Transport Of Photogenerated Electrons Research Articles

An Enhanced Extend Interface via the π–π Interaction to Achieve the Soluble Light‐Assisted Lithium–Oxygen Batteries

AbstractThe light‐assisted strategy is considered as an effective way to reduce the overpotential of lithium‐oxygen (Li─O2) batteries, however, the generated solid discharge products are prone to cover active sites of the solid‐state photocatalyst, causing the premature death of the cell. Herein, for the first time, the feasibility of soluble photocatalysts in Li─O2 battery system using Iron (II) Phthalocyanine (FePc) is verified. A micro reaction channel is constructed between the sp2‐carbon cathode and the soluble photocatalyst‐phthalein iron through π–π interaction, which can effectively increase the three‐phase reaction interface, facilitating the rapid separation and the transportation of photogenerated electrons and holes, thus improving the photocatalytic efficiency and the reaction kinetics of Li─O2 battery. Moreover, the FePc soluble photocatalysts induced the dual growth modes of surface growth and solution‐mediated growth pathways for the discharge products lead to an additional discharge capacity in the Li─O2 battery. Accordingly, the battery exhibits a lower overpotential of 0.33 V between discharge and charge plateaus at a current density of 0.01 mA cm−2, displaying the excellent cyclic stability (remaining a round‐trip efficiency of 81.1% after 130 cycles). The novel strategy provides new approaches for the construction of the light‐assisted Li─O2 batteries with reduced overpotential and boosted energy efficiency.

Reduction of the photogenerated electron transport path by modulating the conduction band region to achieve the highest lignin β–O–4 bond photocleavage efficiency under xenon excitation

Photocracking of lignin β–O–4 bonds is a green approach for the high-value modification of lignin. Graphitic carbon nitride (g-C3N4) that can photocleave the β–O–4 bond is presently the only stable, metal-free photocatalyst owing to the residual metal ions generated due to photocorrosion of metal sulfides. Herein, g-C3N4 with a N–C3 vacancy structure is prepared by etching site–engineering strategy based on the protection of C–N=C structure by chlorine atom. The N–C3 vacancy structure can reduce the transport path of the photogenerated electrons by tuning the conduction band (CB) region to the edge of the photocatalyst, which impedes the critical complexation of the photogenerated electron–hole pairs and enhances the photoelectric conversion efficiency five-fold. Combined with the unique chemisorption capacity (137.82 kJ/mol) of N–C3 vacancies for oxygen, the g-C3N4 photocatalysts with N–C3 vacancy structure can generate 9.6-fold higher superoxide radicals and 13-fold higher lignin β–O–4 bond photocleavage efficiency lignin compared with untreated g-C3N4. Based on the reaction enthalpy changes and free energies investigated through simulations, a route of lignin Cα–Cβ bonds being oxidized and dehydrogenated twice by photogenerated cavities is proposed for the first time. This work reveals the relation between the properties of g-C3N4 and the photocleavage efficiency of lignin β–O–4 bonds.

Mussel-inspired polydopamine and Zr-porphyrin MOF co-decoration of a cellulose paper-based composite membrane for efficient photoreduction of Cr(VI) and photothermal antibacterial in wastewater

Abundant hazardous pollutants, in particular heavy metal ions and microbes, in aqueous systems seriously threaten ecological safety and human health. Photocatalysis is deemed an appealing solution yet remains challenging to exploit more efficient, economical, and sustainable photocatalytic materials. In this study, we successfully fabricated a cellulose paper-based composite membrane, namely Zr-TCPP@PDA@FP, for photoreduction of Cr(VI) and photothermal antimicrobial. For the resultant composite membrane, the self-polymerization polydopamine (PDA)-coated cellulose fibers act as sustainable scaffolds to anchor the in-situ synthesized porphyrin-doped UiO-66-NH2 (Zr-TCPP) nano-photocatalysts. The hypotheses are that: 1) porphyrin doping in Zr-TCPP can both reinforce the visible-light absorption and the transport of photogenerated electrons; 2) mussel-inspired PDA coating on fiber surface not only services as binder to promote the Zr-TCPP loading and dispersion, but also functions as heterojunction interface to accelerate photogenerated electron separation and transfer from Zr-TCPP; As a result, Zr-TCPP@PDA@FP exhibited significant photocatalytic reduction towards Cr(VI), achieving a removal efficiency of 93.9 % within 20 mins and cycling stability. Besides, the hybrid membrane also featured excellent photothermal antibacterial performance (over 99 % for both E. coli and S. aureus). This work will inspire the development of economic and sustainable cellulose-based functional materials for efficient wastewater remediation.

