Photocatalytic Reduction of Aromatic Nitro Compounds with Ag/Ag_xS Composites under Visible Light Irradiation

Abstract

A series of silver sulfide composites were prepared via the hydrothermal method with L-cysteine and AgNO 3 in water at a range of Lcysteine/AgNO 3 molar ratio of 0.5−8. The prepared Ag/Ag x S materials were consisted of Ag, Ag 2 S, Ag 2 S 2 , and Ag 2 S n species as confirmed by XRD, TEM, and XPS. The Ag/Ag x S composites are active for the photocatalytic reduction of aromatic nitro compounds under the visible light irradiation. The composition of the stoichiometric Ag 2 S, the nonstoichiometric Ag 2 S 2 and Ag 2 S n , and metallic Ag species affected the photocatalytic performances largely. When more nonstoichiometric Ag 2 S 2 and Ag 2 S n presented on the surface, the absorption in the visible (vis) light region was enhanced remarkably and presented a blue shift, leading to a bigger band gap energy value (E g ) and higher cathodic conduction band edge potential (E CB ), which promoted the formation of photogenerated electrons and inhibited the combination of photoelectrons and holes. When the more Ag 0 presented on the surface, the more photogenerated electrons were transferred from the conduction band of Ag x S to Ag 0 , preventing the combination of photoelectrons and holes. Thus, the photocatalytic performances of the Ag/Ag x S composites could be controlled by varying the surface composition.

Reduction of Nitro Group by Sulfide and Its Applications in Amine Synthesis

“…虽然硫化物还原硝基的官能团耐受性良好, 但由于 硫化物的硫元素处于最低价态, 在还原硝基过程中都是 以硫阴离子的形式亲核进攻氮原子, 因此硫元素在还原 反应中有时也会伴随着烷基氧化反应 [30] 、卤素取代反 应 [31] 、 叠氮还原反应 [17a] 等副反应. 除了能够发生以上的 副反应之外, 还可能发生硫化反应以及硫化脱硝反应, 进而合成应用广泛的硫代酰胺类 [32] 、磺酰胺类 [33] 、噻唑 类 [34] 硫化物作为还原剂的独特之处在于硫原子具有吸 电子和供电子双重能力, 不仅在常规反应中用作还原 剂, 在光化学方面也可以合成光催化剂, 用于氧化还原 反应 [36] . 因此, 我们希望以后的工作中可以开发出更多 的硫化物作为还原剂用于光化学反应.…”

Electrochemical detection and catalytic reduction of nitrobenzene using a bimetallic NiS2/Fe3S4 magnetic heterostructure: an innovative approach for environmental remediation

“…The reduction of nitroaromatics generally uses catalysts made of noble metals (such as Au, Ag, Pd, and Pt) together with excessive quantities of substances that aid in the reduction process. 36–39 Nevertheless, using such precious metals as catalysts for nitrobenzene reduction is economically a non-viable option. A further significant hurdle is the metal nanoparticles’ tendency to aggregate amid catalytic reactions, which frequently causes a fast decline in the catalytic capacity.…”

“…[42][43][44][45] A green catalysis method can be quite useful for environmental cleansing and selective organic transformations into fine compounds in gaseous and liquid phases [46][47][48] Transition metal chalcogenides (TMCs) have attracted a lot of interest in the fields of energy and the environment. [49][50][51][52] Among TMCs, iron sulfides are commonly found and are widely used as anode materials for battery applications. Fe 3 S 4 is a cutting-edge magnetic material among iron sulfide nanoparticles.…”

The Journal of Physical Chemistry C Virtual Special Issue on “Energy and Catalysis in China”

“…Photocatalysis can directly convert solar energy into chemical energy, and two important photocatalytic reactions are included in this VSI: photocatalytic water splitting on Au nanoparticles embedded in g -C 3 N 4 , BiVO 4 , Ta 3 N 5 , SnNb 2 O 6 nanoplates, silicon material, MoO 3 –ZnIn 2 S 4 , carbon nitride, NiFe metal–organic framework (MOF) and cobaloxime-modified Ti-doped hematite, and photocatalytic CO 2 conversion on α-Fe 2 O 3 /CdS heterostructures, CdSe/CdSe x S 1– x /CdS alloyed quantum dots/TiO 2 , AgTaO 3 , perylene diimide/graphene- g -C 3 N 4 , P-doped ZnIn 2 S 4 , MCo 2 O 4−δ (M = Zn, Ni, Cu), and PtRu/TiO 2 . A few other photocatalytic reactions, such as the selective oxidation of cyclohexane to cyclohexanone on In 2 O 3 /N-doped TiO 2 , the reduction of aromatic nitro compounds on Ag/Ag x S, and NO removal on Ba-doped BiOBr, are also discussed.…”