Separation Efficiency Of Carriers Research Articles

Sm-doped ZnO with enhanced photocatalytic performance toward destruction of RhB

In this work, Sm-doped ZnO was prepared by a Sol-Gel method. The structure, morphology, composition and optical properties of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), surface photovoltage spectrum (SPS) and X-ray photoelectron spectros­copy (XPS). Sm-doping results in high specific surface area and boosted photogenerated carriers separation efficiency, and produces more active free radicals to participate in the photocatalytic reaction. Photocatalytic activities of the samples toward removal of rhodamine B(RhB) were evaluated under UV light irradiation, the results display that Sm-doped ZnO shows higher photocatalytic activity than the reference ZnO.

Ultrathin 2D Alloyed Cu−Ga−Zn−S Curved Nanobelts for Boosting Visible‐Light Photocatalytic Hydrogen Evolution

Abstract2D semiconductor nanomaterials have received significant attention as photocatalysts for solar‐to‐hydrogen conversion due to their robust light absorption capacity, large specific surface area, and superior electron transport characteristics. Nevertheless, it is challenging to develop 2D quaternary copper‐based sulfides (QCSs) with functional integration of conducive structural features for photocatalysis from multiple elements and intricate control conditions. Herein, ultrathin 2D alloyed Cu−Ga−Zn−S (CGZS) curved nanobelts (NBs) are fabricated by using a facile one‐pot colloidal method. Subsequently, the derived Cu31S16‐CGZS Janus heterostructures are designed by increasing Cu concentrations. The formation mechanism of 2D curved alloys and Janus heterostructures is systematically investigated. Without cocatalysts, curved alloyed CGZS NBs demonstrated superior photocatalytic activities of 1264.2 µmol g−1 h−1 compared to Janus heterostructured Cu31S16−CGZS (463.1 µmol g−1 h−1) under visible light (> 400 nm). Experimental and theoretical results unveiled that the improved photocatalytic activities of curved CGZS NBs can be attributed to enhanced charge–carrier separation efficiency resulting from high crystallinity and ultrathin 2D structure, abundant active sites from curved structure, high‐active (0001) crystal facet with the lowest reaction Gibbs energy, work function, and metal‐like properties. This work offers new insights into functional integration into ultrathin 2D QCSs with enhanced visible‐light photocatalytic performance.

Boosting the UV-vis-NIR Photodetection Performance of MoS2 through the Cavity Enhancement Effect and Bulk Heterojunction Strategy.

Navigating more effective methods to enhance the photon utilization of photodetectors poses a significant challenge. This study initially investigates the impact of morphological alterations in 2H-MoS2 on photodetector (PD) performance. The results reveal that compared to layered MoS2 (MoS2 NLs), MoS2 nanotubes (MoS2 NTs) impart a cavity enhancement effect through multiple light reflections. This structural feature significantly enhances the photodetection performance of the MoS2-based PDs. We further employ the heterojunction strategy to construct Y-TiOPc NPs:MoS2 NTs, utilizing Y-TiOPc NPs (Y-type titanylphthalocyanine) as the vis-NIR photosensitizer and MoS2 NTs as the photon absorption enhancer. This approach not only addresses the weak absorption of MoS2 NTs in the near-infrared region but also enhances carrier generation, separation, and transport efficiency. Additionally, the band bending phenomenon induced by trapped-electrons at the interface between ITO and the photoactive layer significantly enhances the hole tunneling injection capability from the external circuit. By leveraging the synergistic effects of the aforementioned strategies, the PD based on Y-TiOPc NPs:MoS2 NTs (Y:MT-PD) exhibits superior photodetection performance in the wavelength range of 365-940 nm compared to MoS2 NLs-based PD and MoS2 NTs-based PD. Particularly noteworthy are the peak values of key metrics for Y:MT-PD, such as EQE, R, and D* that are 4947.6%, 20588 mA/W, and 1.94 × 1012 Jones, respectively. The multiperiod time-resolved photocurrent response curves of Y:MT-PD also surpass those of the other two PDs, displaying rapid, stable, and reproducible responses across all wavelengths. This study provides valuable insights for the further development of photoactive materials with a high photon utilization efficiency.

