Successive Ionic Layer Adsorption And Reaction Research Articles

Bi2Se3 nanoparticles anchored MWCNTs: Counter electrode in a dye-sensitized solar cell

Anchoring of Bi2Se3 nanoparticles over ‘dip and dry’ coated multiwalled carbon nanotubes (MWCNTs) has been accomplished using a room-temperature (27 °C), inexpensive, and convenient chemical route, namely, successive ionic layer adsorption and reaction (SILAR), to yield a nanohybrid composite electrode to serve as a counter electrode (CE) in dye-sensitized solar cell (DSSC) applications. The growth of Bi2Se3 on MWCNTs has been well-tuned through varying SILAR cycles (MBSe-series) and tested as counter electrodes (CEs) with reference to MWCNTs and Bi2Se3 in FTO/ZnO/Eosin-Y/Iodide-triiodide/Counter electrode/FTO assembly. Grown CEs have been validated through XRD, XPS, Raman, FTIR, and FESEM studies, while the assembled DSSCs have been assessed through JV, EQE, EIS, and electrochemical stability studies. Well-optimized Bi2Se3/MWCNTs nanohybrid composites have been used as CEs in DSSCs and showed superior device performance (0.52 %) compared to bare MWCNTs (0.14 %) and Bi2Se3 (0.09 %) due to the well-anchored Bi2Se3 over one-dimensional MWCNTs through a large number of synergistic electrochemical active sites. A DSSC fabricated with MBSe-12 as the CE exhibits enhanced stability compared to bare Bi2Se3 and MWCNTs. Also, it reveals a charge transfer resistance of 7.92 Ω/cm2 and an electron lifetime of 16 μs, yielding a maximum efficiency of 0.52 % and an external quantum efficiency of 28.20 %.

One-step spin-coating of methylammonium lead iodide on SILAR-deposited tin oxide, SnO2 films for effective electron transport

Tin oxide (SnO2) materials were prepared via successive ionic layer adsorption and reaction (SILAR) technique at varying deposition times. The synthesized tin oxide layer served as an electron transport layer for the deposition of a perovskite layer via spin coating method. The morphology, structure, elemental, optical features and vibration modes of the prepared samples have been studied using scanning electron microscopy (SEM), X-ray diffractometry (XRD), energy dispersive X-ray spectroscopy (EDX), UV–vis spectrophotometry, and Raman spectrophotometry, respectively. The films revealed granular-shaped nanograins with a maximum average grain size of 197.03 nm. XRD results showed a cassiterite pure-phase crystal structure with several prominent peaks. EDX studies confirmed the as-deposited elemental constituents with good optical properties obtained from the optical studies. The band gap energies ranged from 4.01 to 4.24 eV at increasing deposition times. The phonon modes and crystal structures were also revealed from the Raman studies. The materials find applications in solar cells and electronic devices.

Facial synthesis of reduced graphene oxide – Amorphous nickel tungstate composite for flexible hybrid asymmetric solid state supercapacitor application

Supercapacitors are crucial as an additional type of energy storage device assisting various types of energy storage systems for high power requirement. Herein, using successive ionic layer adsorption and reaction (SILAR) method, thin films of reduced graphene oxide (rGO) composited with nickel tungstate (NiWO4) were synthesized with different rGO content. The synthesized material showed spherical morphology with rGO sheets and a specific surface area in the range of 85 to 107 m2 g−1. The three-electrode method was used, and the electrochemical performance of rGO-NiWO4 films was assessed in 2 M KOH electrolyte. A composite film deposited at 12 mg mL−1 concentration of rGO (CNW3) film exhibited a specific capacitance of 779 F g−1 at a current density of 2 A g−1. At a current density of 4 A g−1, CNW3 film showed outstanding electrochemical stability with 95 % capacitance retention after 5000 galvanostatic charge-discharge (GCD) cycles. This study emphasizes the usage of rGO-NiWO4 (CNW3) thin films deposited using SILAR method as a cathode in solid-state asymmetric supercapacitors (ASC). The rGO-NiWO4/PVA-KOH/AC ASC device exhibited a specific capacitance of 94.2 F g−1 at 5 A g−1, a specific energy of 33.5 Wh kg−1 and a specific power of 12.37 kW kg−1 with 83 % capacitance retention after 5000 GCD cycles. This suggests that rGO-NiWO4 thin film produced using SILAR method is a suitable candidate for supercapacitors.

