The paper by Nørskov et al. (2005) investigates the trends in the exchange current for hydrogen evolution. Using density functional theory (DFT) calculations, they determine hydrogen chemisorption energies on various transition and noble metals. These energies are used to understand the trends in the exchange current, which is the rate of hydrogen evolution per unit area at equilibrium. A volcano curve is observed when exchange currents are plotted against hydrogen adsorption energies, indicating that Pt is the most efficient electrocatalyst for hydrogen evolution. The volcano curve is explained by a simple kinetic model, showing that the reaction is thermo-neutral on Pt, making it highly effective. The study also discusses the relationship between the volcano curve and other volcano curves in electrochemistry. The results demonstrate that the exchange current is influenced by the thermochemistry of the reaction, and that the volcano curve provides a systematic way to understand the intrinsic H-metal interaction energy. The paper also addresses the effect of surface coverage and the possibility of surface oxide coverage on the measured exchange currents. The findings suggest that the volcano curve is a useful tool for predicting bimetallic electrocatalysts for hydrogen evolution and for hydrogen electro-oxidation in fuel cells.The paper by Nørskov et al. (2005) investigates the trends in the exchange current for hydrogen evolution. Using density functional theory (DFT) calculations, they determine hydrogen chemisorption energies on various transition and noble metals. These energies are used to understand the trends in the exchange current, which is the rate of hydrogen evolution per unit area at equilibrium. A volcano curve is observed when exchange currents are plotted against hydrogen adsorption energies, indicating that Pt is the most efficient electrocatalyst for hydrogen evolution. The volcano curve is explained by a simple kinetic model, showing that the reaction is thermo-neutral on Pt, making it highly effective. The study also discusses the relationship between the volcano curve and other volcano curves in electrochemistry. The results demonstrate that the exchange current is influenced by the thermochemistry of the reaction, and that the volcano curve provides a systematic way to understand the intrinsic H-metal interaction energy. The paper also addresses the effect of surface coverage and the possibility of surface oxide coverage on the measured exchange currents. The findings suggest that the volcano curve is a useful tool for predicting bimetallic electrocatalysts for hydrogen evolution and for hydrogen electro-oxidation in fuel cells.