Visible Light Absorption Range Research Articles

Effect of phosphating on NiAl-LDH layered double hydroxide form S-scheme heterojunction for photocatalytic hydrogen evolution

NiAl-LDH was completely phosphate to obtain Ni2P with strong adsorption characteristics, and a simple physical stirring method was used to fix Ni2P in the 3D layered double hydroxide NiAl-LDH layer to obtain a new type of Ni2P@NiAl-LDH (NNP) S-scheme heterojunction catalyst. The Ni2P obtained by phosphating process can provide 3D reaction sites for photoelectrons and absord photogenerated carriers to participate in the photocatalytic reaction. Moreover, the S-scheme interface heterojunction can directionally change the transfer path of electric charges and improve the effective utilization of electrons. The hydrogen evolution test results show that the hydrogen production of the composite material NNP-3 (Ni2P-15%@NiAl-LDH) within 5 h can reach 107.62 μmol (2152.4 μmolg−1 h−1), 17.27 times and 2.59 times of NiAl-LDH and Ni2P, respectively. And after 25 h hydrogen production cycle, the composite catalyst still has a high hydrogen production rate and showed strong stability. Optical tests show that the composite material Ni2P@NiAl-LDH (NNP) has a strong visible light capturing ability and can increase the absorption range of visible light. Photochemical tests show that the use of Ni2P to modify NiAl-LDH can reduce the overpotential of hydrogen evolution, accelerate the transfer of photoelectrons and improve the utilization of electrons. This research provides a new idea for improving the performance of NiAl-LDH using the phosphating process, and provides an effective method for NiAl-LDH to participate in the photocatalytic hydrogen evolution technology with high efficiency.

Performance of sunlight responsive WO3/AgBr heterojunction photocatalyst toward degradation of Rhodamine B dye and ofloxacin antibiotic

A sunlight responsive WO3/AgBr heterojunction photocatalyst was prepared using hydrothermal and chemical precipitation methods. The photocatalyst with band gap of 2.93 eV exhibited high efficiency of 86% toward degradation Rhodamine B (RhB) dye under visible light. Interestingly, nearly complete degradation of RhB dye and ofloxacin (OFL) antibiotic under natural sunlight was achieved. Creation of the WO3/AgBr heterojunction is a promising strategy for enhancement of the photoactivity. This may be due to a decrease of charge carrier recombination rate at the interface and an increase in visible light absorption range of the resultant photocatalyst in comparison to those obtained from the pristine photocatalysts. Photogenerated hole plays the major role in photodegradation of the pollutant. The photocatalyst remains stable and still shows high efficiency after five consecutive cycles confirming its excellent cycling ability. This research demonstrates a promising performance of the sunlight active WO3/AgBr heterojunction photocatalyst for detoxification of dye and antibiotic in wastewater by utilization of an economical solar energy.

RGO decorated ZnO/CdO heterojunction as a photoanode for photoelectrochemical water splitting

A ternary photoanode of ZnO/CdO heterojunction decorated with reduced graphene oxide (rGO) was firstly fabricated by electrochemical deposition and thermal decomposition that is simple and effective compared with other method reported in literature. The structure and morphology of the photoanode were systematically characterized by various spectrum technologies. The photoanode expands the visible light absorption range to 428 nm, the photocurrent density reaches 1.15 mA·cm−2 at 1.23 V (vs. RHE) that is 3 times and 1.85 times of pure ZnO (0.38 mA·cm2) and ZnO/CdO (0.62 mA·cm2) photoanodes. The highest IPCE value reaches 42.63% at 380 nm. The enhancement is attributed to the architecture of semiconductor heterojunctions and the decoration of rGO nanosheets, the former promotes charge separation, while the latter accelerates electron transfer thus both synergistically enhance PEC water splitting efficiency. Here fabricated photoanode has never been reported before, only Cd and other metal elements doped ZnO photoanodes were reported in the literature.

High Anisotropic Optoelectronics in Two Dimensional Layered PbSnX2 (X = S/Se).

