A5084596534- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Perovskite Materials and Applications
- Advanced Photocatalysis Techniques
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Mass Spectrometry Techniques and Applications
- Electrohydrodynamics and Fluid Dynamics
- MXene and MAX Phase Materials
- Catalytic Processes in Materials Science
- Spectroscopy and Quantum Chemical Studies
- Molecular Junctions and Nanostructures
- Transition Metal Oxide Nanomaterials
- Semiconductor materials and interfaces
- Semiconductor materials and devices
- Conducting polymers and applications
- Advanced Chemical Physics Studies
- Electrocatalysts for Energy Conversion
- Analytical chemistry methods development
- Solid-state spectroscopy and crystallography
- Copper-based nanomaterials and applications
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Gas Sensing Nanomaterials and Sensors
- Graphene research and applications
Worcester Polytechnic Institute
2015-2024
African Institute of Science and Technology
2021
Moi University
2021
Worcester State University
2021
Bioengineering Center
2019-2020
University of Worcester
2017-2020
California Institute of Technology
2002-2019
University of Illinois Urbana-Champaign
2011
University of California, Irvine
2008-2010
Hebrew University of Jerusalem
2010
There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but current lead-free PSCs are still plagued with critical issues of low efficiency and poor stability. This is primarily due their inadequate photovoltaic properties chemical Herein we demonstrate use lead-free, all-inorganic cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) solid-solution as light absorber in PSCs, delivering promising up 7.11%. More importantly, these show very...
Framework nitrogen atoms of carbon nitride (C3N4) can coordinate with and activate metal sites for catalysis. In this study, C3N4 was employed to harvest visible light Co2+ sites, without the use additional ligands, in photochemical CO2 reduction. Photocatalysts containing single on were prepared by a simple deposition method demonstrated excellent activity product selectivity toward CO formation. A turnover number more than 200 obtained production using synthesized photocatalyst under...
We recently reported that strong electric fields may be employed to directly extract positive and negative ions for mass analysis, including intact proteins, from neutral droplets. The present study investigates the dynamics of this process using switched high enable time-resolved studies droplet distortion, Taylor cone formation, charged progeny extraction 225 μm methanol After a specific time in field, flashlamp is triggered record distortions shadow photography. At critical field strength...
Abstract Photoactive perovskite semiconductors are highly tunable, with numerous inorganic and organic cations readily incorporated to modify optoelectronic properties. However, despite the importance of device reliability long service lifetimes, effects various on mechanical properties perovskites largely overlooked. In this study, cohesion energy containing cation combinations methylammonium, formamidinium, cesium, butylammonium, 5‐aminovaleric acid is reported. A trade‐off observed...
Thin (10 nm) films of manganese oxide have been deposited by atomic layer deposition (ALD) onto n-type silicon and degenerately doped p-type silicon. The photoelectrochemical properties the resulting semiconductor/metal-oxide structures were evaluated in contact with aqueous 0.35 M K4Fe(CN)6–0.05 K3Fe(CN)6, 1.0 KOH(aq), as well a series nonaqueous one-electron, reversible, outer-sphere redox systems. Under simulated air mass (AM) 1.5 illumination K3Fe(CN)6(aq), MnO-coated n-Si photoanodes...
Solar water splitting in acidic solutions has important technological implications, but not been demonstrated to date a dual absorber photoelectrochemical cell. The lack of functionally stable water-oxidation catalysts (WOCs) acids is key reason for this slow development. only WOCs that are at low pH Ir-based systems, which typically too expensive be implemented broadly. It now shown deficiency may corrected by applying an ultra-thin monolayer molecular Ir WOC hematite solar solutions....
Tin-based halide perovskite solar cells (PSCs) hold the most promise among lead-free PSCs, but they are plagued with inadequate environmental stability and power-conversion efficiency (PCE). Here we demonstrate that optimum incorporation of a bulky divalent organic cation, 4-(aminomethyl)piperidinium (4AMP), in FASnI3 thin films improves stability, optoelectronic properties, PSC performance. The optimized yields maximum PCE 10.9% good 500-h operational under continuous illumination. This is...
Dispersed atomic catalysts can achieve high catalytic efficiency and have the potential to enable chemical transformation of inert molecules like CO2. The effect surface defects on photocatalytic reduction CO2 using supported single atom however requires clarification. Using density functional theory experimental techniques, we investigated role oxygen vacancies (Ov) photoexcited electrons Cu reduction. Adsorption was strong TiO2 surface, charges atoms were highly dependent whether present....
We investigate the Rayleigh discharge and evaporation dynamics of highly charged two-component droplets consisting principally methanol with 2-methoxyethanol, tert-butanol, or m-nitrobenzyl alcohol. A phase Doppler anemometer (PDA) characterizes generated by electrospray ionization (ESI) according to size, velocity, charge as they move through a uniform electric field within an ion mobility spectrometer (IMS). Repeated reversals result in droplet "ping-pong" PDA. This generates individual...