Boosting photocatalytic activity in ternary lamellar hierarchical structured ZnFe2O4/polymeric carbon nitride by constructing an electronic bridge

Photocatalytic technology is one of the ideal approaches for clean energy production and environmental pollution control in the future. However, the rapid recombination of photo-generated charge carriers is a bottleneck problem of low solar energy conversion efficiency. Herein, a magnetic ZnFe2O4/Pt/polymeric carbon nitride (PCN) semiconductor catalyst is designed and prepared for high-performance photocatalytic hydrogen production reaction and photocatalytic degradation rate of RhB. It exhibits 339.31 μmol·g−1·h−1 hydrogen production rate and 96.08 % photocatalytic degradation rate of RhB within 120 min under visible light. The introduction of Pt, constructing an electronic bridge, accelerated the transfer of photo-generated carriers, meanwhile, the smaller band gap of the ternary composites enabled the generation of more photo-generated electrons. The internal electric field accelerated the accumulation of electrons and holes in the conduction band of ZnFe2O4 and valence band of PCN, thus photocatalytic activity is greatly enhanced. The electron-hole separation is also improved and the transport of photo-generated electrons is facilitated by the special structure of the heterojunction and the unique morphology of PCN. In addition, the used catalyst can be recovered through magnetic fields, and this magnetic catalytic system has great application prospects in the fields of photocatalytic hydrogen production and pollutant degradation.

Insight into bay-/end-substituted perylene diimide and its S-scheme heterojunction for enhanced photocatalytic H2O2 production under visible-light irradiation

Here, 1D bis(N-carboxymethyl) peryleneimide (H2PDI), 0D 1,6,7,12-tetrachloro-bis(N-carboxymethyl) peryleneimide (4Cl-H2PDI), and 2D 4Cl-H2PDI/graphene quantum dot (4Cl-H2PDI/GQD) nanostructures are synthesized and carefully analyzed. The effect of bay-/end-substitution and S-scheme heterojunction of PDI-based materials as main catalysts on the photocatalytic H2O2 evolution is first studied through the oxygen reduction reaction (ORR). Under the visible-light irradiation (> 420 nm), 4Cl-H2PDI and 4Cl-H2PDI/GQD as photocatalysts exhibit the ∼7 and ∼16 times H2O2 evolution rate than H2PDI (1059.6 vs. 2484.0 vs. 160.0 µM g−1 h−1), respectively. The systematical experiments reveal that 4Cl-H2PDI and 4Cl-H2PDI/GQD should prefer a two-step single-electron ORR process, while H2PDI may involve a 4e‒ water oxidation and one-step 2e‒ ORR process. Further experiments confirm that the bay-substitution and GQD doping of H2PDI can promote the generation, transportation, and separation of photogenerated electrons and holes, and prolong the carrier lifetime. This work provides insight into PDI-based photocatalytic H2O2 production.

Precise Regulation in Chain-Edge Structural Microenvironments of 1D Covalent Organic Frameworks for Photocatalysis.

Covalent organic frameworks (COFs) constitute a promising research topic for photocatalytic reactions, but the rules and conformational relationships of 1D COFs are poorly defined. Herein, the chain edge structure is designed by precise modulation at the atomic level, and the 1D COFs bonded by C, O, and S elements is directionally prepared for oxygen-tolerant photoinduced electron transfer-atom transfer radical polymerization (PET-ATRP) reactions. It is demonstrated that heteroatom-type chain edge structures (─O─, ─S─) lead to a decrease in intra-plane conjugation, which restricts the effective transport of photogenerated electrons along the direction of the 1D strip. In contrast, the all-carbon type chain edge structure (─C─) with higher intra-plane conjugation not only reduces the energy loss of photoexcited electrons but also enhances the carrier density, which exhibits the optimal photopolymerization performance. This work offers valuable guidance in the exploitation of 1D COFs for high photocatalytic performance. This work offers valuable guidance in the exploitation of 1D COFs for high photocatalytic performance.