We systematically study the giant anisotropic optoelectronics in layered PbSnX2 (X = S/Se). The highly anisotropic optoelectronics mainly originates from the asymmetric sublattices SnX, resulting in the anisotropy of photoelectronic properties with fascinating visible light absorption range in single-layer and bilayer PbSnX2. We employ uniaxial strain in both the x and y directions and find an indirect-to-direct band gap transition, while the quasiparticle indirect band gap presents excellent linear scaling with biaxial strain in monolayer PbSnX2. We also demonstrate ultrahigh anisotropic mobilities of electrons (μy > μx) and holes (μx > μy) in both single-layer and bilayer PbSnX2 (X = S/Se), and spin-orbit coupling effects and the increase of layer number significantly reduce exciton binding energies and band gaps. Finally, the strong layer dependence of the band structure is clearly seen when the film thickness is less than 4 layers. Our results provide a fundamental understanding of highly anisotropic PbSnX2 (X = S/Se) and show two potential candidates in photoelectric applications.

Tungsten Trioxide Photoanode-Palladium Cathode Cell for Solar Seawater Splitting

N-type semiconductor-tungsten trioxide (WO3) finds application in a large variety of fields including photocatalysis, gas sensors, smart windows or as a substrate for heterogeneous catalysts. This presentation will focus on recent improvements in optoelectronic and photoelectrochemical (PEC) properties of WO3 thin films achieved in our laboratory. The semitransparent WO3 films are formed on F-doped tin oxide (FTO) conductive glass substrates, using a sol-gel method, by depositing the precursor layer-by-layer and annealing sequentially in the flow of oxygen. Use of appropriate mixtures of tungstic acid and organic structure-directing agents that form the WO3 film precursor, combined with a two-step annealing, allows the formation of highly crystalline nanostructured (NS) electrodes with controlled, large porosity. This renders possible the permeation of the whole mesoporous film by the electrolyte. Annealing of the as-deposited samples in oxygen above 500°C ensures structural ordering with formation of monoclinic WO3. Since none among photostable (metallic oxide) semiconductors exhibits band-edge energy levels that match those of hydrogen and oxygen evolution reactions to allow unassisted water splitting, the present efforts focus on minimizing the bias voltage required to perform visible light-driven photooxidation of water. In fact, a bias voltage of the order of 1 V may be provided by several single-junction PV cells likely to operate in a tandem device with the PEC cell. Despite visible-light absorption range of the WO3 films restricted to 500 nm, under standard conditions, i.e. at 1.23 V vs RHE and under simulated AM 1.5G solar light (100 mW/cm2), stable anodic water splitting photocurrents exceeding 4.5 mA/cm2 are regularly attained.This presentation will principally focus on photoelectrolysis experiments employing synthetic seawater electrolyte, in a two compartment (separated by a sintered glass diaphragm) cell, that showed dominant (with 60-70% Faradaic efficiency) formation of chlorine at the WO3 photoanode with remarkably stable photocurrents reaching 4.7 mA/cm2. In fact, as demonstrated in an earlier work from our laboratory1, the WO3 photoelectrodes exhibit preferentially oxidation of anions (including Cl-) of the acidic aqueous electrolytes. However, in contrast with the Cl- ions, the photooxidation of oxy-anions of acidic electrolytes leads generally to the "passivation" of the WO3 electrodes due to the formation of the surface layers of peroxo species.1 The only identified exception is the methane-sulfonic acid that allows oxygen generation at the WO3 photoanode with large stable photocurrents.2 In the case of seawater photoelectrolysis, the operating potential point at which the photocurrent approaches saturation occurs at ca 0.4 V below E(Cl-/Cl2)=1.36 V vs SHE. Consistently, the incident photon conversion efficiencies (IPCEs) reach a maximum of 85% over 390-410 nm range of wavelengths.3 Good mechanical and chemical stability of the WO3 electrodes in the presence of chlorine evolved from seawater was confirmed by monitoring the photocurrents over a 20 hours-long continuous photoelectrolysis runs.A schematic diagram of the seawater splitting PEC cell, including a NS WO3 film photoanode and a Pd sheet cathode, used in our experiments is shown below.Fig. 1 Schematic diagram of the seawater splitting PEC cell.The current of CO2 gas passing through the seawater represents a possible option for maintaining slightly acidic pH in the cathodic cell compartment. The important advantage of the adopted PEC cell configuration is to circumvent the problem of gas separation, i.e. chlorine/oxygen formed at the photoanode and hydrogen generated at the Pd cathode that is stored in the form of a Pd-H hydride. The storage of hydrogen generated in a PEC water splitting device in the form of a hydride, opens the possibility of its subsequent use as an anode in a hydride-oxygen battery.Such sunlight-driven PEC seawater splitting device can be implemented in remote places to provide on-site relatively small amounts of chlorine for disinfecting purposes including purification of drinking water.More generally, the prospect of using seawater electrolyte for a larger scale PEC hydrogen generation would release the strain on vital fresh water resources. Considering relatively low concentration of Cl- ions in seawater, roughly equivalent to 0.5 M NaCl, the photoelectrolysis delivering photocurrents in the range of mA/cm2 appears well suited for such applications.

