Photocurrent Intensity Research Articles

Polymeric Iodoargentate Hybrids Incorporating Octakis- or Heptakis-Solvated Lanthanide Complexes: Syntheses, Crystal Structures, and Photocatalysis.

New iodoargentate hybrids containing lanthanide complexes, [La(DMA)8]Ag9I12·2H2O (1) and [Ln(DMA)7]2Ag16I22 (Ln = Pr (2), Sm(3); DMA = N,N-dimethylacetamide), were prepared by diffusion methods using DMA-solvated lanthanide complexes as structure-directing agents. The octakis-solvated La3+ cation leads to formation of the 1-D nonanuclear [Ag9I12]n3n- polymeric anion constructed by AgI4 tetrahedral units through edge sharing, while the heptakis-solvated Ln3+ (Ln = Pr, Sm) cation affords the new 1-D hexadecanuclear [Ag16I22]n6n- polymeric anion built up from AgI4 units by both corner and edge sharing. Compounds 1-3 possess band gaps of 2.58, 2.77, and 2.74 eV, respectively, and show steady photocurrents in the range 14.2-18.0 μA under Xe light irradiation. They are photocatalytic active in the degradation of organic pollutants of crystal violet (CV) and rhodamine B (RhB) in water at room temperature. 2 and 3 perform higher photocatalytic activities than 1 in the CV degradation, which is attributed to the different photocurrent intensities. Photocatalytic mechanism investigations on compounds 2 and 3 show that h+ hole and ·O2- radical play major roles in the CV degradation, respectively.

Double S-scheme AgBr heterojunction co-modified with g-C3N4 and black phosphorus nanosheets greatly improves the photocatalytic activity and stability

A ternary heterojunction composite photocatalyst g-C3N4/AgBr/black phosphorus was constructed by co-modifying AgBr with g-C3N4 (CN) and black phosphorus nanosheets (BPNs). The photoluminescence (PL), photocurrent intensity and electrochemical impedance spectroscopy (EIS) results proved that, compared with bare AgBr and binary CN/AgBr and AgBr/BPNs, ternary CN/AgBr/BPNs effectively promoted the separation and suppresses the recombination of electron-hole pair. The photocatalytic experiment proved that the CN/AgBr/BPNs photocatalyst exhibited almost 8 times for degradation rate of MO，and well above those of binary CN/AgBr and AgBr/BPNs. According to trapping experiments of the active species, the analysis of the energy band, we proposed the double S-scheme to explain the charge transfer and the boosting of photocatalytic activity in ternary CN/AgBr/BPNs. Impressively, this double S-scheme facilitated the transmittance of electrons at the CB position of AgBr to the VB of CN and BPNs, and greatly overcome the light corrosion and enhance the stability of AgBr. This work designed a novel S-scheme mechanism heterojunction photocatalytic material, which provides a convenient way for efficient wastewater treatment.

Synthesis of functional conjugated microporous polymer/TiO2 nanocomposites and the mechanism of the photocatalytic degradation of organic pollutants

We successfully synthesize six kinds of functional conjugated microporous polymer (CMP) containing amino, hydroxyl, carboxyl and ester groups by a Sonogashira–Hagihara coupling reaction. These CMPs exhibit type-I nitrogen gas sorption isotherms, and their pore widths are approximately 1.28–1.86 nm with a relatively narrow pore size distribution that is attributed to microporous structures. By blending CMPs with TiO2 under solvothermal conditions, TiO2 is uniformly coated onto the surfaces of the CMPs, and CMP/TiO2 nanocomposites are synthesized successfully. The novel nanocomposites show excellent photocatalytic properties for the degradation of organic pollutants, such as methylene blue, ciprofloxacin and tetracycline, under visible light. The degradation rate of organic pollutants is higher than 96.8%, and after 5 recycling cycles, the degradation efficiency is still more than 93%. The effects of the different functional groups of CMPs on the photocatalytic properties are discussed for the first time. CMP/TiO2 with carboxyl groups show the smallest band gap, highest photocurrent intensity and lowest resistance compared to those of nanocomposites with amino, hydroxyl and ester groups. This result may be caused by the high electronegativity of carboxyl groups, which enhances the charge transfer rate. The photocatalytic mechanism of the CMP/TiO2 nanocomposites is investigated, and the superoxide anion (·O2−) is the main active species in the photocatalytic degradation process.

