Separation Of Photoinduced Carriers Research Articles

TiO2/BP/g-C3N4 heterojunction photocatalyst for the enhanced photocatalytic degradation of RhB.

The efficiency of graphite carbon nitride (g-C3N4, CN) as a photocatalyst is limited due to its quick recombination of photogenerated carriers and layer re-stacking. To enhance its photocatalytic activity, a multi-heterojunction photocatalyst was developed using TiO2 and black phosphorus (BP) coupled with CN through a liquid-phase ultrasonic method. The composite, TiO2/BP/CN, demonstrated a wider range of light response and higher photo-induced carrier separation efficiency. The presence of TiO2 nanoparticles on CN nanolayers reduced interlayer stacking and increased specific surface area, thereby providing more reactive sites. As a result, the optimized TiO2/BP/CN composite demonstrated enhanced photocatalytic efficiency for the degradation of Rhodamine B (RhB), with a first-order kinetic constant of 2.8, 4.3, and 6.4 times that of CN, TiO2, and BP, respectively. Active substance capture experiments confirmed that superoxide radical (·O2) was the primary reactive species. This study highlights the potential of the developed TiO2/BP/CN composite as a promising photocatalyst for environmental remediation applications.

MOF-Derived Hollow Spheres of MIL-100(Fe)-NH2(20) with Well-Developed Hierarchical Mesoporous and Uniform Distribution of Fe and N Active Phases for the Photocatalytic Removal of Organic Dyes.

For the first time, MIL-100(Fe)-derived microspheres with a hollow structure were perfectly constructed and used as a photocatalyst to decompose organic dyes under visible light irradiation. The prepared MIL-100(Fe)-NH2(20) could boost the separation, migration, and transfer of photoinduced carriers effectively, together with efficient photocatalytic performance. In simulated sunlight, the MIL-100(Fe)-NH2(20) exhibits the best degradation efficiency as well as excellent reusability and stability, and the degradation rate for rhodamine B (RhB) can be more than 99.5% within 80 minutes. Structural analysis proves that the porous MIL-100(Fe)-NH2(20) catalyst reaps an amazing hollow structure, large specific surface areas (2784.9 m2·g-1), and uniform distribution of Fe and N active phases. Besides, the enhanced visible light response and lower recombination rate of e--h+ pairs are both confirmed, and the band gap is significantly reduced to 2.53 eV. Finally, the photocatalytic mechanism and the possible degradation pathway were suggested. Owing to the enhanced photocatalytic activity, good tolerance to pH and water quality, and excellent stability, the MIL-100(Fe)-NH2(20) catalyst can be potentially used in a wide range of dye wastewater purifications.

Construction of CuBi2O4/CdO p-n buried junction for boosted photoelectrochemical water splitting

The rational design and construction of interface heterostructures, which can simultaneously accelerate the photoinduced carrier separation and enhance the surface hydrogen evolution kinetics, is of great necessity for photoelectrochemical (PEC) water splitting. Here we construct a CuBi2O4/CdO p-n buried junction for boosting the PEC hydrogen evolution. Compared to the bare CuBi2O4 photocathode, the CuBi2O4/CdO heterojunction reveals an anodic shift of 170 mV for the onset potential and achieves a cathodic photocurrent density of 0.32 mA cm−2 at 0.4 V vs. RHE, as well as improved long-term stability under AM 1.5 G illumination without sacrificial reagent. The experimental characterizations and theoretical calculations confirm the significance of the CuBi2O4/CdO p-n junction in increasing the photoinduced charge separation efficiency and reducing the activation energy of hydrogen evolution reaction (HER), which accounts for enhanced PEC performance. Meanwhile, the change of photoexcited charge-transition route evidenced by DFT calculation in CuBi2O4/CdO provides the fundamental explanation for spatial charge separation, which is responsible for the improved PEC hydrogen evolution stability. The present work highlights the importance of constructing heterojunctions to boost the PEC performance and elucidates the probable intrinsic mechanism involved in the interface.

