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.

Effect of swift heavy ion irradiation on structure, optical, and gas sensing properties of SnO2 thin films

Abstract: Swift heavy ion irradiation has been successfully used to modify the structural, optical, and gas sensing properties of SnO 2 thin films. The SnO 2 thin films prepared by sol–gel process were irradiated with 75 MeV Ni + beam at fluences ranging from 1 × 10 11 ion/cm 2 to 3 × 10 13 ion/cm 2 . Structural characterization with glancing angle X-ray diffraction shows an enhancement of crystallinity and systematic change of stress in the SnO 2 lattice up to a threshold value of 1 × 10 13 ions/cm 2 , but decrease in crystallinity at highest fluence of 3 × 10 13 ions/cm 2 . Microstructure investigation of the irradiated films by transmission electron microscopy supports the XRD observations. Optical properties studied by absorption and PL spectroscopies reveal a red shift of the band gap from 3.75 eV to 3.1 eV, and a broad yellow luminescence, respectively, with increase in ion fluence. Gas response of the irradiated SnO 2 films shows increase of resistance on exposure to ammonia (NH 3 ), indicating p-type conductivity resulting from ion irradiation.

p-Type gas-sensing behaviour of undoped SnO2 thin films irradiated with a high-energy ion beam

Abstract: We report novel p-type behaviour of undoped SnO 2 thin films irradiated with a 75 MeV Ni + ion beam. Gas response of the irradiated films to NH 3 (reducing) and NO 2 (oxidizing) gases shows an increase and decrease in resistance, respectively, indicating p-type conduction that also increases with an increase in ion fluence. Photoluminescence spectroscopy of the irradiated films shows a strong yellow peak corresponding to interstitial oxygen ions. The observed p-type conductivity is attributed to the holes generated by these interstitial oxygen ions. The presence of interstitial oxygen ions is also confirmed by X-ray photoelectron spectroscopy. The conduction activation energy decreases with increasing the ion fluence, indicating an increase in hole density that supports the gas sensing and photoluminescence results.

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.