BiOI Particles Confined into Metal-Organic Framework NU-1000 for Valid Photocatalytic Hydrogen Evolution under Visible-Light Irradiation.

Herein, a surface site engineering strategy is used to construct a porous Z-scheme heterojunction photocatalyst for photocatalytic hydrogen evolution (PHE) by integration of BiOI in a mesoporous Zr-based metal-organic framework (MOF) NU-1000. Three high-quality and highly dispersed BiOI@NU-1000 heterojunction materials are synthesized, and a set of methods is used to characterize these materials, indicating that the BiOI@NU-1000 heterojunction can retain high porosity and crystallinity of the parent NU-1000. Furthermore, the built-in electric field of the BiOI@NU-1000 composite can effectively tune the band gap, promote the separation of photoinduced charge carriers, improve photocurrent intensity, and reduce photoelectric impedance. Under visible-light irradiation, BiOI@NU-1000-2 showed the best photocatalytic performance in the field of MOF-based photocatalysts for PHE, with a hydrogen production rate of up to 610 μmol h-1 g-1. This study will open up opportunities for the construction of Z-scheme photocatalysts based on the highly porous MOF materials to inspire the development of innovative photocatalysts.

Fabrication of CDs hybrid MIL-68(In) derived In2O3[sbnd]In2S3 hollow tubular heterojunction and their exceptional self-powered PEC aptasensing properties for ampicillin detecting

A visible-light-driven self-powered photoelectrochemical (PEC) aptasensor was developed for ampicillin (AMP) detecting based on carbon dots (CDs) hybrid MIL-68(In)-derived In2O3In2S3 hollow tubular heterojunction (CDs/In2O3In2S3). In2S3 nanosheets uniformly grew in-situ on the surface of In2O3 hollow tubes, forming a close contact heterogeneous interface, which significantly promoted the transfer and separation of photo-generated carriers, and provided a large specific surface area and rich active sites for the PEC aptasensing platform. Furthermore, the CDs/In2O3In2S3/ITO electrode, which was obtained by dipping assembly, showed remarkable and stable photoelectric signals at zero-bias under visible light irradiation. The amino-functionalized AMP aptamer was fixed on the working electrode as a biological recognition element, and the concentration of AMP was determined by observing the change in photocurrent intensity caused by the specific capture of AMP molecules in solution. Under optimized conditions, the developed PEC aptasensor displayed a relatively wide linear range from 0.001 ng mL−1 to 300 ng mL−1, as well as a low detection limit (LOD) of 0.06 pg mL−1. Besides, the novel self-powered PEC AMP-aptasensor exhibited excellent reproducibility, good stability and selectivity, which open a potential avenue for antibiotic residues detection in environmental media.

UV-Vis-NIR-light-driven Ag2O/Ag2S/CuBi2O4 double Z-scheme configuration for enhanced photocatalytic applications

The Ag2O/Ag2S/CuBi2O4 double Z-scheme heterostructures photocatalysts with different Ag2O proportion were successfully synthesized via the hydrothermal and coprecipitation methods. Compared with those of pure CuBi2O4 and Ag2S, the absorption of near-infrared light of Ag2O/Ag2S/CuBi2O4 samples is enhanced, their photocurrent intensity is significantly increased, and the charge transfer resistance is reduced. Obviously, all the Ag2O/Ag2S/CuBi2O4 samples exhibited significantly enhanced photoactivities under the UV, Vis or NIR light irradiation. Of them, under the simulated sunlight, Ag2O/Ag2S/CuBi2O4 with 36.7 wt% Ag2O showed the highest catalytic activity with RhB degradation rate of 99.2% and the reduction rate of Cr(VI) of 53%. The construction of double Z-scheme heterojunction reduced the recombination of electrons and holes and improved the separation efficiency of electron. Moreover, Ag2S and Ag2O broadened the photoresponse range to a wide spectrum, and then improved the photocatalytic efficiency. In addition, the stability of Ag2O/Ag2S/CuBi2O4 containing 36.7 wt% Ag2O was demonstrated through three successive cycling experiment.

