Ashish Yengantiwar | University of Alabama - Tuscaloosa (original) (raw)
Papers by Ashish Yengantiwar
Materials Science and Engineering: B
2020 IEEE PES Transactive Energy Systems Conference (TESC), 2020
An increased share of distributed renewable energy sources requires flexible tools for providing ... more An increased share of distributed renewable energy sources requires flexible tools for providing reliable and cheap electricity. Smart meters provide information at the consumer level, which could be used as the main source for real-time energy micro-transactions, however, one of the main concerns about direct transactions is information security. Conventional electricity markets rely on centralized information exchange, nevertheless, when intra-day, distributed, electricity consumption and production exchanges are required between customers, this approach might not be enough. This paper presents a proof-of-concept for using Blockchain as a tool for managing the operational transactions in a DC microgrid. The distributed nature of this technology provides an inherently safer approach, by providing an immutable database for transaction history. One of the challenges of using this technology, however, is the required computing power at the nodes and the limited capacity available in the smart meter. To overcome these issues, the authors used a distributed computing technology, -edge computing-, where computation and storage are located closer to the customer, to improve response times by handling the required computational tasks of the Blockchain tool. This approach proved not only to be practically viable but also, offers important insights about the scalability and capabilities of the technology.
Materials Science and Engineering: B
ECS Journal of Solid State Science and Technology, 2022
In the present study, we designed and fabricated cost-effective miniaturized versatile electroche... more In the present study, we designed and fabricated cost-effective miniaturized versatile electrochemical deposition cell, which is found to be at par performance as compared with conventional electrodeposition techniques. A case study is being undertaken for the electrodeposition of varied thickness of bismuth ferrite (BiFeO3) films on FTO glass substrates. X-ray diffraction (XRD) patterns confirms the structural perovskite phase of BiFeO3 (BFO). UV-Visible absorption spectra and Tauc plot of BFO estimates the direct band gap which lies between 1.9 to 2.1 eV. The properties of bismuth ferrite crystal system such as electronic band structure and density of states (DOS) are investigated theoretically. Photoelectrochemical (PEC) water splitting application is carried out to investigate the best performance of BFO films of varied thickness. The best performer (BFO15) working electrode yields a photocurrent density of ~ 35 µA/cm2 at 0.2 V vs RHE under visible LED (light intensity of 100mW/...
Materials Today: Proceedings
Nanoscale, 2011
Cu(2)O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing amb... more Cu(2)O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing ambient annealing protocol. ZnO nanorods are grown on ITO coated glass by a low temperature chemical route. The electronic and photo-response properties of the p-Cu(2)O/n-ZnO flip-chip heterojunction are then studied and analyzed. We show that the I-V characteristic is rectifying and the junction exhibits a good photoresponse (∼120% under 1 V reverse bias) under AM 1.5 (1 Sun) illumination. This nano-heterojunction photo-response is far stronger as compared to that of a pulsed laser deposited thin film p-Cu(2)O/n-ZnO heterojunction, which can be attributed to higher junction area in the former case.
Energy & Environmental Science, 2011
In this work we report on the synthesis of various ZnO mesostructures (rods, spheres, flakes and ... more In this work we report on the synthesis of various ZnO mesostructures (rods, spheres, flakes and flower-like morphologies) by hydrothermal and co-precipitation methods and their remarkable and complete transformation into anatase TiO 2 mesostructures with nominally similar shapes using controlled low temperature TiCl 4 treatment. Various techniques are used to demonstrate the phase purity and morphology details. Based on the careful examination of the transformation of ZnO rods into TiO 2 tubes we suggest a mechanism which embodies initial formation of a thin TiO 2 shell on the ZnO surface by ion exchange (Ti 4+-Zn 2+) followed by Zn diffusion through the shell and its oxidation on the surface. We used these converted TiO 2 mesostructures for light harvesting in Dye Sensitized Solar Cells (DSSCs) to enhance the conversion efficiency. It is shown that DSSCs made using a doctor bladed film of TiO 2 nanoparticles with an overlayer of TiCl 4 treated ZnO flowers yield a solar cell efficiency of 6.9% which is considerably higher than that with only TiO 2 nanoparticle film (5.4%) of comparable thickness.
