@article { ISI:000284238000010, title = {Fabrication of homogeneous nanoparticle/nanoneedle BaTiO3 and Ba0.8Sr0.2TiO3 smooth thin films by simple dip coating}, journal = {International Journal of Nanotechnology}, volume = {7}, number = {9-12, SI}, year = {2010}, month = {DEC}, pages = {919-931}, publisher = {INDERSCIENCE ENTERPRISES LTD}, address = {WORLD TRADE CENTER BLDG, 29 ROUTE DE PRE-BOIS, CASE POSTALE 896, CH-1215 GENEVA, SWITZERLAND}, abstract = {

Ferroelectric BaTiO3 (BTO) and Ba0.8Sr0.2TiO3 (BSTO) thin film materials have been successfully prepared by sol-gel processing and simple dip coating on glass and silicon supports. Above thin films were characterised by x-ray diffraction (XRD), Raman spectroscopy, photoelectron spectroscopy, thermal analysis, atomic force microscopy (AFM) and spectroscopic ellipsometry. Phase identification of BaTiO3 and Ba0.8Sr0.2TiO3 was performed by XRD. XRD and Raman spectroscopy investigations demonstrate that thc Ba0.8Sr0.2TiO3 film exhibits tetragonal structure. AFM analysis demonstrates the elongated nanospherical particles on glass substrate and nanowires on silicon substrate, which represent a strong influence of the crystallinity of underlying substrate on the grain morphology in this technique. The thin films on both the substrates are uniformly coated without any pinhole to significant area (similar to 2.5 cm(2)), and this method might be extended to large area uniform coating. Spectroscopic ellipsometric measurements reveal the exact thickness, refractive index and extinction coefficient of the thin films.

}, keywords = {barium strontium titanate, barium titanate, dip coating, fabrication, ferroelectric material, large area coating, nanotechnology, thin film}, issn = {1475-7435}, author = {Saini, Mamta and Vivekanand, K. and Poddar, Pankaj and Murty, K. V. G. K. and Thushara, K. S. and Gopinath, Chinnakonda S.} } @article {48077, title = {Facile, sustainable and unassisted plain water oxidation on Au/Ce0.9Ti0.1O2 nanorods in direct sunlight}, journal = {Journal of Chemical Sciences}, volume = {134}, year = {2022}, month = {JUN}, pages = {61}, type = {Article}, abstract = {

Impressive rate of solar water oxidation to molecular oxygen (O-2) has been demonstrated on nanorods (NRs) of Ce0.9Ti0.1O2 (CT-NR) and Au-deposited CT-NR (Au-CT-NR) photocatalysts with a sacrificial agent (Fe3+) and in plain water in one sun condition, direct sunlight and with lambda \>= 455 nm. Probably the highest 0 2 yield of 11 mmol/h.g was observed with Au-CT-NR thin film in plain water in direct sunlight, with no sacrificial agent or applied potential. Photoelectrochemical measurements demonstrate a marked reduction in oxidation onset potential of Au-CT-NR by 150 mV with stable photocurrent (0.75 mA/cm(2)), compared to CT-NR (0.23 mA/cm(2)), indicating the operative of plasmon-induced resonant energy transfer (PIRET) process. Effective electron quenching by nanogold and hence low recombination in the depletion region is a critical step for the observation of a high rate of oxygen evolution. In addition to this, a predominant change in the nature of the valence band from O-2p dominated on CeO2 to Ce-4f dominated with CT-NR (due to Ti4+ introduction in CeO2), the efficient light absorption of photocatalysts in thin-film form, functional and effective PIRET process, and facile E-F alignment, enhances the oxygen evolution with Au-CT-NR in direct sunlight and make it highly sustainable. A possible mechanism of water oxidation is proposed from the observed experimental findings.

}, keywords = {ceria, Electronic integration, Photocatalysis, thin film, water splitting}, issn = {0974-3626}, doi = {10.1007/s12039-022-02055-z}, author = {Dubey, Anjani and Mishra, Abhaya Kumar and Negi, Sanjay Singh and Gopinath, Chinnakonda S.} } @article {48980, title = {Facile one-pot synthesis of Cu x O/TiO2 photocatalysts by regulating Cu oxidation state for efficient solar H2 production}, journal = {ACS Applied Energy Materials }, volume = {7}, year = {2023}, month = {DEC }, pages = {104-116}, type = {Article}, abstract = {

