Electron-hole Recombination Probability Research Articles

AlxSr1-xTiO3 perovskites with enhanced hydroxyl radicals and anions are highly reactive and break down organic dye molecules forming nontoxic by-products like H2O and CO2

AlxSr1-xTiO3 (x = 0, 0.005, 0.01, 0.05, 0.09) photocatalysts were prepared by solid state technique. The synthesized materials were characterized using various analytical techniques like PXRD, UV–visible and SEM etc. To study the phase purity, composition, surface morphology and bandgap. The bandgap was estimated to be 3.2 eV, and the crystalline structure is identified to be perovskite from PXRD results. The photocatalytic behaviour of AlxSr1-xTiO3 (x = 0, 0.005, 0.01, 0.05, 0.09) nanoparticles was tested by the photocatalytic degradation of methylene blue (MB) under ultraviolet light irradiation. These results demonstrated good photocatalyst efficiency of AlxSr1-xTiO3 (x = 0, 0.005, 0.01, 0.05, 0.09) which may be attributed to the bandgap, high adsorbing of the dye molecules on the surface, large surface area, availability of large number of active centres on the surface and possibly low electron-hole (e−/h+) recombination probability. AlxSr1-xTiO3 (x = 0, 0.005, 0.01, 0.05, 0.09) in addition, showed excellent stability against photocatalytic degradation even after repeated cycles of reusability. The degradation percentage was more than 90 %, at the natural pH of the solution. Based on the results a suitable photocatalytic degradation mechanism has been proposed. Thin films of AlxSr1-xTiO3 (x = 0, 0.005, 0.01, 0.05, 0.09) nanoparticles were deposited on a substrate and I-V measurements are carried to confirm the degradation of MB dye. These results reveal possible use of the material in large scale applications.

One-step synthesis of highly active cotton floc like ZnO–BiOI: Visible-light photocatalytic performance, recovery and degradation mechanism

As a new technology for wastewater treatment and new energy development, semiconductor photocatalysis technology has been widely studied in recent year. In this study, a series of ZnO–BiOI (1:1, 1:2, 1:3, 1:3, 2:1, 2:3, 3:1, 3:2) binary composite photocatalysts were synthesized by one-step solvothermal method. XRD, SEM, TEM, HR-TEM, UV–vis DRS and PL characterization methods were used to analyze the physicochemical properties. Compared with pure ZnO, the band gap of ZnO–BiOI composite was narrower, the light absorption ability was enhanced, and the photogenerated electron-hole recombination probability was reduced. Among all the samples, ZnO–BiOI (3:2) had the best activity to degrade RhB, and the degradation rate reached 98% after 240 min under visible light, and the first-order reaction rate constant was 34.8 times that of pure BiOI. In addition, ZnO–BiOI (3:2) showed good stability in the cycle experiment. The interfacial electric field was formed in the photocatalytic process of ZnO–BiOI (3:2), which promoted more photogenerated electron-holes to participate in the oxidation reaction. The degradation process of organic matter was mainly through the oxidation of ·O2− and h+.

Effects of CuAlO2 on the heterojunction interface and performance of Cu2ZnSn(S,Se)4 thin-film solar cells

Carrier transportation and efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are seriously inhibited due to heterojunction interface (HEI) recombination. Herein, we firstly propose a novel HEI doping strategy to address HEI recombination issue by introducing Cu-poor (& Al-rich) CuAlO2 (CAO). Our results indicate that interfacial elements interdiffusion took place between Cu from absorber and Al from CAO during selenization. Then, occupation of Al on the Cu site leads to the absorber shallow bulk inversion from p to n-type, and thereout constructs a desirable homogeneous field passivation (HFP) for HEI. It has not only a superior photo-induced charge carrier transportation function and penalizes the probability of electron-hole recombination but also leads to the superior carrier separation capacity via enlarging depletion region. In addition, CAO itself can bring about a chemical passivation effect owing to its high resistivity. As a result, synergistic passivation effect combining common chemical passivation with novel HFP was realized. Finally, we achieved 9.34% efficiency kesterite device involving chemical and field passivation effects simultaneously despite the relatively not top efficiency. In this regard, HEI doping engineering induced with characteristic Cu-poor (& Al-rich) material for absorber shallow bulk inversion and appreciable passivation effect achieved here shine a new light on the development of kesterite device.

