Sulfonate-Functionalized Metal-Organic Framework as a Porous "Proton Reservoir" for Boosting Electrochemical Reduction of Nitrate to Ammonia.

The electrochemical reduction reaction of nitrate (NORR) is an attractive route to produce ammonia at ambient conditions, but the conversion from nitrate to ammonia, which requires nine protons, has to compete with both the two-proton process of nitrite formation and the hydrogen evolution reaction. Extensive research efforts have thus been made in recent studies to develop electrocatalysts for the NORR facilitating the production of ammonia. Rather than designing another better electrocatalyst, herein, we synthesize an electrochemically inactive, porous, and chemically robust zirconium-based metal-organic framework (MOF) with enriched intraframework sulfonate groups, SO-MOF-808, as a coating deposited on top of the catalytically active copper-based electrode.