhancing the capability of producing oxoammonium species.

Sono-precipitation fabrication of ZnO over modified SAPO-34 zeotype for effective degradation of methylene blue pollutant under simulated solar light illumination

Implementation of hierarchical SAPO-34 zeotype, which was synthesized via a hard-template technique using secondary hard template, as a photocatalyst support for ZnO photocatalyst has been investigated. The ZnO/SAPO-34 (AC-U)-U photocatalyst was applied for photodegradation of dye molecules under simulated-solar-light irradiation. X-ray diffraction (XRD), field-emission scanning-electron-microscope (FESEM), Barrett–Joyner–Halenda (BET-BJH), Differential reflectance spectroscopy (DRS), Temperature-programmed reduction of hydrogen (H2-TPR) and Photoluminescence spectroscopy (PL) analyses have been applied to investigate the physiochemical properties of the catalysts. The BET-BJH results indicated that applying hard-template (active carbon) coupled with sonication leads to a raise in mean pore diameter of sample from 0.5 to 16.6 nm (about 32 folds higher). H2-TPR analysis confirms that the ZnO is dispersed uniformly by utilizing sonication. Furthermore, morphological analyses showed that the sonicated sample have more channel-like defect on the surface. PL analysis demonstrates the lower recombination rate of electrons-holes for the composite structure. The hierarchical architecture compared to the conventional pore structure has significantly increased adsorption capacity of dye from 10.8% to 50.3% by modifying the texture and pore structure. Sonicated photocatalyst showed the highest methylene blue degradation efficiency (95.7%). Hence, the ZnO/SAPO-34 (AC-U)-U nanocomposite photocatalyst depicts as a promising reusable photocatalyst for the photodegradation of dye-polluted water.

Insight into Potassium Vanadates as Visible-Light-Driven Photocatalysts: Synthesis of V(IV)-Rich Nano/Microstructures for the Photodegradation of Methylene Blue.

Photocatalysis is regarded as a promising tool for wastewater remediation. In recent years, many studies have focused on investigating novel photocatalysts driven by visible light. In this study, K2V6O16·nH2O nanobelts and KV3O8 microplatelets were synthesized and investigated as photocatalysts. Samples were obtained via the facile method based on liquid-phase exfoliation with ion exchange. By changing the synthesis temperature (20–80 °C), different compositions, morphologies, and V4+/V5+ ratios were obtained and investigated as photocatalysts for organic dye degradation. Potassium vanadates’ structural, morphological, and optical properties were characterized using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Physical Property Measurement System (PPMS), thermogravimetric analysis (TGA) with mass spectrometry (MS), N2 adsorption, scanning electron microscopy (SEM), photoluminescence (PL), and UV–vis diffuse reflectance spectroscopy (DRS). Synthesized K2V6O16·nH2O and KV3O8 showed an efficient absorption in the visible wavelength region with a narrow band gap energy of 1.80 and 1.91 eV, respectively. Their photocatalytic activity was evaluated by the degradation of methylene blue (MB) under simulated solar light illumination. The KV3O8 microplatelets exhibited the greatest photocatalytic activity, resulting in more than 90% degradation of the dye within the first 30 min. It is suggested that the observed excellent photocatalytic performance is attributed to the high content of V4+ species. Furthermore, the influence of active species was investigated, and the mechanism responsible for the photodegradation of the MB dye was discussed for the first time for potassium vanadates.

Photocatalytic Reduction of Cr VI by TiO2/GO Nanocomposite

AbstractGraphene Oxide (GO) was successfully deposited on TiO2 NPs through sol‐gel process. The fabricated TiO2/GO (T/G) nanocomposite was used for reduction of CrVI under simulated solar light illumination. 10 wt. % GO was used for the preparation of T/ G nanocomposite. Several analytical methods such as powder X‐ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and UV‐visible diffuse reflectance spectra (DRS) spectrophotometer was used to characterize the samples. The PXRD revealed the formation of the anatase phase of TiO2 NPs and T/G nanocomposites, as per literature more favourable form of TiO2 for photocatalytic activity. The average crystallite size was found 5.1 nm and 23 nm for TiO2 NPs and T/G nanocomposite respectively. Under the simulated sunlight illumination, the TiO2 NPs was excited to generate the electron‐hole pairs and then the photo‐generated electron transferred by the GO to the CrVI which further converted into CrIII. The band gap for T/G nanocomposite was calculated 2.92 eV. Under visible light,27.3 % photoreduction of (10 mg/L) CrVI solution at λmax=347 nm was achieved within 90 min on the T/G sample at the pH 5–6 while overall reduction was 48 % including adsorption. The rate of reaction was found 0.00305 min−1 and the order of reaction was pseudo first order.