Li sensitized CdS/TiO2 nanocomposite photoanode for solar water splitting, hydrogen generation and photoelectrochemical (PEC) performance

Li–CdS/TiO2 nanocomposite with different composition 10Li–CdS/TiO2, 20Li–CdS/TiO2, 30Li–CdS/TiO2, 40Li–CdS/TiO2, 50Li–CdS/TiO2 were coated on FTO surface by using doctor blade followed by successive ionic layer adsorption and reaction (SILAR) method. As synthesized Li–CdS/TiO2 photoanode is characterized with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). FE-SEM analysis suggests that, Li–CdS/TiO2 film is 10.2 μm thick, porous, spongy and uniformly covered on FTO surface. The HR-TEM images reveal that the CdS nanoparticles are in intimate contact with the TiO2 nanocrystal shells with the CdS/TiO2 interfaces and the particle size of CdS and Li2S lies in the range of 20 nm–50 nm. UV-DRS analysis shows that, as the loading of Li in CdS/TiO2 films increases, there is decrease in band gap energy. The XPS analysis supports the presence of Li+ in Li–CdS/TiO2 nanocomposite. The PL spectra suggest that, with the increase in extend of Li+ ions into Li–CdS/TiO2, intensity of green emission band increases and it is shifted to higher wavelength. This reflects the low recombination rate of photo generated charge carrier in Li–CdS/TiO2 which is responsible for higher photocatalytic H2 production. The visible light photoanodic performance of Li–CdS/TiO2 was investigated for H2 evolution using aqueous Na2SO3 and Na2S solution under natural sunlight. Among the all-synthesized nanocomposite material, the highest amount of hydrogen produced over 20Li–CdS/TiO2 was found to be 38.61 ml/g/h in natural sunlight. Photoelectrochemical (PEC) performance of Li–CdS/TiO2 was examined. A possible mechanism for photocatalytic hydrogen generation is also discussed.

Control of Manganese Oxide Hybrid Structure through Electrodeposition and SILAR Techniques for Supercapacitor Electrode Applications

Manganese oxide has been studied as a promising supercapacitor electrode due to its high theoretical capacitance, low cost, and environmental friendliness. Supercapacitor performance such as specific capacitance, resistance, and cycle life greatly depends on the morphology and crystal structure of manganese oxide. In this study, a Mn3O4 hybrid structure was successfully synthesized using electrodeposition and successive ionic layer adsorption and reaction (SILAR) techniques which are simple, cost-effective, and low-temperature wet chemical processes. It was found that Mn3O4 morphology is different depending on manganese precursors and synthesis techniques. Sea-grape-like and bird nest-like morphologies were obtained via the electrodeposition technique, while flower-like and nanoparticle morphologies were formed via the SILAR technique using manganese acetate and manganese sulfate as precursors, respectively. The hybrid structure of the nanoparticle-decorated bird nest-like heterostructure was prepared using manganese sulfate electrodeposition and subsequent SILAR deposition of manganese acetate. X-ray photoelectron spectroscopy confirmed the Mn3O4 formation. Electrochemical properties of manganese oxide hybrid structure were systematically studied with cyclic voltammetry and galvanostatic charge–discharge, showing the highest areal capacitance of 390 mF cm−2 at 0.1 mA cm−2 with series and charge transfer resistances down to 4.55 and 4.91 Ω in 1 M sodium sulfate electrolyte.

Highly sensitive CO gas sensor based on ternary metal sulfides PbSbS quantum dots: Experimental and DFT study

Quantum dots (QDs) thin films based on binary metal sulfides (PbS) and ternary metal sulfides (PbSbS) were fabricated utilizing the Successive Ionic Layer Adsorption and Reaction (SILAR) method. Using the Tauc plot, 2.32 eV and 3.22 eV optical bandgaps were calculated for TiO2/Pb5Sb8S17 (TiO2/PbSbS) and TiO2/PbS, respectively. The sensing performance of TiO2/PbSbS and TiO2/PbS QDs has been investigated for the detection of carbon monoxide (CO) gas at room temperature (300 K). At 25 ppm, ∼2.5 times higher CO gas response was measured for TiO2/PbSbS (0.63) than for TiO2/PbS (0.2469) QDs with response/recovery time (tres./ trec) 14.8/10.21 s. Furthermore, TiO2/PbSbS QDs showed a good response of 0.247 with tres./ trec 20 /9 s at 5 ppm. These results provide a simple and highly scalable approach to developing high-performance gas sensors. To understand the gas sensing phenomena of TiO2/PbSbS and TiO2/PbS, a theoretical model has been developed. The simulation results revealed a significant difference in the behavior of TiO2/PbSbS and TiO2/PbS before and after CO interaction. Which have a high level of agreement with experimental results.

