The present work describes the color removal of Rhodamine B (Rh B), a recalcitrant cationic dye by electrocatalysis and electro-photocatalysis on Ba2SnO4 as anode. The double perovskite Ba2SnO4 synthesized by nitrate route was characterized by physical and electrochemical methods, a preamble of Rh B oxidation. The single phase, confirmed by X-ray diffraction, crystallizes in a tetragonal (Space Group: I4/mmm), with spherical crystallites (~ 50 nm). The zeta-sizer analysis gives an average grains size of 0.65 µm and zeta-potential of − 20 mV. The SEM analysis revealed the porosity of the oxide and the Ba–O and Sn–O bonds were confirmed by the FT-IR analysis. The direct optical gap (3.18 eV), determined by diffuse reflectance, is assigned to the charge transfer O2−: 2p → Sn4+: 5 s, and the double perovskite possesses a chemical inertness in the entire pH region. The Mott–Schottky plot indicates n-type behavior with a flat band potential (Efb) of − 0.84 VSCE, due to O2− deficiency and an electron concentration ND of 1.14 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13738_2025_3208_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\times$</EquationSource> <EquationSource Format="MATHML"><math> <mo>×</mo> </math></EquationSource> </InlineEquation> 1017 cm−3. The electrochemical impedance spectroscopy (EIS), plotted at the free potential (+ 0.5 V), reveals the bulk and grain boundaries contributions. The low electrons mobility is assigned to a narrow conduction band of Sn4+: 5 s parentage with activation energy (18 meV) in conformity with a conduction mechanism by small lattice polaron hopping. The intensity-potential J(E) profile in NaCl (10–2 M) exhibits a small hysteresis similar to a chemical diode. The semi-logarithmic plot (logJ – E) indicates a chemical stability of Ba2SnO4 in the working solution (NaCl). Ba2SnO4 is of interest for the environmental protection and as application, Rh B (20 mg L−1) was successfully oxidized by electrocatalysis with an abatement of 66% under a direct current of 150 mA, which has a bactericidal effect. An enhancement up to 92% has been reached by electro-photocatalysis; a quasi-complete discoloration occurred within 70 min in the “Electric Current-Sunlight-Ba2SnO4”. The Rh B elimination follows a pseudo-first-order kinetic with a rate constant of 1.96 ± 0.17 × 10–2 min−1 (t1/2 = 35 min) and a reaction mechanism is suggested.

Efficient oxidation by electro-photocatalysis of Rhodamine B using Ba₂SnO₄ as photo-electrode

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2025年4月10日

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A. Sahmi,
H. Lahmar,
M. Benamira,
M. Trari

摘要

The present work describes the color removal of Rhodamine B (Rh B), a recalcitrant cationic dye by electrocatalysis and electro-photocatalysis on Ba₂SnO₄ as anode. The double perovskite Ba₂SnO₄ synthesized by nitrate route was characterized by physical and electrochemical methods, a preamble of Rh B oxidation. The single phase, confirmed by X-ray diffraction, crystallizes in a tetragonal (Space Group: I4/mmm), with spherical crystallites (~ 50 nm). The zeta-sizer analysis gives an average grains size of 0.65 µm and zeta-potential of − 20 mV. The SEM analysis revealed the porosity of the oxide and the Ba–O and Sn–O bonds were confirmed by the FT-IR analysis. The direct optical gap (3.18 eV), determined by diffuse reflectance, is assigned to the charge transfer O²⁻: 2p → Sn⁴⁺: 5 s, and the double perovskite possesses a chemical inertness in the entire pH region. The Mott–Schottky plot indicates n-type behavior with a flat band potential (E_fb) of − 0.84 V_SCE, due to O²⁻ deficiency and an electron concentration N_D of 1.14 $\times$ $\times$ 10¹⁷ cm⁻³. The electrochemical impedance spectroscopy (EIS), plotted at the free potential (+ 0.5 V), reveals the bulk and grain boundaries contributions. The low electrons mobility is assigned to a narrow conduction band of Sn⁴⁺: 5 s parentage with activation energy (18 meV) in conformity with a conduction mechanism by small lattice polaron hopping. The intensity-potential J(E) profile in NaCl (10^–2 M) exhibits a small hysteresis similar to a chemical diode. The semi-logarithmic plot (logJ – E) indicates a chemical stability of Ba₂SnO₄ in the working solution (NaCl). Ba₂SnO₄ is of interest for the environmental protection and as application, Rh B (20 mg L⁻¹) was successfully oxidized by electrocatalysis with an abatement of 66% under a direct current of 150 mA, which has a bactericidal effect. An enhancement up to 92% has been reached by electro-photocatalysis; a quasi-complete discoloration occurred within 70 min in the “Electric Current-Sunlight-Ba₂SnO₄”. The Rh B elimination follows a pseudo-first-order kinetic with a rate constant of 1.96 ± 0.17 × 10^–2 min⁻¹ (t_1/2 = 35 min) and a reaction mechanism is suggested.

Efficient oxidation by electro-photocatalysis of Rhodamine B using Ba2SnO4 as photo-electrode

摘要

Efficient oxidation by electro-photocatalysis of Rhodamine B using Ba₂SnO₄ as photo-electrode