@article { ISI:000263073800056, title = {N,S-Co-doped TiO2 Nanophotocatalyst: synthesis, electronic structure and photocatalysis}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {9}, number = {1, SI}, year = {2009}, month = {JAN}, pages = {423-432}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

N,S-co-doped anatase-phase TiO2 (N,S-TiO2) nanophotocatalysts were prepared from either benzothiazoline or aminothiol with titanium isopropoxide followed by a systematic thermal decomposition. The chemical nature of S and N in N,S-TiO2 have been identified by XPS to be sulfate and NO-like, respectively. A significant band broadening and red-shift in the UV-visible absorption spectrum of N,S-TiO2 suggests a band gap reduction compared to TiO2. A maximum band-gap narrowing of 0.22 +/- 0.02 eV was observed on N,S-TiO2. Higher energy width observed on N,S-TiO2 is in contrast to 0.13 eV from N-doped TiO2 indicating the sulfate-like species might play a major role in narrowing the band-gap to a Higher level. It is confirmed that the oxidation of N and S to NO and SO42- occurs in the final stage of preparation of N,S-TiO2, during calcination in air. It is predicted that the oxygen associated with sulfate and NO structural features could be crucial in bringing down the energy gap and red shift in optical absorption and the role of sulfur is to facilitate the above. Photocatalytic decomposition of methylene blue has been carried out on N,S-TiO2 shows higher activity than the commercial TiO2 in the visible region. However, sulfate species seems to enhance the activity of N,S-TiO2 marginally compared to N-TiO2, and possible suggestions are given to improve the same.

}, keywords = {nitrogen, Photocatalyst, Sulfur, TiO2, Visible Light Absorption}, issn = {1533-4880}, doi = {10.1166/jnn.2009.J095}, author = {Sathish, M. and Viswanath, R. P. and Gopinath, Chinnakonda S.} } @article {47380, title = {One-dimensional multichannel g-C3N4.7 nanostructure realizing an efficient photocatalytic hydrogen evolution reaction and its theoretical investigations}, journal = {ACS Applied Energy Materials}, volume = {4}, year = {2021}, month = {APR }, pages = {3118-3129}, type = {Article}, abstract = {

The emerging metal-free carbon nitride (C3N4) offers prominent possibilities for realizing the highly effective hydrogen evolution reaction (HER). However, its poor surface conductivity and insufficient catalytic sites hinder the HER performance. Herein, a one-dimensional vermicular rope-like graphitic carbon nitride nanostructure is demonstrated that consists of multichannel tubular pores and high nitrogen content, which is fabricated through a cost-effective approach having the final stoichiometry g-C3N4.7 for HER application. The present g-C3N4.7 is unique owing to the presence of abundant channels for the diffusion process, modulated surface chemistry with rich- electroactive sites from N-electron lone pairs, greatly reduced recombination rate of photoexcited exciton pairs, and a high donor concentration (4.26 x 10(17) cm(3)). The catalyst offers a visible-light-driven photocatalytic H-2 evolution rate as high as 4910 mu mol h(-1)g(-1) with an apparent quantum yield of 14.07\% at band gap absorption (2.59 eV, 479 nm) under 7.68 mW cm(-2) illumination. The number of hydrogen gas molecules produced is 1.307 x 10(15) s(-1) cm(-2), which remained constant for a minimum of 18 h of repeated cycling in the HER without any degradation of the catalyst. In density functional theory calculations, a significant change in the band offset is observed due to N doping into the system in favor of electron catalysis. The theoretical band gap of a monolayer of g-C3N4.7 was enormously reduced because of the presence of additional densities of states from the doped N atom inside the band gap. These impurity or donor bands are formed inside the band gap region, which ultimately enhance the hydrogen ion reduction reaction enormously.

}, keywords = {carbon nitride, Density functional theory, hydrogen evolution reaction, nitrogen-rich, Photocatalyst}, issn = {2574-0962}, doi = {10.1021/acsaem.0c02858}, author = {Antil, Bindu and Kumar, Lakshya and Ranjan, Ravi and Shenoy, Sulakshana and Tarafder, Kartick and Gopinath, Chinnakonda S. and Deka, Sasanka} } @article {48225, title = {Enhanced hydrogen fuel production using synergistic combination of solar radiation and TiO2 photocatalyst coupled with Burkholderia cepacia lipase}, journal = {International Journal of Hydrogen Energy}, volume = {47}, year = {2022}, month = {APR }, pages = {14483-14492}, type = {Article}, abstract = {

Promising and sustainable alternatives for hydrogen production have been investigated. Among these, the use of enzymes may represent an efficient alternative. In this work, an increase in hydrogen production under simulated sunlight by combining TiO2 and TiO2/MgCl2 with Burkholderia cepacia lipase (BCL) was reported. The samples (TiO2, TiO2/MgCl2, and TiO2 /MgCl2/BCL) were characterized by X-ray diffraction (XRD), thermo-gravimetric (TGA), N-2 adsorption-desorption isotherms (BET), scanning electron microscopy (SEM), and UV-Visible absorption spectra. Hydrogen production tests were performed in aqueous methanol solutions under simulated sunlight. The results demonstrated that 130-times greater increase in hydrogen production rate was observed by the addition of BCL than individual TiO2. This better hydrogen production rate can be attributed to the increase in the amount of reduction equivalent of the system due to the oxidation of protein peptides caused by TiO2. In conclusion, the results indicate that hydrogen production efficiency can be significantly improved when integrating TiO2/MgCl2 with BCL. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {hydrogen production, Lipase, Nano-conjugated enzymes, Photocatalyst, Solar radiation, Titanium dioxide}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2022.02.220}, author = {de Souza Brandao, Luma Mirely and Barbosa, Milson dos Santos and de Jesus, Roberta Anjos and Bharad, Pradnya Arunrao and Lima, Alvaro Silva and Faria Soares, Cleide Mara and Navarro Yerga, Rufino Manuel and Bilal, Muhammad and Romanholo Ferreira, Luiz Fernando and Iqbal, Hafiz M. N. and Gopinath, Chinnakonda S. and Figueiredo, Renan Tavares} }