Fluoride Ions Post-Treatment Regulates Interfacial Charge Separation and Transport to Promote Solar Water Splitting of Bismuth Vanadate.

Herein, we propose a simple and effective fluoride (F-) ions post-treatment method to improve the solar water splitting performance of BVO. The surface modification of BVO with functional F- ions not only facilitates the transfer and separation efficiency of carriers at the electrode/electrolyte interface but also promotes the adsorption and activation of water, resulting in a photocurrent of 3.2 mA/cm2 at a bias voltage of 1.2 VRHE. Furthermore, the transfer and separation of carriers in the bulk and on the surface are further regulated by the oxygen vacancies induced by F- ions, thereby enhancing the PEC water splitting performance of BVO. Notably, the experimental findings demonstrate that the inclusion of F- ions in the KBi electrolyte enhances the photo-charging process of BVO. Specifically, at a bias voltage of 0.6 VRHE, the BVO-0.12F sample exhibits a stable photocurrent of 1.2 mA/cm2, which is twice as high as that of the initial BVO sample. Remarkably, our study unveils that the addition of F- ions into the KBi electrolyte solution plays a pivotal role in facilitating the separation of charge carriers and promoting interfacial charge transport. Consequently, this further leads to a substantial enhancement in the solar water splitting performance for BVO-0.12F photoanode.

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction.

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

Regulation of Charge Transfer Pathway in Ag-ZnIn2S4 Nanowires for Visible Photodynamic Therapy on Candida Albicans Infections.

Photodynamic therapy (PDT) is receiving extensive attention as an antimicrobial strategy that does not cause drug resistance by reactive oxygen species (ROS). Herein, hierarchical Ag-ZnIn2S4 (Ag-ZIS) core-shell nanowires are synthesized by in situ Metal-Organic Framework derived method for efficient PDT of Candida albicans (C. albicans). The core-shell structure enables spatial synergy strategy to regulate the charge transfer pathway under visible light excitation, in which the Ag nanowires are like the highway for the photogenerated electrons. The enhanced charge carrier separation efficiency greatly increased the chances for the generation of ROS. As expected, the optimized Ag-ZIS nanowires exhibit excellent performance for inactivation of C. albicans under visible light irradiation (λ ≥ 420 nm, 15 min), and the effective sterilization concentration is as high as 107CFU mL-1. Moreover, in vivo infection experiments suggested that the PDT effect of Ag-ZIS nanowires on the mouse wound healing is better than that of the clinical Ketoconazole drug. The PDT antifungal mechanism of Ag-ZIS nanowires is also investigated, and superoxide anion is found to be the predominant active species to causes C. albicans damage. This work provides a new perspective for designing novel interface structures to regulate charge transfer to achieve efficient PDT antifungal therapy.

Integration of TiO2/ZnIn2S4 p‐n Heterojunction with Titanium Defects to Boost PEC Oxygen Production

TiO2 is a widely used photoelectric conversion semiconductor material. However, due to its selective absorption of ultraviolet light and high recombination rate of photogenerated carriers, it exhibits poor photoelectrochemical water splitting performance. In this study, intrinsic defect titanium vacancy and semiconductor recombination agents ZnIn2S4 were introduced into an anodization‐annealed TiO2 film (TiO2 NT) to enhance the photoanode activity. The activity‐enhanced TiO2 photoanode (ZIS@TiO2 NT‐EA) was characterized by surface analyses and photoelectrochemical measurements. The results indicated that the introduction of titanium vacancies into the TiO2 NT‐EA changed its semiconductor type from n to p. After the ZnIn2S4 nanoparticles were loaded on the TiO2 NT‐EA film, the carrier concentration of the ZIS@TiO2 NT‐EA increased nearly 12 times than the pristine TiO2 NT. Due to the higher carrier separation efficiency resulting from the formation of p‐n heterojunction, the photocurrent density of the ZIS@TiO2 NT‐EA reached 3.89 mA cm‐2 at 1.23 V vs. RHE, nearly 3 times higher than that of the original TiO2 NT. The maximum applied bias photon‐to‐current efficiency (ABPE) value of the ZIS@TiO2 NT EA reached 2.15% at 0.496 V vs. RHE, which is very competitive if compared with all the reported TiO2 film electrodes in the PEC water splitting application.

