Somnath C. Roy

Bio: Somnath C. Roy is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Materials science & Thin film. The author has an hindex of 30, co-authored 143 publications receiving 3992 citations. Previous affiliations of Somnath C. Roy include Instituto Superior Técnico & Indian Institute of Technology Kharagpur.

Novel ammonia-sensing phenomena in sol–gel derived Ba0.5Sr0.5TiO3 thin films

Abstract: In this paper, ammonia-sensing behavior of barium strontium titanate (BST) thin films have been reported for the first time. Thin films of BST deposited by sol–gel spin coating technique have been found to show an increase in resistance when exposed to ammonia gas. The sensitivity variation was from 20 to 60%, with lowest detection limit of about 160 ppm. The films were prepared with different pre-sintering temperatures and thickness and effect of these parameters on the ammonia-sensing have been studied. The optimum temperature for operation was found to be close to 270 °C. The ammonia-sensing studies were also performed for other gases like ethanol, NO 2 and CO; but the sensitivity in these cases was negligibly smaller than that in case of ammonia.

Enhanced photoelectrochemical performance of multi-leg TiO2 nanotubes through efficient light harvesting

Abstract: Multi-leg TiO2 nanotubes have been synthesised by electrochemical anodisation of Ti foils with suitable optimisation of the electrolyte (containing NH4F and HF) composition and concentration. As a result, multi-leg nanotube morphology shows a 4-fold enhancement in photocurrent density compared with that of compact tubes of comparable length under UV-VIS (320–500 nm) light illumination. We attribute this enhancement in photocurrent to efficient light scattering within the multi-leg morphology and the availability of a large contact area with the electrolyte compared to that of compact nanotubes. A model has been presented for light trapping and scattering ability on the basis of the graded refractive index behaviour associated with multi-leg nanotubes. Such graded refractive index behaviour is found to reduce specular reflectance, leading to a greater scattering of light into the nanotube structure. The diffused reflectance spectra confirm higher scattering in the multi-leg nanotube arrays, which indicates greater light harvesting by the multi-leg nanotube arrays.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Nano‐photocatalytic Materials: Possibilities and Challenges

Abstract: Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

Photocatalytic reduction of CO2 on TiO2 and other semiconductors.

Abstract: Rising atmospheric levels of carbon dioxide and the depletion of fossil fuel reserves raise serious concerns about the ensuing effects on the global climate and future energy supply. Utilizing the abundant solar energy to convert CO2 into fuels such as methane or methanol could address both problems simultaneously as well as provide a convenient means of energy storage. In this Review, current approaches for the heterogeneous photocatalytic reduction of CO2 on TiO2 and other metal oxide, oxynitride, sulfide, and phosphide semiconductors are presented. Research in this field is focused primarily on the development of novel nanostructured photocatalytic materials and on the investigation of the mechanism of the process, from light absorption through charge separation and transport to CO2 reduction pathways. The measures used to quantify the efficiency of the process are also discussed in detail.

An overview of current status of carbon dioxide capture and storage technologies

Abstract: Global warming and climate change concerns have triggered global efforts to reduce the concentration of atmospheric carbon dioxide (CO2). Carbon dioxide capture and storage (CCS) is considered a crucial strategy for meeting CO2 emission reduction targets. In this paper, various aspects of CCS are reviewed and discussed including the state of the art technologies for CO2 capture, separation, transport, storage, leakage, monitoring, and life cycle analysis. The selection of specific CO2 capture technology heavily depends on the type of CO2 generating plant and fuel used. Among those CO2 separation processes, absorption is the most mature and commonly adopted due to its higher efficiency and lower cost. Pipeline is considered to be the most viable solution for large volume of CO2 transport. Among those geological formations for CO2 storage, enhanced oil recovery is mature and has been practiced for many years but its economical viability for anthropogenic sources needs to be demonstrated. There are growing interests in CO2 storage in saline aquifers due to their enormous potential storage capacity and several projects are in the pipeline for demonstration of its viability. There are multiple hurdles to CCS deployment including the absence of a clear business case for CCS investment and the absence of robust economic incentives to support the additional high capital and operating costs of the whole CCS process.