Selective alcohols production through CO2 photoreduction using Co3O4 /TiO2 photocatalyst exploiting synergetic interactions between Ti3+, Co2+ and Co3+

In general, CO2 photoreduction to produce alcohols has shown low conversion efficiency and low selectivity of the products. In this investigation, Co3O4/TiO2 photocatalysts were used for efficient alcohols production during CO2 photoreduction with H2O, using UV or visible light. Photocatalysts characterization by XPS, HTEM, and UV–vis spectroscopy suggested that the high activity of the photocatalysts for ethanol, propanol and iso-propanol production can be attributed to the presence of Ti3+, Co2+ and Co3+ which, decrease the TiO2 band-gap energy and the photogenerated electron-hole recombination probability. Ti3+, Co2+ and Co3+ improve adsorption of CO2 and of generated CO, on the photocatalyst surface, increasing the formyl-radical formation rate, which is the essential step for alcohols production. The effect of CO2 photoreduction factors, on alcohol production was evaluated, considering different cobalt concentrations and irradiance intensities, through a design experiment. Results revealed that cobalt concentration and irradiation intensity have a significant effect for the reaction.

“Edge/Basal Plane Half-Reaction Separation” Mechanism of Two-Dimensional Materials for Photocatalytic Water Splitting

Two-dimensional (2D) materials are long considered as potential candidates for photocatalytic water splitting, but their applications are limited by high electron–hole recombination probability, low solar-to-hydrogen (STH) efficiencies, or “catalyst poisoning” issues. Herein, we propose an “edge/basal plane half-reaction separation” mechanism of 2D photocatalysts for water splitting with superior photocatalytic efficiency. As a proof-of-concept, we design a group of stable and potentially exfoliable 2D rhodium chalcogenide halide (RhXY, X = S, Se, Te; Y = Cl, Br, I) photocatalysts with band gap values from 1.93 to 2.71 eV and suitable band edges. The half-reactions for photocatalytic water splitting, i.e., hydrogen/oxygen evolution reaction (HER/OER), prefer to happen on the edge and basal planes of RhXY, respectively, and RhSCl, RhSeCl, and RhSeBr can also trigger HER and OER simultaneously without sacrificial reagents or cocatalysts. This work paves the way for the rational design of 2D photocatalysts with spatially separated half-reactions.

Synergistic effect of doping and nanotechnology to fabricate highly efficient photocatalyst for environmental remediation

Nanotechnology and metal-doping are two promising techniques to make semiconductive material-based photocatalysts with higher surface area and modulating electronic structure. Using the simple surfactant-assisted co-precipitation approach; we synthesized nanostructured Zn-doped CuO (Zn0.4Co 0.6 O) as a visible-light-driven catalyst for environmental remediation. The morphology, texture, crystal structure, phase, charge transport properties, and chemical constitution of the as-prepared materials were characterized through advanced physiochemical characterization. Using the Rhodamine B (RhB) dye and the bacteria Escherichia coli (E-coli), the photocatalytic and antibacterial activities of CuO and Zn-doped CuO were investigated and compared to evaluate the effect of the doping technique. Surfactant-assisted synthesized Zn-doped CuO samples demonstrated excellent photocatalytic practicability against Rhodamine B dye, with a mineralization efficiency of up to 92.89% within 70 min and a high pseudo-first-order kinetic constant (K) of 0.033 min-1. The photocurrent response of the Zn-doped CuO sample was about double that of the CuO sample, demonstrating that the nanoarchitecture and modified electronic structure of the Zn-doped CuO sample resulted in increased photocatalytic activity. Furthermore, the Zn-doped CuO photocatalyst demonstrated enhanced antibacterial activity, killing E. coli bacteria by creating reactive oxygen species (ROS) that disrupt their important cellular processes and functions. Thus, our proposed Zn-doped CuO photocatalytic with faster degradation kinetics, good recyclability, and a lower electron-hole recombination probability could be used for environmental remediation. • Nanostructured Zn-doped CuO was prepared by using the surfactant co-precipitation approach. • Physicochemical and electrical properties of the Zn-doped and pristine CuO samples were investigated. • Zn-doped CuO mineralized 92.89% RhB dye in 70 min under visible light irradiation. • The kinetics, photoelectrochemical properties and reusability tests were also performed. • The Zn-doped CuO catalyst also showed excellent potential against E-coli .

