Enhanced Photoconversion Efficiency Research Articles

A new type of core-shell nanowire array structured quantum dot-composite perovskite solar cell with near full-spectrum absorption

The core-shell structured nanowire array solar cell has a larger absorption area and enhanced light capturing capability, thus enabling more efficient absorption of solar energy. By using perovskite materials as the absorber material, it can effectively absorb ultraviolet light and a portion of visible light, but its absorption capacity for red light and infrared light is relatively weak. Quantum dots (QDs) can effectively extend the absorption range of the solar cell, particularly in the infrared regions. Therefore, in this work, QDs were combined with perovskite materials, and then an electron transport layer/quantum dot/perovskite/hole transport layer core-shell structure nanowire array solar cell was constructed. Compared to structures without QDs, the new structure has a broader absorption range, improved charge carrier transport, and enhanced photoconversion efficiency. This would provide a new structure for wide-spectrum absorbing solar cells.

Bismuth sulfide/carbon black: as a pt free and efficient counter electrode in DSSC

A hydrothermal method was utilized to synthesize microstructures of bismuth sulfide (Bi2S3) across a range of reaction temperatures, spanning from 140 to 180 °C. The impact of varying reaction temperatures on the structural, morphological, and optical properties of the deposited Bi2S3 material was thoroughly examined. The x-ray diffraction (XRD) patterns confirmed the presence of an orthorhombic crystal structure. The formation of intricate three-dimensional Bi2S3 microstructures was evident under field emission scanning electron microscopy (FESEM), with the reaction temperature playing a pivotal role in this process. Furthermore, Bi2S3-carbon black composites were employed as the counter electrode in dye-sensitized solar cell (DSSC) applications. The current density–voltage characteristics of the DSSCs revealed a clear correlation between photoconversion efficiency and the reaction temperature. Notably, the Bi2S3-carbon black film with a 1:1 ratio achieved a peak photoelectric conversion efficiency of 4.37 ± 0.01%. It also exhibited a short-circuit current density of 10.29 mA cm−2 and an open-circuit potential of 0.70 V. Future studies should explore the broader implications of Bi2S3-carbon black composites in various optoelectronic and photocatalytic devices. Secondly, while our findings provide valuable insights, a more in-depth understanding of the underlying mechanisms governing the enhanced photoconversion efficiency, especially with the 1:1 ratio of Bi2S3-carbon black, requires further exploration.

Enhanced photoconversion efficiency of Cu2MnSnS4 solar cells by Sn-/Zn-based oxides and chalcogenides buffer and electron transport layers

Copper Manganese Tin Sulfide, Cu2MnSnS4 (CMTS), has emerged as a potential candidate for cost-competitive, eco-friendly single- or multiple p-n junction kesterite quaternary photovoltaics (PVs) due to its distinct optical and electrical properties, with earth-abundant as well as non-toxic constituents. In this article, Cu2MnSnS4 absorber-based heterostructures with ZnMgO, WS2, SnO2, CdS electron transport (window) and SnS2, ZnSe, ZnSnO, Zn(O,S) buffer layers have been investigated by executing a systematic study and proposing the mostly efficient device structures containing the favourable band alignment using the SCAPS-1D simulator. Initially, an effective buffer and electron transport (window) layers have been optimized from Al:ZnO/window (ZnMgO, WS2, SnS2, or CdS)/buffer (SnS2, ZnSe, ZnSnO, Zn(O,S))/Cu2MnSnS4/Pt structures. Subsequently, the impact of different properties of each active layer of optimized structures, such as bandgap, layer thickness, carrier concentration, bulk and interface defect densities, and working temperature, was determined by measuring PV parameters and corresponding quantum efficiency. The present study exhibited the maximum photocurrent, JSC of 23.69 mA/cm2, open circuit voltage, VOC of 1.236 V, fill factor, FF of 85.49% and photoconversion efficiency, PCE of 25.03% with optimized SLG/Mo/Cu2MnSnS4/SnS2/ZnMgO/ZnO:Al/Pt structure under AM1.5G irradiation. Furthermore, a detailed comparison among recent studies has been carried out to demonstrate the significance of the proposed structure, challenges, and future prospects. Thus, obtained results pave significant resources and emancipate a new pathway to fabricate enviro-benign, cost-competitive, high-efficiency CMTS-thin film photovoltaics.