Palladium Nanoparticles Grown by Using Successive Ionic Layer Adsorption and Reaction Method: Ethanol Electrooxidation and Electrochemical Quartz Crystal Microbalance Studies

A facile wet chemical method namely successive ionic layer adsorption and reaction (SILAR) is implemented to grow palladium nanoparticles on graphite substrate. The grown Pd nanoparticles are successfully applied for electrooxidation of ethanol in alkaline solution. The electrocatalytic activity of grown Pd nanoparticles is studied by performing cyclic voltammetry (CV) measurements. Electrooxidation of ethanol by Pd nanoparticles is shown to be affected by growth parameters such as precursor concentration and number of SILAR growth cycles. Excessive growth of Pd nanoparticles due to large number of SILAR growth cycles shifts the pattern of cyclic voltammograms from period-one cyclic voltammograms to high order periodic/aperiodic cyclic voltammograms. Pd nanoparticles are also grown on gold coated quartz crystal and implemented to track any mass changes that occur during electrochemical surface oxidation/reduction over Pd nanoparticles, with and without ethanol in alkaline solution. To measure the mass changes occurring during CV measurements electrochemical quartz crystal microbalance (EQCM) is implemented in situ along with potential scanning.

Carbon as a hole extracting layer for CdS based self-powered photodetector devices

In this work, self-powered photodetectors were fabricated by a simple, cost-effective method using cadmium sulfide (CdS) as photoactive layer and carbon as a hole transport layer. A study on the performance of photodetectors with varied thickness of CdS layers deposited on an FTO coated glass substrate via the Successive Ionic Layer Adsorption and Reaction (SILAR) method is studied in detail. X-Ray diffraction (XRD) data confirms the formation of the CdS layer. Field emission scanning electron microscopy (FESEM) and elemental mapping shows the spherical clustered formation with a uniform distribution of CdS nanoparticles. The band gap of the CdS layers in the range of 2.25 to 2.38 eV is closer to the desired band gap of visible light photodetector. Though solution-processed photodetectors show a very weak photoresponse, the fabricated device shows a responsivity of 0.11✗10−3 A/W and a rapid rise and fall time as fast as 0.16 s and 0.12 s.

Effect of Ultraviolet Light on Mn3O4 Thin Films that are Grown Using SILAR for Room-Temperature Ozone Gas Sensors

Successive ionic layer adsorption and reaction (SILAR) is a promising technique to fabricate gas sensors at room temperature. However, the quality of the films is poor, leading to reduced surface area and increased defects within the film structure, thus decreasing the overall gas response. Inferior film quality also negatively affects the stability and reproducibility of the gas sensors over time. This study determines the effect of UV treatment on the structural, morphological, and ozone (O3) gas-sensing properties of p-type Mn3O4 thin films. As UV treatment time increases, the O3 gas-sensing characteristics increase because a porous structure with a higher surface area is formed and electrical conductivity is increased. Under a UV intensity of 20 mW cm−2, the Mn3O4 sensor exhibits gas response, response time, and recovery time of 1.62, 58, and 39 s, respectively, against 5 ppm concentration of O3 gas. Moreover, the Mn3O4 gas sensor exhibits excellent long-term stability showing around 3% variation in gas response over 60 d. This strategy allows the deposition of high-quality p-type Mn3O4 thin films using SILAR for applications in flexible gas sensors.

Thickness dependent physical and optical properties of SILAR deposited titania films

Uniform and crystalline titanium dioxide (TiO2) thin films were obtained using Successive Ionic Layer Adsorption and Reaction (SILAR) technique. Films having varied thicknesses over a range from 700 nm to 1000 nm are deposited on glass substrate. Further TiO2 films were annealed at 673 K for 2 h. X-ray diffraction measurements of both annealed and as deposited films were done to analyze the effect of temperature. Crystallite size and micro strain of the TiO2 films were calculated to study their trend with different thicknesses of the film. Morphological and compositional characteristics are studied by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX) respectively. Images showed formation of uniform film without discontinuities on the base substrate. Optical constants of the films are figured out using UV–vis spectrophotometry. Absorbance spectra showed that as the thickness of the films increased absorbance of the films also increased. Direct and indirect bandgap values of TiO2 films was found using Tauc’s plot.

