First-principles DFT calculations and AIMD simulations were carried out to provide a detailed atomistic understanding of the underlying reactions and energetics. In line with our previous work, we carried out periodic AIMD simulations in the canonical (NVT) ensemble using the Vienna Ab initio Simulation Package (VASP) to obtain the hydration shells for the key solution-phase species and the dynamics of radical intermediates in the solution. The solvated molecular structures established from the AIMD simulations were subsequently optimized with the Gaussian-16 software program to determine the energetics for these species and the reaction energies for corresponding redox reactions (see SI for details). Thermodynamic redox potentials and the inner-and outer-sphere reorganization energies were subsequently calculated and used along with Marcus theory to determine the electron-transfer barriers for reactions involved in the S2O8 2-/C2O4 2-autocatalytic reaction cycle. Our previous work described, in detail, the mediated reduction of S2O8 2-to SO4 •-using the outer-sphere Ru(NH3)6 3+/2+ redox electrocatalyst. Ru(NH3)6 3+ is first reduced at the electrode to form Ru(NH3)6 2+ (eq 17), which subsequently reduces S2O8 2-to S2O8 3•-in a rate-limiting step with a free energy barrier of ∆𝐺 ǂ = 62 kJ/mol and regenerates Ru(NH3)6 3+ , eq 18 (Scheme 4). S2O8 3•- rapidly disproportionates to form SO4 2-and the highly oxidizing SO4 •-species (eq 8).