Enhanced visible-light photocatalytic performance of Co/Ni doped Cu2MoS4 nanosheets for Rhodamine B and erythromycin degradation

In this study, Co and Ni were successfully doped into molybdenum-copper sulphide(Cu2MoS4) via a simple green solution synthesis method. Characterisation of the catalyst structure and properties revealed that the Co and Ni doped Cu2MoS4 exhibited a narrower bandgap, stronger photocurrent, and lower Photoluminescence Spectroscopy (PL) emission intensity compared to pure Cu2MoS4. The photocatalytic experiments showed that the Co/Ni doped Cu2MoS4 exhibited the highest photocatalytic activity, which in an hour of Cu2MoS4, Co-doped Cu2MoS4, Ni-doped Cu2MoS4 and Co/Ni-doped Cu2MoS4 samples were estimated to be 63.8%, 84.5%, 81.4% and 93.5%, respectively. The improved photocatalytic performance of Co/Ni doped Cu2MoS4 may be due to the fact that Co/Ni doping promotes light trapping and reduces the bandgap of Cu2MoS4 and the synergistic effect of Co/Ni doping. Furthermore, the five successive catalytic cycles reveal the superior stability of Co/Ni-doped Cu2MoS4 photocatalyst.

Facile Synthesis of Mesoporous Ag2O-ZnO Heterojunctions for Efficient Promotion of Visible Light Photodegradation of Tetracycline.

Fabrication of 3D mesoporous Ag2O–ZnO heterojunctions at varying Ag2O contents has been achieved through poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic F-108) as the structure-directing agent for the first time. The mesoporous Ag2O–ZnO nanocomposites exhibited a mesoporous structure, which revealed a large pore volume and high surface area. The photocatalytic efficiency over mesoporous Ag2O–ZnO nanocomposites for tetracycline (TC) compared with that over commercial P-25 and pristine ZnO NPs through the visible light exposure was studied. Mesoporous 1.5% Ag2O–ZnO nanocomposites indicated the highest degradation efficiency of 100% of TC during 120 min of the visible light exposure compared with 5% and 10% for pristine ZnO NPs and commercial P-25, respectively. The TC degradation rate took place much rapidly over 1.5% Ag2O–ZnO nanocomposites (0.798 μmol L–1 min–1) as compared to either commercial P-25 (0.097 μmol L–1 min–1) or ZnO NPs (0.035 μmol L–1 min–1). The mesoporous 1.5% Ag2O–ZnO nanocomposite revealed the highest degradation rate among all synthesized samples, and it was 23 and 8 orders of magnitudes greater than those of pristine ZnO NPs and P-25, respectively. The photoluminescence and transient photocurrent intensity behaviors have been discussed to explore photocatalysis mechanisms. It is anticipated that the present work will contribute some suggestions for understanding other heterojunctions with outstanding behaviors.

In Situ Depositing Ag NPs on PDA/SiW11V Co‐encapsulated Fe3O4@TiO2 Magnetic Microspheres as Highly Efficient and Durable Visible‐light‐driven Photocatalysts

AbstractThe design and preparation of highly efficient and durable visible‐light‐driven photocatalysts remain a great challenge in the environment remediation. In this paper, a new multi‐component composite, Fe3O4@TiO2@PDA/SiW11V−Ag, is successfully fabricated by in situ assembling Ag nanoparticles (NPs) onto polydopamine (PDA) and mono‐vanadium substituted silicotungstate (SiW11VO406−, simplified as SiW11V) co‐encapsulated Fe3O4@TiO2 magnetic microspheres. In the photodegradation of methyl orange (MO) and photocatalytic reduction of Cr(VI) under visible light, the multi‐component composite displays the enhanced catalytic efficiency in comparison with other catalysts with less‐components. Structure‐reactivity relationship is established based on the correlation between photocatalytic efficiency and transient photocurrent intensity. Notably, the multi‐component composite exhibits high stability and durability in wide range of pH aqueous solutions and most of organic solvents. The successful preparation of this novel type of materials provides a promising approach for constructing stable photocatalysts with multi‐components, where poor compatibility of each component can be well bridged via PDA as an efficient linker and charge transport.

Facile ball-milling synthesis of CeO2/g-C3N4 Z-scheme heterojunction for synergistic adsorption and photodegradation of methylene blue: Characteristics, kinetics, models, and mechanisms

