Structural Effects in Polyoxometalate‐Based Supramolecular Assemblies for Enhanced Proton Conduction
Bo Hu, Bailing Liu, Qingqing Pan, Hongda Ren, Feiyang Yu, Qiuchen Du, Yang‐Guang Li, Hong‐Ying Zang
Abstract
Abstract Proton conductors with engineered charge‐assisted hydrogen‐bonding networks are pivotal for advancing proton exchange membrane fuel cells (PEMFCs). Herein, a novel proton‐conducting supramolecular clusters, ([Bi 6 O 5 (OH) 3 ] 2.24 [PW 12 O 40 ] 1 [NO 3 ] 2.4 [H 3 O] 5.8 , BPN) has been synthesized and characterized. Molecular dynamics (MD) simulations reveal that charge‐assisted dynamic O─H⋯O hydrogen bonds mediate the supramolecular assembly, while water molecules facilitate proton transport pathways. The material exhibits a maximum proton conductivity of 0.12 S cm −1 at 90 °C and 97% (RH) relative humidity, which is comparable to that of Nafion. The spin‐lattice relaxation time ( T 1 ) of the Bi–O adsorbed protons is significantly shorter than that of the W‐O adsorbed protons, indicating that the protons at the Bi–O sites have a higher migration rate. 1 H magic‐angle spinning NMR ( 1 H MAS NMR) and density functional theory (DFT) calculations reveal [Bi 6 O 8 ] enhances proton mobility, while [PW 12 O 40 ] stabilizes transition states, lowering the activation barrier to 0.14 eV. The BPN‐Nafion hybrid membrane enhances direct methanol fuel cell performance with an open‐circuit voltage of 0.82 V and power density of 86 mW cm −2 . This integrative design strategy—synergizing inorganic cluster units with dynamic hydrogen‐bonding networks—establishes a scalable platform for developing PEMFC materials with programmable proton transport pathways and improved operational stability.