Current Applied Physics, 2011
... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwa... more ... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwar*1, Ramakant Sharma1, Onkar Game2 and Arun Banpurkar3 1Department of Physics, Fergusson College, Pune (India) 2Physical and Materials Chemistry ... [9] CS Rout, SH Krishna ...
Ultraviolet (UV) photosensitive device was fabricated using ZnO nanorod array on substrate with c... more Ultraviolet (UV) photosensitive device was fabricated using ZnO nanorod array on substrate with copper electrodes. Facile open aqueous solution deposition technique was used to grow the ZnO nanorods forming an electrical bridge between copper electrodes. Powder X-ray diffraction patterns was used to confirm the polycrystalline wurtzite ZnO phase and scanning electron microscopy (SEM) techniques was employed to characterize the growth morphology of ZnO nanorods. A current-voltage (I-V) characterization in the dark exhibits the back-to-back diode characteristics. In the presence of ultraviolet (UV) radiation, enhanced photo-response was reported wherein photocurrent increases by two orders of magnitude at 2 V bias. This enhancement is mainly due to lateral interfacial contacts between neighboring grain-boundary of the nanorods arrays.
ADVANCES IN BASIC SCIENCE (ICABS 2019), 2019
Journal of Mountain Research
Ultraviolet (UV) photosensitive device is fabricated using ZnO nanorods array on commercially ava... more Ultraviolet (UV) photosensitive device is fabricated using ZnO nanorods array on commercially available printed circuit board (PCB). Facile open aqueous solution deposition (OASD) method is used to deposit ZnO nanorods array in a trenched region between closely spaced Cu-electrodes. X-ray diffraction (XRD) patterns confirm the wurtzite phase of ZnO nanorods arrays and scanning electron microscopy (SEM) characterizes the multidimensional growth of ZnO nanorods across the trenched part of PCB. The current-voltage (I-V) characteristics of the device in dark is analogous to the back-to-back diode behaviour. However, the device exhibits an excellent photoresponsivity wherein the photocurrent value increases by two orders of magnitude at 2 V bias under the illumination ultraviolet (UV wavelength ~ 254 nm) light source. The enhancement in photocurrent is mainly due to formation of multiple contacts between neighbouring grain-boundaries of the nanorods arrays extending to the Cu-electrode...
Journal of The Electrochemical Society
The Journal of Physical Chemistry C, 2017
Small, 2013
For the last few decades plasmonic noble metal nanoparticles (NPs) have been used in the semicond... more For the last few decades plasmonic noble metal nanoparticles (NPs) have been used in the semiconductor-based phocatalytic water splitting processes as effi ciency boosters. In most of these works it is claimed that the effi ciency enhancement is due to the charge transfer from the semiconductor to the metal. However it is only recently that more focus is being put on developing an understanding of the precise nature of the contribution(s) of such metal NPs in the observed enhancements of photocatalytic or photoelectrochemical (PEC) performance of different materials. [ 3 , 4 ] Thus far most of the work regarding plasmonic enhancement of PEC water splitting has been reported on TiO 2 -Au systems and in most such cases Au nanoparticles have been deposited on the surface of TiO 2 fi lm or TiO 2 nanoparticles. It has been shown that for particle size less than 50 nm (above this the scattering effect is predominant), gold can act as a sensitizer to TiO 2 by absorbing in the visible region of solar spectrum due to localized surface plasmons (LSP) and transferring hot electrons to the conduction band of TiO 2 . This is mainly possible because of the tendency of the gold nanoparticles to undergo charging and causing negative shift of the Fermi level of TiO 2 to achieve Fermi level equilibration. However, it has also been noticed that although there is plasmonic enhancement in the visible region in the TiO 2 -Au photoelectrode, the performance in the near-UV region gets deteriorated. This is due to the lower photon fl ux reaching to TiO 2 and less area of TiO 2 exposed to the electrolyte. Therefore, the overall enhancement for the entire solar spectrum is compromised. In line with this, most of the other semiconductor photocatalysts such as Fe 2 O 3,
Journal of Materials Chemistry, 2012
Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu 2 O) nanoneedles to form ... more Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu 2 O) nanoneedles to form a Cu 2 O/ZnO hetero-nanobrush assembly. This increases the overall aspect ratio, which helps to enhance the field emission properties of the system. Also, the charge separation and transport are facilitated because of the multiple p-n junctions formed at p-Cu 2 O/n-ZnO interfaces and quasi-1-D structures of both the materials, respectively. This helps to significantly enhance the photocatalytic properties. As compared to only Cu 2 O nanoneedles, the Cu 2 O/ZnO hetero-nanobrush shows excellent improvement in both field emission and photocatalytic applications.