Optimistic exploitation of Poly(3-hexyl thiophene-benzothiadiazole) D-A copolymer for low Voc loss bulk heterojunction solar cells

A novel copolymer possessing greater potential to yield high open circuit voltage for photovoltaic devices is presented here. Donor-Acceptor (D-A) type copolymer, based on benzothiadiazole (BTZ) as acceptor unit and 3-hexylthiophene (3-HT) as donor unit, was designed, synthesize, characterized and its possibilities for solar cell applications were studied. Copolymers, synthesized using direct arylation, were undergone electrochemical, thermal, morphological studies along with the determination of its electronic structure. Potential of the copolymer to function as vital part of a photovoltaic device was analyzed by fabricating solar cells with basic device structure of ITO/ZnO/P(3-HT-BTZ):PCBM/Ag. Here the entire device fabrication except Ag deposition was undergone in an open atmosphere without using any glove box setup. Photovoltaic (PV) parameters of the device, especially Voc observed to have a strong dependence on copolymer-PCBM interfacial area, where the probability of electron-hole recombination is dominant. Device configuration having an optimum copolymer-PCBM interfacial area ensures efficient exciton dissociation and long charge carrier life time and yielded Voc of 1.85 V.

Green Synthesis of Carbon Nitride-Based Conjugated Copolymer for Efficient Photocatalytic Degradation of Tetracycline.

Upcycling waste plastics into advanced semiconductor photocatalysts provides a new strategy to reasonably and economically solve the huge amount of waste plastics, which remains challenging. Herein, a carbon nitride-based donor-acceptor (D-A) conjugated copolymer by copolymerization of dicyandiamide and terephthalic acid from discarded polyethylene terephthalate (PET) using Zn(OH)2 as catalyst and template at 360-440°C is synthesized. The morphology and structure of the conjugated copolymer are well regulated by the calcination temperature. The resultant conjugated copolymer exhibits merits of high light absorption and low electron-hole recombination probability. Consequently, it works excellently in the persulfate-based advanced oxidation process for visible light-driven photocatalytic degradation of tetracycline. The kinetic constant (3.4×10-2 min-1 ) is 40.5 and 2.3 times that of the conjugated copolymer system and persulfate system, respectively. Furthermore, the reactive species (including •OH, SO4 •- , •O2 - , 1 O2 , and h+ ) and degradation intermediates of tetracycline are analyzed to expound its degradation process. This work not only pioneers design guidelines on upcycling of waste plastics in a sustainable manner, but also provides a facile strategy to synthesize carbon nitride-based D-A conjugated copolymers for the efficient activation of persulfate-based advanced oxidation process in wastewater treatment.