P-Type cuprous oxide (Cu2O) photoelectrodes prepared by the thermal oxidation of Cu foils exhibited open-circuit voltages in excess 800 mV nonaqueous regenerative photoelectrochemical cells. In contact with decamethylcobaltocene+/0 (Me10CoCp2+/0) redox couple, yielded voltage, Voc, values 820 and short-circuit current density, Jsc, 3.1 mA cm−2 under simulated air mass 1.5 illumination. The energy-conversion efficiency 1.5% was limited solution absorption optical reflection losses that...
Abstract Significant optical absorption in the blue–green spectral range, high intralayer carrier mobility, and band alignment suitable for water splitting suggest tin disulfide (SnS 2 ) as a candidate material photo‐electrochemical applications. In this work, vertically aligned SnS nanoflakes are synthesized directly on transparent conductive substrates using scalable close space sublimation (CSS) method. Detailed characterization by time‐resolved terahertz photoluminescence spectroscopies...
We recently demonstrated scalable, one-pot syntheses of one-dimensional, titania lepidocrocite microfilaments by reacting Ti-containing water-insoluble, earth-abundant compounds such as TiC, TiB2, TiN, etc., with tetraalkylammonium hydroxide, TMAOH, for a few days at 85 °C under ambient pressure. The resulting one-dimensional (1DL) titania-based nanofilaments, NFs, tend to self-align along the [100] growth direction form that sometimes into pseudo-two-dimensional (2D) sheets. With...
The photoelectrochemical behavior of methyl-terminated p-type and n-type Si(111) surfaces was determined in contact with a series one-electron, outer-sphere, redox couples that span >1 V the Nernstian potential, E(A/A–), solution. dependence current vs potential data, as well open-circuit photovoltage, Voc, on E(A/A–) compared to H-terminated these same electrolytes. For particular value, CH3-terminated p-Si(111) electrodes showed lower Voc values than electrodes, whereas n-Si(111) higher...
A neutral droplet elongates along the axis of a strong electric field, ejecting opposing jets positively and negatively charged progeny droplets. Images droplets from vibrating orifice aerosol generator illustrate this phenomenon, mass spectrometric sampling demonstrates that they are viable source desolvated gas-phase ions. Field-induced ionization (FIDI) spectra presented for several species, including tetraheptylammonium cation, deprotonated benzene tetracarboxylic acid anion, multiply...
A combination of experiments and molecular dynamic (MD) simulations has been applied to elucidate the nature water on organic self-assembled monolayers (SAMs) before after oxidation. SAMs mimic organics adsorbed environmental urban surfaces. Water clean or SAM-coated borosilicate glass surfaces was measured at equilibrium as a function relative humidity (RH), using transmission Fourier transform infrared (FTIR) spectroscopy 1 atm 22 +/- degrees C. The included C18 C8 alkanes, well terminal...
Several complementary experimental and theoretical methodologies were used to explore water uptake on sodium chloride (NaCl) particles containing varying amounts of dodecyl sulfate (SDS) elucidate the interaction with well-defined, environmentally relevant surfaces. Experiments probed hygroscopic growth mixed SDS/NaCl nanoparticles that generated by electrospraying aqueous 2 g/L solutions SDS NaCl relative NaCl/SDS weight fractions 0, 5, 11, 23, or 50 wt/wt %. Particles mobility-equivalent...
Metal oxides with moderate band gaps are desired for efficient production of hydrogen from sunlight and water via photoelectrochemical (PEC) splitting. Here, we report an α-SnWO4 photoanode synthesized by hydrothermal conversion WO3 films that achieves photon to current at wavelengths up 700 nm (1.78 eV). This is promising overall PEC water-splitting because the flat-band potential voltage photocurrent onset more negative than evolution. Furthermore, utilizes a large portion solar spectrum....
The recently developed technique of field-induced droplet ionization (FIDI) is applied to study interfacial chemistry a single droplet. In new variation the FIDI method, 1-2-mm-diameter droplets hang from capillary and undergo heterogeneous reactions between solution-phase analytes gas-phase species. Following specified reaction time, application high electric field induces in droplet, generating fine jets highly charged progeny that are characterized by mass spectrometry. Sampling over...
ZSM-5 zeolite degrades the crystal surface framework and internal acid sites, dependent on unique thermophysical nature of water solvent.
Recent reports post conflicting results on the atmospheric stability of Cs2TiBr6, a nontoxic, Earth-abundant solar energy conversion material. Here, high-temperature melt CsBr and TiBr4 yielded large-grain samples with >1 mm2 facets as verified by optical microscopy scanning electron (SEM). With pristine-material properties particular interest, we investigated series physicochemical surface treatments including rinsing, abrasion, cleaving in ultrahigh vacuum (UHV). For each treatment, X-ray...
We report studies of the evaporation and discharge dynamics highly charged droplets generated by electrospray ionization from n-heptane, n-octane, p-xylene doped with Stadis-450, a conductivity-enhancing agent. A phase Doppler anemometer (PDA) characterizes individual moving through uniform electric field within an ion mobility cell according to size, velocity, charge. Repeated reversal allows multiple PDA measurements on selected diameters ranging 3 60 microm up 10(7) elementary positive...