Enhancing the Accuracy of Urea Quantification in Electrocatalysis Through a Modified Diacetylmonoxime-thiosemicarbazide Detection Protocol
Diksha Mittal a b, Viktoria Golovanova a, F. Pelayo Garcia de Arquer a
a ICFO- The Institute of Photonic Sciences, Mediterranean Technology Park, Avinguda Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona
b Indian Institute of Science Education and Research Berhampur, India
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Spring 2024 Conference (MATSUS24)
#MatInter - Materials and Interfaces for emerging electrocatalytic reactions
Barcelona, Spain, 2024 March 4th - 8th
Organizers: Marta Costa Figueiredo and María Escudero-Escribano
Poster, Diksha Mittal, 518
Publication date: 18th December 2023

Electrocatalytic synthesis of urea by co-reduction of CO2 and activated-nitrogen species (NO3¯) has garnered significant attention to sustainably address the rising global need for nitrogen-based fertilizers (as opposed to the carbon-intensive Haber-Bosch-Meiser process). Despite numerous advances in achieving C-N coupling, the low urea yields at low current densities (16 μmol h-1 cm-1)[1] pose a significant challenge to its accurate quantification. The issue of nitrogen-based contamination from the surroundings, which leads to false positives in electrochemical ammonia synthesis,[2] is well known but relatively underexplored in the context of urea electrosynthesis.[3,4] Among various methods for urea detection, the conventional diacetylmonoxime-thiosemicarbazide (DAMO-TSC) colorimetric method has a low limit of quantification and is most commonly used. However, it is susceptible to environmental interferences, mainly NO2¯ as a significant by-product, leading to false positive or negative results. Here, we explore the role of NO2¯ in causing suppression or over-expression of urea and alleviate its effect with a modification in the traditional DAMO-TSC method.[5,6] The improved method can effectively remove NO2¯ up to 5 mM in the extracted electrolyte, allowing reliable and accurate urea quantification. Investigating the impact of our methodology using various catalysts on a gas diffusion electrode, we found that NO2¯ interference resulted in a twofold increase in the quantity of urea determined using the conventional DAMO-TSC method compared to the quantity determined after NO2¯ suppression.

Our findings highlight the importance of accurate urea quantification protocols to enable solid progress in sustainable C-N coupling technologies, ensuring reliable and reproducible results.

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