First principles approach to solar energy conversion efficiency of semiconductor heterojunctions

We present an approach to determine from first principles the expected efficiency of semiconductors heterojunctions in solar light absorption and electron-hole pairs generation for photocatalysis and solar cells applications. In a composite material, upon absorption of photons of appropriate wavelength, electrons and holes can migrate towards different components of the junction, thus reducing the electron-hole recombination probability. This occurs when the bands of the two semiconductors are properly aligned. However, a favorable band alignment is not a sufficient condition to have a device able to convert efficiently solar light into chemical or electrical energy. Using the Transfer Matrix Method and Density Functional Theory calculations we evaluate the transmittance and reflectivity of the charge carriers, and we determine two descriptors, the injection efficiency and the maximum conversion efficiency, that allow us to predict in a more realistic way the performance of the device. This method is based on the explicit inclusion of surface, interface, and quantum confinement effects that can be present when the heterojunction is formed. By using the YP/TiO2 (Y = Al, Ga, In) and the CsPbX3/TiO2 (X = Cl, Br, I) systems as examples we show that the approach provides an excellent agreement with the available experimental data.

Terahertz control of photoluminescence emission in few-layer InSe

A promising route for the development of opto-electronic technology is to use terahertz radiation to modulate the optical properties of semiconductors. Here, we demonstrate the dynamical control of photoluminescence (PL) emission in few-layer InSe using picosecond terahertz pulses. We observe a strong PL quenching (up to 50%) after the arrival of the terahertz pulse followed by a reversible recovery of the emission on the timescale of 50 ps at T=10 K. Microscopic calculations reveal that the origin of the photoluminescence quenching is the terahertz absorption by photo-excited carriers: this leads to a heating of the carriers and a broadening of their distribution, which reduces the probability of bimolecular electron-hole recombination and, therefore, the luminescence. By numerically evaluating the Boltzmann equation, we are able to clarify the individual roles of optical and acoustic phonons in the subsequent cooling process. The same PL quenching mechanism is expected in other van der Waals semiconductors, and the effect will be particularly strong for materials with low carrier masses and long carrier relaxation time, which is the case for InSe. This work gives a solid background for the development of opto-electronic applications based on InSe, such as THz detectors and optical modulators.

Band-Gap Modulation for Enhancing NO Photocatalytic Oxidation over Hollow ZnCdS: A Combined Experimental and Theoretical Investigation

The photocatalytic treatment of NO at ppm-level concentrations for the environment and human health protection has attracted ever-increasing interest in academia and industry. Here, hollow ZnCdS nanocage catalysts with different Cd dopings were prepared and used to remove NO under visible light, and a high removal rate of 85% was achieved. Density functional theory (DFT) theoretical calculations and experiments showed that Cd ions could effectively modulate the band gap of ZnS into the visible-light-absorbing range (2.69 eV). Zn0.5Cd0.5S with a cavity structure has an excellent photoelectric response and low electron–hole recombination probability. A relaxation signal of up to 2.33 μs was detected in the transient absorption spectrum, indicating the long lifetime of the photoexcited carriers. Furthermore, the photocatalytic oxidation process of NO was dynamically monitored by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). It is found that NO adsorbed on the surface of Zn0.5Cd0.5S rapidly transformed into dimers (N2O2) under dark and facilitated NO conversion to nitrate via intermediates such as nitrite after illumination (N2O2 → NO → NO3–). The high activity and stability of Zn0.5Cd0.5S present a high potential for scale-up application of the catalyst for NO oxidation under visible light.

Efficient degradation of organic pollutants by S-NaTaO3/biochar under visible light and the photocatalytic performance of a permonosulfate-based dual-effect catalytic system

