Abstract
<jats:p>Thermogalvanic cells convert thermal gradients into electrical voltage through temperature-dependent redox equilibria. Controlling the reaction entropy of redox couples is therefore central to molecular design for low-grade heat utilization. Here, we show that charged metal-organic polyhedra (MOP s)provide structurally defined molecular platforms for tuning thermogalvanic redox entropy in aqueous media. Ru-based MOPs combine multielectron redox chemistry with tunable peripheral charge environments and molecular-scale dispersibility in solution. Comparison of cationic t-Bu-RuMOP and anionic SO3-RuMOP shows that molecular surface charge governs the sign of the thermogalvanic response, giving positive and negative temperature coefficients, respectively. The identity of the supporting cation further modulates the redox thermodynamics of SO 3-RuMOP, leading to distinct temperature coefficients and corresponding Seebeck coefficients. The resulting nonmonotonic cation trend is consistent with Hofmeister-type specific ion effects at the sulfonate-rich surface. These results establish charged MOPs as molecular nanofluid platforms for thermogalvanic entropy engineering, where molecular surface charge controls the directio n of redox-entropy change and counterion identity tunes its magnitude.</jats:p>