bluuebunny/crossref_metadata_2025_split huggingface dataset:
BiVO4 Photoelectrodes for Use in Solar Water Splitting
Authors: Choi Kyoung-Shin 
Published: February 2020

Many recent efforts have focused on the development of n-type semiconductors that can serve as efficient photoanodes for solar water oxidation. Desirable photoanodes should have a small bandgap to utilize a significant portion of visible light, and a valence band (VB) edge that is positive enough to provide sufficient overpotential for the water oxidation reaction. The position of the conduction band (CB) edge or the flatband potential of the photoanode is also important because it determines the potential of the photoexcited electrons that will be used for the cathode reaction (i.e., water reduction). If these electrons do not have sufficient overpotential to reduce water, an external bias needs to be provided, effectively reducing the cell efficiency. Bismuth vanadate (BiVO4) has recently emerged as a promising material for use as a photoanode in water splitting photoelectrochemical cells. It is because it absorbs a substantial portion of the visible spectrum (bandgap energy, ca. 2.4 eV) and has a favorable conduction band (CB) edge position very near the thermodynamic H2 evolution potential. Significant advancement in the understanding and construction of efficient BiVO4-based photoanode systems has been made within a short period of time owing to various newly developed ideas and approaches. In this presentation, we will discuss our recent efforts in improving the photoelectrochemical properties of BiVO4 photoanodes, which include an enhancement in photon absorption and charge transport properties. These efforts resulted in an applied bias photon-to-current efficiency (ABPE) for water splitting higher than 2% using all oxide-based electrodes.
Catalyst Modified Ternary Oxide Photoanodes for Photoelectrochemical Water Splitting
Authors: Pilli Satyananda Kishore , Furtak Thomas E. , Chidambaram Dev , Deutsch Todd G , Turner John A , Herring Andrew M 
Published: February 2020

Recently, BiVO4 with moderate band gap of 2.4-2.6 eV and conduction band edge at 0 V vs. NHE at pH 0, has emerged as a promising water oxidation photoanode. However, water oxidation activity of BiVO4 is relatively low compared to the theoretical efficiency that could be achieved with this material. Poor charge carrier separation characteristics, relatively low electron transport properties and slow charge transfer at electrode-electrolyte interface are attributed to the poor performance characteristics of BiVO4 photoelectrode. However, recent advances in the material science and the development of efficient water oxidation electrocatalysts have assisted to design BiVO4 photoelectrodes with enhanced efficiencies. For this instance, various strategic approaches that were intended towards the enhancement of charge carrier separation, light absorption and charge injection characteristics of BiVO4 photoelectrodes and recent studies on application of these modified BiVO4 electrodes for solar energy conversion are presented in this talk.
Photoelectrochemical Ion Pumping with Dye-Functionalized Polymer Membranes
Authors: Sanborn Christopher D. , Ardo Shane 
Published: February 2020

Artificial photosynthesis could be a cost-effective and sustainable means of converting sunlight energy into usable energy. Most artificial photosynthetic systems mimic nature’s properties of light absorption, electronic charge separation, and electronic charge collection, where ultimately electrons make and break chemical bonds. However, nature also transduces photon energy into proton gradients whose electric potential also drives chemical-bond formation. In my presentation I will report on my research group’s progress toward mimicking nature in function, by using light to drive endergonic proton transfer, ultimately converting photon energy into ionic current. The applicability and practicality of this material as a membrane in solar fuels devices and as a separate ionic photoelectrochemical device will also be discussed.
My research group’s near-term goal is to provide a proof-of-concept demonstration of an artificial proton pump where light-driven ion transport results in photovoltaic action. For an initial model system we utilized a conical nanopore etched in a polyethylene terephthalate plastic sheet. This pore was formed via swift heavy ion bombardment followed by alkaline chemical etching which resulted in a pore lined with fixed anionic functional groups. Then, using peptide coupling chemistries, the pore was asymmetrically functionalized with novel photoacids to generate a region containing fixed cationic dyes. This ordered distribution of interfacial charge was intended to mimic a solid-state semiconductor pn-junction and be used to separate photogenerated charges. We demonstrated that under visible-light illumination and a small reverse bias, excitation of the photoacid molecules resulted in an ionic photocurrent. We are currently expanding this initial research and successful demonstration of an artificial light-driven ion pump to other polymeric materials with hopes of generating ionic power through sunlight absorption and incorporating these materials as ion-exchange membranes in solar fuels devices.
Using Protection Layers for a 2-Photon Water Splitting Device
Authors: Seger Brian , Mei Bastian Timo , Frydendal Rasmus , Permyakova Anastatia , Bae Dowon , Pedersen Thomas , Castelli Ivano , Malacrida Paolo , Vesborg Peter C. K. , Stephens Ifan E. L. , Hansen Ole , Jacobsen Karsten , Chorkendorff Ib 
Published: February 2020