In Situ Etching-Hydrolysis Strategy To Construct an In-Plane ZnIn2S4/In(OH)3 Heterojunction with Enhanced CO2 Photoreduction Performance.

The in-plane heterojunctions with atomic-level thickness and chemical-bond-connected tight interfaces possess high carrier separation efficiency and fully exposed surface active sites, thus exhibiting exceptional photocatalytic performance. However, the construction of in-plane heterojunctions remains a significant challenge. Herein, we prepared an in-plane ZnIn2S4/In(OH)3 heterojunction (ZISOH) by partial conversion of ZnIn2S4 to In(OH)3 through the addition of H2O2. This in situ oxidation etching-hydrolysis approach enables the ZISOH heterojunction to not only preserve the original nanosheet morphology of ZnIn2S4 but also form an intimate interface. Moreover, generated In(OH)3 serves as an electron-accepting platform and also promotes the adsorption of CO2. As a result, the heterojunction exhibits a remarkably enhanced performance for photocatalytic CO2 reduction. The production rate and selectivity of CO reach 1760 μmol g-1 h-1 and 78%, respectively, significantly higher than those of ZnIn2S4 (842 μmol g-1 h-1 and 65%). This work puts forward a feasible and facile approach to construct in-plane heterojunctions to enhance the photocatalytic performance of two-dimensional metal sulfides.

Piezoelectric Polarization and Sulfur Vacancy Enhanced Photocatalytic Hydrogen Evolution Performance of Bi2S3/ZnSn(OH)6 Piezo-photocatalyst.

The combination of piezoelectric catalysis and photocatalysis could effectively enhance the carrier separation efficiency and further improve the hydrogen production activity. However, piezoelectric polarization always suffers from a low polarization strength, which severely restricts its actual applications. In this study, we successfully synthesized a novel sulfur vacancy-rich Bi2S3/ZnSn (OH)6 (BS-12/ZSH) piezo-photocatalyst for hydrogen evolution through water splitting. Notably, the piezo-photocatalytic hydrogen generation rate of the 8% BS-12/ZSH catalyst (336.21 μmol/g/h) was superior to that of pristine ZSH (29.71 μmol/g/h) and BS-12 (21.66 μmol/g/h). In addition, the hydrogen generation for 8% BS-12/ZSH (336.21 μmol/g/h) under ultrasonic coupling illumination was significantly higher than that under single illumination (52.09 μmol/g/h) and ultrasound (121.90 μmol/g/h), owing to the cooperative interaction of the sulfur vacancy and piezoelectric field. Various characterization analyses confirmed that (1) the introduction of sulfur vacancies in BS-12 provided more active sites, (2) BS-12 with sulfur vacancies acted as a co-catalyst to accelerate the hydrogen production rate, and (3) the piezoelectric field eliminated the electrostatic shielding and offered an additional driving force, which effectively promoted the separation of electron-hole pairs. This research clearly reveals the synergistic effect between piezocatalysis and photocatalysis as well as offers a promising sight for the rational design of high-efficiency piezo-photocatalysts.

Broad-spectrum absorptive ZnCr LDHs/ZIF-67 S-scheme heterojunction for hydrogen evolution reaction under visible light irradiation

Zinc-chromium layered double hydroxides (ZnCr LDHs) occupy longer wavelength of the absorption range due to the existence of trivalent Cr ion, which is beneficial to capture more photons. However, the catalytic performance of single ZnCr LDHs is limited by the feeble dynamics. Herein, the 2D/3D S-scheme heterojunction ZnCr LDHs/ZIF-67 was coupled together by moderate electrostatic self-assembly to block the recombination of photogenerated charges on single ZnCr LDHs. Thanks to the successful formation of S-scheme heterojunction, the prepared ZZC-25 heterojunction presents a high hydrogen evolution of about 3.0 mmol g−1 h−1, which is 308.34 times and 4.82 times higher than that of ZnCr LDHs and ZIF-67, respectively. The results demonstrate that the incorporation of an S-scheme heterojunction serves as an effective strategy to enhance the photocatalytic performance of a single wide spectrum semiconductor. The present study offers experimental guidance for the efficient separation of photo-generated carriers in LDHs-based wide-spectrum semiconductors.