Photoelectrochemical Enhancement of Graphene@WS2 Nanosheets for Water Splitting Reaction.

Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using high-energy ball milling, followed by 0.5 and 1 wt% graphene loading. The corresponding vibrational and structural characterizations are consistent with the fabrication of a pure WS2 structure for neat sampling and the presence of the graphene characteristic vibration modes in graphene@WS2 compounds. Additional morphological and crystal structures were examined and confirmed by high-resolution electron microscopy. Subsequently, the investigations of the optical properties evidenced the high optical absorption (98%) and lower band gap (1.75 eV) for the graphene@WS2 compared to the other samples, with good band-edge alignment to water-splitting reaction. In addition, the photoelectrochemical measurements revealed that the graphene@WS2 (1 wt%) exhibits an excellent photocurrent density (95 μA/cm2 at 1.23 V bias) compared with RHE and higher applied bias potential efficiency under standard simulated solar illumination AM1.5G. Precisely, graphene@WS2 (1 wt%) exhibits 3.3 times higher performance compared to pristine WS2 and higher charge transfer ability, as measured by electrical impedance spectroscopy, suggesting its potential use as an efficient photoanode for hydrogen evolution reaction.

Insight into the Growth Mechanism of Mixed Phase CZTS and the Photocatalytic Performance.

In this work, CZTS particles with a mixed phase of wurtzite and kesterite were synthesized by the solvothermal method. The time-dependent XRD patterns, Raman spectra, SEM, and EDS analysis were employed to study the growth mechanism of CZTS. The results revealed that the formation of CZTS started from the nucleation of monoclinic Cu7S4 seeds, followed by the successive incorporation of Zn2+ and Sn4+ ions. Additionally, the diffusion of Zn2+ into Cu7S4 crystal lattice is much faster than that of Sn4+. With increasing time, CZTS undergoes a phase transformation from metastable wurtzite to steady kesterite. The morphology of CZTS tends to change from spherical-like to flower-like architecture. The mixed-phase CZTS with a bandgap of 1.5 eV exhibited strong visible light absorption, good capability for photoelectric conversion, and suitable band alignment, which makes it capable to produce H2 production and degrade RhB under simulated solar illumination.

Towards energy level cascaded “quantum armours” combating metal corrosion

Stainless steels typically feature high toughness and good corrosion resistance. However, pitting corrosion can easily occur on stainless steel and the passivation film tends to be vulnerable under pressure or in brine environments. Metal corrosion is a long-standing challenge for the steel industry, forging a path to net-zero. Herein, by successive growth of a series of quantum confined nanocrystals such as quantum dots and nanorods with gradient band energy level alignment, high-performance photoelectrochemical cathodic protection for steel is demonstrated with remarkable mechanical and electrochemical stability. Under simulated solar light illumination, effective photoinduced protection can be realized for 304 stainless steel which enables long-term corrosion resistance in a 3.5 wt% NaCl solution. Unique nanotree-like structures and the quaternary material combination can store excess charges and release them gradually, enabling time-delay protection for metals after light excitation. Various promising functionalities as unique photoelectrodes can be envisioned arising from the proposed 3D nanotree morphology.