Removing large concentrations of organic pollutants from water efficiently and quickly under visible light is essential to developing photocatalytic technology and improving solar energy efficiency. This study used a simple hydrothermal method to prepare a non-metallic, S-doped NaTaO3 (S-NTO) photocatalyst, which was then loaded onto biochar (BC) to form a S-NTO/BC composite photocatalyst. After uniform loading onto BC, the S-NTO particles transformed from cubic to spherical. The photogenerated electron-hole pair recombination probability of the composite photocatalyst was significantly lower than those of the NTO particles. The light absorption range of the catalyst was effectively widened from 310 nm UV region to visible region. In addition, a dual-effect catalytic system was constructed by introducing peroxymonosulfate (PMS) into the environment of the pollution to be degraded. The Rhodamine B, Methyl Orange, Acid Orange 7, tetracycline, and ciprofloxacin degradation efficiency at 40 mg/L reached 99.6%, 99.2%, 84.5%, 67.1%, and 70.7%, respectively, after irradiation by a 40 W lamps for 90 min. The high-efficiency visible-light catalytic activity of the dual-effect catalytic system was attributed to doping with non-metallic sulfur and loading of catalysts onto BC. The development of this dual-effect catalytic system provides new ideas for quickly and efficiently solving the problem of high-concentration organic pollution in aqueous environments, rationally and fully utilizing solar energy, and expanding the application of photocatalytic technology to practice.

Waste biomass-assisted synthesis of TiO2 and N/O-contained graphene-like biochar composites for enhanced adsorptive and photocatalytic performances

Titanium dioxide (TiO2) is a promising semiconductor photocatalyst for degradation of organic pollutants but is hampered by bandwidth prohibition and high probability of photo-generated electron-hole recombination. Searching for effective modification strategies to alleviate these issues is thus particularly significant. Herein, two series of composites of TiO2 and graphene-like biochar (PC) were prepared via a simple biomass-assisted pyrolysis coupled with activation strategy and characterized by various techniques. The methylene blue (MB)-simulated waste water was used to evaluate their adsorptive and photocatalytic performances. The results showed that the optimal TiO2-PC composite delivered an excellent photocatalytic performance, nearly 4 times as TiO2. The enhanced performance was probably caused by the synergistic effect among the graphene-like PC, the self-introduced N/O heteroatom, and the interaction between TiO2 and PC. Furthermore, the possible photocatalytic process was also proposed. This work may provide a guidance on preparing high-performance composites through a simple, cheap, and environmental biomass-assisted strategy for highly-efficient photocatalysis application.

Characterization and thermoluminescence study of gamma irradiated Tb-doped ZnO and undoped ZnO synthesized by spray pyrolysis method

High gamma dose-resistant undoped ZnO and Tb-doped ZnO thermoluminescent (TL) micro-phosphors were prepared by the spray pyrolysis method. Scanning electron microscopy shows crystalline rods with hexagonal morphology, (0.1-0.4 µm diameter, and about 1 µm length). Raman spectra dispersion reveals a würtzite form. Photoluminescence (PL) study of irradiated zinc oxide films indicates the generation of defects produced by gamma irradiation resulting in an increased probability of electron-hole exciton recombination. PL spectrum shows emission bands from 5D4-7Fj=6,5,4,3 transitions ascribed to Tb3+ dopant in zinc oxide phosphor. X-ray diffraction patterns for both types of films growth (undoped ZnO and Tb-doped ZnO) are typical of zinc oxide crystalline structure, with no noticeable effect of Tb ions. Dosimetric properties, for both samples, show a low TL fading signal and TL reproducibility signal for undoped ZnO and Tb-doped ZnO samples was 29 and 57 %, respectively. The kinetic parameters such as activation energy E, frequency factor s, and Rm values, were obtained by Computerized Glow Curve Deconvolution (CGCD) assuming Mixed Order Kinetic model (MOK). The results show that the MOK well described the glow curves of zinc oxide films. The heating rate effects produced a broadening of glow peak located at 420 K. For purposes like radiation detector, atomic effective number (Zeff) was obtained: 27.74 and 56.47 for undoped ZnO and Tb-doped ZnO samples, respectively. The samples were exposed to gamma radiation in a wide range of 0.25–20 kGy dose. TL properties of undoped ZnO and Tb-doped ZnO samples show that these materials could be used to detect high doses in a gamma radiation field.