High efficiency hydrogen production with visible light layered MgAl-LDH coupled with CoSx

The research work of photocatalytic decomposition of water to produce hydrogen is wider and wider. A highly efficient composites photocatalyst was prepared by hydrothermal method. The composite photocatalyst was composed of spherical CoSx and layered nanosheets of MgAl-LDH. The composite photocatalyst retained the advantage of a wide range of visible light absorption, and can effectively prevent the photocorrosion phenomenon caused by sulfide. The hydrogen production of composite photocatalyst was 262.5 μmol. Compared with MgAl-LDH and CoSx, there was a significant improvement. The combination of the two accelerated the separation of photogenerated electrons and holes, which made the hydrogen production effect of the composite catalyst obvious. To investigate the stability of the composite catalyst, a cycle test was carried out and it showed good stability during the test. According to PL, XPS, XRD, TEM, SEM, UV–Vis DRS and electrochemical characterization, the possible reaction mechanism was proposed. A high performance photocatalyst for hydrogen production with low cost MgAl-LDH combined with CoSx had been explored, which provided a convenient way for research work.

Construction of 2D/2D/2D BiOBr/(001)-TiO2/Ti3C2Tx heterojunction for enhancing photocatalytic degradation of dye

Coupling a semiconductor with exposed high-activity crystal facets and a suitable co-catalyst to form a heterojunction is considered to be a feasible measure to improve photocatalytic activity. Therefore, the novel BiOBr/(001)-TiO2/Ti3C2Tx (BTT-y) were synthesized by in-situ construction. The BTT-y possess a remarkable Rhodamine B (RhB) degradation performance due to there is a better synergy among the three substances. The improvement of RhB degradation performance is mainly attributed to the perfect matching of BiOBr and (001)-TiO2 band structure positions, which is conductive to the formation of heterojunction and thus could expand visible-light absorption range and inhibit the recombination of photo-generated carriers. Furthermore, Ti3C2Tx in the heterojunction would further separate the photo-generated carriers. This study provided reference insights for improving photocatalytic performance with 2D/2D/2D structure.

Thermo‐Enhanced Photocatalytic Activity in Aerobic Oxidative Coupling of Amines to Imines over Cu‐Doped MIL‐125‐NH2

AbstractPhotocatalytic oxidation of raw organic molecules to value‐added chemicals provides a cost‐effective and sustainable strategy in organic synthesis. In this work, a series of Cu‐doped MIL‐125‐NH2 with narrower band gaps were synthesized by a one‐pot hydrothermal method and used as photocatalysts for thermo‐enhanced aerobic oxidative coupling of amines to imines under visible light irradiation. With optimal doping content, the conversion of benzylamine over MIL‐125‐NH2/Cu2% can reach 100% at 60 °C under visible light irradiation for 8 h using molecule oxygen as oxidant. It is proved that doping MIL‐125‐NH2 with a suitable Cu content can broaden the visible light absorption range, promote the separation of photo‐induced charge carriers and improve the photocatalytic performance. Moreover, the increase of reaction temperature of the photocatalytic system promotes the performance. Free radical capture experiments and ESR tests show that holes and superoxide free radicals are the main active species. Such an excellent photocatalytic performance can be attributed to the strong light absorption and more efficient electron‐hole separation efficiency via the Cu‐doping strategy in MIL‐125‐NH2 catalysts.