TiN/TiO2/MXene ternary composite with photocathodic protection for 304 stainless steel

A ternary composite was prepared by calcinating Ti3C2 MXene at different temperature, and then doping different contents of TiN nanoparticles on the calcinated MXene sheets. The nanocomposites were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. UV–visible spectroscopy was used to investigate the optical properties of the composites. The results demonstrated that the calcinated MXene at temperature 450 °C had the best photocatalytic activity for the methylene blue under UV-light illumination compared with the other temperatures, due to existence of proper amounts of anatase and rutile TiO2 and intimate contact with MXene. After doping 4 wt% TiN, the absorption peak of the ternary composite in the visible light range further shifts redly, and the energy bandgap decreases compared with the calcinated MXene. The ternary composite photoanode coupled with 304 stainless steel (304 SS) exhibited certain photocathodic protection effect with its potential shifting negatively compared to natural corrosion potential of the 304 SS under simulated solar light illumination. Besides, protection without illumination is also demonstrated because of its lower potential than that of the 304 SS. The enhanced photocathodic protection performance of the ternary composite photoanode are attributed to the intimate contact of MXene and TiO2, as well as the ‘hot’ electrons and photothermal effect of the TiN due to localized surface plasmonic resonance effect, accelerating the electrons migration from TiO2 to Ti3C2.

Optimizing the Photovoltaic Performance of Organic Solar Cells for Indoor Light Harvesting

Organic solar cells (OSCs) harvesting indoor light are highly promising for emerging technologies, such as internet of things. Herein, the photovoltaic performance of PTB7-Th:PC71 BM solar cells constructed using "optimized (with 1,8-diiodooctane (DIO))" and "non-optimized (without DIO)" processing conditions are compared for indoor and outdoor applications. We find that in comparison to the "optimized" solar cell, the "non-optimized" solar cell is less efficient under simulated solar light illumination (100 mW cm-2 , spectral range 350-1100 nm), owing to significant bimolecular charge carrier recombination losses. However, under simulated indoor illumination (3.28 mW cm-2 , spectral range 400-700 nm), bimolecular recombination losses are effective suppressed, thus the power conversion efficiency of the solar cell without DIO was increased to 14.7 %, higher than that of the solar cell with DIO (14.2 %). These results suggest that the common strategy used to optimize the OSCs could be undesired for indoor OSCs. We demonstrate that the efforts for realizing the desired "morphology" of the active layer for the outdoor OSCs may be unnecessary for indoor OSCs, allowing us to realize high-efficiency indoor OSCs using a non-halogenated solvent.

White-Light-Driven Resonant Emission from a Monolayer Semiconductor.

Resonant emission in photonic structures is very useful to construct all-photonic circuits for optical interconnects and quantum computing. Optical generation of most resonant-emitting modes in photonic structures is obtained by coherent pumping rather than incoherent illumination. Particularly, the development of white-light- or even solar-powered on-chip light sources remains challenging but is very attractive in view of the much facile availability of these incoherent excitation sources. Here, net resonant emission from a monolayer semiconductor is demonstrated under simulated solar illumination by a white-light-emitting diode. The device is formed by embedding a 2D gain medium into a planar microcavity on a silicon wafer, which is compatible with the prevailing on-chip photonic technology. Coherent and white-light excitation sources are, respectively, selected for optical pumping, where the output light in two cases exhibits well-consistent resonant wavelength, linewidth, polarization, location, and Gaussian-beam profile. The fundamental TEM00 mode behaves as a doublet emission, resulting from anisotropy-induced non-degenerate states with orthogonal polarizations. The extraordinary spectral flipping is attributed to the competitive interplay of resonant absorption and emission. This work paves a way toward white-light or solar-powered state-of-the-art photonic applications at the chip scale.

Influence of solvent on solvothermal fabrication of BixOyIz nanophotocatalyst over Zn-Fe spinel for comparative demineralization of orange II and methylene blue under simulated solar light illumination

Novel p-n type BixOyIz/ZnFe2O4 nanoheterojunction was prepared in various solvents via two step solvothermal-precipitation route. The influence of solvent on physicochemical and optical properties of samples were investigated by FESEM, XRD, TEM, FTIR, EDX, pHpzc, BET and, UV-Vis DRS techniques. The results indicate that different solvents lead to distictive physicochemical properties. The results revealed that ethanol mediated samples possess superior performance than ethylene glycol, methanol and, water mediated samples. This is ascribed to band position of nanophotocatalysts as Bi7O9I3/ZnFe2O4 and BiOI/ZnFe2O4 are type I and type II heterojunction structures, respectively. The type II heterojunction is the most effective architecture for the semiconductor heterojunctions. The photocatalytic performance of BixOyIz/ZnFe2O4 is tested under simulated sunlight irradiation via elimination of acid orange 7 and methylene blue. Furthermore, the photocatalytic mechanism of degradation was proposed for the both heterojunctions. The effect of catalyst dosage, dye concentration and pH were also investigated.