Enhanced photo conversion efficiency of Nb2O5/TiO2 bilayer photoanode for Dye-Sensitized Solar Cells

This work is focused to improve the photovoltaic parameters in DSSC by introducing a bilayer photoanode. Nb2O5/TiO2 bilayer photoanodes were prepared by screen printing method. The microstructural, crystalline nature, and morphological properties were analysed. Charge transfer processes in Nb2O5/TiO2 bilayer photoanode and TiO2 photoanode were analysed. The electron behavior in the device was investigated by electrochemical impedance spectroscopy (EIS) measurement. It was inferred that charge transfer resistance significantly lowered in the Nb2O5/TiO2 bilayer photoanode. In addition, the effective electron lifetime was significantly improved, and the recombination rate was reduced. DSSCs devices were fabricated using Nb2O5/TiO2 bilayer and TiO2 unilayers as photoanode, N719 dye, iodide-based electrolytes and platinum counter electrode. Highest efficiency of 5.4% was achieved in the bilayer photoanode system for an optimum thickness of Nb2O5.

Core-double-shell structure and heterojunction in CdS/SnS2 boosting fast carrier separation for ultrasensitive detection of carbohydrate antigen 125

Combining heterojunctions and advanced structures is an effective strategy for improving light capture capability and electron-hole pair separation of photoactive materials. In this work, we facilely constructed CdS/SnS2 with a unique core-double-shell structure (CS-CDSSs) using cobalt glycerate nanospheres as sacrificial templates. The one-step hydrothermal cation exchange method was used to construct energy-matched heterojunctions, simultaneously endowing CS-CDSSs with a distinctive morphology of coexisting core-shell and multi-shell structures. The enhanced photoconversion efficiency was attributed to (i) unique structural features and a narrow shell spacing; (ii) broadened optical response and shift toward the visible-light range; (iii) scattering/reflection effect of the incident light to increase light enrichment; and (iv) close contact at the interface between CdS and SnS2. Based on the excellent photoelectric conversion efficiency of CS-CDSSs, the fabricated photoelectrochemical (PEC) biosensors exhibit high performance with a wide linear range from 10−7 to 102 U·mL−1, and an ultralow detection limit of 5.48 × 10−8 U·mL−1 for carbohydrate antigen 125 (CA125). This novel strategy significantly improves the PEC performance of heterojunctions by preparing core-double-shell structures, which could provide more inspiration for constructing other functionalized photoactive materials.

Investigation on the effect of neodymium ion doping in TiO2 on the photovoltaic performance of dye-sensitized solar cells

Titanium dioxide (TiO2), neodymium (Nd3+) doped TiO2 with the doping levels of 0.3% and 0.5% were synthesised by hydrothermal method and were characterized by powder X-ray diffraction (XRD), UV–vis diffused reflectance spectroscopy (DRS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet X-ray photoelectron spectroscopy (UPS) and high resolution transmission electron microscopy (HRTEM). Doping of Nd3+ ions have been created new surface energy states below the conduction band of TiO2 which mediate the photoinjected electrons through TiO2 network to external load without any impediment. The Fermilevel (Ef) of TiO2 was shifted to downward direction upon Nd3+ ion doping confirmed from UPS analysis. An enhanced photoconversion efficiency (PCE) of 10.7% was achieved for the device fabricated using 0.3% Nd3+ ion doped TiO2 which is higher than that of the device with undoped TiO2 (10.1%). The noticeable increment in the PCE was due to the reduced charge recombination, longer electron lifetime and improved charge injection form LUMO of the N719 dye to the CB of TiO2.