In Situ Construction of CuTCPP/Bi4O5Br2 Hybrids for Improved Photocatalytic CO2 and Cr(VI) Reduction.

Global warming and heavy metal pollution pose tremendous challenges to human development, and photocatalysis is considered to be an effective strategy to solve these problems. Herein, copper(II) tetra (4-carboxyphenyl) porphyrin (CuTCPP) molecules were successfully in situ loaded onto Bi4O5Br2 by a hydrothermal approach. A series of experimental results show that the light absorption capacity and photogenerated carrier separation efficiency were synchronously enhanced after the construction of CuTCPP/Bi4O5Br2 composites. Hence, the as-prepared composites possess significantly improved photocatalytic ability for both CO2 and Cr(VI) reduction. Specifically, CuTCPP/Bi4O5Br2-2 achieves a CO generation rate of 17.14 μmol g-1 under 5 h irradiation, which is twice as high as that of Bi4O5Br2 (8.57 μmol g-1). Besides, the optimized CuTCPP/Bi4O5Br2-2 also exhibits a removal rate of 61.87% for Cr(VI) within 100 min under irradiation. Furthermore, the mechanism of CO2 and Cr(VI) photoreduction was explored by in situ Fourier transform infrared spectroscopy and capture experiments, respectively. This work can be a reference toward the construction of photocatalysts with high activity for solar energy conversion.

Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration

AbstractPhotocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD‐COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 μmol g−1 h−1 in O2 and air) than TBC‐COF with hcb topology through the O2‐O2⋅−‐H2O2, O2‐O2⋅−‐O21‐H2O2, and H2O‐H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅− generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O21, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high‐performance photocatalysts for H2O2 production by topological structure modulation.

Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration.

Photocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD-COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 μmol g-1 h-1 in O2 and air) than TBC-COF with hcb topology through the O2-O2⋅--H2O2, O2-O2⋅--O2 1-H2O2, and H2O-H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅- generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O2 1, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high-performance photocatalysts for H2O2 production by topological structure modulation.

Transition‐Metal‐Doped TiO2 Nanorods with High‐Visible‐Light Response via a Simple Hydrothermal Method

Transition‐metal‐ion doping is an effective method to shorten bandgap and enhance visible‐light absorption of TiO2, but there are still some serious challenges for most doping technologies, such as nonuniform doping, severe lattice damages, metal atoms agglomeration, and inactivated impurities. Herein, a simple and universal hydrothermal method is developed to realize the effective transition‐metal ions doping of TiO2 (including Fe, Co, Mn, Cu, V, and Cr). The photoelectrochemical water splitting performances of Cr‐doped TiO2 nanorods with multifarious Cr ion valence states (Cr3+ or Cr6+ ions), various Cr‐ion concentrations, with or without oxygen vacancy activation are emphatically and systematically studied. Experiments and theoretical calculations demonstrate that the remarkably enhanced carrier separation and injection efficiencies are the key factors to improve the visible‐light photoactivity, benefiting from the homogeneous distribution of impurity atoms and the incorporation of oxygen vacancies. The Cr3+‐ion‐doped TiO2 nanorod arrays with oxygen vacancy activation (Cr3+/Ov–TiO2) displays an impressive incident photon‐to‐electron conversion efficiency of 5.4% at 450 nm visible light, far superior to the pure TiO2 of 0.03%. Furthermore, no obvious photocurrent decay is observed in the Cr3+/Ov–TiO2 photoanode after 12 h continuous light illumination.

Photocatalytic CO2 reduction of CuO-Zn1-xCuxO (ZCO)/Ti3C2Tx MXene heterojunctions with enhanced interfacial charge transfer

Photocatalytic CO2 reduction reaction (CO2RR) synthesis of recycled fuel is a promising pathway to assist the mitigating fossil fuel depletion. Finding efficient and inexpensive high performance CO2RR semiconductor photocatalysts is a giant challenge in the field of photocatalytic reduction. This work constructs the novel-designed interfacial Schottky junction of CuO-Zn1-xCuxO (ZCO)/Ti3C2Tx via electrostatic spinning and electrostatic self-assembly techniques. The catalysts exhibit tight contact heterogeneous interface companies with enhanced CO2 chemisorption capability and proved by various characterizations for efficient carrier separation and migration capacity. The optimized ZCO/Ti3C2Tx nanosheet composites significantly improved their photocatalytic performance. The best samples yielded 5.855 and 2.518 μmol g−1 h−1 of CO and CH4, which are 6 and 1.73 times higher than the conversion of ZCO, respectively, and maintain stability after four cycles without the use of sacrificial agents. In addition, the mechanism and reaction pathways of the photocatalytic process are proposed through In-situ diffuse reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTS) and X-ray absorption near edge structure (XANES) analysis. This work provides a new semiconductor/co-catalyst system for the photocatalytic reduction of CO2 and demonstrates that Ti3C2Tx MXene is a hopeful and inexpensive co-catalyst.

