Carbonate doped Bi2MoO6 hierarchical nanostructure with enhanced transformation of active radicals for efficient photocatalytic removal of NO

Insights into the Surface/Interface Modifications of Bi2MoO6: Feasible Strategies and Photocatalytic Applications

“…[ 159 ] With the flourishment of semiconductor‐based photocatalysis, various advanced catalysts have been designed and manufactured to ameliorate the atmospheric environment, including visible‐light‐responsive Bi 2 MoO 6 . [ 160–162 ]…”

Tailored Co3O4-Based Nanosystems: Toward Photocatalysts for Air Purification

“…The latter react with adsorbed water and oxygen molecules to yield highly reactive oxygen species [ROS; mainly hydroxide ( • OH) and superoxide radicals ( • O 2 − )], which, in turn, trigger NO x removal (De-NO x ; x = 1,2) by a sequential photo-oxidative process: NO → NO 2 − → NO 2 → NO 3 − . 1,2,8,18,21 Although various research works have been aimed at the development of De-NO x photocatalysts, 1,3,14 key problems still far from being completely overcome are related to the low activity and the generation of undesired/toxic byproducts, 1,5 in particular, the NO 2 intermediate. 6,13,20,22,23 Hence, an important goal to be fulfilled for an efficient NO x degradation, an actual open challenge, 2,4,10,[14][15][16]24 is the obtainment of a high selectivity toward harmless nitrates (NO 3 − ) as the major process products.…”

“…4,6,14 In fact, the assembly of high-area nanocrystalline and defective structures positively affects material reactivity and charge transport phenomena, paving the way to an improved photocatalytic activity. 4,9,13,20,22,25 Most literature works have involved the use of TiO 2 , 1,12,13,20,26 ZnO, 1,14,22,27 tems, [2][3][4]15,20 whereas other studies have focused on materials based on C 3 N 4 , 21,26 Mn 3 O 4 , 5 SnO 2 , 6 InVO 4 , 7 ZnFe 2 O 4 , 19 ZnWO 4 , 10 Bi 2 GeO 5 , 8 Bi 2 MoO 6 , 18 Bi 2 Mo 3 O 12 , 16 and Bi 2 WO 6 . 28 To overcome the disadvantages exhibited by single photocatalysts, including limited Vis light absorption (as for TiO 2 1,3,20,24 ) and/or detrimental electron−hole recombination, 8,20,29−31 a valuable tool is provided by the construction of heterojunctions between different semiconductors.…”

“…The increasing concern about the environment and human health has significantly boosted the attention toward the effective degradation of harmful air pollutants. − Among the latter, nitrogen monoxide (NO) can generate a variety of problems, including ozone depletion, acid rain, and photochemical smog, with negative effects on human health even at sub-ppm levels. − Accordingly, several efforts have been undertaken to reduce NO emissions, especially in urban and industrialized areas. ,,, In this context, photocatalytic technologies assisted by largely available natural resources, such as oxygen, water, and light, are low-cost and sustainable routes for NO degradation at ambient temperature. ,,− These processes are initiated by the photoexcitation of suitable semiconductors, resulting in the generation of electron–hole pairs (e – /h + ). The latter react with adsorbed water and oxygen molecules to yield highly reactive oxygen species [ROS; mainly hydroxide ( • OH) and superoxide radicals ( • O 2 – )], which, in turn, trigger NO x removal (De-NO x ; x = 1,2) by a sequential photo-oxidative process: NO → NO 2 – → NO 2 → NO 3 – . ,,,, …”

“…Over the last decade, semiconductor metal oxide nanosystems have been investigated as De-NO x photocatalysts, thanks to their favorable chemico-physical properties, relatively low cost, and good chemical stability. ,, In fact, the assembly of high-area nanocrystalline and defective structures positively affects material reactivity and charge transport phenomena, paving the way to an improved photocatalytic activity. ,,,,, Most literature works have involved the use of TiO 2 , ,,,, ZnO, ,,, and Fe 2 O 3 -containing systems, − ,, whereas other studies have focused on materials based on C 3 N 4 , , Mn 3 O 4 , SnO 2 , InVO 4 , ZnFe 2 O 4 , ZnWO 4 , Bi 2 GeO 5 , Bi 2 MoO 6 , Bi 2 Mo 3 O 12 , and Bi 2 WO 6 . To overcome the disadvantages exhibited by single photocatalysts, including limited Vis light absorption (as for TiO 2 ,,, ) and/or detrimental electron–hole recombination, ,,− a valuable tool is provided by the construction of heterojunctions between different semiconductors. ,,,,, The latter enable, in principle, to extend the radiation absorption range and favorably enhance charge carrier separation at the junction interfaces. ,,, An additional important issue is the development of supported photocatalysts, scarcely investigated so far at variance with the homologous powdered counterparts, ,, which allow to reduce the active material amount and are less hazardous, more stable, and more easily recoverable after use than the homologous powders. ,, …”