Visible Light Active Single-Crystal Nanorod/Needle-like α-MnO₂@RGO Nanocomposites for Efficient Photoreduction of Cr(VI)

Abstract

Herein, we report a highly efficient template or surfactant free hydrothermal method to fabricate a graphene based single-crystal tetragonal needle-and nanorod-like α-MnO 2 composite, a kind of semiconductor photocatalyst for the reduction of hexavalent chromium [Cr(VI)] under visible irradiation. Hydrothermal reaction time and in situ introduction of graphene played a important role in tuning the morphology of α-MnO 2 . The as-synthesized reduced graphene oxide (RGO)/α-MnO 2 nanorod composite exhibited outstanding photoreduction ability as compared to RGO/α-MnO 2 needle composite. The higher activity of RGO/α-MnO 2 nanorod composite was successfully derived from photoluminescence (PL) and photocurrent measurements. The low PL intensity and high photocurrent density of RGO/α-MnO 2 nanorod composite concludes that change in aspect ratio as well as the presence of RGO favors intimate strong interaction of a two-dimensional layer of graphene and one-dimensional α-MnO 2 nanorod which facilitates for enhanced photoexcited charge (e − /h + ) separation and simultaneously increases its photoreduction ability under visible light irradiation.

Synthesis of a MnO2/Fe3O4/diatomite nanocomposite as an efficient heterogeneous Fenton-like catalyst for methylene blue degradation

“…6 ) exhibits two individual peaks at 653.9 and 642.2 eV, attributed to the Mn 2p 1/2 and Mn 2p 3/2 binding energies, respectively. As a result, the spin energy separation of Mn 2p peaks can be calculated as 11.7 eV, which is well in agreement with reports for MnO 2 [ 33 ]. In Fig.…”

Dynamics of Charge-Transfer Behavior in a Plasmon-Induced Quasi-Type-II p–n/n–n Dual Heterojunction in Ag@Ag3PO4/g-C3N4/NiFe LDH Nanocomposites for Photocatalytic Cr(VI) Reduction and Phenol Oxidation

“…The residual concentration of Cr(VI) over a period of time was colorimetrically analyzed by the 1,5-diphenylcarbazide method using a JASCO-V-750 UV–vis spectrophotometer at λ max 540 nm. 36 In addition, the remaining Cr(VI) concentration in the sample was also determined after the photocatalytic activity. 37 The photocatalytic degradation of phenol was carried out by adding 0.02 g of the catalyst to 20 mL of phenol (20 ppm) taken in a 100 mL stoppered Pyrex conical flask.…”

Surfactant-assisted hydrothermal synthesis of rGO/SnIn4S8 nanosheets and their application in complete removal of Cr(vi)

“…27,28 In this regard, a few reports on the photocatalytic reduction of Cr(VI) over graphene-based material such as a-FeOOH nanorod/RGO, a-MnO 2 @RGO, SnS 2 /RGO have already been reported. [29][30][31] To the best of our knowledge, few groups have reported the concurrence of photocatalysis of Cr(VI) and adsorption of Cr(III) by the graphene-based material.…”