G-C3N4@CPP/BiOClBr-OV biomimetic fractal heterojunction synergistically enhance carrier dynamics for boosted CO2 photoreduction activity

In recent years, there has been significant interest in generating high-value solar fuels via the photocatalytic reduction of CO2. Nonetheless, its large-scale application is impeded by low energy utilization efficiency and limited photocatalytic activity. This study employed carbonized pomelo peel (CPP), a waste biomass material, to successfully craft a CN@CPP/BOCB-OV ternary heterojunction abundant in N/O vacancy defects through secondary calcination and in-situ growth. The construction of the heterojunction and the emergence of defect-induced donor energy levels create a built-in interface electric field (IEF) and an interfacial electron transmission channel respectively, fortifying the separation and transport of photogenerated electrons. Crucially, following the incorporation of CPP, its distinctive 3D porous and heterojunction bionic flower structures expand the spectral absorption range. Acting as a superior electron acceptor, CPP reinforces the IEF, notably boosting carrier transport efficiency. Simultaneously, it operates as a hub for photothermal synergy and CO2 adsorption activation, achieving multi-site synergistic enhancement of photoreduction CO2 activity. Hence, the CN@CPP/BOCB-OV heterojunction demonstrates a substantial quantitative enhancement in CO2 photoreduction activity. Remarkably, it exhibits the capability to catalyze CO2 reduction even under infrared light excitation, which is of great significance for the cascade utilization of solar energy. Furthermore, employing DFT calculations, we elucidate the electron transfer mechanism at the heterojunction interface and outline potential pathways for photocatalytic CO2 reduction. The combination of waste biomass utilization, heterostructure construction and defect engineering provides a promising strategy for developing efficient heterostructure photocatalysts.

Mn0.5Cd0.5S@NiO composite for boosting visible-light-driven photocatalytic hydrogen evolution

The MnxCd1-xS solid solution is a recently emerged semiconductor with an adjustable bandgap structure, which has great potential for development in the photocatalytic water splitting field. In the present study, a Mn0.5Cd0.5S@NiO composite was constructed through a solvothermal method for efficient visible-light-driven photocatalytic hydrogen evolution. The study results revealed that Mn0.5Cd0.5S@NiO composite possessed excellent photostability, more active sites, reduced recombination and fast charge-separation compared to pure Mn0.5Cd0.5S. As a result, the Mn0.5Cd0.5S@NiO-0.50 composite exhibited significant hydrogen evolution activity upon exposure to visible light (λ ≥ 420 nm), with a rate of 50.53 mmol·g−1·h−1, which was 4.9 times and 632 times greater contrasting to the pure Mn0.5Cd0.5S and NiO, respectively. Of note, NiO exists in the form of a co-catalyst in composite materials, playing a role in accelerating the transport of photo-generated electrons and facilitating H+ reduction sites during the electron transfer process, thereby enhancing the hydrogen production rate of the photocatalyst.

Effect of the Magnetostriction Induced on the Crystalline Structure of Nanoparticulate TiO2 Photoanodes and Their Relationship with the Photovoltaic Response of Black-Dye Sensitized Solar Cells

