T. Rajagopala Rao

Bio: T. Rajagopala Rao is an academic researcher from Indian Institute of Technology Patna. The author has contributed to research in topics: Potential energy surface & Ground state. The author has an hindex of 7, co-authored 16 publications receiving 192 citations. Previous affiliations of T. Rajagopala Rao include University of Burgundy & University of Hyderabad.

A Low-Cost Non-explosive Synthesis of Graphene Oxide for Scalable Applications.

Abstract: A low cost, non-explosive process for the synthesis of graphene oxide (GO) is demonstrated. Using suitable choice of reaction parameters including temperature and time, this recipe does not require expensive membranes for filtration of carbonaceous and metallic residues. A pre-cooling protocol is introduced to control the explosive nature of the highly exothermic reactions during the oxidation process. This alleviates the requirement for expensive membranes and completely eliminates the explosive nature of intermediate reaction steps when compared to existing methods. High quality of the synthesized GO is corroborated using a host of characterization techniques including X-ray diffraction, optical spectroscopy, X-ray photoemission spectroscopy and current-voltage characteristics. Simple reduction protocol using ultra-violet light is demonstrated for potential application in the area of photovoltaics. Using different reduction protocols together with the proposed inexpensive method, reduced GO samples with tunable conductance over a wide range of values is demonstrated. Density functional theory is employed to understand the structure of GO. We anticipate that this scalable approach will catalyze large scale applications of GO.

Quantum dynamics of 16O + 36O2 and 18O + 32O2 exchange reactions

Abstract: We present quantum dynamical investigations of 16O + 36O2 and 18O + 32O2 exchange reactions using a time-independent quantum mechanical method and an accurate global potential energy surface of ozone [Dawes et al., J. Chem. Phys. 135, 081102 (2011)]. Initial state-selected integral cross sections, rate constants, and Boltzmann averaged thermal rate constants are obtained and compared with earlier experimental and theoretical results. The computed thermal rate constants for the oxygen exchange reactions exhibit a negative temperature dependence, as found experimentally. They are in better agreement with the experiments than the previous studies on the same reactions.

Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state.

Abstract: Quantum state-selected dynamics of C(3P) + OH (X2Π) → CO(a3Π) + H (2S) reaction on its first excited electronic potential energy surface (12A″) is examined here using a time-dependent wave packet propagation approach. All partial wave contributions for the total angular momentum, J = 0−95, are included to obtain the converged cross sections and initial state-selected rate constants in the temperature range of 10−500 K. The reaction probability, as a function of collision energy, exhibits dense oscillatory structures owing to the formation of resonances during collision. These resonance structures also persist in reaction cross sections. The effect of reagent rotational and vibrational excitation on the dynamical attributes is examined and discussed. Reagent rotational excitation decreases the reactivity whereas, vibrational excitation of the reagent has minor effects on the reactivity. The results presented here are in good accord with those obtained using the time-independent quantum mechanical and quasi-classical trajectory methods.

Harvesting graphene oxide – years 1859 to 2019: a review of its structure, synthesis, properties and exfoliation

Abstract: In recent years, multilayered graphite oxide and graphene oxide (GO) have attracted considerable attention in fields such as physics, chemistry, biology and materials sciences in general, because they are important building blocks and promising routes towards the large-scale production of graphene, the “wonder material”. This review provides an exhaustive survey of the synthetic methods developed during the last 160 years for the preparation of GO and focuses especially on the work done more recently. The numerous state-of-the-art synthetic methods (>50) are reviewed and regrouped under eight (8) major categories: those which use oxidative (i) chemical, (ii) electrochemical and (iii) microbial exfoliation methods for graphite, for (iv) 3D-carbon structures and for (v) 2D-graphene. Other routes such as (vi) chemical vapor deposition (CVD) methods for hydrocarbon, (vii) hydrothermal methods for carbohydrate and finally, (viii) thermal decomposition methods for organic matter rich in carbon are also covered. Emphasis is placed on the molecular structure of graphene oxide, synthetic methods, impurities, properties, mechanistic insights, reagents, different carbon precursors, its purification, the exfoliation process and finally, its fractionation by size. This review will be a valuable guide (>200 references) for synthetic and materials scientists/engineers in the field of graphene oxide production.

Freestanding Borophene and Its Hybrids.

Abstract: Borophene, an elemental metallic Dirac material is predicted to have unprecedented mechanical and electronic character. Need of substrate and ultrahigh vacuum conditions for deposition of borophene restricts its large-scale applications and significantly hampers the advancement of research on borophene. Herein, a facile and large-scale synthesis of freestanding atomic sheets of borophene through a novel liquid-phase exfoliation and the reduction of borophene oxide is demonstrated. Electron microscopy confirms the presence of β12 , X3 , and their intermediate phases of borophene; X-ray photoelectron spectroscopy, and scanning tunneling microscopy, corroborated with density functional theory band structure calculations, validate the phase purity and the metallic nature. Borophene with excellent anchoring capabilities is used for sensing of light, gas, molecules, and strain. Hybrids of borophene as well as that of reduced borophene oxide with other 2D materials are synthesized, and the predicted superior performance in energy storage is explored. The specific capacity of borophene oxide is observed to be ≈4941 mAh g-1 , which significantly exceeds that of existing 2D materials and their hybrids. These freestanding borophene materials and their hybrids will create a huge breakthrough in the field of 2D materials and could help to develop future generations of devices and emerging applications.

Borophene: New Sensation in Flatland.

Abstract: Borophene, a 2D allotrope of boron and the lightest elemental Dirac material, is the latest very promising 2D material owing to its unique structural and electronic characteristics of the X3 and β12 phases. The high atomic density on ridgelines of the β12 phase of borophene provides a substantial orbital overlap, which leads to an excellent electron density in the conduction level and thus to a highly metallic behavior. These unique structural characteristics and electronic properties of borophene attract significant scientific interest. Herein, approaches for crystal growth/synthesis of these unique nanostructures and their potential technological applications are discussed. Various substrate-supported ultrahigh-vacuum growth techniques for borophene, such as molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition, along with their challenges, are also summarized. The sonochemical exfoliation and modified Hummer's technique for the synthesis of free-standing borophene are also discussed. Solution-phase exfoliation seems to address the scalability issues and expands the applications of these unique materials to various fields, including renewable energy devices and ultrafast sensors. Furthermore, the electronic, optical, thermal, and elastic properties of borophene are thoroughly discussed and are compared with those of graphene and its "cousins." Numerous frontline applications are envisaged and an outlook is presented.