Energy & Environmental Science, 2011
... Subas Muduli, Onkar Game, Vivek Dhas, Ashish Yengantiwar and Satishchandra B. Ogale*. Physica... more ... Subas Muduli, Onkar Game, Vivek Dhas, Ashish Yengantiwar and Satishchandra B. Ogale*. Physical and Materials Chemistry Division, National Chemical Laboratory (NCL), Council of Scientific & Industrial ... 6, K. Saravanan, K. Ananthanarayanan and P. Balaya, Energy Environ. ...
Current Applied Physics, 2011
... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwa... more ... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwar*1, Ramakant Sharma1, Onkar Game2 and Arun Banpurkar3 1Department of Physics, Fergusson College, Pune (India) 2Physical and Materials Chemistry ... [9] CS Rout, SH Krishna ...
Advanced Materials, 2012
A heterostructure formed by a layer of agarose gel drop-cast on a hydrothermally grown layer of Z... more A heterostructure formed by a layer of agarose gel drop-cast on a hydrothermally grown layer of ZnO nanorods on fluorine-doped tin oxide (FTO)-coated glass is examined for photoresponse with a top platinum tip contact. This ionic-gel-based hybrid device shows three orders of magnitude higher photocurrent as compared to the case of bare ZnO nanorods film.
Advanced Materials, 2012
ABSTRACT The image depicts a novel device architecture composed of ZnO nanorods with surface-disp... more ABSTRACT The image depicts a novel device architecture composed of ZnO nanorods with surface-dispensed agarose-gel as a quasiliquid iontronic-electronic light-harvesting hybrid photodetector. On page 3686, S. Ogale and co-workers show that this configuration exhibits a three orders of magnitude stronger photoresponse and a shorter response time as compared to the bare ZnO nanorod-based device. Moreover, this response has an extended tail in the visible region.
Materials Science and Engineering: B
2020 IEEE PES Transactive Energy Systems Conference (TESC), 2020
An increased share of distributed renewable energy sources requires flexible tools for providing ... more An increased share of distributed renewable energy sources requires flexible tools for providing reliable and cheap electricity. Smart meters provide information at the consumer level, which could be used as the main source for real-time energy micro-transactions, however, one of the main concerns about direct transactions is information security. Conventional electricity markets rely on centralized information exchange, nevertheless, when intra-day, distributed, electricity consumption and production exchanges are required between customers, this approach might not be enough. This paper presents a proof-of-concept for using Blockchain as a tool for managing the operational transactions in a DC microgrid. The distributed nature of this technology provides an inherently safer approach, by providing an immutable database for transaction history. One of the challenges of using this technology, however, is the required computing power at the nodes and the limited capacity available in the smart meter. To overcome these issues, the authors used a distributed computing technology, -edge computing-, where computation and storage are located closer to the customer, to improve response times by handling the required computational tasks of the Blockchain tool. This approach proved not only to be practically viable but also, offers important insights about the scalability and capabilities of the technology.
Materials Science and Engineering: B
ECS Journal of Solid State Science and Technology, 2022
In the present study, we designed and fabricated cost-effective miniaturized versatile electroche... more In the present study, we designed and fabricated cost-effective miniaturized versatile electrochemical deposition cell, which is found to be at par performance as compared with conventional electrodeposition techniques. A case study is being undertaken for the electrodeposition of varied thickness of bismuth ferrite (BiFeO3) films on FTO glass substrates. X-ray diffraction (XRD) patterns confirms the structural perovskite phase of BiFeO3 (BFO). UV-Visible absorption spectra and Tauc plot of BFO estimates the direct band gap which lies between 1.9 to 2.1 eV. The properties of bismuth ferrite crystal system such as electronic band structure and density of states (DOS) are investigated theoretically. Photoelectrochemical (PEC) water splitting application is carried out to investigate the best performance of BFO films of varied thickness. The best performer (BFO15) working electrode yields a photocurrent density of ~ 35 µA/cm2 at 0.2 V vs RHE under visible LED (light intensity of 100mW/...
