Electrodeposition of nanostructured γ-MnO2 film for photodegradation of Rhodamine B

Plasma-Assisted Chemical Vapor Deposition of F-Doped MnO2 Nanostructures on Single Crystal Substrates

“…The recorded micrographs evidenced in fact a very open morphology, characterized by the presence of interconnected and anisotropic dendritic structures (mean width ≈ 80 nm) uniformly protruding from the underlying substrate surface. Such features might be beneficial for possible end-uses in photocatalysis [7,19,23,34,39,44], with particular regard to wastewater purification from organic pollutants and to water splitting for hydrogen production. The average length of the observed dendrites was directly affected by the used deposition substrate (220 nm, MgAl 2 O 4 (100); 200 nm, YAlO 3 (010); 270 nm, Y 3 Al 5 O 12 (010)).…”

“…Optical absorption spectra were recorded in transmittance mode at normal incidence on a Cary 50 (Agilent, Santa Clara, CA, USA) spectrophotometer, subtracting the substrate contribution in each case. Estimation of band gap (E G ) values was performed through the Tauc procedure [7][8][9]30,46,48]:…”

“…Manganese oxides have attracted considerable interest thanks to their diversity of oxidation states and crystal structures, yielding broadly tunable characteristics as a function of the adopted preparation conditions [1][2][3][4][5][6][7][8][9][10][11]. In particular, a remarkable attention has been focused on manganese dioxide, thanks to its low-cost, natural abundance, environmental friendliness, and versatile chemico-physical properties [12][13][14][15].…”

“…In particular, a remarkable attention has been focused on manganese dioxide, thanks to its low-cost, natural abundance, environmental friendliness, and versatile chemico-physical properties [ 12 , 13 , 14 , 15 ]. MnO 2 exhibits at least six different structurally related crystalline modifications ( α , β , γ , δ , ε , and λ ) [ 1 , 2 , 4 , 7 , 10 , 16 , 17 , 18 , 19 ]. All these polymorphs are semiconductors with low resistivity [ 2 , 20 , 21 ], and have emerged as attractive candidates for several end-uses, including electrodes in Li- and Na-ion batteries and supercapacitors, thermoelectric materials, chemical sensors, photo- and electrocatalysts for pollutant degradation and hydrogen production, and magnetic devices useful for information storage [ 5 , 8 , 11 , 12 , 13 , 14 , 15 , 18 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”

“…So far, the preparation of MnO 2 thin films/nanosystems has been performed on polycrystalline substrates by various techniques. These include reactive sputtering on Si [ 22 ], pulsed laser deposition on stainless steel [ 30 ], thermal evaporation on glass and quartz [ 9 ], hydrothermal routes on Si, carbon cloth, and Ni foams [ 14 , 33 , 43 ], electrodeposition on stainless steel, glass, carbon fibers, and Ni sheets [ 7 , 8 , 10 , 11 ], chemical bath deposition on stainless steel [ 13 , 30 ], spray pyrolysis on glass and steel [ 15 ], atomic layer deposition on Si [ 6 , 31 , 32 ], and chemical vapor deposition (CVD) on Si and glass [ 23 , 34 , 44 ]. Nevertheless, the use of single crystal substrates can not only stabilize specific polymorphs, but also affect morphology, structure, and crystal quality [ 21 , 41 , 42 , 45 ].…”