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 …

I and i

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.

Nano‐photocatalytic Materials: Possibilities and Challenges

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.

Photocatalytic reduction of CO2 on TiO2 and other semiconductors.

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.

https://www.elsevier.com/__data/assets/pdf_file/0005/96980/Current-status-carbon-capture.pdf

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

A review on g-C3N4-based photocatalysts

We have experimentally demonstrated that slanted, kinked and straight silicon nanowire arrays form a broadband omnidirectional light‐harvesting structure. The unique design of kinked and slanted nanowires allows them to trap more light effectively across a wide wavelength range than straight silicon nanowires (SiNWs). We report that the light absorption in slanted, kinked and straight wires is enhanced by controlling their geometrical parameters. The p‐type SiNWs have less reflection than n‐type SiNWs due to their larger porosity gradient structure. Aperiodic and tapered slanted, kinked and straight SiNWs are remarkably photoactive and promising low‐cost materials for photoelectrochemical water splitting applications.

Improved omnidirectional polarisation‐insensitive optical absorption and photoelectrochemical water splitting using aperiodic and tapered slanted, kinked and straight silicon nanowires

An attempt is made in the present investigation to develop a computational model for the purpose of studying the effect of interstitial flow in the porous media on the distribution of drug eluted f

Computational model of stent-based delivery from a half-embedded two-layered coating.

Adsorption and degradation mechanism of 2,4,6-trinitrotoluene on TiO2 (110) surface

Highly efficient photoelectrochemical ZnO and TiO2 nanorod/Sb2S3 heterostructured photoanodes through one step thermolysis of Sb-MPA complex

Room temperature photoluminescence (PL) spectroscopy was done to investigate luminescent trap states in sol–gel deposited (Ba,Sr)TiO3 thin films. The pre-sintered films showed three distinct PL peaks. Increase in the peak intensity was observed with increase in pre-sintering temperature. These PL peaks were assigned to (a) singly charged oxygen vacancies (b) TiO2 networks and (c) the contribution from the substrate. In contrast, the sintered samples showed only a band-edge luminescence with an intense peak near the band-gap energy. Identification of such observed trap states are important in understanding the results of dielectric measurements because they contribute to the leakage currents and loss mechanisms.

Somnath C. Roy

Papers

Improved omnidirectional polarisation‐insensitive optical absorption and photoelectrochemical water splitting using aperiodic and tapered slanted, kinked and straight silicon nanowires

Computational model of stent-based delivery from a half-embedded two-layered coating.

Adsorption and degradation mechanism of 2,4,6-trinitrotoluene on TiO2 (110) surface

Highly efficient photoelectrochemical ZnO and TiO2 nanorod/Sb2S3 heterostructured photoanodes through one step thermolysis of Sb-MPA complex

Photoluminescence Study of the Sol–Gel Derived (Ba0.5Sr0.5) TiO3 Thin Films for the Characterization of Trap States