Constructing multiple active sites of Bi2WO6 for efficient photocatalytic NO removal and NO2 inhibition

Insufficient photocatalytic NOx oxidation capacity will lead to excessive toxic by-products (NO2), which still seriously restrict its practical application. Herein, the multiple active sites (Cl, Bi0 and OVs) modified Bi2WO6 has been established by in-situ synthesis method. The synergistic effect of multiple active sites greatly increased the photo-electric properties of the Bi2WO6, resulting in the boosting photocatalytic NOx deep oxidation to nitrate. The visible light driven OVs-Bi@BWO-Cl catalyst exhibited a highest NO conversion efficiency (67.3 %) with extremely low NO2 concentration (17.9 ppb). The synergism of structural regulation from the OVs with Cl-doping and surface plasmon resonance of Bi0 significantly enhanced light absorption and provided a fast charge transport channel, improving the separation efficiency of photo-generated carriers. The in-situ DRIFTS and density functional theory (DFT) results shown that the synergistic effect by multiple active sites could enhance the adsorption and activation of reactants to accelerate the processes of H2O/O2-to-ROS and decrease the energy barrier of NO removal to promote deep oxidation of NO-to-NO3−. This work can provide ideas for the design and preparation of the catalyst for safe photocatalytic environment purification.

Ag nanocubes-decorated ammonium hydroxide-treated carbon nitride to improve photocatalytic H2O2 production and fuel cell performance

A novel photocatalyst is designed by surface modification and cocatalyst loading of graphitic carbon nitride (g-C3N4) with ammonium hydroxide and silver nanocubes (AgNCs), respectively. The synergistic effect of the modification in the intralayer of g-C3N4 and surface plasmon resonance (SPR) bands of AgNCs significantly enhances the migration and separation efficiency of photo-induced charge carriers. A nickel mesh coated with photocatalyst and the carbon paper loaded with pristine g–C3N4–mixed iron phthalocyanine (FeIIPc) used as the photoanode and cathode, respectively, are constructed for the self-powered photoelectrochemical cell, which exhibits the maximum power density of 0.74 mW cm−2. The AHCN/AgNCs-based cell reveals approximately a 3.1-times enhancement in maximum power density compared with the pristine g–C3N4–based cell. In addition, the photocatalytically generated H2O2 (chemical energy) can be stored in water, and then used as fuel by the connection of two electrodes in the dark. After the fuel cell is operated for 12 h, the specific capacitance retention rate still maintains as high as 57.2 %, which is the greatest retention rate in comparison with the previously reported H2O2 fuel cell systems. Our work offers a feasible opinion on how to improve the visible light utilization of semiconductors by tuning the intralayer properties and loading plasmonic metal.

In-situ synthesis of V2AlC@V2O5/TiO2 immobilized over honeycomb support with vanadium oxide electron transfer mediator for stimulating selective CO2 photoreduction through bi-reforming in a monolith reactor

