“…Powder samples with general formula Ca1-xMnxCN2 (x = 0, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.1) were synthesized through solid-state reaction from (doped) calcium carbonate and carbon nitride (C3N4) according to the chemical route described in Ref. [13]. 3 g of undoped or doped calcium carbonate precursors Ca1-xMnxCO3 (x = 0, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.1) were prepared by co-precipitation method using CaCl2•6H2O (Aldrich, 98%), MnCl2•4H2O (Alfa Aesar, 99%) and Na2CO3 (Acros Organics, 99.95%) as raw materials.…”