Porous BiVO4 coupled with CuFeO2 and NiFe layered double hydroxide as highly-efficient photoanode toward boosted photoelectrochemical water oxidation

In this paper, the monoclinic bismuth vanadate photoanode with porous structure prepared from successive electrodeposition and metal organic decomposition (MOD) method used as photoanode for photoelectrochemical (PEC) water oxidation. The p-type CuFeO2 ultrathin layer is coupled to form a p-n heterojunction, further promoting charge transfer and inhibit carrier recombination. The NiFe layered double hydroxide (NiFe-LDH) is electrodeposited as oxygen evolution cocatalyst (OEC) for the hole extraction for the water oxidation. Therefore, the BVO/CFO/NiFe LDH heterostructure photoanode exhibits the boosted PEC performance, achieving the a photocurrent density of 4.34 mA·cm−2 at 1.23 V vs RHE and enhanced photoconversion efficiency of 2.48%, which is 3.78 and 5.28 times higher than that of pristine of BiVO4. The heterostructure photoanode exhibits excellent PEC activity, which can provide a promising and simple strategy for fabricating photoanodes with high-efficiency oxygen release promoters.

Enhancement of photoconversion efficiency and light harvesting ability of TiO2 nanotube-arrays with Cu2ZnSnS4

We report an underpotential deposition (UPD) route of Cu2ZnSnS4/TiO2 nanotube arrays (TiO2-NTAs) in which the Kesterite (Cu2ZnSnS4) was employed as a sensitizer to enhance the photoconversion efficiency of the TiO2-NTAs. Cu2ZnSnS4 was simultaneously coated on TiO2-NTAs by depositing its constituent metals from the precursor ions via electrochemical atomic layer deposition (EC-ALD) and subsequent annealing. The detailed synthesis process, the surface morphology, crystalline structure, photoelectrochemical properties and hydrogen production rate of the as-prepared Cu2ZnSnS4/TiO2-NTAs were discussed. Thickened TiO2 nanotubes were observed, suggesting that the Cu2ZnSnS4 coating was about 5 ± 0.5 nm. The results showed that the light harvesting of TiO2-NTAs has an obvious improvement after sensitizing them with Cu2ZnSnS4. In comparison with pure TiO2-NTAs, a two-fold increment in photoconversion efficiency was achieved using the composite of Cu2ZnSnS4/TiO2-NTAs. The novel photoanode of CZTS/TiO2 NTAs achieved a maximum hydrogen generation rate of 49 ml h−1 cm−2.

Optical Absorption and Photoconversion Characteristics of WO<sub>3</sub> Nanofiber Photoanodes Prepared by Electrospinning with Different Calcination Temperatures

This study aims to synthesize and examine the optical and photoelectrochemical properties of tungsten oxide (WO3) nanofibers prepared by electrospinning and calcination using different temperatures (500, 700, and 900 °C). The electrospinning solution contained a mixture of polyvinyl alcohol (PVA, 7.5% w/v) and ammonium metatungstate hydrate (AMH, 16.7% w/v). The morphology of WO3 nanofibers was observed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorbance of calcined WO3 nanofibers was measured, and the data was used to calculate the optical band gap energy (Eg) through Tauc’s relation. The of calcined WO3 nanofibers were found to be from 2.85 to 3.08 eV. The minimum value of was obtained from the sample calcined at 900 °C. Linear sweep voltammetry (LSV) was employed in the photocurrent measurements under simulated AM 1.5G at 100 mW/cm2 irradiance. The WO3 nanofiber photoanode calcined at 900 °C exhibited the maximum photoconversion efficiency (PCE) of 1.53%, a twice enhancement in PCE compared with those obtained from WO3 nanofibers calcined at lower temperatures. This study suggests the potential pathway for the optimal synthesis of high performance nanostructured metal oxide electrodes for photoelectrochemical water splitting.