The 2-photon tandem device for photocatalytic water splitting has been theoretically shown to provide a higher efficiency than a single photon device(1). This increased efficiency can be achieved by having one material optimized to absorb high energy photons (large bandgap) and another material optimized to absorb low energy photons (small bandgap).
To a large degree this approach has been hindered by corrosion issues. In this talk I will first discuss how our computational screening of 2,400 materials showed that very few materials can efficiently absorb light without corroding in water splitting conditions.(2) I will follow this up by discussing how protection layers bypass the corrosion issue by creating a buffer layer.(3) Finally I will show how we integrated a photocatalyst/protection layer/(co-catalyst) scheme to produce highly efficient H2 evolution photocathodes and O2 evolution photoanodes.(3, 4)

1. A. B. Laursen, S. Kegnaes, S. Dahl and I. Chorkendorff, Energy & Environmental Science, 5 (2012).

2. B. Seger, I. E. Castelli, P. C. K. Vesborg, K. W. Jacobsen, O. Hansen and I. Chorkendorff, Energy & Environmental Science, 7, 2397 (2014).

3. B. Seger, T. Pedersen, A. B. Laursen, P. C. K. Vesborg, O. Hansen and I. Chorkendorff, Journal of the American Chemical Society, 135, 1057 (2013).

4. B. Mei, A. A. Permyakova, R. Frydendal, D. Bae, T. Pedersen, P. Malacrida, O. Hansen, I. E. L. Stephens, P. C. K. Vesborg, B. Seger and I. Chorkendorff, The Journal of Physical Chemistry Letters, 5, 3456 (2014).

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Stable Solar-Driven Water Oxidation to O2(g) By Multifunctional Electrocatalysts Coated Small Band Gap Semiconductors
Authors: Sun Ke , Lewis Nathan S. 
Published: February 2020

Technologically important small band gap (<2 eV) semiconductors must be stabilized against corrosion or passivation in aqueous electrolytes before they can be used as photoelectrodes that directly produce fuels from sunlight. In addition, incorporation of electrocatalysts on the surface of the photoelectrodes is required for efficient oxidation of H2O to O2(g) and reduction of H2O or H2O and CO2 to fuels. Stabilization of technologically important semiconductors against photocorrosion and photopassivation would have a significant impact on photoelectrochemical energy conversion, and could enable the development of a new generation of robust integrated devices for efficient solar-driven water splitting and solar-driven CO2 reduction. Previous efforts have been extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction conditions especially during the water oxidation half reaction. To date, the energy conversion performances and stability were limited on these systems, obscuring the realization of integrated solar fuel devices. In this work, we presented our recent effort on preparation of a multifunctional coating using Ni oxide, which provides multiple important functions on semiconductor photoelectrodes surfaces, including chemical/corrosion protection, electrically conducting, optical transparent/antireflective, and inherent electrocatalytic activity. The combination of the extraordinary film properties has resulted benchmark performances and stability on Si photoanodes, as well as other group II-VI and group III-V semiconductors that have never been able to be protected in relevant water oxidation conditions before. Results presented here indicated a viable strategy that is a promising approach to achieve the long-term stability of semiconducting photoanodes for use in solar fuel applications.
New Photocatalyst for the Generation of Environmentally Friendly Fuel Using Visible Solar Spectrum
Authors: Akter Tahmina , Saupe Geoffrey B. 
Published: February 2020

