Tandem catalysis in electrocatalytic nitrate reduction: Unlocking efficiency and mechanism

Abstract

The electrochemical nitrate reduction reaction (NO3RR) holds promise for ecofriendly nitrate removal. However, the challenge of achieving high selectivity and efficiency in electrocatalyst systems still significantly hampers the mechanism understanding and the large‐scale application. Tandem catalysts, comprising multiple catalytic components working synergistically, offer promising potential for improving the efficiency and selectivity of the NO3RR. This review highlights recent progress in designing tandem catalysts for electrochemical NO3RR, including the noble metal‐related system, transition metal electrocatalysts, and pulsed electrocatalysis strategies. Specifically, the optimization of active sites, interface engineering, synergistic effects between catalyst components, various in situ technologies, and theory simulations are discussed in detail. Challenges and opportunities in the development of tandem catalysts for scaling up electrochemical NO3RR are further discussed, such as stability, durability, and reaction mechanisms. By outlining possible solutions for future tandem catalyst design, this review aims to open avenues for efficient nitrate reduction and comprehensive insights into the mechanisms for energy sustainability and environmental safety.

Effects of Ionic Interferents on Electrocatalytic Nitrate Reduction: Mechanistic Insight

“…For example, one of the primary design goals can be the enhancement of adsorption affinity for NO 3 – over ionic impurities in IHP. These features could be achieved by developing materials with tandem catalytic functions, abundant oxygen vacancies or defects, or a positively charged surface via surface coatings. ,, Reconstruction of the electronic structure during electroreduction can also tailor the catalyst surface to enhance the adsorption of intermediates through the interaction with co-existing ions. ,, Developing electrodes with optimal cation-induced electric fields for the stabilization of intermediates and the dissociation of water molecules within the EDL would be of great interest. , Furthermore, given the improved selectivity for NH 3 , albeit often accompanied by an undesired increase in the HER activity, electrodes characterized by an optimal HBE are deemed ideal. , Adjusting catalytic materials to limit HER by minimizing exposure of reactive H* adsorption sites is feasible. Achieving this may involve diminishing the prevalence of surface-terminated OH* and O* groups, which function as active sites for the HER through the facilitation of hydrogen bond formation .…”

“…These features could be achieved by developing materials with tandem catalytic functions, abundant oxygen vacancies or defects, or a positively charged surface via surface coatings. 90,332,333 Reconstruction of the electronic structure during electroreduction can also tailor the catalyst surface to enhance the adsorption of intermediates through the interaction with co-existing ions. 121,334,335 Developing electrodes with optimal cation-induced electric fields for the stabilization of intermediates and the dissociation of water molecules within the EDL would be of great interest.…”

Perovskite Oxides: Syntheses and Perspectives on Their Application for Nitrate Reduction

“…Electrochemical reduction has been reportedly appraised to be highly efficient and easy to deploy, with lesser demand for adding other chemicals when compared to the techniques mentioned above . It has also been reported that electrochemical reduction is a more viable green route for achieving biological denitrification and industrial production of ammonia. , Also, the electrochemical reduction technique allows for selectivity in either producing nitrogen gas or ammonium, thus providing room for control and flexibility over the desired outcome . However, the technique is combated with the limitation of poor adsorption of nitrates and the capacity for activating adsorbed nitrates .…”

“… 10 , 12 Also, the electrochemical reduction technique allows for selectivity in either producing nitrogen gas or ammonium, thus providing room for control and flexibility over the desired outcome. 31 However, the technique is combated with the limitation of poor adsorption of nitrates and the capacity for activating adsorbed nitrates. 12 The efficiency of the electrocatalytic process has been reported to be largely influenced by the rational design of electrocatalysts.…”