Exploitation of Improved Long‐Term Stability and Enhanced Photoconversion Efficiency of Organic Photovoltaics Using Flexible Transparent Conducting Electrode with Dual Functions of Antireflection and Ultrahigh Moisture Barrier

A structure of flexible glass/flexible transparent conducting electrode (TCE) comparable with the conventional glass/indium tin oxide (ITO) substrate is proposed by combining an Ag NW + PEDOT:PSS hybrid TCE (h‐TCE) with triple‐layer a‐SiNx:H/n‐SiOxNy/h‐SiOx ultrahigh barrier (UHB) films. The UHB films have dual functions of both moisture barriers with a water vapor transmission rate (WVTR) of 1.6 × 10−5 × g m−2 day−1 and antireflection (AR) with a gradient refractive index. Flexible PTB7:PC70BM‐based organic photovoltaics (OPVs) with the AR‐UHB film achieve a maximum power conversion efficiency (PCE) of ηmax = 8.33%, saturation current density (Jsc) of 17.67 mA cm−2, and external quantum efficiency (EQE) of 63.3%, which are higher than ηmax = 7.63%, Jsc = 15.25 mA cm−2, and EQE = 59.26% of the OPVs on glass/ITO. These result from the increase in the absorption of the donor PTB7 due to the AR effect of the UHB films. A long‐term stability of the AR‐UHB encapsulation layer in damp heat (40 °C/85% relative humidity [RH]) is confirmed by the result that the measured T80 and T50 values for the OPV device on glass/ITO encapsulated with the AR‐UHB film are about 1008 h (42 days) and 2205 h (92 days), respectively.

Tandem DSSC fabrication by controlled infiltration of organic dyes in mesoporous electrode using electric-field assisted spray technique

Tandem absorber architectures in DSSCs for extending the light absorption range, using two dyes (N719/Red dye and N749/Black dye) appropriately infiltered in the pores of a mesoporous TiO2 photoanode, have been prepared for the first time by electric-field assisted spray technique (E-Spray). In comparison to the conventionally used dip technique, which takes several hours the E-spray technique developed in this study significantly reduces the loading time to 10–15 min by rapid pore filling of dual dyes. The shorter wavelength (450–550 nm) absorber -N719 dye and longer wavelength (550–800 nm) absorber -N749 dye have been infiltrated sequentially and in right proportion by precise control over E-Spray parameters in order to capture a wider range of the incident solar spectrum. The tandem DSSCs (T-DSSCs) thus fabricated show substantial improvement in photo-current density (Jsc), resulting in ~11% enhancement in photoconversion efficiency (PCE), as compared to a single-dye device. The best performing T-DSSC (N719:N749-75:25) yields the Jsc, Voc and FF of ~16 mA/cm2, ~0.75 V and ~0.69, respectively, resulting in PCE of 7.5%, which is ~40% higher than the PCE of 5.33% for the conventionally fabricated dip-coated DSSC. This study opens up door for tandem device fabrication using E-spray technique which is suitable for large area and roll-to-roll manufracturing aiming for high PCE solar cells.

N719 Sensitized Solar Cell Features of Photoanodes Prepared with CDS Coated Hydrothermally Derived Anatase Tio2 Nanobelts

Herein, DSSC performance of the photo-anodes of (i) TiO2 powders derived from simple basic precipitation (SP) reaction (SP-TiO2-1), (ii) TiO2 powders derived from conventional hydrothermal reaction (CH-TiO2-2) and (iii) hydrothermally derived TiO2 coated with CdS by dip method (CdS-CH-TiO2-3) is reported. The XRD, UV-visible spectroscopy, FESEM and HRTEM techniques are used for the characterization of resultant films. The characterization studies indicated the crystallization of anatase TiO2 in all resultant films and CdS with hexagonal symmetry in case of CdS-CH-TiO2-3 film. The crystallization of spherical agglomerates having average size of 36.05 nm with nearly uniform size distribution is realized in case of SP-TiO2-1 by using FESEM. Further, HRTEM indicated the coating of CdS nanoparticles with average particle size of 15.86 nm on hydrothermally crystallized anatase TiO2 nanobelts of width 200 nm in case of CdS-CH-TiO2-3 films. The N719 sensitized solar cell properties these photoanodes obtained at 1000 W/m2 input power indicated the enhancement of photoconversion efficiency (η) by 95.83 % in case of CH-TiO2-2 (η = 1.41) as compared to SP-TiO2-1 (η = 0.72) photoanode whereas 34.75 % in case of CdS-CH-TiO2-3 (η = 1.90) as compared to CH-TiO2-2 photoanode. The improvement in photoconversion efficiency (η) in case of CH-TiO2-2 and CdS-CH-TiO2-3 can be attributed due to increase in charge transfer current density (J) and decrease in re-combination rate of electron at electrode-electrolyte/dye contact. This is due to blocking of back scattered electrons and effective electron-hole charge separation created by co-sensitizer CdS nanoparticles coated on TiO2 nanobelts.