• The solvent-free ball-milling method obtains Z-scheme CeO 2 /g-C 3 N 4 heterojunction. • CeO 2 /g-C 3 N 4 thermodynamically has stronger redox potential and active radicals. • 70% CeO 2 /g-C 3 N 4 exhibited the best removal efficiency for MB photodegradation. • Synergy between adsorption and photodegradation of MB by CeO 2 /g-C 3 N 4 was identified. As a green solvent-free process, ball milling has attracted considerable attention in fabricating nanocomposites. Herein, we synthesized novel Z-scheme heterojunction CeO 2 /g-C 3 N 4 nanocomposites by simply direct ball milling CeO 2 and g-C 3 N 4 at three different mass ratios (3:7, 7:3, and 9:1). In comparison to individual CeO 2 and g-C 3 N 4 , the ball-milled nanocomposites showed stronger UV light response, higher charge carrier separation efficiency, greater photodegradation potential, higher photocurrent intensity, and faster electron transfer, indicating much better photocatalytic activity. When used as photocatalysts to remove methylene blue (MB) under UV light irradiation, 70% CeO 2 /g-C 3 N 4 exhibited the highest removal rate (90.1%), much better than that of CeO 2 (6.2%) or g-C 3 N 4 (45.7%). The synergistic interact between adsorption and photodegradation of the CeO 2 /g-C 3 N 4 nanocomposites was simulated by kinetic models, and a strong positive correlation (r = 0.834 and r s = 0.777) between adsorption and photocatalysis was identified. The results indicate that adsorption can promote photodegradation by accelerating the kinetics, while photodegradation can regenerate adsorption sites. This work provides not only a facile synthesis of Z-scheme heterojunction photocatalysts but also a novel perspective for better understanding the synergy between adsorption and photocatalysis.

Highly improved electrical and photoelectrical properties of electro-deposited p-type cuprous oxide

In this work, the effect of annealing on the electrical and optical properties of electro-deposited [Formula: see text]-type cuprous oxide was studied in detail. It is found that the flat band potential linearly increased with annealing temperature and the carrier concentration was improved from 6.56 × 10[Formula: see text] cm[Formula: see text] to 23.3 × 10[Formula: see text] cm[Formula: see text]. The photocurrent intensity of cuprous oxide was improved from 12.1 [Formula: see text]A to 106.6 [Formula: see text]A after annealing. The dramatically improved electrical and photoelectrical properties might be ascribed to the highly improved crystallinity and the lower surface defect density caused by annealing.

Improved photocatalytic H2 evolution performance of mesoporous graphitic carbon nitride with cyano-group

In this paper, two modification strategies were introduced in g-C3N4 system to improve its photocatalytic activity. In detail, mesoporous g-C3N4 with cyano-group was successfully synthesized. Its chemical structure and states, specific surface area, optical absorption, photo-electrochemical properties and photocatalytic ability for hydrogen evolution were characterized. It was indicated that mesoporous g-C3N4 with cyano-group photocatalyst exhibited better charge separation rate, and the higher photocurrent intensity, For hydrogen evolution, it achieved the higher hydrogen evolution rate of 4531 μmol·h−1 g−1, which was 3 folds that of mesoporous g-C3N4 and 13 folds that of bulk g-C3N4, and kept excellent stability. Obviously, current work shed light for developing high efficient photocatalysts by combining multiple modification.

The effects of sub-bandgap transitions and the defect density of states on the photocurrent response of a single ZnO-coated silica nanospring

The electrical and optoelectronic properties of nanometer-sized ZnO structures are highly influenced by its native point defects. Understanding and controlling these defects are essential for the development of high-performance ZnO-based devices. Here, an electrical device consisting of a polycrystalline ZnO-coated silica nanospring was fabricated and used to characterize the electrical and photoconductive properties of the ZnO layer using near-UV (405 nm) and sub-bandgap (532 and 633 nm) excitation sources. We observe a photocurrent response with all three wavelengths and notably with 532 nm green illumination, which is the energy associated with deep oxygen vacancies. The polycrystalline ZnO-coated silica nanospring exhibits a high responsivity of 1740 A W−1 with the 405 nm excitation source. Physical models are presented to describe the photocurrent rise and decay behavior of each excitation source where we suggest that the rise and decay characteristics are highly dependent on the energy of the excitation source and the trapping of electrons and holes in intermediate defect levels in the bandgap. The energy levels of the trap depths were determined from the photoconductive decay data and are matched to the reported energy levels of singly and doubly ionized oxygen vacancies. A phenomenological model to describe the dependence of the saturation photocurrent on excitation intensity is presented in order to understand the characteristics of the observed breaks in the slopes of the saturation photocurrent versus excitation intensity profile.

