Efficient solid-state synthesis of biomineralized vaterite-derived pure CaMnO3 perovskite for effective photocatalysis.

In recent years, perovskite materials have gained immense popularity due to their role in energy-based applications. Calcium manganese oxides are analogous to the systems that perform water-splitting in the natural photosynthesis process. In this work, we report a convenient method to synthesize CaMnO3 perovskite. Biomineralized vaterite was used as the calcium source to synthesize pure CaMnO3 efficiently. In contrast, commercial CaCO3, which contains the calcite phase, led to the formation of a mixture of calcium manganese oxides. The low bandgap energy of pure CaMnO3 (1.21 eV) enabled it to absorb visible light and be employed as a photocatalyst in the photolytic degradation of toxic dyes viz. rhodamine 6G, rhodamine B, methylene blue and methyl orange. The photocatalytic degradation of rhodamine 6G was studied in detail, and 72% dye degradation was observed within 2 h in the presence of pure CaMnO3 in contrast to 46% in the presence of the mixed-phase calcium manganese oxide. The mechanistic pathway of dye degradation was also analysed. [ABSTRACT FROM AUTHOR]