Elektrokatalyysin

Elektrokatalyysin, or electrocatalysis, is the acceleration of electrochemical reactions at electrode surfaces by catalysts. The catalyst lowers activation barriers and overpotential, enabling faster reaction rates without being consumed in the process. Electrocatalytic reactions involve electron transfer and surface adsorption, and occur in systems such as electrolyzers, fuel cells, and electrochemical reactors.

The mechanism often combines adsorption of reactants on active sites, electron transfer between the electrode and species, and sometimes coupled proton transfer. The activity and selectivity depend on surface structure, electronic properties, and the reaction environment. Common catalysts include noble metals (platinum, palladium, ruthenium, iridium), transition metals and alloys (nickel, cobalt, iron), metal sulfides, and carbon-based supports, including single-atom catalysts.

Key applications are energy-related: hydrogen evolution and oxygen evolution in water splitting, oxygen reduction in fuel cells, and electrochemical reduction of carbon dioxide to fuels or chemicals. Electrokatalysis also enables nitrogen reduction to ammonia and various sensing and remediation processes.

Historically, ideas trace back to early electrochemistry work inspired by Faraday. The term gained prominence with advances in catalysis and materials science. Researchers use metrics such as overpotential, exchange current density, and Tafel slope to quantify performance, often with operando spectroscopic tools.

Current challenges include achieving high activity and selectivity at low cost, ensuring long-term stability, and preventing catalyst poisoning or degradation. Ongoing research explores nanoscale design, alloying, single-atom catalysts, and novel supports to improve efficiency and durability.