Fabrication of CdS/PbS and CdS:Al/PbS solar cells: Optimization of the Al content in CdS and the solution pH during PbS deposition

The CdS/PbS and CdS:Al/PbS thin film solar cells were fabricated using chemical bath deposition (CBD) process. The CdS thin film was deposited onto the ITO/glass substrate with different aluminum dopant concentration, whereas PbS layer was deposited over CdS thin film with different solution pH. The deposited CdS, CdS:Al and PbS thin films were characterized by scanning electron microscopy (SEM), Xray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Rutherford Backscattered Spectroscopy (RBS) and Hall effect measurements. The results indicated that the aluminum concentration in CdS films reduces the crystallite size and increases the band gap and film resistivity. From PbS film characterization, it was obtained that increasing the solution pH the crystallite size augmented, meanwhile the band gap and electrical resistivity decreased.Photovoltaic characteristic performed to the different thin films solar cells, revealed that the highest conversion efficiency (ɳ %) 1.45% was observed in the bilayer system composed by a CdS layer doped with 9% of Al, and a PbS film grown at pH 10. Interestingly, CdS film with the highest resistivity and PbS with a medium band gap (1.48 eV) resulted in the highest conversion efficiency. Characterization of CdS, PbS and CdS/PbS samples suggested that the crystallite size, band gap and electrical resistivity were easily tuned with the help of CBD process that enhanced photo-conversion efficiency of the solar cells.

A Hybrid Hole Transport Layer for Perovskite-Based Solar Cells

This paper presents the effect of a composite poly(3,4-ethylenedioxythiophene) polystyrene sulfonate PEDOT:PSS and copper-doped nickel oxide (Cu:NiOx) hole transport layer (HTL) on the performance of perovskite solar cells (PSCs). Thin films of Cu:NiOx were spin-coated onto fluorine-doped tin oxide (FTO) glass substrates using a blend of nickel acetate tetrahydrate, 2-methoxyethanol and monoethanolamine (MEA) and copper acetate monohydrate. The prepared solution was stirred at 65 °C for 4 h and spin-coated onto the FTO substrates at 3000 rpm for 30 s in a nitrogen glovebox. The Cu:NiOx/FTO/glass structure was then annealed in air at 400 °C for 30 min. A mixture of PEDOT:PSS and isopropyl alcohol (IPA) (in 1:0.05 wt%) was spun onto the Cu:NiOx/FTO/glass substrate at 4000 rpm for 60 s. The multilayer structure was annealed at 130 °C for 15 min. Subsequently, the perovskite precursor (0.95 M) of methylammonium iodide (MAI) to lead acetate trihydrate (Pb(OAc)2·3H2O) was spin-coated at 4000 rpm for 200 s and thermally annealed at 80 °C for 12 min. The inverted planar perovskite solar cells were then fabricated by the deposition of a photoactive layer (CH3NH3PbI3), [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and a Ag electrode. The mechanical behavior of the device during the fabrication of the Cu:NiOx HTL was modeled with finite element simulations using Abaqus/Complete Abaqus Environment CAE. The results show that incorporating Cu:NiOx into the PSC device improves its density–voltage (J–V) behavior, giving an enhanced photoconversion efficiency (PCE) of ~12.8% from ~9.8% and ~11.5% when PEDOT:PSS-only and Cu:NiOx-only are fabricated, respectively. The short circuit current density Jsc for the 0.1 M Cu:NiOx and 0.2 M Cu:NiOx-based devices increased by 18% and 9%, respectively, due to the increase in the electrical conductivity of the Cu:NiOx which provides room for more charges to be extracted out of the absorber layer. The increases in the PCEs were due to the copper-doped nickel oxide blend with the PEDOT:PSS which enhanced the exciton density and charge transport efficiency leading to higher electrical conductivity. The results indicate that the devices with the copper-doped nickel oxide hole transport layer (HTL) are slower to degrade compared with the PEDOT:PSS-only-based HTL. The finite element analyses show that the Cu:NiOx layer would not extensively deform the device, leading to improved stability and enhanced performance. The implications of the results are discussed for the design of low-temperature solution-processed PSCs with copper-doped nickel oxide composite HTLs.