Self-assembled ZnIn2S4/SnS2 QDs S-scheme heterojunction for boosted photocatalytic hydrogen evolution: Energy band engineering and mechanism insight

Rapid and efficient transfer and separation of photo-induced carriers are critical for designing environmentally friendly and efficient photocatalysts in catalytic hydrogen evolution. Here, we design a 0D/2D S-scheme heterojunction involving ZnIn2S4 (ZIS) nanosheets self-assembled with SnS2 quantum dots (QDs). The formation of the S-scheme ZIS/SnS2 QDs heterojunction is demonstrated by experimental characteristics and density functional theory (DFT) analyzes, which greatly promotes charge transfer and transport under the interfacial electric field (IEF), lengthens carrier lifetime, enhances light-harvesting properties, and significantly decreases the Gibbs free energy during the catalysis reaction. Therefore, the optimized ZIS/SnS2 photocatalyst achieves a high hydrogen production rate of 1.13 mmol g−1 h−1, which is 16.14 folds the one of pure ZIS. This study provides novel perspectives into the reasonable design of S-scheme photocatalyst by virtue of the theories of energy band engineering and IEF adjustment.

2D/2D NiTi-LDH/BiOBr photocatalyst with extraordinary NOx removal under visible light

Many current studies are focused on the development of 2D/2D nanosystems based on non-traditional semiconductors as efficient visible light-active photocatalysts, due to their interesting structural and optical properties. Thus, the charge-separation in heterostructures can be enhanced by boosting the interfacial contact. In this work, robust 2D/2D NiTi/BiOBr composites have been prepared by incorporating a 2D layered BiOBr into NiTi-layered double hydroxides (LDH) for the subsequent study of their photocatalytic action in the control of NOx pollution. The successful formation of a type-II heterojunction between both semiconductors has been confirmed by several characterization techniques (including XPS, NMR and electrochemical studies), indicating an intimate contact interface that helps enhance the visible light photocatalytic performance of NiTi-LDH. In particular, the NiTi–LDH/BiOBr–0.6 heterojunction, with a more efficient separation of photoinduced carriers, showed exceptional NO removal efficiency under visible light and remarkable robustness for the recycling process.

In situ self-heterogenization of Cu2S/CuS nanostructures with modulated d band centers for promoting photocatalytic degradation and hydrogen evolution performances

Photocatalytic technology is a promising remedy for energy crises and environmental pollution, but it is still challenging to develop a stable, low-cost, and active photocatalyst for both environmental protection and clean energy production. Herein, a controlled synthesis of stable Cu2S/CuS hetero-nanostructures (HNCs) is achieved by controlling the temperature and time in the hot-injection process, where the Cu2S primary units are grown on certain facets of CuS nanocrystals through an ‘in situ self-heterogenization’ route. It thus creates abundant Cu2S|CuS hetero-interfaces as charge transfer channels to efficaciously increase the quantity of valid active sites and promote the separation of photo-induced carriers. The Cu2S/CuS HNCs achieved a high kinetic constant of 31.7 × 10−3 min−1 for photocatalytic pollutant elimination and exhibited an impressive rate of 1293 μmol h−1 g−1 for photocatalytic hydrogen evolution. Additionally, density functional theory (DFT) calculations indicate that the d band centers of active Cu sites are effectively modulated to reach better positions after building hetero-interfaces, which consequently optimizes the adsorption/desorption of the guest reactants/intermediates on critical active Cu centers following the Sabatier Principle. This can effectively promote the decomposition efficiency of dye molecules and water splitting kinetics for highly improving photocatalytic activities in both photo-degradation for pollutant removal and photo-splitting water for hydrogen generation.

Photothermal Cocatalytic Carbonylation of Isobutyl Amine with CO2 over Bi2O3 Polymorphs under Visible-Light Irradiation