Development of highly efficient CuxO/TiO2 photocatalysts by regulating the oxidation state of Cu exclusively in either single or mixed oxidation state(s) is desirable but difficult to achieve without employing any external reagents. The present work describes a one-pot synthesis strategy to obtain CuxO/TiO2 photocatalysts with Cu in +1 and/or +2 by using a suitable combination of ethylene diamine tetra acetic acid (EDTA) and ethylene diamine, carefully varying the Cu content, and heat treatment process. CuxO/TiO2 nanocomposite catalysts were characterized thoroughly by physicochemical methods. Textural analysis indicates a high dispersion of CuxO on porous TiO2 with p-n heterojunctions between them in CuxO/TiO2 catalysts. UV-visible spectral analysis suggests the presence of CuxO on TiO2 with significantly extended absorption from the UV to the visible region. X-ray photoelectron spectroscopy (XPS) analysis indicates a strong synergetic interaction between TiO2 and CuxO due to the comparable CB potential and p-n heterojunction at the interface among them. Photoelectrochemical studies demonstrate excellent charge-carrier separation efficiency, low charge-transfer resistance, and high double-layer capacitance with Cu2O/TiO2 photocatalysts. Photocatalytic efficacy of a CuxO/TiO2 nanocomposite in thin-film form has been demonstrated for solar hydrogen generation in sunlight. The incorporation of Cu+ in TiO2 largely improves the H-2 production, and all of the CuxO/TiO2 nanocomposites in thin-film form exhibited higher efficiency compared to their particulate/suspension counterpart. Among the composite catalysts, TiCu-1 in thin-film form, with Cu exclusively in +1 oxidation state, exhibited a high hydrogen production rate of 7.06 mmol/hg, which is 6 times higher than its suspension counterpart; also catalysts containing mixed Cu-oxidation states exhibited about 60-70\% activity as that of TiCu-1. The superior performance of Cu2O/TiO2 nanocomposites in thin-film form was due to their enhanced light harvesting ability, high mass transfer rate, and easy accessibility of the reactant species to the active sites.

}, keywords = {heterojunction, Photocatalysis, Solar hydrogen, thin film, titania}, issn = {2574-0962}, doi = {10.1021/acsaem.3c02272}, author = {Rajendran, Sivaraj and Mani, Sunesh S. and Nivedhitha, Thazhath R. and Asoka, Anantha Krishnan and Arun, Pushkaran S. and Mathew, Thomas and Gopinath, Chinnakonda S.} } @article {49554, title = {Multiphasic heterojunctions: a strategic approach to enhance the charge transfer dynamics of titania for superior solar photocatalytic hydrogen production}, journal = {International Journal of Hydrogen Energy}, volume = {113}, year = {2025}, month = {MAR}, pages = {133-146}, type = {Article}, abstract = {

Multiphasic titania has been prepared to study the role of multiple heterojunctions on the charge transfer dynamics and resultant photocatalytic hydrogen production. Through an acid regulated hydrothermal method, four materials with following phase compositions were prepared viz. single phase anatase and rutile, biphasic anatase-rutile and triphasic anatase-brookite-rutile. The phase compositions of the materials were confirmed through XRD and HRTEM studies. The biphasic and triphasic materials were found to be highly nanoparticulate in nature while forming numerous and diverse heterojunctions. In the triphasic material, various binary and ternary heterojunctions were observed. These heterojunctions performed in harmony to ensure efficient charge transport as shown by the low charge transfer resistance and high electron lifetime. This subsequently ensured a high reduction capability and photocurrent response. This all culminated into the triphasic material outperforming all other materials in solar photocatalytic hydrogen production. The H2 yield from the triphasic material was 81\% and 40\% higher than the pristine anatase and the biphasic material respectively. Additionally, by using the triphasic material in thin film form, a 4-fold increase in the hydrogen yield with a high apparent quantum efficiency of 8.2 \% was achieved over the particulate form. The superior charge transport and photocurrent response due to the greater varied heterojunction formation in the anatase-rutile-brookite material as opposed to that in the biphasic material led to this superior performance. Thus, multiple heterojunctions, in this case, a triphasic heterojunction of anatase, rutile and brookite phases opens up a new avenue of research for efficient green hydrogen production.

}, keywords = {Green hydrogen production, heterojunction, Photocatalysis, Photoelectrochemical analysis, thin film, titania}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.02.395}, author = {Ningthoukhongjam, Pujita and Gopinath, Chinnakonda S. and Nair, Ranjith G.} }