This lecture covers the fundamental and applied aspects of electrocatalysis for renewable energy conversion and storage, focusing on catalysis for hydrogen evolution, oxygen evolution, and CO2 reduction reactions. It discusses the importance of catalyst performance in hydrogen evolution, the challenges of using Pt as a catalyst, the potential of MoS2 as a catalyst, and the computational methods for catalyst design. The lecture also explores the active edge sites for electrochemical H2 evolution from MoS2 nanocatalysts and the role of DFT-based catalyst design in understanding hydrogen evolution mechanisms.