Research progress on degradation of VOCs by metal ions doped titanium dioxide nanoparticles

The use of anatase nanotitanium dioxide (T1O2) is a current research hotspot in this field due to its unique features such as chemical stability, non-toxicity, resistance to photocorrosion and low capital, etc., in the degradation of wastewater and photocatalytic degradation of VOCs. In this paper, the mechanism of VOCs degradation by titanium dioxide nanoparticles is studied, and it is found that this catalyst still has a small visible light absorption range and unstable crystalline shape, which limit its photocatalytic efficiency. Recent research results show that the modification of TiO2 by ion doping can change its charge density, lattice structure and forbidden band width, which can effectively enhance the photocatalytic ability of TiO2 nanoparticles and increase the utilization of visible light. In this paper, we summarize the research progress of titanium dioxide photocatalyst modification by metal ion doping and its application in production in recent years, compare and summarize different doping preparation methods, and outlook the development trend of rare metal ion doped titanium dioxide, in order to prepare highly stable and efficient titanium dioxide nanocatalysts in visible light. It provides a scientific basis and reference for the preparation of highly stable and efficient photocatalysts under visible light, and lays the foundation for the wide application in the field of VOCs degradation.

Facile synthesis and enhanced photocatalytic activity of a novel FeVO4/Bi4O5Br2 heterojunction photocatalyst through step-scheme charge transfer mechanism

Construction of a step-scheme (S-scheme) heterojunction photocatalyst is currently under investigation as it is known to facilitate a decrease in the e – /h + recombination rate and preserves a strong redox ability. This research work has reported on the use of microwave irradiation combined with the wet impregnation synthesis of FeVO 4 /Bi 4 O 5 Br 2 heterojunctions at different weight percentages (%wt) of FeVO 4 (0.5%, 1%, 3% and 5%wt). The visible-light-driven photocatalytic activities for the photoreduction of Cr(VI), and the decontamination of certain organic pollutants (bisphenol A; BPA, rhodamine B; RhB, and tetracycline hydrochloride; TC) were also investigated. Ethylene glycol that was used as a reaction medium in the microwave synthesis process played a key role in the formation control of a flower-like structure of bismuth-rich Bi 4 O 5 Br 2 . Among the heterojunction photocatalysts, FeVO 4 /Bi 4 O 5 Br 2 with 1%wt of FeVO 4 markedly maximized the photocatalytic activity. Specifically, 95% of Cr(VI) was reduced by a reduction rate that was 6.0 times higher than that of Bi 4 O 5 Br 2 . Similarly, this photocatalyst was able to degrade 90%, 97%, and 88% of BPA, RhB, and TC at degradation rates that were 2.0, 1.2, and 1.6 times higher than Bi 4 O 5 Br 2 , respectively. Trapping experiments indicated that •O 2 − and h + were the main active species responsible for the organic pollutant degradation, while •OH played a minor role in this process. These outcomes were confirmed with the use of the nitrotetrazolium blue transformation method and the terephthalic acid photoluminescence probing technique. Enhancement in the photo-activity of 1%wt-FeVO 4 /Bi 4 O 5 Br 2 was attributed to the extended visible-light absorption range as well as the efficient generation, separation, and migration of photo-generated charge carriers through the S-scheme charge transfer mechanism which was supported by the results from the trapping experiments, XPS and UV–vis DRS analyses, Ag and PbO 2 photo-deposition experiments, and electrochemical studies, along with the consideration of the reduction potentials of reactive oxygen species. • Novel FeVO 4 /Bi 4 O 5 Br 2 catalyst for Cr(VI) reduction and organic pollutant degradation. • Ethylene glycol played a key role in the formation of flower-like Bi 4 O 5 Br 2 structure. • Activity of Bi 4 O 5 Br 2 promoted with optimum content of FeVO 4 coupling (1%wt). • This FeVO 4 /Bi 4 O 5 Br 2 nanocomposite displayed excellent recyclability and stability. • Improved activity was ascribed to S-scheme charge transfer mechanism.