Construction of Z-scheme g-C3N4 / MnO2 /GO ternary photocatalyst with enhanced photodegradation ability of tetracycline hydrochloride under visible light radiation

A facile wet-chemical method was adopted to synthesize g-C3N4/MnO2/GO heterojunction photocatalyst for visible-light photodegradation of tetracycline hydrochloride (TC). The addition of MnO2 and GO increased the absorption of visible light and the specific surface area of the photocatalyst. The results of photoluminescence, electrochemical impedance spectroscopy, and photocurrent response indicated that CMG-10 had the lowest electron–hole recombination probability, which was beneficial for the photocatalytic reaction. The ternary photocatalyst exhibited enhanced photoelectric performance and superior photocatalytic activity with 91.4% removal of TC (10 mg/L) under a mere 60 min visible light illumination, which showed enhanced photocatalytic degradation when compared with binary (CM, 77.95%; CG, 78.83%) and single (C3N4, 55.5%; MnO2, 36.41%) photocatalysts. A pH of 6 was optimal for the CMG-10 photocatalytic degradation of TC, and the optimal photocatalyst dosage was 0.5 g/L. Common coexisting ions influenced the removal of TC by influencing the production of active species. The catalyst is stable and reusable with only a 10% reduction in removal efficiency after four cycles. According to the active species analysis, the Z-scheme mechanism was a charge transfer behavior in the composite photocatalyst, which could prevent the recombination of photogenerated carriers. This study presents a photocatalytic approach to the effective removal of TC from water bodies, which provides practical implications to advance the use of photocatalytic technology in the restoration of aqueous environmental pollution.

TiO2-graphene composite as an application of photoelectrochemical photodetectors with enhanced performances

Ultraviolet (UV) photodetectors have attracted increasing attention in military and civilian fields.In this work, the prepared TiO2-graphene composite was fabricated by hydrothermal synthesis method and it was used in photoelectrochemical type photodetector for UV detection. The results of the photoelectrochemical measurements demonstrate that the TiO2-graphene composite have a remarkable enhancement on photoresponse compared to pure TiO2, which is effectively demonstrate the introduction of graphene will reduce the probability of electron-hole recombination and increase the photocurrent of light detection. In addition, owing to the unique solid-liquid contact mechanism of PEC-type photodetector, it can work under 0 V bias and exhibited excellent photoresponse ability that can reach11uA/W at the UV wavelength of 365 nm. Moreover, the as-prepared TiO2-graphene composite based photodetector possessed preferable performance with the weak irradiation. Even if the light intensity reduced to 6 mW/cm2, the photocurrent density can also reach to 5 uA/cm2. With the excellent absorbtion of the UV and remarkable self-powered ability make the TiO2-graphene composite based PEC-type photodetector have great promising on UV detection field.

Preparation and fluorescence characteristics of CdTe/CdS and CdTe/ZnS core-shell semiconductor quantum dots

Core-shell semiconductor quantum dots materials are being investigated due to their special performance in repairing surface defects for the single quantum dots and greatly improving the optical performance of quantum dots. Instead of a traditional small flask as a reaction vessel to prepare NaHTe, the preparation of the CdTe core using a three-necked flask was achieved. 10 CdTe/CdS and CdTe/ZnS core-shell semiconductor quantum dots with different core sizes, shell thicknesses and shell materials were synthesized. The UV–visible absorption and fluorescence spectrum of 10 kinds of core-shell semiconductor quantum dots materials were measured and analyzed. The absorption spectrum of quantum dots in the UV-visible band shows that with the increase of quantum dots size, the absorption peak is red-shifted. The CdTe/CdS quantum dots differ in fluorescence lifetime and intensity due to the conversion of different core and shell sizes of quantum dots between types I and II. When the shell thickness of CdTe/ZnS increases, the shell thickness of ZnS reduces the number of dangling bonds and defect states on the core surface, which increases the probability of electron-hole pairs recombination and causes the fluorescence peak red-shift.

