The electrochemical dinitrogen reduction reaction (NRR) has recently gained much interest as it can potentially produce ammonia from renewable intermittent electricity and replace the Haber-Bosch process. Previous literature studies report Fe- and Mo-carbides as promising electrocatalysts for the NRR with activities higher than other metals. However, recent understanding of extraneous ammonia and nitrogen oxide contaminations have challenged previously published results. Here, we critically assess the NRR performance of several Fe- and Mo-carbides reported as promising by implementing a strict experimental protocol to minimize the effect of impurities. The successful synthesis of α-Mo₂C decorated carbon nanosheets, α-Mo₂C nanoparticles, θ-Fe₃C nanoparticles, and χ-Fe₅C₂ nanoparticles was confirmed by X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron and Mössbauer spectroscopy. After performing NRR chronoamperometric tests with the synthesized materials, the ammonia concentrations varied between 37 and 124 ppb and are in close proximity with the estimated ammonia background level. Notwithstanding the impracticality of these extremely low ammonia yields, the observed ammonia did not originate from the electrochemical nitrogen reduction but from unavoidable extraneous ammonia and NO_x impurities. These findings are in contradiction with earlier literature studies and show that these carbide materials are not active for the NRR under the employed conditions. This further emphasizes the importance of a strict protocol in order to distinguish between a promising NRR catalyst and a false positive.

N-doped carbon materials can be efficient and cost-effective catalysts for the electrochemical CO₂ reduction reaction (CO₂RR). Activators are often used in the synthesis process to increase the specific surface area and porosity of these carbon materials. However, owing to the diversity of activators and the differences in physicochemical properties that these activators induce, the influence of activators used for the synthesis of N-doped carbon catalysts on their electrochemical performance is unclear. In this study, a series of bagasse-derived N-doped carbon catalysts is prepared with the assistance of different activators to understand the correlation between activators, physicochemical properties, and electrocatalytic performance for the CO₂RR. The properties of N-doped carbon catalysts, such as N-doping content, microstructure, and degree of graphitization, are found to be highly dependent on the type of activator applied in the synthesis procedure. Moreover, the overall CO₂RR performance of the synthesized electrocatalysts is not determined only by the N-doping level and the configuration of the N-dopant, but rather by the overall surface chemistry, where the porosity and the degree of graphitization are jointly responsible for significant differences in CO₂RR performance.

Copper is one of the most promising catalysts for the CO₂ reduction reaction (CO₂RR) due to its unique capability of producing multicarbon products in appreciable quantities. Most of the CO₂RR research efforts have been directed towards the development of new electrocatalysts to either increase product selectivities or decrease overpotentials. In contrast, only a few studies have systematically tested or benchmarked CO₂RR performances of electrocatalysts. In this paper, for the first time, the performances of five different polycrystalline copper foils purchased from different suppliers are benchmarked for their CO₂RR performance. Their differences are characterized in terms of microstructural features and the effect that these microstructural properties have on the electrocatalytic behavior during potentiostatic CO₂RR experiments are evaluated. It is shown that the potential applied is the dominant factor controlling CO₂RR selectivities, leading to the conclusion that microstructural properties of polycrystalline copper electrodes have a negligible effect on the outcome of CO₂RR experiments.