Effective capture and utilization of CO2 is critical to reduce greenhouse gas emissions and to reach the low-carbon economy target. Herein, bismuth oxides with four different crystallized phases (α-, β-, δ-, γ-) are successfully synthesized and employed for the first time as photo, thermal, and photothermal catalysts for the successful catalytic carbonylation of isobutyl amine with CO2 to N,N′-diisobutylurea. The results displayed that the photothermal catalytic performances of Bi2O3 polymorphs followed the order of α-Bi2O3 > δ-Bi2O3 > γ-Bi2O3 > β-Bi2O3, in which the conversion of i-BuNH2 and the selectivity of N,N′-diisobutylurea for α-Bi2O3 was 50.38% and 91.79%, respectively, using N-methyl-2-pirrolidinone (NMP) as solvent and 500 W Xe lamp as the light source under the conditions of 1.0 MPa CO2 (initial pressure at room temperature) and 4 h reaction time at 100 °C. Further characterization of Bi2O3 polymorphs including XRD, SEM, BET, XPS, EPR, TPC, PL, and UV–vis absorption spectra reveals that such differences in the photothermal catalytic activity of Bi2O3 could be closely related to the efficiencies of photoinduced carriers separation. And the surface oxygen vacancies rather than bulk oxygen vacancies are favorable for the improvement of their both thermal and photothermal catalytic performances in the carbonylation of i-BuNH2 with CO2.

Promoting photocatalytic H2 evolution through interfacial charge separation on the direct Z-scheme ZnIn2S4/ZrO2 heterojunction

Reasonably constructing direct Z-scheme heterojunction photocatalysts is the most essential issue for enhancing the capacity of photocatalytic hydrogen evolution (PHE). Based on outstanding visible light response and photocatalytic capacity of ZnIn2S4, as well as unique photoelectrochemical properties of ZrO2, a direct Z-scheme ZnIn2S4/ZrO2 heterojunction photocatalyst system has been built up by hydrothermal process for PHE for the first time. The PHE rate of the optimal catalyst ZnIn2S4/ZrO2 heterojunction can achieve 9319 μmol g−1 h−1, which is 3.5 times or 2330 times that of virginal ZnIn2S4 (2679 μmol g−1 h−1) or ZrO2 (4 μmol g−1 h−1), and an AQE at 365 and 420 nm are 16.35% and 4.92%, respectively. The boosted photocatalytic properties can be ascribed to the direct Z-scheme heterojunction to accelerate photo-induced carrier separation, which is beneficial to the generation of active sites. Meanwhile, a direct Z-scheme photo-induced carrier exchange mechanism is verified by ISI-XPS, DFT calculation and EPR test. This strategy will provide an efficient scheme for reasonably constructing direct Z-scheme heterojunction photocatalysts with superior hydrogen evolution properties.

Highly synergistic and polarized KNbO3/WO3 heterojunction for piezo-photocatalytic degradation of organic pollutant

The superior piezo-photocatalytic performances of KNbO3-based materials were achieved by the enhanced photo-induced carrier separation and migration based on the effective strategies of heterojunction construction and polarization engineering. A KNbO3/WO3 type-II heterojunction was fabricated by an impregnation-calcination method, and its outstanding piezo-photocatalytic performance was demonstrated. Compared to individual KNbO3 and WO3, KNbO3/WO3 composites exhibited better degradation performance for RhB solution under visible light irradiation, and the degradation rate of 30%KNbO3/WO3 composite for RhB solution was 98% within 80 min (its reaction rate constant k was 0.03894 min−1). Inspiringly, the polarized 30%KNbO3/WO3 composite degraded RhB solution completely within 60 min under visible light irradiation with auxiliary ultrasonic activation, and its reaction rate constant was up to 0.0612 min−1 (3.35 times that of individual KNbO3). The synergistic effects of heterojunction construction, polarization engineering, and ultrasonic vibration in KNbO3/WO3 composite were confirmed, and the multi-electric fields in polarized KNbO3/WO3 heterojunction significantly enhanced carrier separation, thus promoting piezo-photocatalysis. This work proposes an important strategy for designing multi-electric field-driven ferroelectric-based heterojunction photocatalysts.

