Ligand-Mediated Hydrogenic Defects in Two-Dimensional Electrically Conductive Metal-Organic Frameworks

Compared to dense analogues, high-surface-area metals offer several key advantages in electrocatalysis and energy storage. Of the porous manifolds, metal-organic frameworks (MOFs) boast the highest known surface area of any material class, and a subset of known frameworks also conduct electricity. The premier conductive scaffolds, Ni3(HITP)2 and Ni3(HIB)2, are both predicted to be metallic, but experiments have yet to measure bulk metallicity. In this paper, we explore the thermodynamics of hydrogen vacancies and interstitials and demonstrate that interstitial hydrogen is a plausible and prevalent defect in the conductive MOF family. The existence of this defect is predicted to render both Ni3(HITP)2 and Ni3(HIB)2 as bulk semiconductors, not metals, and emphasizes that hydrogenic defects play a critical role in determining the bulk properties of conductive MOFs.