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.

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Herein, we report a facile and flexible synthesis of porous and highly faceted platinum nanoparticles (NPs) performed in the liquid phase. The synthesis is performed by reduction of platinum 2,4-pentantedionate in the presence of oleylamine and oleic acid in dibenzyl ether at 200 °C. The growth process was monitored by time-course transmission electron microscopy (TEM), revealing a peculiar progressive evolution that, in comparison with previous methodologies, is quite unusual. In fact, the morphology evolves first through nanocubes, nanostars, and dendrites to arrive at porous multifaceted NPs. This offers the possibility to selectively obtain materials with different degrees of complexity at a different time of reaction with one synthetic approach. Moreover, fine tuning of the reaction conditions was achieved by assessing, in dedicated experiments, the effects of temperature, surfactant concentration, and surfactant ratio, allowing control on NPs' dispersity and shape reproducibility. The dimensionally monodispersed NPs have a mean diameter of 52 ± 2 nm and display small regular crystallites with uniform facets exposed on the surface as evinced by high-resolution-TEM analysis. The as-prepared multifaceted platinum NPs were tested for oxygen reduction and methanol oxidation reactions exhibiting improved catalytic activity with respect to conventional Pt-based nanomaterials.