Photodissociation of PdCl₄^2- in aqueous/EtOH solution using TDDFT calculations

Nuclear spent fuel discharged from atomic power plant contain platinum group elements (PtGs) such as palladium. Recently, it is proposed to be reused as resource by separation and recovery of PtGs from nuclear spent fuel. We focused on that laser-induced can reduce metal and separate element. We proposed and succeed a method for the separation of PtGs using laser-induced particle formation (LPF) and recovery after growing to nanoparticle. The irradiation of UV laser at 266 nm induced the reduction of Pd²⁺ in aqueous/EtOH solution, which has charge-transfer absorption band at UV range, neutralizing Pd²⁺ into Pd⁰ [1]. In this study, we report dissociation energy and absorbed spectrum for n-Cl (n = 1-4) loss from PdCl₄^2- in the gas phases and aqueous/EtOH solution by TD-DFT and Complete Active Space Multiconfiguration SCF calculations performed with B3LYP, SDD for Pd and 6-311+G(d,p) for Cl using Gaussian 16.
As a results, we assume 4Cl^- loss from the PdCl₄^2- and calculate low-lying potential energy curves where the binding energy of ground state and excited states of PdCl₄^2- for Pd-Cl bond length. We clear that PdCl₄^2- is dissociate into Pd0, 2Cl^- and 2Cl.
[1] M.Saeki, et al., J. Phys. Chem. C 123 (2019) 817