Plasmmonia · Electrochemical reduction of molecular nitrogen to ammonia using plasmonic catalysts: Towards more sustainable ammonia production

Ammonia (NH3) production is essential for human development, as it is a key precursor in manufacturing synthetic fertilizers, chemicals, and hydrogen storage. Currently, NH3 is produced via the Haber-Bosch (H-B) method. Achieving sustainable alternatives to the H-B process will significantly contribute to the climate, environmental protection, and energy efficiency goals of the EU's 2030 Plan. The electrochemical reduction of molecular nitrogen (eNRR) to obtain NH3 is one of today's most promising routes. This methodology allows the direct conversion of N2 and water into NH3 at normal temperature and pressure without CO2 emissions. Due to their unique optical properties, an innovative strategy to improve eNRR involves using plasmonic-metal nanoparticles (NPs) as electrocatalysts. The excitation of the surface electrons occurs by illuminating the plasmonic substrates, generating localized surface plasmon resonance (LSPR). LSPR provides an additional source of high-energy electrons to the electrocatalytic system, which can increase efficiency and improve selectivity towards NH3 formation. This plasmonic-electrochemical combination is termed Plasmon-Assisted Catalysis. This research aims to design, synthesize, and characterize plasmonic NPs made of Au, Cu, and Au/Cu alloys to maximize their activity as electrocatalysts for eNRR. The synthesis of NPs with different morphologies will be carried out through various chemical, and hydrothermal methods. The evaluation of the electrocatalytic activity will be conducted in an H-type electrochemical cell and the different synthesized electrocatalysts be supported on carbonaceous electrodes as the working electrode. The activity and stability of the materials will also be evaluated using aqueous and ionic liquids as electrolytes. Furthermore, real-time monitoring of the electrochemical process and determination of the eNRR mechanism will be achieved through in situ spectroelectrochemical techniques (SEIRAS, SERS).