Development of binder-free, amorphous nickel vanadate cathodes by SILAR method for hybrid supercapacitors: Exploiting surface area by monitoring growth rate

Developing self-supported electrode material in the absence of electro-inert binders considering the effortless transfer of charges and manipulating physicochemical properties of electrodes in energy storage devices is essential. Hence, the present attempt emphasizes the facile synthetic strategy of successive ionic layer adsorption and reaction (SILAR) for controlled nickel vanadate (NV) growth over the conducting plate. In SILAR synthesis, the growth rate is monitored by rinsing and adsorption/reaction time variation to tune the surface area, mesoporous structure, and surface morphology of NV thin films. As a result, the formation of mesoporous, amorphous, hydrous nanoparticles of NV over the stainless-steel substrate is affirmed by structural analysis. Furthermore, alteration in specific surface area with variation in growth rate is observed in BET analysis. As a result, the optimal NV(1:2) thin film electrode exhibited the highest specific capacity (capacitance) of 355C g−1 (710 F g−1) at 1 A g−1 current density. Moreover, the fabricated aqueous hybrid supercapacitor device (NV(1:2)//rGO) delivered 109 F g−1 specific capacitance at 1.3 A g−1 current density, and the device exhibited a maximum specific energy (SE) of 44 Wh kg−1 at a particular specific power (SP) of 1.14 kW kg−1. Furthermore, the solid-state hybrid supercapacitor (NV(1:2)//PVA-KOH//rGO) device conferred a specific capacitance of 89 F g−1 at 0.5 A g−1 current density and an SE of 36 Wh kg−1 at 0.482 kW kg−1 SP. This research paved an avenue to the binder-free, scalable synthesis of NV electrodes and employed them as a cathode in practical applications of hybrid energy storage devices.

Efficient Electrocatalytic Hydrogen Evolution Reaction on CuO Immobilized Stainless‐Steel Electrode Prepared by the SILAR Method

AbstractThe development of cost‐effective and efficient catalysts for the hydrogen evolution reaction (HER) has been a subject of intense research for sustainable and clean energy in recent decades. For this purpose, CuO‐modified stainless steel (CuO‐SS) electrode was fabricated to attain HER in acidic media. Here in, CuO film was fabricated on a stainless steel (SS) surface following successive ionic layer adsorption and reaction (SILAR) method. A 60‐cycle CuO modification resulted in enhanced HER activity compared to the bare SS or CuO electrode with an average 99 % Faradic efficiency. Based on the Electrochemical Impedance Spectroscopy (EIS), at an HER potential, the bare SS electrode exhibited charge transfer resistance of 24.7 Ω whereas CuO‐SS electrode exhibited 6.47 Ω only. The overpotential was calculated to be 154 mV at the CuO‐SS electrode regarding HER. The results have significant implications for the development of cost‐effective and efficient electrocatalysts for hydrogen production.

Development of BiOBr/TiO2 nanotubes electrode for conversion of nitrogen to ammonia in a tandem photoelectrochemical cell under visible light

Ammonia (NH3) is one of the important chemicals for human life. The demand for ammonia is expected to increase every year. Conventionally, the fixation process of N2 to produce NH3 in the industrial sector is carried out through the Haber−Bosch process, which requires extreme temperature and pressure conditions that consume a high amount of energy and emit a considerable amount of CO2. Therefore, it is necessary to develop alternative technology to produce ammonia using environmentally friendly methods. Many studies have developed the photo-electrochemical conversion of nitrogen to ammonia in the presence of semiconductor materials, but the resulting efficiency is still not as expected. In this research, the development of the tandem system of Dye-Sensitized Solar Cell - Photoelectrochemistry (DSSC - PEC) was carried out for the conversion of nitrogen to ammonia. The DSSC cell was prepared using N719/TiO2 nanotubes as photoanode, Pt/FTO as cathode, and electrolyte I-/I3-. The DSSC efficiency produced in this research was 1.49%. PEC cell at the cathode and anode were prepared using BiOBr/TiO2 nanotubes synthesized by the SILAR (Successive Ionic Layer Adsorption and Reaction) method. The resulting ammonia levels were analyzed using the phenate method. In this study, ammonia levels were obtained at 0.1272 µmol for 6 hours of irradiation with an SCC (Solar to Chemical Conversion) percentage of 0.0021%.