One-step hydrothermal synthesis of telluride molybdenum/reduced graphene oxide with Schottky barrier for fabricating label-free photoelectrochemical profenofos aptasensor

Schottky barrier with a suitable barrier height which acts as the electron tank can reduce the recombination of photogenerated electronic-hole pairs, consequently leads to higher photoelectric properties. Telluride molybdenum nanoparticles (MoTe2 NPs) are a kind of transition-metal dichalcogenides, which is a burgeoning class of materials with low toxicity, high specific surface area, high carrier mobility, and wide spectral absorption. In order to enhance the photoelectric performance of MoTe2, we adopted a one-step hydrothermal synthesis to construct MoTe2 NPs/reduced graphene oxide (RGO) heterostructures with suitable Schottky barrier. The photocurrent intensity of MoTe2 NPs/RGO heterostructures was 21.8 times of RGO and 10.5 times of MoTe2 NPs. On the basis of excellent visible light-responsive of MoTe2 nanoparticles/RGO, a label-free PEC aptasensor for the detection of profenofos (PRO) was successfully constructed, indicating that MoTe2 nanoparticles/RGO would be a promising visible light-responsive photoactive material for PEC biosensors. This aptasensor exhibited a wide linear range (10−9 g L–1 and 10−2 g L–1) and a relatively low detection limit (3.3 × 10−10 g L−1). At the same time, the application of Schottky barrier in the field of photoelectric sensing was expanded.

Study on cobalt-phosphate (Co-Pi) modified BiVO4/Cu2O photoanode to significantly inhibit photochemical corrosion and improve the photoelectrochemical performance

The serious recombination of photogenerated carriers and the photochemical corrosion of the electrode extremely restricted its photoelectrochemical (PEC) performance, which could not reach the theoretical photocurrent intensity. However, so far, there are few comprehensive reports on the mechanism of corrosion inhibition and stability improvement of electrodes in photocatalytic degradation. In this paper, BiVO4/Cu2O heterojunction modified by Cobalt-phosphate (Co-Pi) co-catalyst was successfully prepared to address the aforementioned issues. Co-Pi completed the holes capture and release process through the change of its own chemical state (Co2+/3+→Co4+→Co2+/3+), and also affected the energy band bending of the BiVO4/Cu2O heterojunction. In addition, the effect mechanism of the Co-Pi film thickness on the PEC performance of the photoanode was systematically discussed in this report. When the deposition amount was 0.05C∙cm−2, the photocurrent density reached 2.22 mA∙cm−2 at 1.23 V (vs. RHE), which was 2.8 times that of bare BiVO4. The LSV curves, EIS and UV–vis absorption spectra reveal the enhanced PEC performance and light stability of the prepared electrode materials. When it is applied to photocatalytic degradation of organic pollutants, BiVO4/Cu2O/0.05Co-Pi shows high activity and potential for MB and CIP degradation, and is expected to be stably applied to the field of photocatalytic degradation of refractory organic pollutants in water.

Improvement of Photocatalytic Performance for the g-C3N4/MoS2 Composite Used for Hypophosphite Oxidation

The synthesized g-C3N4/MoS2 composite was a high-efficiency photocatalytic for hypophosphite oxidation. In this work, a stable and cheap g-C3N4 worked as the chelating agent and combined with the MoS2 materials. The structures of the fabricated g-C3N4/MoS2 photocatalyst were characterized by some methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS). Moreover, the photocatalytic performances of various photocatalysts were measured by analyzing the oxidation efficiency of hypophosphite under visible light irradiation and the oxidation efficiency of hypophosphite using the g-C3N4/MoS2 photocatalyst which was 93.45%. According to the results, the g-C3N4/MoS2 composite showed a promising photocatalytic performance for hypophosphite oxidation. The improved photocatalytic performance for hypophosphite oxidation was due to the effective charge separation analyzed by the photoluminescence (PL) emission spectra. The transient photocurrent response measurement indicated that the g-C3N4/MoS2 composites (2.5 μA cm–2) were 10 times improved photocurrent intensity and 2 times improved photocurrent intensity comparing with the pure g-C3N4 (0.25 μA cm–2) and MoS2 (1.25 μA cm–2), respectively. The photocatalytic mechanism of hypophosphite oxidation was analyzed by adding some scavengers, and the recycle experiments indicated that the g-C3N4/MoS2 composite had a good stability.

