Synthesis and Characterization of a New Monometallic Manganese Layered Double Hydroxide with Unique Redox Properties

Iron and cobalt monometallic Layered Double Hydroxide (LDH), combining divalent and trivalent cations of the same chemical element, are commonly used respectively for nitrate reduction and oxygen evolution reaction. This article reports the first synthesis of a LDH using only manganese as metallic ion. X-Ray diffractograms, infrared and Raman spectra show that the structure obtained through the oxidation of a basic Mn II salt with persulfate is comparable to the structure of Fe-LDH also known as Green Rust. XPS shows that in this solid coexist Mn II and Mn III states. Thermodynamic considerations predict that this solid can reduce nitrate into gaseous nitrogen without further reduction into ammonium or ammonia unlike what is observed for Fe-LDH. Keywords Mn 6 (OH) 12 SO 4 • LDH • Mn • Green rust • Mn basic salts • XPS • XRD • Raman • IR • SEM • Monometallic LDH • Water remediation • Nitrate reduction • Pourbaix diagram • Thermodynamic calculation