Fast Screening Method for Nitrogen Reduction Reaction (NRR) Electrocatalytic Activity with Rotating Ring‐Disc Electrode (RRDE) Analysis in Alkaline Environment

Abstract

The Haber‐Bosch process for NH3 production leads to a considerable greenhouse gas release due to the remarkable use of fossil fuels. Therefore, there is an increasing interest in developing alternative and environmental friendly approaches. Among the possible solutions, the electrocatalytic conversion of N2 has recently gained significant attention; on the other hand, not only scientific but also important technical aspects remain fundamental issues to be clarified. Particularly relevant is the need to improve the analytical protocols to ascertain that any detected NH3 is actually produced from N2 rather than from any external contaminations or partial decomposition of the catalyst itself. Here, a rotating ring‐disc electrode (RRDE) setup is used for the first time to study the N2 electroreduction process with the aim to recognize the product species formed at the disc and detected at the ring electrodes, respectively. We demonstrated that this experimental approach is effective to discern also a low‐level ammonium concentration through monitoring the ammonia oxidation peak at the ring electrode for a fast and preliminary electrocatalytic performance evaluation and to prevent false positives. The versatility of the RRDE method employed as a fingerprint of new electrocatalyst candidates could allow to reserve time and cost.

On the Optimization of Nitrogen‐Reduction Electrocatalysts: Breaking Scaling Relation or Catalytic Resonance Theory?

“…In a sustainable energy economy, alternatives for the large‐scale production of ammonia are urgently needed [11] . Here, electrochemical nitrogen reduction reaction (NRR), preferably in aqueous electrolytes because water as solvent is non‐toxic, comes into play [12–14] . The NRR, catalyzed by a solid‐state material, can be considered as an environmentally benign reaction route for ammonia formation if the required electricity is supplied from renewable solar or wind energy [15] .…”

“…[11] Here, electrochemical nitrogen reduction reaction (NRR), preferably in aqueous electrolytes because water as solvent is non-toxic, comes into play. [12][13][14] The NRR, catalyzed by a solid-state material, can be considered as an environmentally benign reaction route for ammonia formation if the required electricity is supplied from renewable solar or wind energy. [15] Yet, this process is still in its infancy due to the low solubility of N 2 in water, the competing hydrogen evolution reaction (HER) under cathodic reaction conditions, and the slow reaction kinetics due to the transfer of six proton-electron pairs to form NH 3 .…”

Atomic‐Layer‐Deposited Oxygen‐Deficient TiO2 on Carbon Cloth: An Efficient Electrocatalyst for Nitrogen Fixation

“…Specifically, 0.01 M H 2 SO 4 solution was used to remove possible NH 3 in N 2 and Ar, and the de‐NO X tank was used to remove possible trace NO X impurities and water vapor from the gas. We cleaned all electrochemical components (sulfuric acid absorption solution, Nafion 211 membrane, catalyst and cathode chamber) and gas in the experimental device several times before each measurement [48,49] . The sweep rate of the linear sweep voltammetry (LSV) polarization curve in the experiment was 1.0 mV s −1 .…”

Revealing Ammonia Quantification Minefield in Photo/Electrocatalysis

“…The experimental results indicated that the IC can be optimized to meet the low‐concentration quantitative requirements and the optimized ion chromatography with customized loop size was employed in our following experiments. Furthermore, the frequency‐selective NMR method as an advanced ammonia quantification method offers many advantages (high sensitivity, good reproducibility, straightforward discrimination against contaminant NH 3 , and convenience without the need for NH 3 transfer or advanced chemical manipulation) [11b] . Each 1 H NMR spectrum consists of an accumulation of 128 scans for a total experiment time of ≈10 min, which is comparable to the detection efficiency of ion chromatography.…”