TY  - CONF
AU  - Azua Humara, Ana Daniela
AU  - Luna Barron, Ana Laura
AU  - Mechler, Anna
AU  - Eichel, Rüdiger-A.
TI  - Understanding Nitrate Electrochemical Reduction to Ammonia by Identifying Changes in pH
PB  - RWTH Aachen
M1  - FZJ-2025-00028
PY  - 2024
AB  - Electrochemical nitrate reduction into ammonia is an attractive technology that promotes nitrates removal from wastewater while delivering ammonia as a profitable product.[1] Electrochemical nitrates S reduction to ammonia in aqueous media under ambient conditions has been reported, using noble metal-based electrodes (e.g., Ru, Rh, Pt). [2] It has been shown that the nitrates reduction is a complex process due to its polyatomic nature, forming several intermediate compounds before its complete reduction into ammonia. The ammonia selectivity depends on the electrocatalyst, the applied potential, and the electrolyte media. [3] Jaramillo’s group studied the effect of the initial pH electrolyte on the ammonia Faradaic efficiency, concluding ammonia formation is favored at low pH (<1).[1] Clearly, pH plays an essential role in nitrates reduction. However, there is limited knowledge of pH changes through the reaction, since only initial pH is reported, and how and why such changes impact the ammonia selectivity. In this work, the changes in pH during the electrochemical reduction of nitrates to ammonia are evaluated using Ti and Cu-foils. We investigate four different electrolytes ranging from pH 1 to pH 10, tracking the changes in pH over the course of a 30 min experiment. Our results show that when the initial pH is equal to or above pH 3 the media undergoes alkalinization, reaching pH values close to 12.  On the other hand, in acidic conditions the pH only increases slightly. In addition, the highest faradaic efficiency is obtained at more alkaline initial conditions. The intermediate products are also detected and correlated to the pH increase.
T2  - Gesellschaft Deutscher Chemiker - Electrochemistry 2024
CY  - 16 Sep 2024 - 19 Sep 2024, Braunschweig (Germany)
Y2  - 16 Sep 2024 - 19 Sep 2024
M2  - Braunschweig, Germany
LB  - PUB:(DE-HGF)24
UR  - https://juser.fz-juelich.de/record/1034907
ER  -