Electrocatalytic nitrate reduction to ammonia (NitRR) represents a highly promising green route for ammonia (NH 3 ) synthesis. However, NitRR involves complex multi-step reactions, and its efficiency and selectivity are largely governed by the supply balance of active hydrogen (*H). A comprehensive understanding of *H behavior is essential for achieving precise regulation of *H. Yet, *H is a transient, highly reactive intermediate that is difficult to capture using conventional characterization methods. Therefore, developing in situ electrochemical characterization techniques capable of monitoring its behavior in real time under authentic reaction conditions is of critical importance.
Despite the central role of *H as a key intermediate, a systematic review on how to rationally select in situ electrochemical characterization techniques for its in situ , real-time probing remains absent. In particular, there is a lack of clear definition regarding the “detection targets, quantitative accuracy, and application boundaries” of these advanced techniques when applied to probe *H. This methodological gap hinders a deeper understanding of the microscopic mechanisms underlying *H-mediated reactions.
This review focuses on in situ electrochemical characterization techniques, systematically summarizing their fundamental principles and application examples in deciphering *H behavior during NitRR. Furthermore, it discusses how different techniques can directly detect or indirectly reflect the generation and consumption of *H, evaluates their quantitative analysis capabilities, and clarifies the advantages and applicable scopes of various methods. By clearly defining the “detectable targets, quantitative accuracy, and application boundaries” of each technique, this review serves as a definitive guide for researchers aiming to master the art of *H management. The authors also highlight future directions, including the development of multimodal coupled techniques and standardized characterization frameworks to accelerate the transition of NitRR from lab curiosity to industrial reality.
The work titled “ In s itu Electrochemical Characterization Techniques for Active Hydrogen in Electrocatalytic Nitrate Reduction to Ammonia ”, was published in Journal of Electrochemistry (published on August 28, 2026).
Journal of Electrochemistry
Experimental study
Not applicable
In situ Electrochemical Characterization Techniques for Active Hydrogen in Electrocatalytic Nitrate Reduction to Ammonia
28-Aug-2026