Heterovalent Substitution in Mixed Halide Perovskite Quantum Dots for Improved and Stable Photovoltaic Performance

One of the strategies to improve the device performance of metal-halide perovskite solar cells is to alter the electronic and optical properties of the perovskite lattice by metal ion doping. In this work, aliovalent doping of silver at the lead site of CsPbBr1.5I1.5 quantum dots (QDs) shows striking prospects in improving the photovoltaic (PV) device performance. Lattice doping could be achieved only up to ∼3.5 atom % Ag+ with respect to Pb2+ which has significant impact on the electronic and optical properties of the QDs. The band gap could be reduced from 2.15 eV for pristine QDs to 2.12 eV with 3.5 atom % Ag-doping, beyond which midband gap states are created along with the formation of a secondary AgI phase with higher Ag+ substitution. Density functional theory (DFT) shows enhanced optical absorption coefficient and p-type character of the Ag-doped QDs. With the QDs having 3.5 atom % Ag, a significant ∼20% enhancement in photoconversion efficiency (PCE) is observed up to 9.67 ± 0.12% due to the reduction of surface and intrinsic defects, decrease in nonradiative recombination leading to an increase in carrier lifetime, and increase in charge transfer. Although in general all-inorganic perovskite (AIPSK) QDs are attractive because of their higher crystallinity, better optical property, and easy solution processability, the solution stability of AIPSK QDs is not the same as that in PV devices. After 3.5 atom % Ag-doping, our PV devices show extremely promising ambient stability for 575 h (24 days) with less than 5% drop in PCE in comparison to 12% drop for pristine QD devices.

Vertically aligned Co3O4 nanorods as a platform for inverted all‐oxide heterojunctions

AbstractDirect stacking of n‐type and p‐type metal oxide (MOx) semiconductors is one of the appealing directions toward low cost and environmentally friendly photovoltaics (PVs). However, the main shortcoming, hindering the PV performance of MOx heterojunction devices is attributed to the tradeoff between light absorption and maximized carrier extraction in p‐type MOx. In this work, we demonstrate that the nanorod (NR) geometry of Co3O4 light absorber with a nearly ideal bandgap of ∼1.48 eV, can remove this hurdle through strong internal light trapping of adjacent one‐dimensional (1D) structure and enhanced carrier mobility. The inverted n‐on‐p configuration of the core‐shell 1D heterojunction, obtained by depositing a thin TiO2 n‐type layer, resulted in enlarged charge generation compared to the typical p‐on‐n counterpart device. Fine‐tuning of Co3O4 NRs length, permits PV investigation of the heterojunctions with respect to absorber layers thickness. The optimized Co3O4 NRs/TiO2 heterojunction (30 nm Co3O4 NR length) presented a record high open circuit photovoltage (Voc) of (0.52 ± 0.03) V under 1 sun irradiation. Impedance analysis of the heterojunctions, indicates formation of the p+‐p depletion. The presented work can highlight some vital venues to enhance photoconversion efficiency of the all‐oxide heterojunctions while introducing a pioneer contender as inverted (n‐on‐p) MOx heterojunction.

