Bi2O3/CaSiO3/g—C3N4 particulate crystalline nanocomposite

A method of preparing a particulate crystalline nanocomposite, the method including:

• forming a solution of a calcium salt and an alkali metal silicate in a solvent including water and a C1-C4 alkanol;
• heating the solution at a temperature of from about 150 to about 250° C. to form a dry product of CaSiO3;
• forming g-C3N4 by heating urea in a closed vessel at a temperature of from about 500 to about 700° C.;
• forming an acidified solution in a polar protic solvent of a bismuth salt and reducing sugar;
• heating the acidified solution at a temperature of from about 150 to about 250° C. for a sufficient duration to carbonize the reducing sugar;
• comminuting the carbonized product of the heating stage;
• calcining the comminuted carbonized product at a temperature of from about 500 to about 1200° C. for a duration of from about 1 to about 5 hours (h) to form Bi2O3;
• dispersing the CaSiO3, g-C3N4, and Bi2O3 in a polar protic solvent and heating the dispersion at a temperature of from about 150 to about 250° C. at a pressure of from about 2 to about 8 bar;
• and,
• separating the particulate crystalline nanocomposite from the heated dispersion,
• wherein the particulate crystalline nanocomposite comprises:
• a monoclinic bismuth oxide (Bi2O3) crystalline phase;
• a calcium silicate (CaSiO3) crystalline phase;
• and
• a graphitic carbon nitride (g-C3N4) crystalline phase,
• wherein at least a fraction of the g-C3N4 is in the form of mesoporous nanosheets.