Debabrata Sarkar

Bio: Debabrata Sarkar is an academic researcher from SRM University. The author has contributed to research in topics: Thin film & Photocatalysis. The author has an hindex of 15, co-authored 28 publications receiving 758 citations. Previous affiliations of Debabrata Sarkar include Hebrew University of Jerusalem & Jadavpur University.

Three dimensional Ag2O/TiO2 type-II (p-n) nanoheterojunctions for superior photocatalytic activity.

Abstract: Type-II p–n junction three-dimensional Ag2O/TiO2 microspheres have been fabricated by assembling p-type Ag2O nanoparticle on n-type TiO2 3D microsphere. Ag2O/TiO2 microsphere nanoheterojunctions were obtained by hydrothermal synthesis of TiO2 microspheres at 180 °C followed by photoreduction of AgNO3. The samples were carefully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The photocatalytic activity toward degradation of methyl orange (MO) aqueous solution under UV light was investigated. The result showed that type-II p–n nanoheterojunctions Ag2O/TiO2 significantly enhanced the photocatalytic degradation compared to n-type TiO2 microsphere. It was found that the photocatalytic degradation followed the pseudo first-order reaction model. In particular, heterostructure with molar ratio of TiO2 and AgNO3 of 4:1 exhibited best photocatalytic activity and the corresponding appar...

Morphology control of rutile TiO2 hierarchical architectures and their excellent field emission properties

Abstract: Titanium dioxide nanoarchitectures with well-defined morphologies have been successfully synthesized by a hydrothermal process at temperature 180 °C for 4 h using titanium butoxide, oleic acid and hydrochloric acid as precursor materials. Different hierarchical morphologies such as cauliflower, 3D microsphere, densely-packed nanorod array, step edge faceted nanorod, branched structures of the rutile TiO2 nanostructures could be easily controlled by varying the volume fraction of the added hydrochloric acid. The structural, photoluminescence and field emission properties of the as-prepared nanoarchitectures were investigated. Among the different morphologies, dense nanorod arrays and multilevel branched architectures showed good field emission properties. Morphology, surface-related defects and oxygen vacancies were found to be the major responsible factors for the observed variations of field emission properties. Compared to any previously reported TiO2 based field emitter, lower turn-on field at 2.76 V μm−1 and higher field-enhancement factors 7.44 × 103 were observed for the hierarchically dense TiO2 nanorods array. Therefore, these nanoarchitectures can be used in vacuum microelectronic applications.

Improved dielectric constant and breakdown strength of γ-phase dominant super toughened polyvinylidene fluoride/TiO2 nanocomposite film: an excellent material for energy storage applications and piezoelectric throughput.

Abstract: Titanium dioxide (TiO2) nanoparticles (NPs) embedded I³-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m-1). It also exhibits a high energy density of 4 J cm-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.

Oxygen-Deficient Titania with Adjustable Band Positions and Defects; Molecular Layer Deposition of Hybrid Organic–Inorganic Thin Films as Precursors for Enhanced Photocatalysis

Abstract: Molecular layer deposition (MLD) of TiCl4 and ethylene-glycol (Ti-EG) was recently demonstrated as a vapor phase synthetic route for preparation of photocatalytic thin films via hybrid organic–inorganic thin films. The organic moieties of the hybrid material function as sacrificial components that undergo controlled decomposition during thermal annealing. Anneal temperature was shown to be an important factor determining the overall photocatalytic performances of the treated films with 650 °C optimal for photodegradation of dye molecules and anneal at 520 °C showing optimal performance for the direct photocatalytic production of H2O2. Both systems exhibit activities that are not typically attainable by titania, yet a fundamental understanding of the underlying details leading to these improved reactivities for the specific cases is still lacking. Here we demonstrate that thermal anneal of hybrid organic–inorganic thin films prepared by MLD yield oxygen-deficient titania with controllable levels of oxygen ...

Branch density-controlled synthesis of hierarchical TiO2 nanobelt and tunable three-step electron transfer for enhanced photocatalytic property.

Abstract: The successful adjustment of phase composition and morphology of hierarchical TiO2 nanobelts, which feature homoepitaxial nanobranches, has been developed via the hydrothermal method and chemical bath deposition technique. Effects of hydrothermal reaction time, titanium butoxide treatment in chemical bath deposition, and calcination temperature are systematically investigated. For the first time, three-step ultrafast electron transfers between the band edges of the engaged phases are realized through the enhanced photocatalytic activity results. Growth mechanism related to branch density control on nanobelt surface under such soft chemical process is discussed in detail on the basis of classical nucleation theory. The current work might provide new insights into the fabrication of one-dimensional homoepitaxial branched TiO2 nanostructures as high performance photocatalysts and facilitate their application in environmental cleanup.