Wide band gap semiconductor photocatalysts, such as titanium dioxide, along with a metal co-catalyst have been used to generate hydrogen fuel from water. However, ultraviolet light is required, which limits their utility in solar energy conversion. Modification of these types of semiconductors can sensitize them to visible light, providing a promising way to create clean, renewable hydrogen fuel. Many photocatalysts suffer from poor hydrogen production efficiencies under visible light, due to inadequate visible light absorption. In this research, co-precipitating [Ru(bpy)3]2+ sensitizer dye molecules into nanosheet agglomerates provides a new way to modify porous oxide (POX) photocatalysts. A series of dye-sensitized POX materials have been synthesized from KTiNbO5, KNb3O8 and K4Nb6O17. These materials were characterized by XRD, TEM, SEM and EDS and water photolysis.
Novel Hybrid 1-D Structure of PEDOT/TiO2 Nanotubes As the Pt-Free Catalyst of Counter Electrodes in Dye-Sensitized Solar Cells
Authors: Chen WeiChieh , Yeh Min-Hsin , Peng Jia-De , Lin Lu-Yin , Ho KuoChuan 
Published: February 2020

Due to its outstanding electrocatalytic ability and reliable stability under severe circumstances, Pt is one of promising catalysts in electrochemical applications. However, cost issue and delicate process is inevitable for this kind of precious metals. How to provide a dependable material is an interesting issue. Hence, in this study, novel one-dimensional (1-D) hybrid structure of poly(3,4-ethylenedioxythiophene) (PEDOT) supported with TiO2 nanotubes (PEDOT/TNTs) were successfully synthesized and further applied as catalysts of counter electrodes (CEs) for dye–sensitized solar cells (DSSCs). PEDOT/TNTs were formed with electropolymerization of 3,4-ethylenedioxythiophene onto TiO2 nanotubes (TNTs) by the pulse current process, in which TNTs were obtained by anodization of Ti foils. After optimizing the sintering temperature of TNTs and electropolymerizing charge density of PEDOT, a high solar–to–electricity conversion efficiency (η) of 8.82% is achieved for a DSSC containing the CE of PEDOT/TNTs, with the optimized sintering temperature of 400 oC for TNTs and electropolymerizing charge density of 400 mC/cm2 for PEDOT deposited onto TNTs (PEDOT/TNTs-400 mC/cm2); a η is higher than those of the cells with the CEs of flat PEDOT (6.50%) and Pt (8.24%). Cyclic voltammetry (CV), symmetric electrochemical impedance spectra (s–EIS) and Tafel polarization plots reveal that the highest h of the cell with PEDOT/TNTs is due to the higher electrocatalytic ability of the CE for the reduction of triiodide ions (I3
–) and lower charge transfer resistance (R
ct) at the interface between the CE and the electrolyte. Incident photon–to–current conversion efficiency (IPCE) spectra are used to substantiate the explanations on the photovoltaic parameters of the cells.
The Relationship Between Segmental Motions, Hydration and Overall Mass Transport in Pfsas
Authors: Zawodzinski Thomas A. , Elgammal Ramez A. , Bai Yujia 
Published: February 2020