The study of ferromagnetism (FM) in semiconductor oxides having non-cubic crystalline structures (e.g. TiO2) is attractive due to their applications in spintronics [1]. FM can be activated in TiO2 nanomaterials by promoting oxygen vacancies (VO) located in paramagnetic defected sites Ti3+VOTi4+. In this context, the VO can induce in Ti3+-doped TiO2 structures remarkable magnetic anisotropy energy (MAE) of 6.51x106 erg/cm3, thus indicating the magnetic saturation (Ms) should be achieved by applying external magnetic fields (MFs) of ~425 gauss [2,3]. Therefore, magnetostriction can be observed in ferromagnetic TiO2 films containing Ti3+VOTi4+ sites as a phenomenon in which their dimensions and shapes are changed when they are magnetized. In this work, black dye-sensitized solar cells (BD-SSC) were prepared using TiO2 nanoparticle films enriched by Ti3+VOTi4+ sites, to gain an understanding of the effects of magnetostriction on the photovoltaic responses of BD-SSC. In this way, photocurrent density-cell potential plots were obtained for the BD-SSC in the absence and presence of MFs having intensities of 125, 250, 500, 1000, and 2000 gauss. MFs lines were parallel applied to the surface of the BD-sensitized TiO2 photoanodes. Our results indicated that the photogenerated electron transport through the dyed TiO2 photoanodes was not limited by electron transfer to I3 - anions at the electrolyte in the absence or the presence of MFs, because all the values for the open-circuit potential (-Eoc ~ 0.553±0.014 V) remain constant. On the contrary, the obtained values for the short-circuit current density Jsc and the global conversion efficiency, revealed that both parameters increased as a function of the MFs intensities, thus indicating that the magnetic lines were responsible for decreasing the degree of disorder (0<b<1) of the electron-traps at the intra-bandgap state's distribution of the TiO2 film (Jsc is proportional to Q1/ b where Q is the number of trapped electrons) [4,5].[1] M. Stiller et al., Front. Phys., 11(2023)1124924.; [2] D. Kim et al., J. Phys.: Condens. Matter, 21(2009)195405.; [3] B. Shao et al., J. Appl. Phys., 115(2014)17A915. [4] N. Kopidakis et al., J. Phys. Chem. B, 107(2003)11307. [5] J. van de Lagemaat et al., J. Phys. Chem. B, 104(2000)4292. Acknowledgements The authors thank the National Council for Science and Technology (CONACyT) Mexico for the funding support (grants CB No. 258789 and FOINS No. 3838). JIVN thanks CONACyT for his doctoral fellowship support (grant No. 893260).

Enhanced photoelectrocatalytic performance of ZnO/Co3O4 nanoflowers modified TiO2 nanotube array under visible light

The efficient degradation of organic pollutants from the water has been attracted greater public attention and remains to be the main challenge of environmental problems. In this work, ZnO/Co3O4 nanoflowers are deposited on the surface of TiO2 nanotube arrays (ZnCo-TiO2) via the one-pot hydrothermal method by adjusting the Zn/Co ratios. The images of scanning electron microscope show that the ZnCo11-TiO2 (the addition of the Zn/Co ratios is 1:1) presents nano spherical nano-flowers morphologies. In addition, the energy bandgap of ZnCo11-TiO2 is calculated to be 2.8 eV by UV–visible diffuse reflectance spectroscope, which was smaller than that of other semples. Moreover, the lowest peak intensity of photoluminescence spectroscopy for ZnCo11-TiO2 indicates that it has high electron-hole separation efficiency. From the results of UV–visible diffuse reflectance spectroscope and EIS, we can see that ZnCo11-TiO2 has a wider spectral absorption range (200–380 nm and 450–800 nm) and a smaller electron transfer impedance (137.4 Ω). The photoelectrocatalytic removal efficiencies of ZnCo11-TiO2 is 97.5% toward the removal of methylene blue (MB), which is higher than that of other semples. The excellent photoelectrocatalytic performances of ZnCo11-TiO2 are ascribed to the high visible light absorption and rapid transportation of photogenerated electrons on ZnO/Co3O4 nanoflowers. In addition, this paper tentatively stated the detailed photoelectrocatalytic mechanism of ZnCo11-TiO2 electrode for the removal of MB.

