Silver Modified Degussa P25 for the Photocatalytic Removal of Nitric Oxide

Abstract

A study of the photocatalytic behaviour of silver modified titanium dioxide materials for the decomposition and reduction of nitric oxide (NO) gas has been carried out. The effects of silver loading, calcination temperature, and reaction conditions have been investigated. Prepared photocatalysts were characterised using XRD, TEM, and XPS. A continuous flow reactor was used to determine the photocatalytic activity and selectivity of NO decomposition in the absence of oxygen as well as NO reduction using CO as the reducing agent, over the prepared photocatalysts. XRD and TEM analysis of the photocatalysts showed that crystalline silver nitrate particles were present on the titanium dioxide surface after calcination at temperatures of up to200∘C. The silver nitrate particles are thermally decomposed to form metallic silver clusters at higher temperatures. XPS analysis of the photocatalysts showed that for each of the temperatures used, bothAg+andAg0were present and that theAg0/Ag+ratio increased with increasing calcination temperature. The presence of metallic silver species on theTiO2surface dramatically increased the selectivity forN2formation of both decomposition and reduction reactions. When CO was present in the reaction gas, selectivities of over 90%were observed for all the Ag-TiO2photocatalysts that had been calcined at temperatures above200∘C. Unfortunately these high selectivities were at the expense of photocatalytic activity, with lower NO conversion rates than those achieved over unmodifiedTiO2photocatalysts.

Noble Metal‐Modified Porous Titania Networks and their Application as Photocatalysts

“…Before the photocatalytic reactions were studied, the photocatalyst was stirred in the MB solution in the dark overnight to reach adsorption-desorption equilibrium. [30] From the XPS results presented here, the gold oxidation state is zero (elemental), which is expected to boost the PC activity. The PC activity can be classified as either significantly boosted, as in the case of Pd and Au, or slightly enhanced (or even negatively influenced), as in the case of Ag and Pt.…”

NOx abatement from stationary emission sources by photo-assisted SCR: Lab-scale to pilot-scale studies

“…However, in the presence of C4H10, it could further promote the formation of N2 from NO2 [11,12,32], resulting in the decrease of NO2 selectivity along with the increase of NOx removal. On the other hand, in the absence of C4H10, NO2 might be oxidized to nitrates or nitrites [20,22].…”

“…For a traditional approach, the powder particles photocatalyst has been considered in most of the photocatalytic NOx removal [20][21][22][23]. Despite wide-spread use, this approach suffers from many drawbacks including how to recycle/regenerate the photocatalysts, and poorly exposed to the light source.…”

Photocatalytic performance analysis of Degussa P25 under various laboratory conditions

“…Many researchers have attempted to improve the photocatalytic performance of Degussa P25 further by doping, sensitization and preparing its composites [7][8][9] photocatalytic performance [7]. Neil Bowering et al reported the photocatalytic activity of silver modified Degussa P25 materials for the decomposition and reduction of nitric oxide [8].…”

“…Neil Bowering et al reported the photocatalytic activity of silver modified Degussa P25 materials for the decomposition and reduction of nitric oxide [8]. Hao Zhang et al reported the P25-graphene composite photocatalyst possessed great absorptivity of dyes with extended light absorption range, and efficient charge separation properties simultaneously [9].…”