S-Doped rGO-Enwrapped Magnetically Porous NiFe2O4/CuS Heterojunction: An Efficient Z-Scheme Nano-Photocatalyst for Visible-Light-Driven Tetracycline Degradation and 4-Nitrophenol Reduction

The photocatalytic degradation of economically hazardous compounds has been thoroughly researched with the aid of numerous photocatalysts and techniques. The efficient degradation and removal of lingering contaminants from the aquatic environment are still difficult to accomplish. Hereby, we present a sulfur-doped reduced graphene oxide (SrGO) enwrapped magnetic porous nickel ferrite (NiFe2O4)/copper sulfide (CuS) nanocatalyst (SrGO/NiFe2O4/CuS:GNFC) constructed through a facile solvothermal-reflux route. Under exposure to visible light, the fabricated GNFC photocatalyst exhibits outstanding catalytic activity for the photodegradation of tetracycline hydrochloride (TCH) and photoreduction of 4-nitrophenol (4-NP). Diverse analytical techniques were used to characterize the fabricated nanomaterials. In terms of photocatalytic activity, GNFC-13 outperforms all other nanocatalysts in eliminating model pollutants. According to our findings, 94.39% of TCH (80 ppm) can be degraded within 90 min, and 90.62% of 4-NP (30 ppm) can be reduced within 120 min by the GNFC-13 nanohybrid, which is significantly better than that of pristine and doublet nanomaterials, respectively. The explanations for the improved photocatalytic efficiency of GNFC nanocatalysts are due to the porous structures of the magnetic NiFe2O4 and the SrGO surface, which can offer a lot of adsorption sites and, therefore, advantageous for the adsorption enrichment of harmful pollutants. Additionally, in situ photocatalytic degradation and adsorption enrichment working together synergistically may lead to improved pollutant removal efficacy. The Raman and XPS analytical techniques verified the formation of SrGO in the GNFC nanocomposites. The free-radical trapping studies, terephthalic acid test, nitroblue tetrazolium test, and electron spin resonance test disclosed that holes (h+), hydroxy radicals (·OH), electrons (e–), and superoxide radicals (·O2–) are cardinal reactive species in the photocatalytic system. A Z-scheme charge transfer channelization mechanism of the as-produced photocatalyst is explained in light of the various experimental findings. The developed Z-scheme system has led to the increase of catalytic activity due to the effective photoinduced carrier separation, wider photoabsorption range, high hole oxidation capacity, and high electron reduction power. In addition, the GNFC photocatalyst ability to catalyze TCH and 4-NP shows no discernible decline even after five recycles. Moreover, the GNFC nanocatalysts are magnetically detachable for recycling. Thus, this study reveals that the as-obtained GNFC nanocatalysts have an excellent prospect for environmental remediation of toxic pollutants.

Mott‐Schottky Heterostructure Photocatalysis of Ag/h‐BN/Bi2O3 for Water Pollutants Degradation

AbstractThe Ag/h‐BN/Bi2O3 ternary composite was facilely fabricated via self‐assembly combined with in situ reduction. Characterization results showed that the as‐prepared Ag/h‐BN/Bi2O3 possessed distinct surface plasma resonance (SPR) and Mott‐Schottky heterostructure, resulting in significant enhancement of catalytic activity for RhB removal, the reaction rate constant (2.26×10−2 min−1) is 2.5 times that of h‐BN/Bi2O3 under visible‐light irradiation for 2 hours, which was mainly ascribed to the SPR and Mott‐Schottky heterostructure result in Ag/h‐BN/Bi2O3 enhanced visible‐light harvesting capacity and the effectual spatial separation of photoinduced carriers. The quenching process of reactive species indicated that h+ and ⋅O2− play dominant role in the degradation for pollutants. This work demonstrates that Ag/h‐BN/Bi2O3 is a promising stability photocatalyst for water purification.

A novel carbon‐fiber geopolymer composite‐coated electrodes for photoelectrocatalysis: Fabrication and application

AbstractThe photoelectrocatalysis is an efficient and sustainable degradation method for organic contaminant, where the photoanode material plays a critical role. Development of novel, inexpensive, and high‐performance photoanode materials is significant to enhance the degradation performance of anodes catalysis. Herein, a novel carbon‐fiber geopolymer composite‐coated electrode with low cost and facile production was prepared by incorporating carbon fibers in a geopolymer matrix. The as‐developed photoelectrocatalyst coupled with persulfate could effectively degrade more than 98 % of rhodamine B within 6 min, which demonstrated superior catalytic activity compared with various catalysts reported in the literature. Moreover, the composite electrodes exhibited excellent reusability. The endogenous Fe2O3 and TiO2 in the geopolymer matrix were the main active materials, providing photoelectron‐hole pairs for dye molecule degradation. Significantly, the carbon fibers in the matrix effectively connected the scattered oxide species and prompted the separation and migration of photoinduced carriers while enhancing the stability of the catalysts and improving the conductivity of the matrix. When the carbon content was increased from 0 to 6 wt%, the conductivity of the composite increased by 17.75 times. This study offers a cost‐effective and eco‐friendly photoelectrocatalyst, which shows significant potential for further development.