Platinum-free dye-sensitized solar cells by flower-like mixed-phase CoxSy/NixSy/MoxSycomposites

Fabricated DSSCs using CoxSy/NixSy/MoxSycomposites as counter electrodes showed an enhanced photoconversion efficiency.

Enhanced photoconversion efficiency of hybrid TiO2/nox-MWCNT/Si photoanode for water splitting in neutral medium

Hybrid films composed by TiO2 and functionalized MWCNTs were synthesized and used as photoanodes to perform the water splitting process under neutral and free of sacrificial agents medium. The results show that introducing a sublayer of MWCNTs functionalized with –NO2 and –COOH groups leads to structural modifications on TiO2 that decrease the band gap and reduce the recombination phenomenon. Those groups anchored to nanotubes also play an important role in their dispersibility and provide an additional electron withdrawing effect to the pristine nanotubes. These conditions significantly improve the photoconversion efficiency of the hybrid system until 15-fold regarding pristine TiO2 prepared under the same conditions.

Optimized fabrication of BiOBr/TiO2 nanotube arrays for efficient degradation of organic pollutant under visible light irradiation

The BiOBr modified TiO2 nanotube arrays (BiOBr/TNAs) heterojunctions were fabricated through anodic oxidation followed by successive ionic layer adsorption and reaction method. The optimum synthetic parameters of BiOBr/TNAs were obtained by the response surface methodology. The surface structure analysis showed that BiOBr nanoflakes were successfully deposited on the surface of TNAs and formed BiOBr/TNAs heterojunctions. The BiOBr/TNAs displayed higher visible light absorption property than bare TNAs due to the intrinsic visible light response of BiOBr and excellent light-scattering property of the formed heterostructure. The photoelectrochemical properties and photoluminescence spectra analysis revealed that an appropriate loading amount of BiOBr on the TNAs could effectively enhance photoconversion efficiency and the separation of photogenerated electron-hole pairs. The photocatalytic degradation efficiency of Rhodamine B (Rh B) by the optimum BiOBr/TNAs reached almost 85% under visible light irradiation, which was much higher than that of bare TNAs (less than 20%). The radical scavenging experiments and electron spin resonance spectra suggested that ·O2– and h+ played crucial roles in the photocatalytic degradation of Rh B. The possible mechanism and degradation pathways of Rh B by BiOBr/TNAs were proposed under visible light irradiation.

Design and fabrication of WSe2/CNTs hybrid network: A highly efficient and stable electrodes for dye sensitized solar cells (DSSCs)

This study presents a rational-designed structure and facile strategy to fabricate tungsten selenide/carbon nanotube (WSe2/CNT) hybrid photoanodes as promising anodes for DSSC applications. The fundamental physic-chemical properties proved that the uniform, pure and tubular WSe2/CNT hybrid nanoparticles were produced and WSe2 nanoparticles were anchored the CNT surface successfully. The WSe2/CNT hybrid nanostructure exhibits higher surface area (107.8 m2/g) and pore size (45.3 nm) than compared with pure WSe2 (86.2 m2/g and 19.8 nm). WSe2/CNT composite exhibits enhanced photo-conversion efficiency (8.85%), electro-catalytic activity and high electron life time (87 ns). The improved PCE of the WSe2/CNT composite is due to the CNTs can reduce electron-hole pair recombination and efficiently inhibit the aggregation of WSe2 for fully exposing the active edges. Those outstanding electrochemical performances of WSe2/CNT hybrid can be assigned to its unique nanoarchitecture: the CNT with high conductivity work as the skeleton of WSe2/CNT anode facilitating the electron transfer; the CNT can effectively prevent WSe2 from the aggregation and promote the in-situ growth of WSe2 on CNT. Moreover, the hybrid structure, which can allow for efficient ionic diffusion and easy electrolyte infiltration.