Nanomaterials have recently garnered significant attention and practical importance for heterogeneous electrocatalysis. This book presents recent developments in the design, synthesis, and characterisation of nanostructured electrocatalytic materials, with a focus on applications to energy and wastewater treatment. Electrocatalytic nanomaterials can enhance process efficiency and sustainability, thus providing innovative solutions for a wide array of areas such as sustainable energy production, conversion, and wastewater treatment. Readers will gain insights into the latest breakthroughs in electrocatalysis and the activity of nanomaterials in energy conversion applications, e.g., fuel cells, hydrogen production, water splitting, and electro/photocatalytic water splitting, as well as for wastewater treatment. The book explores the development of advanced electrocatalysts, particularly hybrid materials.