Emerging paradigms in two-dimensional materials: Classification, synthesis, and the role of defects in electrocatalysis for water splitting and oxygen reduction reaction

The realm of two-dimensional (2D) materials, with its burgeoning array of members exceeding a thousand, presents a paradigm shift in material science, promising revolutionary applications across a spectrum of technologies. This review delineates a comprehensive classification of 2D materials into graphene and its derivatives, MXenes, chalcogenides, and 2D oxides, each characterized by unique atomic configurations and intrinsic properties. The graphene family, including novel structures like graphene and its variants, emerges as a cornerstone for electrical and filtration applications, owing to its remarkable semiconducting and nanoporous features. MXenes, identified by their singular elemental composition and anisotropic lattice structures, unveil potential in bioimaging, theragnostic, and sensing technologies. The synthesis methodologies for these 2D materials are critically analyzed. Furthermore, this review accentuates the strategic manipulation of defects within 2D materials as a pivotal methodology for tailoring their electronic, chemical, and mechanical properties to enhance application-specific performance. It elucidates how defect engineering, through the introduction of vacancies, dislocations, and heteroatom doping, can modulate the physicochemical landscape of 2D materials, thereby augmenting their functionality in energy conversion and storage. In conclusion, this review offers an in-depth exploration of the classification, synthesis strategies, and defect engineering of 2D materials, focusing on their applications. It underscores the necessity for advanced synthesis methods and intentional defect manipulation to unlock the full application spectrum of 2D materials, heralding a new era in material science and engineering. In the last future aspects are discussed to provide the future basis for research to produce efficient electrode catalysts.