A novel scheelite-like structure of BaBi₂Mo₄O₁₆: photocatalysis and investigation of the solid solution, BaBi₂Mo_4-xW_xO₁₆ (0.25 ≤ x ≤ 1)

Abstract

A barium bismuth molybdate, BaBi₂Mo₄O₁₆, was synthesized for the first time. The compound was made by the solid-state technique and studied for photocatalytic degradation of water pollutants. The compound crystallizes in the monoclinic C2/c system with a = 5.317 (1) Å, b = 12.875 (2) Å, c = 19.390 (3) Å, β= 101.512 (4)°, V = 1327.1 (4) ų and Z = 4. The crystal structure along the a-axis consists of layers of [Bi₂O₂] units and BaO₁₀ polyhedra both surrounded by isolated MoO₄ tetrahedra representing a scheelite-like structure. Photocatalytic degradation of phenols and substituted phenols, acids and dyes were studied using BaBi₂Mo₄O₁₆ as catalyst. The catalyst shows selectivity towards chlorine containing aromatics. Substitution of tungsten for molybdenum resulted in retention of structure within the limits 0.25 ≤ x ≤ 1 of the solid solution, BaBi₂Mo_4-xW_xO₁₆. The phases, x = 0.25, 0.50, 0.75 and 1.0, in the solid solution were also used to study the photocatalytic degradation of water pollutants like phenol, substituted phenols and dyes. The photocatalytic activity increases slightly with an increase in substitution of tungsten in the solid solution domain.