Carbon layer derived carrier transport in Co/g-C3N4 nanosheet junctions for efficient H2O2 production and NO removal

Co nanoparticles are embedded in N-doped carbon nanotubes (Co-N-carbon nanotubes) using combinations of mechano-chemical pre-treatment and thermal polymerization process (at 760 °C). A further thermal polymerization process done on these Co-N-carbon nanotubes and ultrathin graphitic carbon nitrate (g-C3N4) leads to the formation of Co nanoparticles (coated with carbon layers) embedded g-C3N4 nanosheets composite, along with the disappearance of carbon nanotube morphology on the material. The Co/g-C3N4 junctions are constructed with a Schottky barrier formed between the carbon layer coated Co nanoparticles and the g-C3N4 nanosheets. The presence of carbon layers in the composite system facilitates transport of photogenerated electrons at the Fermi level of Co, which results in enhanced photocatalytic H2O2 generation and NO oxidation performances of the composite material in visible light irradiation condition with excellent cyclic stability. The Schottky junction composites constructed using optimized preparation conditions in case of no co-catalyst incorporation shows a photocatalytic H2O2 generation efficiency of 3618 μmolL−1h−1 which is about 1000 times of that of pristine g-C3N4 nanosheets. A NO removal rate of 62 % (higher than that of the commercial P25 (TiO2)) is also observed. These results provide possible approaches on constructing advanced photocatalysts for energy and environmental applications.

Organic-inorganic p-type PEDOT:PSS/CuO/MoS2 photocathode with in-built antipodal photogenerated holes and electrons transfer pathways for efficient solar-driven photoelectrochemical water splitting

Organic PEDOT:PSS thin film and n-type MoS2 flakes were incorporated on CuO photocathode as the underlying layer and surface co-catalysts, respectively, establishing a rationally-designed novel integrated structure of PEDOT:PSS/CuO/MoS2. The organic-inorganic interface of PEDOT:PSS/CuO effectively shuttles photogenerated holes towards the FTO/PEDOT:PSS junction. Furthermore, the surface MoS2 co-catalysts form a p-n junction with CuO, which accelerates the transport of photogenerated electrons towards the photocathode/electrolyte junction, in addition to providing more reactive sites for the H2 evolution reaction. These synergistically formed antipodal charge transfer pathways have led to improved charge separation, rapid interfacial charge transfer kinetics and impeded electron-hole recombination in the PEDOT:PSS/CuO/MoS2 photocathode, which can achieve a photocurrent density of – 2.26 mA/cm2 at −0.6 V vs Ag/AgCl (2.1 times higher than that of the bare CuO photocathode). Analytical characterisations, electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS), also provide supporting evidence for its dramatically enhanced PEC water splitting performance.

Construction of rare-metal neodymium-doped ZnO and g-C3N4 Z-type heterostructures enhance the photocatalytic efficiency of methylene blue removal

Herein, Nd-ZnO/g-C3N4 (NZCN) composites were obtained by doping rare-earth element Nd with ZnO using a hydrothermal method, coupled with g-C3N4 (CN) electrostatic ultrasonic self-assembly. The NZCN composite exhibited an impressive methylene blue (MB) removal rate of 94.88 %, with a degradation rate of 0.02637 min−1 after 105 min exposure to 500 W xenon lamp irradiations. Comparatively, the degradation rate of MB by the NZCN composite was five and twice times higher than ZnO and CN samples, respectively. This significant improvement can be attributed to the synergistic effect of Nd, ZnO, and CN, which not only widened the light absorption range but also enhanced the density, separation, and transport of photogenerated electrons (e−) and holes (h+), thus improving the photocatalytic performance of the NZCN composites. An in-depth investigation into the photocatalytic reaction process was carried out using free-radical active-species capture experiments, confirming the critical role of h+. Furthermore, the reproducibility and stability of the NZCN composites were assessed over five experimental cycles, demonstrating consistent and stable MB degradation rates of 90.1 % while retaining the crystal structure unchanged. Overall, the construction of rare-earth-metal-doped ZnO and Z-type heterojunctions synergistically improves photocatalytic activity and provides a green and environmentally friendly approach for the removal of organics from wastewater.

Ferri-hydrite: A Novel Electron-Selective Contact Layer for InP Photovoltaic and Photoelectrochemical Cells.

