Phosphorous Acid Mediated Novel Synthesis of MnPO4.H2O and Mn2P2O7 with Unique Flower-Like Morphology: A New Approach to Manganese Phosphates Supercapacitors

Abstract

Manganese phosphates in various forms have garnered substantial interest because of their applications in energy storage, catalysis, and material science. In this study, we present a novel phosphorous acid (H3PO3 ) mediated approach for the facile synthesis of MnPO4•H2O and Mn2P2O7 with a unique flower-like morphology. As precursors, KMnO4 and H3PO3 were chosen to hydrothermally synthesize MnPO4.H2O. The crystalline Mn2P2O7 was produced by heating MnPO4.H2O for two hours at 700 oC. XRD, FTIR, FESEM, TEM, and other techniques were used to characterize the materials. The monoclinic structure of MnPO4.H2O and Mn2P2O7 was confirmed by XRD. A possible formation mechanism is proposed, highlighting the role of H 3 PO 3as both a phosphorus source and a structure-directing agent. The electrochemical study showed that Mn2P2O7 has a specific capacitance of 169 F.g⁻¹, whereas that of MnPO4•H2O is 63 F.g⁻¹ at a current density of 1 A.g⁻¹. This approach provides a straightforward, economical, and scalable pathway to manganese phosphates with unique morphology, paving the way for a potential future material with enhanced performance in electrochemical and catalytic applications.