Preparation of flower-like BiOBr/Bi2WO6 Z-scheme heterojunction through an ion exchange process with enhanced photocatalytic activity

Flower-like BiOBr/Bi2WO6 Z-scheme heterojunction was prepared by an ion exchange process. Bi2WO6 was evenly coupled with BiOBr which was confirmed by structure and composition characterization. Compared with single Bi2WO6 or BiOBr, the BiOBr/Bi2WO6 heterojunction showed significantly enhanced photocatalytic performance in degradation of Rhodamine B (RhB), tetracycline hydrochloride (TC) and potassium dichromate (K2Cr2O7). The formation of BiOBr/Bi2WO6 heterojunction broadened the visible light absorption range and prohibited recombination of the charge carries remarkably. The mechanism of yielding photocatalytic performance with the BiOBr/Bi2WO6 heterojunction was proposed.

Preparation of TiO2-Based Photocatalysts Synergistically Modified with Fe3+–Graphene and Their Visible-Light-Catalyzed Hydrogen Production from Ammonia Borane

TiO2-based photocatalysts are promising materials that show great potential in the field of catalysis due to their excellent properties including nontoxicity, high photocatalytic performance, and outstanding thermal and chemical stability. However, several challenges exist regarding TiO2 applications for catalytic hydrogen production. In this work, Fe- and graphene-comodified TiO2 (Fe–rGO/TiO2) was synthesized via a two-step solvothermal method. In addition, the effect of Fe3+ and graphene addition upon the catalytic performance of TiO2 was investigated based on the ammonia borane hydrogen production reaction, and the catalysts were characterized by SEM, XRD, XPS, UV–vis, FT-IR, and Raman methods. Batch experiments showed that the synthesized Fe–rGO/TiO2 composites exhibited high photocatalytic performance for hydrogen production from ammonia borane under visible-light irradiation. Moreover, the highest photocatalytic hydrogen production rate (1235.32 μmol·min–1·gcat–1) of 2%Fe–1%rGO/TiO2 was observed under visible-light irradiation at 25 °C, and the photocatalytic activity of the sample remained almost unchanged after the fifth cycle. The XRD, XPS, FT-IR, and Raman analyses showed that Fe and graphene successfully modified TiO2 and the presence of Ti4+. In addition, the extended visible-light absorption range and a reduction of the band gap of Fe–rGO/TiO2 were demonstrated by UV–vis diffuse reflectance spectra and calculation of the band gap. Also, the preparation of hydrogen from the hydrolysis of ammonia borane photocatalyzed by TiO2 composites was discussed. These findings are crucial for designing TiO2-based photocatalysts with high performance for photocatalytic hydrogen production.

Construction of ternary hollow TiO2-ZnS@ZnO heterostructure with enhanced visible-light photoactivity

Through a simple fiber template method, we combined the n-type TiO2 catalysts with n-type ZnS@ZnO heterojunction to synthesize a high-efficiency ternary hollow TiO2-ZnS@ZnO n-n heterojunction. Under these modified conditions, the composite catalysts could broaden the visible light absorption range of the pure TiO2, and both the hollow structure and heterojunction could inhibit the recombination ability of the photon-generated carriers. Optical and Electrochemical characterizations indicated that the photogenerated electrons and holes can be separated efficiently and the composites have visible light absorption. The experimental results show that, the removal efficiency of the optimal composites for photocatalytic degradation of Tetracycline Hydrochloride (TC) under visible light (λ ≥ 420 nm) was 86.67% due to the ·O2− free radicals of efficient production, it exhibited 5 times higher degradation rate towards Tetracycline Hydrochloride (TC) than pure TiO2. The composites with high photocatalytic activity could also effectively degrade Methylthionine Chloride (MB), Xylenol Orange (XO), Acid Red 18 and Rhodamine B (RhB) under the driving of visible light. This work provided a simple method to construct ternary heterojunction, and also provided a promising strategy to solve the environmental pollution problem in the future.

Rational fabrication of Bi2WO6 decorated TiO2 nanotube arrays for photocatalytic degradation of organic pollutants

Photocatalysis shows great potential in pollution degradation without environmental harm. Herein, TiO2 nanotube arrays (TNTAs) were prepared on titanium mesh by an anodic oxidation method, and Bi2WO6/TiO2 nanocomposites (BWO/TNTAs) with different Bi2WO6 contents were synthesized by a hydrothermal method. The Bi2WO6 nanosheets decorated on TNTAs significantly improved the photocatalytic degradation of tetracycline (TC). 0.2BWO/TNTAs exhibited the degrading rate of 92.2% within 180 min under visible light. The enhancement of photocatalytic performance was ascribed to the II-type mechanism via Bi2WO6 coupled with TiO2, which further extended the visible light absorption range and promoted the charge separation. In addition, •OH is the main active species to dominate the degradation of TC. The possible decomposition mechanism of TC was proposed by gradual loss of hydroxyl groups and C-ring cleavage. It provides a feasible strategy to remove organic pollutants for wastewater treatment.