Mesostructured ellipsoidal capsules barium stannate based perovskite photocatalysts anchored PtO nanoparticles for hydrogen evolution

Background: The separation and transportation of photocarriers are considered significant factors in photocatalytic H2 evolution. Method: Mesoporous BaSnO3, with superior electron mobility with a large surface area, was chosen to integrate PtO nanoparticles (NPs) to obtain a highly effective photocatalytic system. PtO NPs (5–10 nm) are uniformly hosted with high crystallinity on the mesoporous BaSnO3 networks by impregnation-calcination approach. Significant Findings: TEM images of BaSnO3 exhibited ellipsoidal capsules with lengths of 200 ± 10 nm and a diameter of 50 nm. The construction PtO/BaSnO3 heterojunction system with better electron transport ability was modulated to achieve better photocatalytic ability than BaSnO3. The H2 evolution over 1.2% PtO/BaSnO3 nanocomposite was about 21,550 μmol·g−1 after 9 h visible illumination, while bare BaSnO3 was produced only 3750 μmol·g−1. The optimal 1.2% PtO/BaSnO3 nanocomposite revealed the largest H2 evolution, and it was promoted 5.75 times larger than BaSnO3. The H2 evolution rate over-optimized 1.2% PtO/BaSnO3 photocatalyst was about 2380 μmolg−1h−1, 6 times larger than that of bare BaSnO3 (397.37 μmolg−1h−1). The obtained PtO/BaSnO3 nanocomposites could facilitate the photoinduced electrons transfer from BaSnO3 to PtO, indicating the efficient photoinduced carriers separation for the enhanced H2 evolution rate. The PtO/BaSnO3 nanocomposite displayed high photostability and recyclability even after 45 h of illumination. This work provides a novel approach for perovskites with mesoporous structures and tunable bandgap with low PtO content utilized in energy applications and photocatalytic reactions.

Controllable fabrication of Bi4Ti3O12/C/Bi2S3/MoS2 heterojunction with effective suppression of Bi2S3 assisted by amorphous carbon interlayer for significantly enhanced photocatalysis

BackgroundFabricating heterojunctions by combining with MoS2 is efficient to boost the visible light photocatalytic activity of Bi4Ti3O12 (BTO) but limited by the concurrent formation of Bi2S3 nanorods by in-situ ion exchange reaction. MethodsAn amorphous carbon interlayer that can effectively protect the BTO fibrous structure and suppress the Bi2S3 generation was introduced to construct Bi4Ti3O12/C/Bi2S3/MoS2 (BCBM) composites with enhanced photocatalytic activity. The BCBM fibers were fabricated by electrospinning and subsequent hydrothermal growth of carbon and MoS2. Significant findingsOwing to the important roles of carbon interlayer to keep the integrity of the BTO fibrous structure and provide charge transfer channel, fast separation of photoinduced carriers happens on the semiconductor interface between BTO and MoS2 to improve the visible light photocatalytic activity. The optimum BCBM displays a photocatalytic efficiency of 88.4% and apparent constant of 0.0148 min−1 towards degrading RhB, which are much higher relative to the Bi4Ti3O12/Bi2S3/MoS2 composites prepared without the carbon interlayer. Moreover, it is demonstrated that the thickness of carbon interlayer is crucial for fabricating high-performance BTO heterojunctions with MoS2. The design and results in this work may broaden the horizon to construct the Bi-based semiconductor photocatalyst with high photocatalytic performance.

