Novel MoSe₂ hierarchical microspheres for applications in visible-light-driven advanced oxidation processes

Abstract

Advanced oxidation processes as a green technology have been adopted by combining the semiconductor catalyst MoSe2 with H2O2 under visible radiation. And novel three-dimensional self-assembled molybdenum diselenide (MoSe2) hierarchical microspheres from nanosheets were produced by using organic, selenium cyanoacetic acid sodium (NCSeCH2COONa) as the source of Se. The obtained products possess good crystallinity and present hierarchical structures with the average diameter of 1 μm. The band gap of MoSe2 microspheres is 1.68 eV and they present excellent photocatalytic activity under visible light irradiation in the MoSe2-H2O2 system. This effective photocatalytic mechanism was investigated in this study and can be attributed to visible-light-driven advanced oxidation processes.

One-pot synthesis of MoS2(1−x)Se2x on N-doped reduced graphene oxide: tailoring chemical and structural properties for photoenhanced hydrogen evolution reaction

“…In general, the MoS 2(1Àx) Se 2x nanosheets share a common central spots, which is likely the initial nucleation centre, and diverge from there almost radially, producing a nanoowers morphology, which is commonly reported in the colloidal or solvothermal synthesis of several TMDCs. 40,41 The thickness and extension of the "petals" as well as the voids in between them, increases aer the annealing procedure because of the crystallization of amorphous materials, forming larger and better dened "owers".…”

“…The Raman spectra of the as-produced samples show weak and broad peaks, indicating the partially amorphous nature of the MoS 2(1Àx) Se 2x , as oen reported in hydro-or solvothermal synthesis of TMDCs. 40,[42][43][44][45] However, some trends can be observed: MoS 2 /N-rGO (0 ml sample) exhibits two broad bands centred at about 350 and 460 cm À1 (defective form of E 1 2g and A 1g normal modes of MoS 2 ). 46 Increasing the DMDSe volume, both bands slightly downshi to lower wavenumbers, which is a consequence of the substitution of S with the heavier Se anion.…”

MoSe2/Montmorillonite Composite Nanosheets: Hydrothermal Synthesis, Structural Characteristics, and Enhanced Photocatalytic Activity

“…The contact angles of the water droplets that were collected on the surface of the samples are shown in Figure 6c Figure 7. Under the visible light irradiation, the photogenerated electron and hole pairs are yielded in the conduction band (CB) and the valence band (VB) of MoSe 2 [9]. The surface hydroxyl groups of MMT could trap the photogenerated holes (h + ) to produce hydroxyl radicals (OH) [24], and the oxygen molecules (O 2 ) in the solution could react with photogenerated electrons (e -) to produce superoxide radical anions (O 2 -).…”

“…Their band gaps usually range from 1.0 to 2.0 eV, which are appropriate for visible light catalysis. As it is one of the transition metal dichalcogenides, MoSe 2 , with its structural unit of a Se-Mo-Se sandwich layer, possesses a band gap of 1.4 eV, which matches the solar spectrum very well [9]. MoSe 2 is a promising photocatalytic material with high anti-photocorrosion stability, and its catalytic active sites are located at the edges [10].…”

Nanoparticle-assisted photo-Fenton reaction for photo-decomposition of humic acid

“…It is known (Guo et al 2013) that ZnO NMs can produce ROS under UV illumination as the potential of photo-excited hole at the valence band (2.6 V versus NHE at pH 7 and CB *-0.5 V versus NHE) (Oda et al 2014;Dai et al 2015 (Ebrahiem et al 2013). Since CuO is a p-type semiconductor, it seems that electron transfer from CB of ZnO to OH at this heterojunction (Yu et al 2015) becomes faster, reducing radical (OH) recombination reaction.…”