2D Graphitic Carbon Nitride for Energy Conversion and Storage

Graphitic carbon nitride (g-C3N4) have attracted great attention in the field of energy conversion and storage due to its unique layered structure, tunable bandgap, metal-free characteristic, high physicochemical stability, and easy accessibility. 2D g-C3N4 nanosheets have the features of short charge/mass transfer path, abundant reactive sites and easy functionalization, which are beneficial to optimizing their performance in different fields. However, the reviews of the comprehensive applications of 2D g-C3N4 for energy conversion and storage are rare. Herein, this review first introduces the physicochemical properties of bulk g-C3N4 and g-C3N4 nanosheets, and then summarizes the synthetic strategies of 2D g-C3N4 nanosheets in detail, such as thermal oxidation etching, chemical exfoliation, ultrasonication-assisted liquid phase exfoliation, chemical vapor deposition, and others. Emphasis is focused on the rational design and development of 2D g-C3N4 nanosheets for the diversified applications in energy conversion and storage, including photocatalytic H-2 evolution, CO2 reduction, electrocatalytic H-2 evolution, O-2 evolution, O-2 reduction, alkali-metal ion batteries, lithium-metal batteries, lithium-sulfur batteries, metal-air batteries, and supercapacitors. Finally, the current challenges and perspectives of 2D g-C3N4 nanosheets for energy conversion and storage applications are discussed.