A great many membranes have been studied for use in fuel cells and other electrochemical devices. Prominent amongst these are the perfluorosulfonic acids, including Nafion as an archetype and materials prepared by Dow (later others) and 3M presented over time. Generally, similar mass transport (conductivity and water transport) phenomena have been observed, with high transport rates closely tied to high levels of hydration. However, maintaining high hydration of the membrane by maintaining an environment of high relative humidity requires system level measures that represent parasitic losses.
Achieving high conductivity with less hydration requires more substantial understanding and then control of the transport mechanisms involved at low water content. There are clear differences in the behavior of materials at low and high hydration, with a line of demarcation at hydration levels of ca. 5 or 6 waters per sulfonate. Above this level, the water in the membrane is more continuous across multiple pores and protons move in an environment that increasing resembles that in aqueous solutions as hydration levels increase. Below this level, such factors as the acidity of the sulfonic acid, the mobility of water within the first or second hydration spheres of the sulfonate and proton and possibly sidechain movements in the polymer all have been suggested to play roles in the transport processes.
In this contribution, we will explore various processes in the low water content regime. For a series of PFSAs, we will gather experimental information to reveal the approximate rate of side chain motion, use vibrational spectroscopy and related methods to provide an in-depth view into the hydration of ions and water interactions in the membrane and present information on the energetics of hydration. These will be synthesized into an experimentally supported picture allowing us to assess the relative importance of the motions of anions, cations and water molecules in determining transport in PFSAs at RH < 50% under different conditions.
Hybrid Polymer Electrolytes Based on Linear Siloxane Networks and Crosslinked Polyether Domains: Interplay Between Composition and Properties
Authors: Boaretto Nicola , Brinkmann Christine , Vezzù Keti , Di Noto Vito , Lorrmann Henning 
Published: February 2020

In this study, a new class of hybrid polymer electrolytes was prepared and characterized. The materials consisted of a matrix based on linear oligosiloxane networks and partially crosslinked polyether domains, doped with Lithium bis(trifluorosulfonyl)imide (LiTFSI). These materials are characterized by a maximum conductivity of 8∙10-5 S/cm at 30 °C, and high thermo-mechanical stability, with decomposition temperature of 250 °C and a storage shear modulus of almost 105 Pa at 100 °C. Compositional parameters such as salt, cross-linker concentration, and polyether chain length were varied, and the materials were characterized by several analytical techniques. Vibrational spectroscopy provided details of the hybrid structure and the effect of salt doping. The thermo-mechanical properties were studied by thermogravimetric analysis, differential scanning calorimetry and rheological analysis. Finally, the transport properties were analyzed by means of broadband electric spectroscopy. The study made it possible to describe the relationships between composition, morphology, thermo-mechanical and transport properties of the synthesized hybrid electrolytes, with particular emphasis on the interplay between polymer dynamics and conduction mechanism.

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Development of Electrochemical and Optical Based Biosensors
Authors: Gupta Vinay , Kaur Gurpreet , Paliwal Ayushi , Tak Manvi , Sharma Anjali , Tomar Monika 
Published: February 2020

During recent years, rapid and highly selective determination of nucleic acid (in particularly, DNA) has gained much importance in the field of disease diagnostics, gene analysis, tissue matching, forensic and environmental protection. Various techniques have been employed for DNA detection like fluorescence, surface plasmon resonance (SPR), quartz crystal microbalance (QCM), piezoelectric, electroluminiscene, and electro-chemical. Among all these techniques, electro chemical and SPR based biosensors for nucleic acid detection have attracted researchers worldwide due to their high sensitivity, low detection limit, fast response time, wide detection range, good reliability, easy handling and portability. DNA based biosensors rely on the immobilization of a single-stranded oligonucleotide probe onto a surface to recognize by hybridization its complementary target sequence. The probes are typically short oligonucleotides that are capable of hybridizing with specific and unique regions of the target nucleotide sequence. Due to formation of double helical structure between complementary strands, a change in current or SPR angle could be easily observed.
In the present study, an effort has been made towards the development of ZnO matrix based biosensors for the detection of Meningitidis using electrochemical (Amperometric) and SPR techniques. The surface plasmon modes have been excited at the ZnO-gold interface in the Kretschmann configuration using a right angled BK7 glass prism (np =1.517) with the help of a laboratory assembled system. The shift in SPR reflectance curve for increasing concentration of target DNA ranging from 10 to180 ng/μl were recorded which shows the promising application of SPR technique towards biosensing. The Sensitivity of the ZnO thin film using SPR is found to be about 0.031°/(ng/μl) with the minimum detection limit of 5 ng/μl.
Zinc oxide nanostructures possessing flower-like morphology have been synthesized onto platinized silicon substrate by simple and economical hydrothermal method. The electrochemical sensing response behaviour of the DNA bioelectrode (ssth-DNA/ ZNF/Pt/Si) has been studied by both differential pulse voltammetric (DPV) as well as impedimetric techniques. The fabricated DNA biosensor can quantify wide range of the complementary targets sth-DNA in the range 5–240 ng/μl with good linearity (R=0.98), high sensitivity (168.64μAng/μl/cm2) and low detection limit of about 5ng/μl.
Facile Hydrothermal Synthesis of in2O3 Nanoboxes for Electrochemical Sensing of Paraben
Authors: Rather Jahangir Ahmad , Qureshi Ahsanulhaq 
Published: February 2020