Organic photoelectrocatalytic filtration membrane originated from PEDOT modified PVDF

A Poly 3, 4-ethylenedioxythiophene (PEDOT) modified polyvinylidene fluoride (PVDF) membrane with photoelectric activity was developed by chemical vapor deposition (CVD). Four kinds of membranes were prepared by 10–40% mass concentrations of FeCl3·6H2O oxidant. Modified membrane with 20% oxidant achieved the best performance with 0.07 e−5A photocurrent intensity. The highest removal ratio of tetracycline hydrochloride (TC, 92%), protein (90%), polysaccharide (57%) and humus (63%) were achieved under −1 V (Vs Ag/AgCl) and 210 W xenon lamp photoelectrocatalytic condition. Under optimized conditions, not only the 90% of TC and 80% of sodium humate were removed, but also the membrane flux maintained well during the 12 h continuous filtration tests. Free radicals of SO4−, O2− and 1O2 played a key role in the photoelectrocatalytic degradation. The carrier type of the membrane was changed from p-type to n-type after reaction because of the electron injection.

Size-constrained ultrathin BiOCl nanosheets@C composites with enhanced photocatalytic and photoelectrochemical performance

Size-constrained ultrathin BiOCl nanosheets@C composites were achieved by one-step hydrothermal route. It was found that the carbon coated on the surface of BiOCl nanosheets not only accelerated the separation of electrons and holes, but also restricted the outward growth of the BiOCl crystal structure to expose more active catalytic sites. In addition, the obtained composites have stable and close interface contact, beneficial for the structural stability of products as well as the rapid charge transfer. The average sheet thickness was in the range of 20–60 nm. Compared with the ability for pure BiOCl to degrade RhB, the degradation rate of the optimal composite can reach 100% within 15 min, while the corresponding photocurrent intensity could reach 5.6 µA·cm−2, and its impedance value was also the smallest. The removal experiments of active substances showed that h+ and O−2 play important roles in the process of photocatalytic degradation. It can be expected that the resulted composites in this work can be used as potential materials for photocatalytic and photoelectrochemical applications.

Efficient degradation of organic pollutants by catalytic ozonation and photocatalysis synergy system using double-functional MgO/g-C3N4 catalyst

The catalytic ozonation and photocatalysis system, which was constructed by introducing ozone and using MgO/g-C3N4 as the catalyst, exhibited great degradation performance for phenol solution. The degradation efficiency was nearly 100% within 2 min, which was 18 and 1.5 times higher than individual photocatalytic and catalytic ozonation activity, and has not been reported in previous literature. In the catalytic ozonation and photocatalysis synergy system, MgO played a dual role: MgO could greatly promote the separation of photoinduced charges in photocatalysis due to the formation of C-O and Mg-N coordination bonds between g-C3N4 and MgO, as seen from the photocurrent intensity results. Simultaneously, MgO actively improved the utilization efficiency of ozone and accelerated the conversion of ozone into hydroxyl radicals (OH), which enhanced the catalytic ozonation activity. Thus, MgO was used as a bridge to realize the (O3/MgO/g-C3N4/Vis) synergy between catalytic ozonation and photocatalysis. The EPR results further confirmed this synergy, since the intensity of OH produced by catalytic ozonation and photocatalysis was greatly higher than the photocatalysis and catalytic ozonation progress. Meanwhile, the effects of the amount of ozone and catalyst, initial pH and concentration of the phenol solution on the synergy degradation performance were investigated. Furthermore, the mineralization capabilities of the synergy system for bisphenol A and 2–4 dichlorophenol and the cyclic stable performance were examined. Finally, the degradation mechanism of the synergy system was proposed. This work provided a new idea to design double-acting catalytic materials and developed a coupled oxidation technology to degrade organic pollutants.

Effect of Band Symmetry on Photocurrent Production in Quasi-One-Dimensional Transition-Metal Trichalcogenides.

Photocurrent production in quasi-one-dimensional (1D) transition-metal trichalcogenides, TiS3(001) and ZrS3(001), was examined using polarization-dependent scanning photocurrent microscopy. The photocurrent intensity was the strongest when the excitation source was polarized along the 1D chains with dichroic ratios of 4:1 and 1.2:1 for ZrS3 and TiS3, respectively. This behavior is explained by symmetry selection rules applicable to both valence and conduction band states. Symmetry selection rules are seen to be applicable to the experimental band structure, as is observed in polarization-dependent nanospot angle-resolved photoemission spectroscopy. Based on these band symmetry assignments, it is expected that the dichroic ratios for both materials will be maximized using excitation energies within 1 eV of their band gaps, providing versatile polarization sensitive photodetection across the visible spectrum and into the near-infrared.