Germanium-based monoelemental and binary two-dimensional materials:Theoretical and experimental investigations and promising applications

Two-dimensional(2D)materials based on group IVA elements have attracted extensive attention owing to their rich chemical structures and novel proper-ties.This comprehensive review focuses on the phases of Ge monoelemental and binary 2D materials including germanene and its derivatives,Ge-IVA binary compounds,Ge-VA binary compounds,and Ge-VIA binary compounds.The latest progress in predictive modeling,fabrication,and fundamental and physical property modulation of their stable 2D configurations are presented.Accordingly,various interesting applications of these Ge-based 2D materials are discussed,particularly field effect transistors,photodetectors,optical devices,catalysts,energy storage devices,solar cells,thermoelectric devices,sensors,biomedical materials,and spintronic devices.Finally,this review con-cludes with a few perspectives and an outlook for quickly expanding the appli-cation scope Ge-based 2D materials based on recent developments.