Energy production and storage by electrocatalysis

The development of efficient, cost-effective electrocatalysts is crucial for sustainable energy conversion, including hydrogen production and fuel cells. This doctoral research addresses the design, synthesis, characterization, and implementation of advanced non-noble, hybrid, and bimetallic electrocatalysts for key reactions such as hydrogen evolution (HER), hydrogen oxidation (HOR), oxygen reduction (ORR), and formate oxidation. A self-supported MoO₃₋ₓ/NiMoO₄ powder was synthesized using NiO nanopowder as a structural template. Thermal annealing at 600°C generated sub-stoichiometric Mo oxides and enhanced surface roughness, improving active site accessibility and catalyst–membrane contact. The material exhibited high HER activity in threeelectrode tests and stable operation in 5 cm² and 78.5 cm² AEM electrolyzers, demonstrating its scalability and potential for PGM-free hydrogen production. Silver-supported metal phthalocyanines (M-Pc@Ag/C, M = Fe, Co, Ni, Cu) were developed for ORR in alkaline media. FePc@Ag/C showed the highest onset potential and current density, promoting a selective four-electron reduction to water. The combination of conductive Ag nanoparticles and active metal centers enhanced electron transfer, catalyst dispersion, and surface stability, offering a viable non-PGM alternative to platinum. PdAu bimetallic nanoparticles were prepared via Metal Vapour Synthesis, yielding ultrasmall, ligand-free alloys with Pd-rich cores and Au-enriched surfaces. In direct formate fuel cells, PdAu/C showed higher power density, increased electrochemical surface area, and improved stability compared to Pd/C, highlighting the benefits of nanoscale alloy engineering. Finally, Pd@Ni4W/C catalysts for HER and HOR exhibited superior Pd mass activity (up to 463 A g⁻¹Pd) and reduced charge-transfer resistance, confirming enhanced kinetics and synergistic interactions. Overall, this work demonstrates scalable strategies for synthesizing highperformance electrocatalysts, elucidates structure–activity–stability relationships, and provides a framework for translating lab-scale materials into device-level applications, advancing sustainable hydrogen production and energy conversion technologies.