Ag-modified AgI–TiO₂ as an excellent and durable catalyst for catalytic oxidation of elemental mercury

Abstract

was employed for the removal of elemental mercury (Hg 0 ) from flue gas, and extra elemental silver (Ag) was introduced to enhance the catalytic activity and stability. AgI-TiO 2 displayed an excellent effect on Hg 0 catalytic oxidation, and the Hg 0 oxidation efficiency was almost 100% with only 5 ppm HCl at 350 C, which was better than that of KI-Ti. Adding Ag to AgI-TiO 2 can notably prolong the period of high efficiency, and the Hg 0 oxidation efficiency was still above 90% after 10 h with only 2% Ag added.Doping with silver could suppress the decomposition of AgI and the loss of iodine, which maintains the stability of the catalyst performance. In addition, HCl was readily adsorbed and activated by the silver. The iodine in Ag(2%)-AgI-Ti mainly acted as an accelerant for Hg 0 oxidation by facilitating formation of the intermediate Hg-I*; then, chlorine can further convert the intermediate to HgCl 2 as the finalproduct. In addition, the thermogravimetric (TG) analysis proved that Ag(2%)-AgI-Ti showed a good stability at high temperature. Furthermore, the ion chromatogram tests also showed the chemical stability of AgI-Ti in the presence of Ag.

Preparation and Photoelectrochemical Performance of Visible-Light Active AgI/TiO2-NTs Composite with Rich β-AgI

“…Since β-AgI nanocrystals were reported to exhibit much higher visible light absorption than AgI colloid (β-AgI and γ-AgI mixture), it is possible that the PEC properties of AgI/TiO 2 -NTs will probably be regulated due to different β/γ-AgI ratio. Besides, peaks corresponding to Ag 0 species were not observed by XRD in the present study. , …”

“…Besides, peaks corresponding to Ag 0 species were not observed by XRD in the present study. 33,34 To further corroborate the surface chemical state of AgI, XPS spectra were used to investigate the Ag 3d and I 3d on AgI/ TiO 2 -NTs350. As shown in Figure 2A, two peaks of Ag 3d located at 367.9 eV (Ag 3d 5/2 ) and 373.9 eV (Ag 3d 3/2 ), which were very similar to the reported values for β-AgI.…”

An AgI@g-C3N4 hybrid core@shell structure: Stable and enhanced photocatalytic degradation

“…Importantly, recent works have led to the development of AgI-based composite photocatalysts demonstrating efficient absorption of visible light and suppression of recombination of photogenerated charge carriers. For example, it has been reported that AgI/SiNW [8], AgI/ZnO [9], AgI/TiO 2 [10] can effectively accelerate the separation of photogenerated charge carriers due to the strong interface electric field by band-edge offset. However, the point contact caused by these bulk phase recombination could lead to low conjunctions of AgI with semiconductors, which could limit the photo-induced charge separation.…”

Integrating surface plasmon resonance and slow photon effects in nanoporous anodic alumina photonic crystals for photocatalysis

“…Semiconductor photocatalysts harvest the energy of incoming photons to drive chemical reactions for solar-to-fuel conversion and environmental remediation, including hydrogen (H 2 ) energy generation, [1][2][3] water treatment, [4][5][6][7][8][9][10][11] air purification, 12,13 ammonia (NH 3 ) synthesis, 14,15 carbon dioxide (CO 2 ) reduction 16,17 and warfare agents destruction. 18,19 In land-mark studies, Fujishima 20 and Carey 21 reported production of clean H 2 energy and degradation of organic pollutants by semiconducting titanium dioxide (TiO 2 ) under UV light irradiation, respectively.…”