Understanding the Wettability of C₁N₁ (Sub)Nanopores: Implications for Porous Carbonaceous Electrodes <jats:title>Abstract</jats:title><jats:p>Understanding how water interacts with nanopores of carbonaceous electrodes is crucial for energy storage and conversion applications. A high surface area of carbonaceous materials does not necessarily need to translate to a high electrolyte‐solid interface area. Herein, we study the interaction of water with nanoporous C<jats:sub>1</jats:sub>N<jats:sub>1</jats:sub> materials to explain their very low specific capacitance in aqueous electrolytes despite their high surface area. Water was used to probe chemical environments, provided by pores of different sizes, in <jats:sup>1</jats:sup>H MAS NMR experiments. We observe that regardless of their high hydrophilicity, only a negligible portion of water can enter the nanopores of C<jats:sub>1</jats:sub>N<jats:sub>1</jats:sub>, in contrast to a reference pure carbon material with a similar pore structure. The common paradigm that water easily enters hydrophilic pores does not apply to C<jats:sub>1</jats:sub>N<jats:sub>1</jats:sub> nanopores below a few nanometers. Calorimetric and sorption experiments demonstrated strong water adsorption on the C<jats:sub>1</jats:sub>N<jats:sub>1</jats:sub> surface, which restricts water mobility across the interface and impedes its penetration into the nanopores.</jats:p> 63 50 Wiley