Materials Today: Proceedings
Nanoscale, 2011
Cu(2)O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing amb... more Cu(2)O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing ambient annealing protocol. ZnO nanorods are grown on ITO coated glass by a low temperature chemical route. The electronic and photo-response properties of the p-Cu(2)O/n-ZnO flip-chip heterojunction are then studied and analyzed. We show that the I-V characteristic is rectifying and the junction exhibits a good photoresponse (∼120% under 1 V reverse bias) under AM 1.5 (1 Sun) illumination. This nano-heterojunction photo-response is far stronger as compared to that of a pulsed laser deposited thin film p-Cu(2)O/n-ZnO heterojunction, which can be attributed to higher junction area in the former case.
Energy & Environmental Science, 2011
In this work we report on the synthesis of various ZnO mesostructures (rods, spheres, flakes and ... more In this work we report on the synthesis of various ZnO mesostructures (rods, spheres, flakes and flower-like morphologies) by hydrothermal and co-precipitation methods and their remarkable and complete transformation into anatase TiO 2 mesostructures with nominally similar shapes using controlled low temperature TiCl 4 treatment. Various techniques are used to demonstrate the phase purity and morphology details. Based on the careful examination of the transformation of ZnO rods into TiO 2 tubes we suggest a mechanism which embodies initial formation of a thin TiO 2 shell on the ZnO surface by ion exchange (Ti 4+-Zn 2+) followed by Zn diffusion through the shell and its oxidation on the surface. We used these converted TiO 2 mesostructures for light harvesting in Dye Sensitized Solar Cells (DSSCs) to enhance the conversion efficiency. It is shown that DSSCs made using a doctor bladed film of TiO 2 nanoparticles with an overlayer of TiCl 4 treated ZnO flowers yield a solar cell efficiency of 6.9% which is considerably higher than that with only TiO 2 nanoparticle film (5.4%) of comparable thickness.
Current Applied Physics, 2011
... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwa... more ... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwar*1, Ramakant Sharma1, Onkar Game2 and Arun Banpurkar3 1Department of Physics, Fergusson College, Pune (India) 2Physical and Materials Chemistry ... [9] CS Rout, SH Krishna ...
Ultraviolet (UV) photosensitive device was fabricated using ZnO nanorod array on substrate with c... more Ultraviolet (UV) photosensitive device was fabricated using ZnO nanorod array on substrate with copper electrodes. Facile open aqueous solution deposition technique was used to grow the ZnO nanorods forming an electrical bridge between copper electrodes. Powder X-ray diffraction patterns was used to confirm the polycrystalline wurtzite ZnO phase and scanning electron microscopy (SEM) techniques was employed to characterize the growth morphology of ZnO nanorods. A current-voltage (I-V) characterization in the dark exhibits the back-to-back diode characteristics. In the presence of ultraviolet (UV) radiation, enhanced photo-response was reported wherein photocurrent increases by two orders of magnitude at 2 V bias. This enhancement is mainly due to lateral interfacial contacts between neighboring grain-boundary of the nanorods arrays.
ADVANCES IN BASIC SCIENCE (ICABS 2019), 2019
Journal of Mountain Research
Ultraviolet (UV) photosensitive device is fabricated using ZnO nanorods array on commercially ava... more Ultraviolet (UV) photosensitive device is fabricated using ZnO nanorods array on commercially available printed circuit board (PCB). Facile open aqueous solution deposition (OASD) method is used to deposit ZnO nanorods array in a trenched region between closely spaced Cu-electrodes. X-ray diffraction (XRD) patterns confirm the wurtzite phase of ZnO nanorods arrays and scanning electron microscopy (SEM) characterizes the multidimensional growth of ZnO nanorods across the trenched part of PCB. The current-voltage (I-V) characteristics of the device in dark is analogous to the back-to-back diode behaviour. However, the device exhibits an excellent photoresponsivity wherein the photocurrent value increases by two orders of magnitude at 2 V bias under the illumination ultraviolet (UV wavelength ~ 254 nm) light source. The enhancement in photocurrent is mainly due to formation of multiple contacts between neighbouring grain-boundaries of the nanorods arrays extending to the Cu-electrode...