Reasonable regulation of carbon/nitride ratio in carbon nitride for efficient photocatalytic reforming of biomass-derived feedstocks to lactic acid

Photocatalysis provides a promising opportunity for selective oxidation of biomass to high-value chemicals under mild conditions. The key to realize this transformation is to design a cost-effective and environmentally friendly photocatalyst. Here, we report the preparation of a carbon nitride photocatalyst with controllable carbon/nitride (C/N) ratio and its application in the selective photocatalytic synthesis of lactic acid from biomass-derived monosaccharides. Reasonable C/N ratio in the catalyst can significantly enhance the visible light absorption range and accelerate the mobility of photogenerated carriers. The obtained photocatalyst exhibited excellent photocatalytic activity, yielding 76.8% lactic acid. All of the h+,·O2-,·OH and 1O2 are beneficial for lactic acid production, and the·O2- plays a major role. Furthermore, the photocatalyst exhibited excellent reusability and universality. The 1000-fold scale-up experiments indicated that the system has potential for industrial production of lactic acid. Therefore, the present work offers a promising example for photocatalytic reforming of biomass.

Semiconducting nanomaterials for photocatalytic desulfurization of liquid fuel under sunlight irradiation

Abstract Nanomaterials have fascinated the interest of researchers due to their unique electronic, optical, magnetic, and several other properties. Tin sulfide (SnS2) and Zinc oxide (ZnO) have emerged as promising materials for pharmaceutical, textile, environmental remediation, energy conversion, and storage device design. These two compounds were widely used in waste-water treatment for photocatalytic destruction of organic contaminants. However, the degradation of organic sulfur compounds in the liquid fuel desulfurization process has rarely been investigated using such materials. We hereby, present a hydrothermal method for developing the hexagonal lattice structure of SnS2 and ZnO for the deep desulfurization of model liquid fuel. These materials were further characterized through powder X-ray diffraction for phase purity and crystalline, FTIR analysis to validate functional groups, N2 adsorption-desorption isotherm to study surface properties, UV–vis diffuse reflectance spectroscopy for band gap analysis, scanning and transmission electron microscopy for morphology analysis. The optical behavior reveals that the energy gap for SnS2 and ZnO is 2.09 and 3.21 eV, respectively which corresponds to the visible light absorption range. The photocatalysis experiment was carried out in direct sunlight to degrade 10 ppm DBT in iso-octane. The obtained results show that 60% of the DBT degrade with SnS2 and 15% of the DBT degraded with ZnO in 120 min, with a first-order kinetics rate constant of 0.009 and 0.001 min−1 respectively.

Structure evolution of thiophene-containing conjugated polymer photocatalysts for high-efficiency photocatalytic hydrogen production

Conjugated polymer photocatalysts have received extensive attention in the field of photocatalytic hydrogen evolution owing to their tunable molecular structures and electronic properties. Herein, we developed three donor-acceptor (D-A) type thiophene-containing narrow-band-gap conjugated polymers with pyrene as a donor and different fused-thiophene derivatives as acceptors via direct C-H arylation coupling polymerization. It was found that the band gap of the polymers can be tuned by adjusting the number of the fused-thiophene rings. The visible light absorption range can be extended by increasing the number of the thiophene rings, the planar molecular structure for both donor and acceptor units facilitates the charge transmission along the polymer skeleton, and the D-A type polymer structure promotes the dissociation of photo-induced electrons and holes. As a result, a high photocatalytic hydrogen evolution rate of 33.07 mmolh−1 g−1 was obtained by PyTP-2 with an optimized molecular structure under visible light irradiation (λ > 420 nm) without the aid of Pt co-catalyst. In addition, PyTP-2 also shows a photocatalytic activity for oxygen evolution with an average oxygen evolution rate of 58.37 µmolh−1 g−1.

