Enhanced proton conductivity by incorporating sulfonic acid groups into a zirconium-based metal-organic framework via ligand exchange

Herein, the postsynthetic ligand exchange process was adopted to construct a series of 1,4-naphthalenedicarboxylic acid (H2NDC) and 6-sulfonate-1,4-naphthalenedicarboxylic acid (H3SNDC) based Zr(IV)-MOFs (Zr-(NDC)(x)(SNDC)(1-x)). This strategy anchored functional sulfonic acid groups in the pore of the MOFs. Among them, Zr-(NDC)(0.3)(SNDC)(0.7) exhibited outstanding proton conductivity of 3.18 x 10(-4) S cm(-1) at 90 degrees C and 98% relative humidity (RH), which was approximately three orders of magnitude greater than that of pristine Zr-NDC. This work demonstrated a facile in situ ligand exchange approach for constructing functional group modified MOFs with high proton conductivity.

Automated summary

Herein, a series of Zr(IV)-MOFs (Zr-(NDC)(x)(SNDC)(1-x)) based on 1,4-naphthalenedicarboxylic acid (H2NDC) and 6-sulfonate-1,4-naphthalenedicarboxylic acid (H3SNDC) were constructed using the postsynthetic ligand exchange process. Functional sulfonic acid groups were anchored in the pores of the MOFs. Among them, Zr-(NDC)(0.3)(SNDC)(0.7) exhibited exceptional proton conductivity of 3.18 x 10(-4) S cm(-1) at 90 degrees C and 98% relative humidity (RH), which was significantly higher than pristine Zr-NDC. This work demonstrates a facile in situ ligand exchange approach for constructing functional group modified MOFs with high proton conductivity.