Elucidating the role of PdAgFe charge transfer in ternary aerogels for boosting electro-oxidative degradation of recalcitrant di-butyl phthalate

Abstract

In this work, Pd-based aerogels were modified with transition metals (Ag, Fe) for the degradation and electrochemical oxidation of di-butyl phthalate (DBP) in water. The newly synthesized PdAgFe aerogel showed a uniform dispersion with a practical size of 4–9 nm, and achieved a dense interconnected network revealed by transmission electron microscopy. The PdAgFe-assisted electrochemical oxidation of DBP achieved 97% removal at a pollutant concentration of 90 mg L⁻¹, surpassing that of pollutant concentrations of 90 mg L⁻¹, surpassing that of binary aerogels, i.e., PdFe (86.3%) and PdAg (70.6%). The oxygen evolution potential of PdAgFe increased progressively from 1.61 to 1.97 V with maximum applied DBP concentration. This reflects the enhanced catalytic selectivity and activity of PdAgFe at the optimum operating scan rate (5 mV s⁻¹) in 1 M KOH over 8 h of process duration. Kinetic modeling confirmed that DBP degradation followed a pseudo-first-order rate law, with PdAgFe showing the highest apparent rate constant (k = 0.36 h⁻¹, R² = 0.99) at 90 mg L⁻¹. This enhanced electrochemical potential of PdAgFe is associated with its strong structural and electronic characteristics. For instance, XPS analysis revealed Fe³⁺ oxidation states and a positive shift in Pd 3d binding energy to 334.32 eV, indicative of strong electronic coupling within the trimetallic framework. Our findings provide valuable insights into cost-effective Pd-engineered aerogels with transition metals to enhance the catalytic removal of DBP.