Study of doping effects on the thermal properties of ▫$BiFeO_3$▫ based photocatalysts by combined PDS and PPE technique

Photocatalysis is a environmental purification process in which pollutants are degraded into harmless mineral substances through chemical reactions driven by light energy. This work focuses on the study of the thermal properties of BiFeO3 (BFO) photocatalyst and its Pr- and Co-doped derivatives (Bi(1-x)PrxFe(1-x)CoxO3 (x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.1)), synthesized by sol-gel process and co-precipitation method [1]. The impact of doping on the thermal behaviour of these materials was evaluated using the combined Photopyroelectric calorimetry and Beam Deflection Spectrometry [2,3]. The thermal conductivity and thermal diffusivity for undoped BFO were found to be 1.56 ± 0.06 W/mK and 2.19 ± 0.08 mm2/s, respectively. The results indicate that the increase in doping concentration from 2% to 10% leads to a decrease in thermal conductivity from the value of 1.73 ± 0.07 W/mK to. 1.29 ± 0.04 W/mK, as well as a decrease in thermal diffusivity from 2.42 ± 0.10 mm2/s to 1.84 ± 0.06 mm2/s (Fig.1). Such a behaviour of thermal properties is related to a reduction in both the crystallite size and state of agglomeration with the dopant concentration what is determined using SEM and XRD analysis. Furthermore, at the doping level of 2%, the thermal properties are enhanced as a result of improved crystallinity and reduced number of phonon scattering centers. These results indicatee that Pr-Co doping significantly modifies the thermal and structural properties of the whole material, that further determine its photocatalytic activity.