Rational Design of a {InCu ₆ } Heterometallic Oxo Cluster for Superior Proton Conduction: Mechanistic Insights and Humidity Gradient‐Based Power Generation

ABSTRACT This study employs a template‐directed assembly strategy to synthesize the first In 3+ /Cu 2+ heterometallic oxo cluster, {InCu 6 } . {InCu 6 } costabilized by l ‐(+)‐tartaric and acetic acids, features a central InO 6 octahedron surrounded by six Cu 2+ ions. Benchmarked against structurally analogous heterometallic oxo clusters, {InCu 6 } demonstrates superior proton conductivity of 7.95 × 10 −2 S cm −1 at 30°C and 90% relative humidity (RH). DFT calculations indicate that the introduction of In 3+ significantly reduces the energy barrier for proton detachment from the oxygen atoms in {InCu 6 } , thus elucidating the kinetic mechanism by which In 3+ /Cu 2+ synergy enhances the conduction efficiency. To translate this molecular performance into a functional device for humidity gradient‐based power generators (HGPGs), a novel cationic polymer ( PVA‐CTPP + Br − ) was designed and synthesized as the matrix to form a uniform PVA‐CTPP + ‐{InCu 6 } composite film. The resulting planar generator demonstrated stable performance, delivering an output of 0.63 V and 14.3 µA cm −2 at 92% RH and room temperature.