Solar energy conversion devices with charge-selective contacts are attracting significant research interest as a cost-effective alternative to homojunction counterparts. This study presents a novel approach for fabricating high-performance solar cells based on InP heterojunctions using a solution-processed ferri-hydrite (Fh) electron-selective contact (ESC). The champion cell efficiency of 16.6% is achieved, which is a significant improvement over those from previous studies using other solution-processed ESC materials. X-ray photoelectron spectroscopy measurements showed that the low conduction band offset at the Fh-InP interface facilitated selective transport of photogenerated electrons from InP. Moreover, the Fh electron-selective contact layer provided an excellent photoelectrochemical half-cell water reduction efficiency of 8.4%. The Fh layer not only selectively extracts photogenerated electrons from InP but also simultaneously serves as a surface protection layer, improving the cell's long-term stability. These results demonstrate the potential of Fh as a low-cost and easily fabricated material for use in high-efficiency photovoltaic and photoelectrochemical devices. Our findings pave the way for further improvements in the efficiency of InP heterojunction solar cells by addressing the losses incurred in the cells.

One-Step Fabricated Sn0 Particle on S-Vacancies SnS2 to Accelerate Photoelectron Transfer for Sterling Photocatalytic CO2 Reduction in Pure Water Vapor Environment.

Promoting the proton-coupled electron transfer process in order to solve the sluggish carrier migration dynamics is an efficient way to accelerate the photocatalytic CO2 reduction (PCR) process. Herein, through the reduction of Sn4+ by amino and sulfhydryl groups, Sn0 particles are lodged in S-vacancies SnS2 nanosheets. The high conductance of Sn0 particles expedites the collection and transport of photogenerated electrons, activating the surrounding surface of unsaturated sulfur (Sx 2- ) and thus lowering the energy barrier for generation of *COOH. Meanwhile, S-vacancies boost H2 O adsorption while Sx 2- increases CO2 adsorption, as demonstrated by density functional theory (DFT), obtaining a selectivity of 97.88% CO and yield of 295.06 µmol g-1 h-1 without the addition of co-catalysts and sacrificial agents. This work provides a new approach to building a fast electron transfer interface between metal particles and semiconductors, which works in tandem with S-vacancies and Sx 2- to boost the efficiency of photocatalytic CO2 reduction to CO in pure water vapor environment.

Oxygen vacancies modulation: Visible light elimination of tetracycline and rhodamine B by surface defect-rich 3D rambutan-like hollow TiO2

Organic contaminants in the water environment and liquid foods have posed a great threat to the environment as well as human well-being, and the low catalytic activity of traditional TiO2 photocatalysts limits its further application. Here, inspired by nature, a novel hydrogenated rambutan-like hollow TiO2 (denoted as HRT) was synthesized by facile hydrothermal treatment and in-situ hydrogenation reduction steps. The protruding spikes on the surface of the 3D rambutan-like hollow structure build a fast channel for charge transfer, the suitable cavity enhances light scattering and collection. The available inner/outer surface can bind contaminants more rapidly which facilitates transportation of photo-generated electrons. Relying on its special structure and abundant surface defects, HRT exhibits excellent photocatalytic degradation property. Under visible light irradiation, the photodegradation rate of rhodamine B (RhB) by HRT nearly reached 100.0%, and 80.0% for tetracycline (TC) within only 10 min, whose photocatalytic activity was 6.45 and 2.08 times higher than that of RT, respectively. Moreover, the innovative and practical application of HRT to the degradation of TC in milk revealed favorable degradation efficiency (71.0%) and salient catalytic reusability after five cycles. This work provides a new perspective on the purification of multiple organic contaminants in aqueous systems, points the way to the intractable problem of removing antibiotics from liquid foods and expands the application fields of semiconductor photocatalysts.

A Chiral Nanocomplex for Multitarget Therapy to Alleviate Neuropathology and Rescue Alzheimer's Cognitive Deficits.

