NH3/H2O-mediated proton conductivity and photocatalytic behaviour of Fe(ii)-hydroxyphosphonoacetate and M(ii)-substituted derivatives

Abstract

Synthesis redesign and derivatisation of Fe(II)-hydroxyphosphonoacetate, incorporating different ammonia loads and M(II) isomorphic substitutions (M = Mn, Co and Zn), have been implemented. The NH₃ adsorption led to materials with enhanced proton conductivity, up to ∼10⁻³ S cm⁻¹, although it caused a progressive amorphization. The Pair Distribution Function (PDF) analysis for this material confirmed the loss of crystallinity but the local order appeared to be maintained. The parent compound was shown to be an efficient photocatalyst for phenol, 4-chlorophenol and methylene blue even under mild conditions, with TOC removal of 75–90% at 50–150 min of reaction. The M(II)-substituted derivatives displayed similar behaviour in properties, and therefore their multifunctional character, as the parent compound, although with slightly reduced capabilities.