Journal of The Electrochemical Society
The Journal of Physical Chemistry C, 2017
Small, 2013
For the last few decades plasmonic noble metal nanoparticles (NPs) have been used in the semicond... more For the last few decades plasmonic noble metal nanoparticles (NPs) have been used in the semiconductor-based phocatalytic water splitting processes as effi ciency boosters. In most of these works it is claimed that the effi ciency enhancement is due to the charge transfer from the semiconductor to the metal. However it is only recently that more focus is being put on developing an understanding of the precise nature of the contribution(s) of such metal NPs in the observed enhancements of photocatalytic or photoelectrochemical (PEC) performance of different materials. [ 3 , 4 ] Thus far most of the work regarding plasmonic enhancement of PEC water splitting has been reported on TiO 2 -Au systems and in most such cases Au nanoparticles have been deposited on the surface of TiO 2 fi lm or TiO 2 nanoparticles. It has been shown that for particle size less than 50 nm (above this the scattering effect is predominant), gold can act as a sensitizer to TiO 2 by absorbing in the visible region of solar spectrum due to localized surface plasmons (LSP) and transferring hot electrons to the conduction band of TiO 2 . This is mainly possible because of the tendency of the gold nanoparticles to undergo charging and causing negative shift of the Fermi level of TiO 2 to achieve Fermi level equilibration. However, it has also been noticed that although there is plasmonic enhancement in the visible region in the TiO 2 -Au photoelectrode, the performance in the near-UV region gets deteriorated. This is due to the lower photon fl ux reaching to TiO 2 and less area of TiO 2 exposed to the electrolyte. Therefore, the overall enhancement for the entire solar spectrum is compromised. In line with this, most of the other semiconductor photocatalysts such as Fe 2 O 3,
Journal of Materials Chemistry, 2012
Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu 2 O) nanoneedles to form ... more Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu 2 O) nanoneedles to form a Cu 2 O/ZnO hetero-nanobrush assembly. This increases the overall aspect ratio, which helps to enhance the field emission properties of the system. Also, the charge separation and transport are facilitated because of the multiple p-n junctions formed at p-Cu 2 O/n-ZnO interfaces and quasi-1-D structures of both the materials, respectively. This helps to significantly enhance the photocatalytic properties. As compared to only Cu 2 O nanoneedles, the Cu 2 O/ZnO hetero-nanobrush shows excellent improvement in both field emission and photocatalytic applications.
Energy & Environmental Science, 2011
... Subas Muduli, Onkar Game, Vivek Dhas, Ashish Yengantiwar and Satishchandra B. Ogale*. Physica... more ... Subas Muduli, Onkar Game, Vivek Dhas, Ashish Yengantiwar and Satishchandra B. Ogale*. Physical and Materials Chemistry Division, National Chemical Laboratory (NCL), Council of Scientific & Industrial ... 6, K. Saravanan, K. Ananthanarayanan and P. Balaya, Energy Environ. ...
Current Applied Physics, 2011
... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwa... more ... 1 Growth of aligned ZnO nanorods array on ITO for dye sensitized solar cell Ashish Yengantiwar*1, Ramakant Sharma1, Onkar Game2 and Arun Banpurkar3 1Department of Physics, Fergusson College, Pune (India) 2Physical and Materials Chemistry ... [9] CS Rout, SH Krishna ...
Advanced Materials, 2012
A heterostructure formed by a layer of agarose gel drop-cast on a hydrothermally grown layer of Z... more A heterostructure formed by a layer of agarose gel drop-cast on a hydrothermally grown layer of ZnO nanorods on fluorine-doped tin oxide (FTO)-coated glass is examined for photoresponse with a top platinum tip contact. This ionic-gel-based hybrid device shows three orders of magnitude higher photocurrent as compared to the case of bare ZnO nanorods film.
Advanced Materials, 2012
ABSTRACT The image depicts a novel device architecture composed of ZnO nanorods with surface-disp... more ABSTRACT The image depicts a novel device architecture composed of ZnO nanorods with surface-dispensed agarose-gel as a quasiliquid iontronic-electronic light-harvesting hybrid photodetector. On page 3686, S. Ogale and co-workers show that this configuration exhibits a three orders of magnitude stronger photoresponse and a shorter response time as compared to the bare ZnO nanorod-based device. Moreover, this response has an extended tail in the visible region.