Enhanced photocatalytic efficiency of highly effective and stable perovskite BaSnO3 with monoclinic Li2MnO3 nanoparticles: Atrazine a case study of herbicide

Mesoporous Li2MnO3/BaSnO3 nanocomposites were constructed by sol-gel and impregnation approaches. The photocatalytic performance of Li2MnO3/BaSnO3 nanocomposites was assessed by Atrazine degradation as a probe herbicide molecule under visible light illumination. The optimum 15%Li2MnO3/BaSnO3 photocatalyst degraded the Atrazine completely (100%) after 50 min of illumination, which was enhanced two times larger than bare BaSnO3 NPs. The apparent rate constant of 15%Li2MnO3/BaSnO3 nanocomposite was about 3.11 times greater than bare BaSnO3 NPs. The results revealed that incorporating Li2MnO3 and BaSnO3 efficiently strengthened the separation of photoinduced carriers and extended the absorption of visible light. Due to the obtained nanocomposites having a porous structure, the Atrazine molecules are easily moved to the active sites with a large •OH radical concentration and reduced light scattering. The photocatalytic ability of Li2MnO3/BaSnO3 nanocomposite was a little minimized after five cycles of Atrazine degradation due to its high photocatalytic stability. The appropriate band bending of heterojunction Li2MnO3/BaSnO3 nanocomposite could be promoted the transport of photoinduced electrons toward the heterogeneous interface through the S-scheme mechanism, thus significantly prohibiting recombination and promoting the separation efficiency of carriers.

Relationship of structure and enhanced photocatalytic activity of S-scheme BiOCl/g-C3N4 heterojunction for xanthate removal under visible light

Constructing heterojunctions is an excellent way to enhance the photocatalytic property of semiconductors. Herein, a range of S-scheme BiOCl/g-C3N4 heterojunctions with varying mass ratios were designed using a facile hydrothermal route, and their photocatalytic ability was assessed by degrading the ethyl xanthate (EX) under visible light (λ > 400 nm). The results showed that the degradation efficiency of BiOCl/g-C3N4-0.1 heterojunction for EX was up to 91.2 % within 180 min, and its apparent rate constants (Kapp) were 4.3 and 11 times greater than those of BiOCl and g-C3N4, respectively. The experimental and characterization results revealed that the excellent photocatalytic property was ascribed to the construction of S-scheme heterojunctions. Such structure not only enhanced the visible light response but also facilitated the efficient separation of photoinduced carriers with the S-scheme transfer route, retaining strong redox-capable holes and electrons to participate in surface reactions. Furthermore, the cycling experiments indicated that the fabricated photocatalysts have great recyclability and stability. Based on the results of active substance capture, the S-scheme charge transfer model was proposed and the photodegradation mechanism of EX was reasonably elucidated. Overall, this work offers some theoretical direction for the design and construction of S-scheme heterojunctions with superior visible-light-driven photocatalytic performance.

Microstructures and photovoltaic effect of KNbO3–SrCo0.5Hf0.5O3−δ ferroelectric semiconductors

AbstractPolarization is one of the unique properties of ferroelectric materials; yet the polarization mechanism for enhancing ferroelectric photovoltaic performance is rarely been investigated, particularly in terms of bandgap variation. In this work, the effect of high‐field polarization on the enhanced photovoltaic performance of a ferroelectric ceramic, 0.98KNbO3–0.02SrCo0.5Hf0.5O3−δ (KNSCH2), was explored in terms of bandgap variation. The bandgap of the KNSCH2 sample shrank after polarization because of the increase in potential energy band overlap and the upward shift of the valence band due to increased oxygen‐vacancy defects. The polarization optimized the energy band structure of KNSCH2, promoting the separation and transport of photoinduced carriers and thus further enhancing its photovoltaic performance. The KNSCH2 sample shows a twofold enhancement in Jsc after 60 kV/cm polarization. The degree of the lattice distortion of KNSNH2 increased following polarization, causing a minute increase in its cell asymmetry. The reasons for the bandgap narrowing and the creation of sub‐bandgaps in the KNSCH samples were also investigated. This work opened new doors to understanding the mechanisms underlying the polarization‐enhanced photovoltaic performance of ferroelectric materials.