Activation of cadmium under simulated solar illumination and its impact on the mobility of Cd in flooded soils.

In waterlogged paddy soils, cadmium (Cd) can be precipitated as cadmium sulfide (CdS) under reductive environment, thereby limiting the absorption of Cd by plants. Multiple environmental factors (such as water, pH, and Eh) played a role in the control of Cd mobility and bioavailability. In this study, we investigated the influence of the solar irradiation on the photodissolution of synthetic CdS-montmorillonite composites (CdS-M) in solution and the stability of Cd in natural soil. The release kinetic of Cd2+ showed that after the irradiation of simulated sunlight, CdS-M composites became less stable compared to the dark control. The solar irradiation seemed to enhance the release of Cd2+ from CdS significantly and continuously. Electron paramagnetic resonance (EPR) and quenching experiments confirmed that the photogenerated holes, •O2- and •OH, were possibly involved in the photo-induced release of Cd2+, while the holes was primarily responsible for the reaction. Irradiation under alkaline solution or the presence of DOM, PO43-, CO32-, and urea markedly inhibited the photodissolution process of CdS. The photo-mediated activation of Cd was further confirmed in paddy soil under natural sunlight, with a nearly threefold increase in concentration of extractable Cd during the 15days of irradiation. This study highlights the importance of photochemical transformation of Cd in the environmental water and soil.

Nickel-modified polymeric carbon nitride for improving TiO2-based photoanode: photoelectrocatalytical evaluation and mechanistical insights

Here, we report for the first time the synthesis of a TiO2-based photoanode containing nickel-modified poly (heptazine imide) (Ni–PHI), a polymeric carbon nitride, as well as its application for the methanol oxidation reaction (MOR) under solar simulated and UV illumination. The photoanode was obtained initially as a thin film and the photocurrent response was evaluated in solutions containing Na2SO4 and methanol. For the MOR under illumination in an acidic medium, an optimal composition of the catalyst was found depositing 30-layers of TiO2–Ni–PHI, which yielded a photocurrent of 11 mA cm−2 using UV radiation. The material also showed excellent stability, with a decay of approximately 5% of the photocurrent after 100 min. The improvement in the performance with Ni–PHI is likely due to the formation of a heterojunction between TiO2 and the graphitic carbon nitride, while nickel sites act through a co-catalysis process possibly driven by in situ generation of nickel active species for MOR like Ni(OH)2|NiOOH. Finally, mechanistic insights into in situ infrared Fourier transform spectroscopy showed that TiO2–Ni–PHI can selectively oxidize methanol to formaldehyde in the dark, while under the irradiation of UV light, the oxidized products are CO2 and formic acid, a product with high added value.

Construction of plasmonic Bi/Bismuth oxycarbonate/Zinc bismuth oxide ternary heterojunction for enhanced charge carrier separation and photocatalytic performances

In this work, a novel plasmonic ternary Bi/Bismuth oxycarbonate/Zinc bismuth oxide (Bi-Bi2O2CO3-ZnBi2O4) is synthesized synergistically by a one-step hydrothermal method. The results show that the metallic Bi spheres and ZnBi2O4 nanoparticles are uniformly distributed on the surface of flower-like Bi2O2CO3 layer. Compared with the bare ZnBi2O4 and Bi-Bi2O2CO3, the ternary Bi-Bi2O2CO3-ZnBi2O4 heterojunction displays a significantly improved solar energy harvesting efficiency and enhanced photocatalytic degradation activity for environmental organic pollutants. The degradation efficiency of organics reaches to 98.4% under simulated solar light illumination. The degradation kinetics indicates that the photocatalytic reaction rate constant of ternary system is about 4.4 and 29.5 times higher than that of pure ZnBi2O4 and Bi-Bi2O2CO3, respectively. Moreover, O2− and h+ are the main active species in the photodegradation reaction. The improvement of the photocatalytic activity of the composites is attributed to the synergistic effect of ternary heterostructure and surface plasmon resonance (SPR), which promotes charge transfer and effectively inhibits the recombination of photogenerated carriers.