Photocatalytic H2 production with simultaneous wastewater purification over flower-like 1T/2H-MoS2-decorated CNT/CNU isotype heterojunction photocatalyst

Exploring low-cost and earth-abundant photocatalysts to efficiently release H2 from wastewater is an appealing solution for global energy and environmental issues. Here, we successfully prepared flower-like 1T/2H-MoS2-decorated g-C3N4 (thiourea)/g-C3N4 (urea) (denoted as CNT/CNU) isotype heterojunction photocatalysts via a facile ultrasonic dispersion method and researched the photocatalytic H2 generation and pollutant degradation performance in oxalic acid (OA) simulated wastewater. The results displayed that 20% 1T/2H-MoS2@CNT/CNU sample exhibited the highest photoreactivity, and the H2 release rate was 1563.32 μmolg-1h−1, which was about 96 times higher than the CNT/CNU. Meanwhile, it also showed the highest total organic carbon (TOC) removal rate of 67.5%. The increased photoreactivity of nanocomposites can be ascribed to the double-interface system to effectually improve the separation of photoinduced charges. Additionally, the experimental results further confirmed that the loading of flower-like 1T/2H-MoS2 could provide abundant active sites as well as expand the visible-light absorption range. Significantly, photoelectrochemistry measurements and density functional theory (DFT) calculations also confirmed that 1T/2H-MoS2 cocatalysts accelerated the charge migration. On this basis, the mechanism of 1T/2H-MoS2@CNT/CNU promoting hydrogen production and synergistic OA degradation was proposed. This research presents a prospective idea for the utilization of waste water and the simultaneous production of clean energy.

The first principle screening and design of the high-performance organic photosensitizers based on EY2− dye in homogeneous non-noble metal photocatalytic hydrogen production system

Photocatalytic hydrogen production, capable of dissociating water to make hydrogen using sunlight as abundant and clean energy, provides a promising solution for energy crisis. However, currently dominated metal complexes photosensitizers are based on precious and rare metal elements, which prohibits large scale applications. Herein, based on the experimental dye Eosin Y (EY2−), we report a series of metal-free organic dyes EY2-1- EY2-18 and present a systematic study on their ground-state geometry, electrochemistry, energy gap, reduction potential and driving force by using density functional theory (DFT) and time-dependent DFT (TDDFT). The calculated results show that compared to other dyes, the dye EY2-11 has a large visible light absorption range, a higher reduction potential and greater driving force, which indicates that EY2-11 is a promising candidate for the visible-light-driven hydrogen production. Our theoretical researches are expected to provide valuable insights for designing efficient metal-free organic photosensitizers.

Electrospinning visible light response Bi2MoO6/Ag3PO4 composite photocatalytic nanofibers with enhanced photocatalytic and antibacterial activity

Due to its significant biocompatibility and environmental friendliness, the composite of heterojunction photocatalyst and natural protein is a promising material in the field of photocatalysis. For the first time, direct Z-scheme Bi2MoO6/Ag3PO4 composites with different concentrations of Ag3PO4 were successfully fabricated by an in-situ deposition method, and Bi2MoO6/Ag3PO4@silk fibroin (BMO/APO@SF) films were further constructed by electrospinning technology to explore the photocatalytic activity of heterojunction photocatalysts. The results of various characterizations confirmed that improved photocatalytic performance, including efficient charge separation, and a widened visible light absorption range, could be attributed to the formation of a heterojunction structure between Bi2MoO6 and Ag3PO4, which considerably promoted photocatalytic activity for ciprofloxacin (CIP) degradation. According to the analysis of degradation products measured by Q-TOF, possible CIP degradation pathways were proposed. Density functional theory (DFT) calculation and Laplacian bond order (LBO) analysis were consistent with the results of Q-TOF. Through trapping experiments, the significant contribution of O2– to BMO/APO@SF was demonstrated. Moreover, the antibacterial rates of Bi2MoO6/15Ag3PO4@SF (BMO/15APO@SF) against Escherichia coli and Staphylococcus aureus were greater than 94.36% and 95.72%, respectively, indicating that BMO/15APO@SF had excellent antibacterial performance.