In-situ composition development of Zn/In-doped Ga2O3 nanowire with ultrahigh responsivity and long-term stability for deep-UV photodetector

High-performance deep ultraviolet photodetectors (UV PDs) based on Ga2O3 have been applied widely in civil and military exploration. The incident photon-to-electron conversion efficiency of Ga2O3-based UV PDs could be improved by doping metal or non-metal elements in the lattice. Herein, multi-metallic oxide of InZn co-doped Ga2O3 (InZn-Ga2O3) nanowires is synthesized via the in-situ chemical vapor deposition (CVD) method. The favorable 25%InZn-Ga2O3 exhibits a maximum responsivity of 440.42 A W−1 and a peak external quantum efficiency (EQE) of 2.15 × 105% under 254 nm light illumination at 10 V, which are 1.19 × 104 times higher than that for pure Ga2O3, indicating its enhanced detection ability for deep-UV light and high conversion efficiency from photons to electrons. A high UV/visible rejection ratio of 7.3 × 105 is also obtained, implying a high sensitivity for UV light. Moreover, the responsivity of the InZn-Ga2O3 UV PD remains unchanged after a long period of 8000 s testing. The superior performances of InZn-Ga2O3 UV PD are attributed to the improved crystal quality with decreased oxygen vacancies and elevated conductivity, which facilitate the separation and transfer of photoinduced electron-hole carriers. The DFT calculation and UV–vis spectra results reveal that the InZn-Ga2O3 possesses a narrowed band gap with enhanced light absorption and a decreased work function for the fast escape of electrons. In addition, the ohmic contact between InZn-Ga2O3 and Ag electrode accelerates the transfer and diffusion of photogenerated electrons. The achievements in our work present a multi-metallic oxide nanowire with high performance and an innovative mechanism analysis method for the applications of optoelectronic devices.

Constructing 0D/1D Bi2S3/Sb2S3 Z-scheme heterojunctions for efficient visible-light-driven degradation of dyes, Cr6+ reduction and H2O2 production

Direct Z-scheme heterojunctions can efficiently promote charge separation/shift for the improvement of photocatalytic performances. In this work, the novel 0D/1D Bi2S3/Sb2S3 Z-scheme heterojunctions were prepared via a simple hydrothermal method. These Bi2S3/Sb2S3 heterojunctions could completely degrade 10 ppm of MB, RhB and MO in aqueous solutions under visible light irradiation for 30, 60 and 120 min, respectively. And also, over the heterojunctions, 20 ppm of Cr6+ solution was able to being completely reduced with 80 min of visible light illumination. The excellent H2O2 production rate of 130 μmol·g−1·h−1 was exhibited, which are far more than those of single Sb2S3 (∼17 folds) and Bi2S3 (∼1.9 folds). This is due to the rational design and construction of 0D/1D Bi2S3/Sb2S3 Z-scheme heterojunctions, broadening the light absorption range, promoting the separation and transference of photo-induced carriers and affording rich active area for superior redox reactions. This illustrates the promising application of Bi2S3-based heterojunctions for pollutant removal and energy transfer.

Construction of 2D/2D Bi4O5Br2/Bi2WO6 Z-scheme heterojunction for highly efficient photodegradation of ciprofloxacin under visible light

Enhancing the heterointerface contact determined by the dimensionality of each component is essential for the rapid migration of photogenerated charge carriers. Herein, the 2D/2D Bi4O5Br2/Bi2WO6 Z-scheme heterojunction was successfully synthesized through a simple chemical co-precipitation followed by a hydrothermal process. Remarkably, the optimized Bi4O5Br2/Bi2WO6 heterojunction achieved superior photocatalytic efficiency of 91.0% and ascendant stability for the degradation of ciprofloxacin (CIP) under visible light illumination. More importantly, degradation pathway and photocatalytic mechanism analysis revealed that the reinforced photodegradation efficiency can be ascribed to the intimate heterointerface between 2D Bi4O5Br2 and 2D Bi2WO6, which facilitated the fast migration and separation of photoinduced carriers, thus enhancing the photocatalytic activity. Furthermore, the effect of pH, CIP concentration, inorganic cations and anions, and different contaminants were systematically investigated to explore the potential of practical applications. This work gives rational insight into the developing 2D/2D Z-scheme heterojunction for environmental remediation.