Comparative study of the structural, optical and photocatalytic properties of strontium doped β-tricalcium phosphate (Ca3(PO4)2) toward degradation of rhodamine B

Persistent presence of organic contaminants in aquatic systems has detrimental effects on ecosystems. To alleviate this damaging issue, strontium-doped β-tricalcium phosphate (β-TCP, Ca 3 (PO 4 ) 2 ) compositions have been investigated for their catalytic performance with cationic rhodamine B (RhB) as a model contaminant. Sr doped and undoped compositions of β-TCP, have been synthesized via solid state synthesis at 1000 °C for 10 h and compositions and characterised using a number of techniques. The solid solution samples of Sr-doped Ca 3 (PO 4 ) 2 demonstrate a consistent trend towards lowered angles in their X-ray powder diffraction (XRPD) patterns with increasing Sr doping and this is associated with an increase in lattice parameters. The crystal symmetry of TCP remains unchanged with Sr doping. However, Sr doping causes the PO 4 tetrahedra to become more distorted and oblate in shape. The degradation of rhodamine B (RhB) has been investigated using UV light-driven photocatalytic activity. Sr doping results in substantial photodegradation activity. Furthermore, the x = 0.9 Sr x Ca 3-x (PO 4 ) 2 sample exhibits the maximum photocatalytic degradation towards RhB among the Sr-doped TCP samples, and it is hypothesised that this is due to more efficient partitioning of photogenerated electron-hole pairs. The average degradation of RhB has been calculated to be 74.12 (±3.33) % based on three repetitions of experiments, indicating good reproducibility for the x = 0.9 Sr-doped TCP samples. These results therefore support the fabrication and application of Sr-doped Ca 3 (PO 4 ) 2 as an effective photocatalyst for rhodamine B (RhB) contaminated wastewater treatment. • Structural properties of β-TCP (Ca 3 (PO 4 ) 2 ) were tailored by incorporation of Sr. • Doping β-TCP with Sr resulted in modified bandgap energies. • Sr doping significantly enhanced the photocatalytic efficiency of β-TCP. • Doped β-TCP could have potential as a photocatalyst for wastewater treatment.