Photocatalytic CO2 reduction to valuable chemicals and fuels is a practical approach for climate action; however, available photocatalysts and photoreactors are less efficient. In this work, well-designed V2AlC@V2O5 supported TiO2 and immobilized over honeycomb support for CO2 photoreduction in a monolith reactor have been investigated. The catalysts were loaded over the monolithic support using the sol-gel dip-coating method and found promising for higher light absorbance and charge separation. The performance of V2AlC@V2O5/TiO2 composite for photocatalytic CO2 reduction with water and bi-reforming of methanol was performed using a fixed bed and monolith photoreactor. Using V2AlC@V2O5/TiO2 with a fixed bed reactor and methanol–water mixture, a CO yield of 13.75 mmol g−1h−1 was produced, 26.39 and 38.19-fold higher than using water and pristine TiO2, respectively. Similarly, CH4 production was 1.97 and 12.33 folds higher than using water and TiO2 only, whereas, using water, production of H2 was not detected. The higher photoactivity of the composite with methanol was due to efficient photo-induced carrier separation due to the synergistic effect of V2AlC/V2O5 and more production of protons. Using a monolith photoreactor, CH4, CO and H2 production rates of 55.44, 35.51 and 1.638 mmol g−1h−1 were obtained, 166.50, 2.58 and 3.05 times more than those produced using a fixed bed reactor. This significantly higher photoactivity with monolith photoreactor was due to higher photon flux utilization with surface reactions, resulting in more production and utilization of photoinduced charge carriers. The highest QY after five consecutive cycles was 48.374, 25.358 and 1.51 % for CH4, CO and H2, which is 200.5, 2.54 and 3.87 folds higher than using the fixed bed, respectively. This work provides a new approach to designing and fabricating higher efficient and stable photocatalytic system for CO2 recycling, and it can be further employed for other energy-related applications.

Photocatalytic application towards the degradation of ciprofloxacin and algae by Z-scheme 2D/3D heterojunction of Bi12O17Cl2/UiO-66-NH2

With the continuous emergence of antibiotics in natural water bodies, the crisis of water environment is becoming increasingly serious. To efficiently remove antibiotics, a novel 2D/3D Z-scheme heterojunction of Bi12O17Cl2/UiO-66-NH2 was constructed by in situ growth technology. The formation of Z-scheme heterojunction between Bi12O17Cl2 and UiO-66-NH2 not only significantly improves the transfer rate and separation efficiency of charge carriers, but also greatly prolongs the lifetime of electrons and improves their light absorption ability. Free radical capture experiments and ESR spectra display that ⋅O2− and ⋅OH radicals dominate the degradation process of ciprofloxacin. The synthesized Z-scheme heterojunction shows a high degradation rate of 83.5 % for antibiotic ciprofloxacin within 60 min, much higher than those of Bi12O17Cl2, UiO-66-NH2 monomers and many other reported photocatalysts. The heterojunction Bi12O17Cl2/UiO-66-NH2 also exhibits excellent degrading performance towards antibiotics in three actual water bodies (tap water, lake water and the effluent of domestic sewage treatment plant). Meanwhile, the as-prepared photocatalyst can effectively degrade Microcystis aeruginosa and algal toxin Microcystin-LR in surface water bodies contaminated by algae and antibiotics. The QSAR analysis indicates that the toxicities of both ciprofloxacin and its intermediates are greatly reduced. The degradation pathways of ciprofloxacin were analyzed via Density Functional Theory calculations and QSAR analysis. This study provides an excellent synthesis method of Z-scheme heterojunction for the purification of surface water bodies contaminated by algae and antibiotics via photocatalytic technology.

Photo-induced in-situ synthesis of Cu2O@C nanocomposite for efficient photocatalytic evolution of hydrogen

Cuprous oxide (Cu2O) is an ideal visible light catalyst owing to its narrow band gap, environmental benignity and abundant storage; however, the fast recombination of photogenerated charge carriers and poor stability of Cu2O has impeded its application in photocatalysis. Herein, we demonstrate that Cu2O@C nanocomposite can spontaneously evolve from a methanol aqueous solution containing cupric ions under the induction of irradiation. Compared with the traditional carbon coating method, the Cu2O@C nanocomposite obtained by the photo-induced in-situ synthesis can reserve superior original characteristics of the semiconductor under mild reaction conditions, promote the charge transfer and enhance the separation efficiency of charge carriers; in addition, the carbon shells can also effectively prevent Cu2O from photo-corrosion. As a result, the Cu2O@C nanocomposite exhibits excellent photocatalytic activity in the hydrogen evolution in comparison with the Cu2O particles; the H2 evolution rate over the Cu2O@C nanocomposite reaches 1.28 mmol/(g·h) under visible light, compared with the value of 0.065 mmol/(g·h) over Cu2O. Moreover, the Cu2O@C nanocomposite displays good cycle stability, viz., without any deactivation in the catalytic activity after five cycles.