Novel indium oxide (In2O3) nanoboxes have been prepared by template-less and surfactant-free hydrothermal synthesis. Synthesized In2O3 nanoboxes were characterized by X-ray diffraction (XRD) and field emission scanning electronic microscopy (FESEM). FESEM micrographs revealed highly uniform nanoboxes with smooth surfaces and XRD analysis confirmed that these In2O3 nanoboxes grown with a cubic crystal structure. The synthesized In2O3 nanoboxes were successfully immobilized on the surface of glassy carbon electrode for the detection of Parabens (butylparaben). Owing to the unique structure and intriguing properties of these In2O3 nanoboxes, the film electrode has shown an obvious electrocatalytic activity for the detection of butylparaben (BP), since it facilitates the electron transfer and significantly enhances the oxidation peak current and lowering of the detection limit of BP. The calibration plot of concentration versus peak current was found to be linear over the range of 0.14 µM to 2.4 µM. The detection limit (LOD) was estimated as 3s/m and was found to be 0.08 µM. This sensor showed high sensitivity compared with other electrochemical sensors reported so far for the detection of BP.

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Nano-Asterisks of Vanadium Dioxide As Electrodes for TNT Detection
Authors: Cliffel David , Casey Matthew , Daniel Aaron 
Published: February 2020

Vanadium dioxide (VO2) is a unique transition metal oxide that undergoes a first-order phase transition at approximately 340K from the insulating monoclinic phase (M) to the conducting rutile phase (R). This metal-to-insulator transition (MIT) results in a change in the resistivity and optical absorption of the material, which has made it useful in several electronic and electro-optic applications. Common synthetic techniques such as pulsed laser deposition (PLD), chemical vapor deposition (CVD), and magnetron sputtering allow for the synthesis of high quality films of VO2 for these applications. Recently, however, hydrothermal methods have been used for the synthesis of relatively large quantities of VO2(M) from inexpensive starting materials without the need for expensive instrumentation. While these hydrothermally synthesized VO2(M) particles are being developed for electronic and electro-optic applications, their applicability in other areas, such as catalysis and sensing, is the focus of research in our group.
To make nano-asterisks of VO2, the amount of vanadium precursor present during a hydrothermal treatment was varied to produce several different morphologies of VO2(M) including plates, snowflake asterisks, and truncated asterisks. Films of the particles were drop cast onto glass slides and four-point Van der Pauw resistivity measurements were used to determine the phase transition behavior of the particle films. We observe resistivity changes of more than 2 orders of magnitude for drop cast films of VO2(M) nano-asterisks. Additionally, BET gas adsorption theory was used to determine the surface area of the particles in order to evaluate their potential as electrocatalytic materials.
The electrochemical reduction of 2, 4, 6-Trinitrotoluene (TNT) was investigated using films of vanadium dioxide, from both thin layer films formed by PLD and films composed of nano-asterisks particles. Three distinct reduction peaks were observed in the potential range -0.50 V to -0.90 V (vs. an Ag/AgCl reference electrode), corresponding to the electrochemical reduction of the three nitro-groups on the TNT molecule. Adsorptive stripping voltammetry was performed to achieve detection down to 1 µg/L (4.4 nM), revealing a linear response to TNT concentration. These results are the first describing the use of VO2 films as an electrochemical sensor for TNT, and open new avenues for further electrochemical research using this unique material.