Alzheimer's disease (AD) is a severe neurodegenerative condition characterized by inflammation, beta-amyloid (Aβ) plaques, and neurodegeneration, which currently lack effective treatments. Chiral nanomaterials have emerged as a promising option for treating neurodegenerative disorders due to their high biocompatibility, strong sustained release ability, and specific enantiomer selectivity. The development of a stimulus-responsive chiral nanomaterial, UiO-66-NH2 @l-MoS2 QDs@PA-Ni (MSP-U), for the treatment of AD is reported. MSP-U is found to stimulate neural stem cell (NSCs) differentiation, promote in situ hydrogen (H2 ) production, and clear Aβ plaques. l-MoS2 QDs modified with l-Cysteine (l-Cys) effectively enhance the differentiation of NSCs into neurons through circularly polarized near-infrared radiation. Doped-phytic acid nickel (PA-Ni) improves the activity of l-MoS2 QDs in scavenging reactive oxygen species at the lesion site via photocatalytic H2 production. Loading l-MoS2 QDs with UiO-66 type metal oxide suppresses electron-hole recombination effect, thereby achieving rapid charge separation and improving transport of photogenerated electrons, leading to significantly improved H2 production efficiency. The photothermal effect of MSP-U also clears the generated Aβ plaques. In vivo evaluations show that MSP-U improves spatial cognition and memory, suggesting a promising potential candidate for the treatment of AD using chiral nanomaterials.

Porphyrin Modified UiO-66-NH2 for Highly Efficient Photoreduction of Cr(VI) under Visible Light

Cr(VI) is a common heavy metal pollutants present in the aquatic environment, which possess toxic and carcinogenic properties. In this study, a solvothermal reaction was used to prepare porphyrin (TCPP)-modified UiO-66-NH2 (UNT). The UNT integrated adsorption and photocatalytics in the application for dealing with Cr(VI). The photocatalytic reduction activities of UNT for Cr(VI) were investigated under visible light illumination. We found that the TCPP doping amount of 15 mg UNT (15-UNT) had a 10 times higher reduction rate of Cr(VI) than pristine UiO-66-NH2. The optimal 15-UNT photocatalyst demonstrated the highest photocatalytic activity, and Cr(VI) was completely removed within 80 min. In addition, the introduction of porphyrin not only enhanced the absorption of light but also enabled the transport of photogenerated electrons from porphyrin to UiO-66-NH2, which promoted the separation of charge carriers. Furthermore, the effects of factors such as porphyrin content, pH and light source on the photocatalytic reduction performances of UNT were also explored. Overall, this work presented a possible relationship between the crystal structures and the performance of UNT.

Construction of ZnCdS@CAU-17 heterostructures containing intermediate mediator Bi2S3 as a highly efficient photocatalyst for nitrogen reduction reaction

The construction of heterojunctions between semiconductors and metal-organic frameworks is an effective strategy for improving photocatalytic nitrogen fixation activity. In this paper, CAU-17 was added in the solution during the solvothermal synthesis process of ZnCdS and the byproduct of Bi2S3 was generated on the ZnCdS@CAU-17 heterostructures. The combination of the three catalysts produces more excellent nitrogen fixation performance. The photocatalytic activity can be attributed to the carrier of CAU-17 for adsorption and storage of N2 and the active site of ZnCdS. In addition, the intermediate mediator Bi2S3 accelerates the transport of photogenerated electrons to the ZnCdS more efficiently. The photocatalytic nitrogen fixation performance of ZCS@CAU-100 was 46.96 μmol·g-1·h-1 under simulated sunlight in pure water without sacrificial reagents, which was about 6.8 and 6.2 times that of pure phase CAU-17 and ZnCdS respectively. In this work, the composite of Bi-based MOF and semiconductor prepared enhanced the activity of photocatalytic nitrogen fixation, and provided new insights for the synthesis of more efficient photocatalysts for photocatalytic nitrogen reduction reactions.

Solution-processed pristine metal oxides as electron-transporting materials for perovskite solar cells

In recent years, perovskite material-based photovoltaic devices have attracted great attention of researchers because of an expeditious improvement in their efficiency from 3.8% to over 25%. The electron transport layer (ETL), which functions for the extraction and transportation of photogenerated electrons from active perovskite material to the electrodes, is a vital part of these perovskite solar cells (PSCs). The optoelectronic properties of these electron transport layer materials also have an impact on the performance of these perovskite solar cells, and for commercialized flexible perovskite solar cells, low-temperature and solution-processable electron transport layers having high stability and suitable optoelectronic properties are needed. In this regard, the solution-processable films of different metal oxides have been largely investigated by many research groups. So, this review summarizes the optoelectronic properties of the different metal oxide-based electron transport layers and the development in the performance of the perovskite solar cells, which have solution-processable metal oxides as electron transport layers.