Effect of band gap variation and sensitization process of polyaniline (PANI)-TiO2 p-n heterojunction photocatalysts on the enhancement of photocatalytic degradation of toxic methylene blue with UV irradiation

Abstract Efficient PANI sensitized TiO2 based photocatalytic nanocomposites have been engineered to degrade strong organic dye like methylene blue (MB) under exposure to UV light. Hydrothermal process was adopted for the synthesis of TiO2 nanoparticles which were subsequently sensitized with a narrow band gap PANI via ex‒situ chemical oxidative polymerization. Here, PANI acts as a phototsensitizer which absorbs light in the UV–vis-NIR spectral region. Formation of the p-n junction heterostructure of PANI-TiO2 suppresses electron-hole recombination probability and enhances the separation of photogenerated charge carriers. Hydroxyl radicals present on the surface are evidenced for the formation mechanism of the nanocomposites which take part in photocatalysis reaction process as an active oxidizing agent. XRD confirms existence of anatase phase of TiO2 in nanocomposite samples. Increase of band gap energy with the increase in TiO2 content shifts the absorption spectra from visible to UV region. The first order and second order rate kinetics are determined from the Langmuir-Hinshelwood model. Experimental results demonstrate that 0.6 M PANI-TiO2 nanocomposite sample shows the highest kinetic rate and dye degradation efficiency. The efficiency is nearly 2.5 times higher than the pristine PANI and 3.1 times than pristine TiO2. Thus the synthesized nanocomposite is an economical and promising photocatalytic material for photodegradation of toxic organic methylene blue in water.

Resolving Enhanced Mn2+ Luminescence near the Surface of CsPbCl3 with Time-Resolved Cathodoluminescence Imaging.

Mn2+ doping of lead halide perovskites has garnered recent interest because it produces stable orange luminescence in tandem with perovskite emission. Here, we observe enhanced Mn2+ luminescence at the edges of Mn2+-doped CsPbCl3 perovskite microplates and suggest an explanation for its origin using the high spatiotemporal resolution of time-resolved cathodoluminescence (TRCL) imaging. We reveal two luminescent decay components that we attribute to two different Mn2+ populations. While each component appears to be present both near the surface and in the bulk, the origin of the intensity variation stems from a higher proportion of the longer lifetime component near the perovskite surface. We suggest that this higher emission is caused by an increased probability of electron-hole recombination on Mn2+ near the perovskite surface due to an increased trap concentration there. This observation suggests that such surface features have yet untapped potential to enhance emissive properties via control of surface-to-volume ratio.

Bio-inspired hierarchical assembly of Au/ZnO decorated carbonized spinach leaves with enhanced photocatalysis performance

Inspired by the characteristics that plant leaves are beneficial for solar light absorption, we have prepared a bio-inspired hierarchical assembly of carbonized spinach leaves@Au/ZnO (CS@Au/ZnO) for solar energy utilization. CS@Au/ZnO shows a low light reflectance of 5% and a high specific surface area of 311.41 m2/g. CS@Au/ZnO demonstrates higher photocatalytic degradation efficiency: more than 97% of Rhodamine B (RhB) and 61% of ciprofloxacin (CIP) could be degraded in 180 min under the visible light irradiation. In addition, we also tested the photocatalytic H2 production performance of CS@Au/ZnO and the H2 evolution rate is 2.384 mmol g−1 h−1 under simulated solar light. CS@Au/ZnO shows a high cycling stability in recyclable photocatalytic degradation and photocatalytic water splitting. Moreover, CS@Au/ZnO shows a swift and steady photocurrent of about 63.6 μA/cm2, illustrating a high sensitivity to solar light. The enhanced photocatalysis performance of CS@Au/ZnO could be ascribed to the naturally optimized macroporous structure of CS with high conductivity, which could enhance the light harvesting and carrier transport, simultaneously. Moreover, modification of AuNPs can broaden the light response range of ZnONRs and reduce the probability of electron-hole recombination. Due to the wide availability of plant leaves, CS@Au/ZnO assembly has broad application prospects in photocatalytic degradation of organic pollutions, photovoltaic devices, and photocatalytic H2 evolution.