Visible light driven type II heterostructures and their enhanced photocatalysis properties: a review

Abstract: Considerable efforts have been devoted to enhancing the photocatalytic activity and solar energy utilization of photocatalysts. The fabrication of type II heterostructures plays an important role in photocatalysts modification and has been extensively studied. In this review, we briefly trace the application of type II heterostructured semiconductors in the area of environmental remediation and water splitting, summarize major fabrication methods, describe some of the progress and resulting achievements, and discuss the future prospects. The scope of this review covers a variety of type II heterostructures, focusing particularly on TiO2 and ZnO based visible light driven type II 0D and 1D heterostructured photocatalysts. Some other low dimensional nanomaterials which have shown high-performance photocatalysis are also presented. We expect this review to provide a guideline for readers to gain a clear picture of fabrication and application of type II heterostructures.

A review of one-dimensional TiO2 nanostructured materials for environmental and energy applications

Abstract: One-dimensional TiO2 (1D TiO2) nanomaterials with unique structural and functional properties have been extensively used in various fields including photocatalytic degradation of pollutants, photocatalytic CO2 reduction into energy fuels, water splitting, solar cells, supercapacitors and lithium-ion batteries. In the past few decades, 1D TiO2 nanostructured materials with a well-controlled size and morphology have been designed and synthesized. Compared to 0D and 2D nanostructures, more attention has been paid to 1D TiO2 nanostructures due to their high aspect ratio, large specific surface area, and excellent electronic or ionic charge transport properties. In this review, we present the crystal structure of TiO2 and the latest development on the fabrication of 1D TiO2 nanostructured materials. Besides, we will look into some critical engineering strategies that give rise to the excellent properties of 1D TiO2 nanostructures such as improved enlargement of the surface area, light absorption and efficient separation of electrons/holes that benefit their potential applications. Moreover, their corresponding environmental and energy applications are described and discussed. With the fast development of the current economy and technology, more and more effort will be put into endowing TiO2-based materials with advanced functionalities and other promising applications.

Dual Cocatalysts in TiO 2 Photocatalysis.

Abstract: Semiconductor photocatalysis is recognized as a promising strategy to simultaneously address energy needs and environmental pollution. Titanium dioxide (TiO2 ) has been investigated for such applications due to its low cost, nontoxicity, and high chemical stability. However, pristine TiO2 still suffers from low utilization of visible light and high photogenerated-charge-carrier recombination rate. Recently, TiO2 photocatalysts modified by dual cocatalysts with different functions have attracted much attention due to the extended light absorption, enhanced reactant adsorption, and promoted charge-carrier-separation efficiency granted by various cocatalysts. Recent progress on the component and structural design of dual cocatalysts in TiO2 photocatalysts is summarized. Depending on their components, dual cocatalysts decorated on TiO2 photocatalysts can be divided into the following categories: bimetallic cocatalysts, metal-metal oxide/sulfide cocatalysts, metal-graphene cocatalysts, and metal oxide/sulfide-graphene cocatalysts. Depending on their architecture, they can be categorized into randomly deposited binary cocatalysts, facet-dependent selective-deposition binary cocatalysts, and core-shell structural binary cocatalysts. Concluding perspectives on the challenges and opportunities for the further exploration of dual cocatalyst-modified TiO2 photocatalysts are presented.

State‐of‐the‐Art Progress in Diverse Heterostructured Photocatalysts toward Promoting Photocatalytic Performance

Abstract: Semiconductor photocatalysts have received much attention in recent years due to their great potentials for the development of renewable energy technologies, as well as for environmental protection and remediation. The effective harvesting of solar energy and suppression of charge carrier recombination are two key aspects in photocatalysis. The formation of heterostructured photocatalysts is a promising strategy to improve photocatalytic activity, which is superior to that of their single component photocatalysts. This Feature Article concisely summarizes and highlights the state-of-the-art progress of semiconductor/semiconductor heterostructured photocatalysts with diverse models, including type-I and type-II heterojunctions, Z-scheme system, p–n heterojunctions, and homojunction band alignments, which were explored for effective improvement of photocatalytic activity through increase of the visible-light absorption, promotion of separation, and transportation of the photoinduced charge carries, and enhancement of the photocatalytic stability.