<p>Inorganic, organic, and hybrid two-dimensional (2D) materials are being developed for ever-expanding numbers of applications, though energy and catalysis remain the main drivers of their development. We present overviews of bottom-up and top-down synthetic strategies of such materials and examine manufacturing scalability issues. Mechanical, electrical, and thermal properties and their modulation are highlighted because they are fundamental to the above-mentioned drivers. The burgeoning importance of heterostructures in such materials, particularly for catalysis and electrode design and function is stressed. Detailed attention is given to applications of 2D materials to the electrocatalysis reactions: oxygen reduction, oxygen evolution, hydrogen evolution, carbon dioxide reduction, and nitrogen reduction. Water splitting, carbon dioxide reduction, and nitrogen reduction by photocatalysis are also examined. A perspective of expected advances in the expansion of applications and types of 2D materials, with a focus on heterostructure development, is presented in the conclusion.</p>