Mechanism of Versatile Catalytic Activities of Quaternary CuZnFeS Nanocrystals Designed by a Rapid Synthesis Route

Abstract

Quaternary alloyed nanocrystals (NCs) composed of earth abundant, environment friendly elements are of interest for energy-harvesting applications. These complex NCs are useful as catalysts for the degradation of multiple refractory organic pollutants as well as nitro-organic reduction at a rapid rate. Here, a remarkably fast (∼30 s) and facile synthesis of crystalline quaternary chalcopyrite copper-zinc-iron-sulfide (CZIS) NCs is reported. These NCs show excellent catalytic properties by degrading a number of refractory organic dyes and converting nitro-compounds at a rapid rate. The valence and conduction band information of the newly designed NCs are extracted using scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy, which reveal energy levels suitable for performing redox chemistry by generating reactive radicals establishing NCs as efficient catalyst with multiple uses. Rapid synthesis of high quality phase-controlled CZIS NCs with robust catalytic activities could be useful for organic waste treatment.

Reduction of Nitro Compounds Using 3d-Non-Noble Metal Catalysts

“…In addition to the above described alloy system, recently, also Co-Cu 391 and Zn-Co 392 NPs embedded in nitrogen doped porous carbon, derived by pyrolysis of nitrogen containing MOF, and quaternary CuZnFeS nanocrystals 393 have been used as catalysts in the reduction of 4-nitrophenol.…”

Photon-Free Degradation of Dyes by Ge/GeO2 Porous Microstructures

“…41−44 The electron transfer from Ge core can react with the dissolved O 2 to form the superoxides radical (O 2 •− ) as the redox potential of Ge (E 0 = −4.0 eV) is more negative than that of the O 2 /O 2 •− (E 0 = −4.34 eV). 41 Further, superoxide radical (O 2 •− ) can undergo protonation to produce hydroxyl radicals ( • OH). 41 To maintain a constant flow of electrons from Ge core to the dye/O 2 molecules, a continuous supply of electrons is required.…”

“…41 Further, superoxide radical (O 2 •− ) can undergo protonation to produce hydroxyl radicals ( • OH). 41 To maintain a constant flow of electrons from Ge core to the dye/O 2 molecules, a continuous supply of electrons is required. The electrons may come from the oxidation of Ge.…”

“…42 Similarly, direct electron transfer from Ge/GeO 2 to MB and formation of semireduced MB (MB •− ) and LMB is also possible as the E 0 of MB/MB •− (−4.27 eV) and MB/LMB (−4.51 eV) are lower than the CB of Ge (Figure 4c). 41,42 Considering the large difference in redox potential of H 2 O/ • OH (−6.82 eV) and valence band of Ge (−4.66 eV), the direct oxidation of H 2 O by holes is not favorable (Figure 4c). 43,44 To confirm the dissolution of GeO 2 into the solution during catalysis, Ge/GeO 2 microcrystals are allowed to settle in the solution for 24 h. The clear solution is then removed and dried on the glass plate to check the presence of GeO 2 using Raman spectroscopy.…”

Core-Shell MnO2-SiO2 Nanorods for Catalyzing the Removal of Dyes from Water

“…A number of physical and physicochemical technologies have been developed for the removal of dyes from aqueous solutions, including adsorption techniques [3,4], membrane processes [5,6], and degradation of dyes through oxidation under the assistant of catalysts [7][8][9][10]. Various materials have been used as adsorbents for the removal of dyes, such as biocoagulants [1], fruit peels [3], and cellulose-based bioadsorbents [4].…”