A novel approach in the synthesis of CdS/titania nanotubes array nanocomposites to obtain better photocatalyst performance

Studies that seek to improve the performance of photocatalyst continue to develop. Several observations have been made on the effect of using ultrasonic waves during the synthesis process of CdS/Titania Nanotubes Array (CdS/TiNTA) nanocomposites on an ability to degrade ciprofloxacin solution (CIP) and produce hydrogen. Therefore, the nanocomposite synthesis process uses the Successive Ionic Layer Adsorption and Reaction (SILAR) method, with (CH3COO)2Cd and Na2S as the precursors. During the SILAR process, sonication was applied for 60 minutes and carried out in the amorphous phase of TiO2 to increase the effectiveness of contact between the two semiconductors. The synthesis results were confirmed in term of their crystallinity, morphology, the presence of components on the surface, and the shift of bandgap by means of XRD, FESEM, FTIR, and UV-Vis DRS characterization, respectively. Photocatalytic activities of the nanocomposites were evaluated in a system containing 10 ppm CIP solution, on the purpose of observing their ability to degrade CIP and produce hydrogen. Our findings revealed an improvement in crystallinity, successful semiconductor coupling, and a band gap narrowing in the synthesized nanocomposites. Furthermore, the photocatalysts synthesized in the amorphous TiO2 and by sonication during SILAR offered doubled production capacity of hydrogen (0.191 mmol/m2) as compared to photocatalysts synthesized without sonication (0.092 mmol/m2). Compared to similar photocatalysts synthesized using the SILAR method in the crystalline phase, photocatalysts synthesized in the amorphous phase exhibited four-fold higher hydrogen production (0.044 to 0.191 mmol/m2). This prominent ability of the nanocomposites is related to the success of CdS adhering well to TiO2 surface to form nanocomposites, so that the bandgap energy position of CdS that is strong in the reduction reaction greatly contributes to improve the performance of the resulting photocatalyst, which is very advantageous in terms of its ability in water-splitting reactions.

Fabrication and Characterization of NiSe2 Films Prepared by SILAR Method

Nickel selenide thin films were grown on glass substrates at room temperature using the successive ionic layer adsorption and reaction (SILAR) method. Optical and structural analyses of the thin films were also performed. X‐ray diffraction (XRD), energy dispersive x‐ray analysis (EDAX) and scanning electron microscopy (SEM) were used for structural analysis, and UV–vis spectrometer was used for optical analysis. The XRD results indicate that the NiSe2 thin films had a polycrystalline structure. As a result of the optical analysis, the bandgap value decreased from 2.56 to 2.25 eV as the thickness increased. These results suggest that increasing film thickness improves the crystal structure of NiSe2 thin films. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Photoelectrochemical hydrogen generation with CdS/Ti–Si–O composite photoanode

CdS/TiO2 composite photoanode has attracted great attention due to its favorable electronic and optical properties. In this work, nanostructured Si-doped TiO2 photoanodes modified with CdS were fabricated through anodization of Ti–5Si alloy and depositing CdS by successive ionic layer adsorption and reaction (SILAR) process. The composition and morphology, optical properties and photoelectrochemical (PEC) performance of the composite photoanodes were investigated. The CdS/600-TiSiO composite photoanode with donor density of 2.2 × 1019 cm−3 and flat-band potential of −0.215 V exhibited excellent PEC hydrogen generation properties with remarkable photocurrent density (7.86 mA cm−2 at 0 V vs Ag/AgCl), which was 19.15 times and 9.59 times to that of undoped TiO2 photoanode and Ti–Si–O photoanode, respectively. The joint employment of Si-doping and CdS deposition provided an effective method to prepare excellent photocatalysts for PEC hydrogen generation.

Excellent plasmon-induced photoelectrochemical properties of WO3/Au nanosheets with uniform dispersion of dense Au nanoparticles fabricated by SILAR method

Constructing noble metal-tungsten oxide heterostructure is an effective strategy for extending visible light absorption to longer wavelength owing to the plasmonic effect, thus endowing them with more potential applications in photo(electro)catalysis. Herein, a facile successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate Au NPs decorated WO3 nanosheets (WO3-NSs) electrode for elucidating the mechanism of plasmon-induced charge separation (PICS) and enhancing PICS efficiency. Various characterizations suggested that dense Au NPs with small particle size (<20 nm) were highly dispersed on WO3-NSs by SILAR. The as-prepared WO3/Au electrodes exhibited strong and broad absorption in the visible light region of 500–700 nm, while pristine WO3 electrode had very weak absorption in this region. Anodic photocurrent responses and negative photopotential shifts were observed for WO3/Au electrode, demonstrating that PICS process indeed occurs at the Au-WO3 interface. Beneficial from the good dispersion and high loading amount of Au NPs, as well as formation of large interface between Au NPs and WO3-NSs, the as-prepared WO3/Au electrode achieved satisfactory PICS efficiency. This study paves a new way for the deposition of well-dispersed Au NPs on WO3 photoanodes with excellent PICS-based photoelectrochemical performance.

