Synthesis, structure, oxygen evolution reaction (OER) and visible-light assisted organic reaction studies on A₂M₂TeB₂O₁₀ (A = Ba and Pb; M = Mg, Zn, Co, Ni, Cu, and Fe)

Compounds with the general formula A₂M₂TeB₂O₁₀ (A = Ba and Pb; M = Mg, Zn, Co, Ni, Cu, and Fe) have been synthesised via solid-state techniques and characterised. The structure exhibits M₂B₂O₁₀ layers connected by TeO₆ octahedra giving rise to a three-dimensional structure with voids, where Ba²⁺ ions reside. Substitution of Mg by transition elements (M = Co, Ni, and Cu) in Ba₂Mg₂TeB₂O₁₀ and (Ba_0.5Pb_1.5)Mg₂TeB₂O₁₀ gives rise to interesting colored compounds. NIR reflectivity studies indicated that white-colored compounds exhibited good NIR reflectivity, which was is comparable to that of TiO₂. Dielectric studies indicated reasonable values with low dielectric loss at low frequencies. The cobalt-substituted compounds Ba₂(MgCo)TeB₂O₁₀ and (Ba_0.5Pb_1.5)(MgCo)TeB₂O₁₀ were explored towards the oxygen evolution reaction (OER) in an alkaline medium. The compound (Ba_0.5Pb_1.5)(MgCo)TeB₂O₁₀ was found to be a good electrocatalyst for the OER with a faradaic efficiency of ∼96%. The Cu-substituted compound Ba₂(Mg_1.5Cu_0.5)TeB₂O₁₀ was found to be a good photocatalyst for the formation of α-chloroketones under visible light in the presence of molecular oxygen.