Enhancement in absorption spectrum by ITO coated, down converting glass and increasing the SILAR cycles of PbS/CdS quantum dots sensitized ZnO nano with deposition of MoO3/Au/MoO3 (MAM) as a solid state solar cell

This research describes the first-of-its-kind quantum dots sensitized solar cell (DC/ITO/ZnO/PbS/CdS/MoO3/Au/MoO3) that is efficient and economical. A down-converting (DC) transparent glass was prepared. One side of DC glass was coated with indium tin oxide (ITO) by sputter-coating technique to make it conductive for electric current. Zinc oxide (ZnO) nanorods were produced by the several steps of hydrothermal process. The PbS/CdS quantum dots (QDs) were then grown on top of ZnO nanorods by using a process known as Successive Ionic Layer Adsorption and Reaction (SILAR). The final layer for the back contact was deposited as a trilayer of (MoO3/Au/MoO3).Spin coating was employed in the process of depositing MoO3 layers, while thermal evaporation was used in the process of depositing the intermediate layer of gold (Au). For the deposition of (CdS/PbS) quantum dots with different number of SILAR cycles (10, 15 and 20) were employed. Afterwards MoO3/Au/MoO3 trilayer was deposited on the quantum dots (CdS/PbS) attached with the nanorods ZnO for the complete fabrication of three devices. As compared to the other quantum dots sensitized solar cell (QDSSC), it can absorb light from both ends which produced the remarkable results. Surface morphology, elemental and structural analyses were employed by SEM, EDS and XRD methods. UV–Visible analysis was performed to identify the optical properties of the devices. Overall performances were calculated of the three different devices by their power conversion efficiencies. The highest efficiency among all three devices was 10% corresponding to the 15 SILAR cycles.

Effect of MgO recombination barrier layer on the performance of monolithic-structured solid-state dye sensitized solar cells

ABSTRACT In this paper, the optical, structural and electrical properties of pure and magnesium-doped TiO2 nanoparticles (NPs) of different cycles (2, 4, 6 and 8 cycles) were explored systematically. The magnesium-doped TiO2 was synthesised through successive ionic layer adsorption and reaction (SILAR) and deployed into dye sensitised solar cells. The effects of the MgO barrier layer was evaluated . The results show enhanced optical properties with MgO coating with a diminished band gap energy. The X-ray diffraction studies show that the anatase phase was preserved after doping and the dopant does not change the crystalline phase of the TiO2. The SEM results show well-dispersed morphology. For the device with 4 SILAR cycles of MgO, gains in open-circuit voltage, current density and simultaneous increase in efficiency were observed which is attributed to improved charge collection efficiency as electrons diffusing through TiO2 have a better chance of reaching the electrode before recombining. At greater SILAR cycles (6 and 8), losses in photocurrent caused net decrease in efficiencies. The results presented in this report implies that the modification of TiO2 with a metal oxide (MgO) can result to good photon management.

Carbon fiber cloth@BiOBr/CuO as immobilized membrane-shaped photocatalysts with enhanced photocatalytic H2 production activity

BackgroundHydrogen plays an important role in developing an environment-friendly, low-emission, and sustainable energy system. Carbon fiber (CF) cloth is a useful porous and conductive substrate. Loading appropriate semiconductor nanomaterials on CF cloth is an effective method to fabricate flexible and high-performance photocatalysts. MethodsCarbon fiber (CF) cloth@BiOBr/CuO were synthesized as immobilized membrane-shaped photocatalysts by the growth of BiOBr using successive ionic layer adsorption and reaction (SILAR), followed by calcination and forming the CuO cocatalyst. Significant findingsThe loading of optimized amounts of BiOBr (three immersion cycles in the SILAR process) and the CuO shell leads to enhanced H2 production activity. The CF cloth@BiOBr/CuO photocatalyst (S3BOB3C) is a flexible, membrane-shaped, and immobilized photocatalyst with high activity (1863 μmol h−1g−1), which is 4.4 times active when compared to the CF cloth@BiOBr photocatalyst (S1BOB) (423 μmol h−1g−1). The p-n heterojunctions in BiOBr/CuO composites with type-II band alignment can improve photocatalytic H2 production performance.