Heteroatom-doped graphene materials: syntheses, properties and applications Heteroatom doping can endow graphene with various new or improved electromagnetic, physicochemical, optical, and structural properties. This greatly extends the arsenal of graphene materials and their potential for a spectrum of applications. Considering the latest developments, we comprehensively and critically discuss the syntheses, properties and emerging applications of the growing family of heteroatom-doped graphene materials. The advantages, disadvantages, and preferential doping features of current synthesis approaches are compared, aiming to provide clues for developing new and controllable synthetic routes. We emphasize the distinct properties resulting from various dopants, different doping levels and configurations, and synergistic effects from co-dopants, hoping to assist a better understanding of doped graphene materials. The mechanisms underlying their advantageous uses for energy storage, energy conversion, sensing, and gas storage are highlighted, aiming to stimulate more competent applications. Heteroatom doping can alter the physicochemical and electronic properties of graphene. Tailoring graphene properties by interacting molecules, which either donate or withdraw free electrons, has been demonstrated in many studies and discussed in recent review articles. Herein, we focus the discussion on the doping of graphene with various heteroatoms (oxygen, boron, nitrogen, phosphor, sulfur, etc.), i.e., the graphitic carbon atoms are substituted or covalently bonded by foreign atoms. Although several review articles focusing on specific dopants or particular applications have been published, a more comprehensive and comparative review on this important and quickly evolving topic is necessary. In this article, the synthesis methods, properties and applications of graphene materials doped with various heteroatoms are reviewed extensively. We aim to cover the latest developments, underscore physical mechanisms, highlight unique application-specific advantages conferred by doping, and provide insightful comparison between doped and pristine graphene, different synthesis routes, different dopant atoms, and different doping configurations. Table 1 Summary of graphene doping techniques 2.1 In situ doping 2.1.1 Chemical vapor deposition (CVD). Many CVD methods have been developed to synthesize large, continuous, defect-free, single- or few-layered graphene films. The catalytic growth mechanism makes it a convenient route to dope heteroatoms during the formation of graphene films, particularly to incorporate heteroatoms directly into the graphitic carbon lattices. A large variety of methods have already been developed for the synthesis of graphene materials, from which various doping strategies could be derived. The current methods for heteroatom doping can be categorized into in situ approaches and post-treatment approaches. In situ approaches, which simultaneously achieve graphene synthesis and heteroatom doping, include chemical vapor deposition (CVD), ball milling, and bottom-up synthesis. Post-treatment methods include wet chemical methods, thermal annealing of graphene oxides (GO) with heteroatom precursors, plasma and arc-discharge approaches. In this section, theseHeteroatom-doped graphene materials: syntheses, properties and applications Heteroatom doping can endow graphene with various new or improved electromagnetic, physicochemical, optical, and structural properties. This greatly extends the arsenal of graphene materials and their potential for a spectrum of applications. Considering the latest developments, we comprehensively and critically discuss the syntheses, properties and emerging applications of the growing family of heteroatom-doped graphene materials. The advantages, disadvantages, and preferential doping features of current synthesis approaches are compared, aiming to provide clues for developing new and controllable synthetic routes. We emphasize the distinct properties resulting from various dopants, different doping levels and configurations, and synergistic effects from co-dopants, hoping to assist a better understanding of doped graphene materials. The mechanisms underlying their advantageous uses for energy storage, energy conversion, sensing, and gas storage are highlighted, aiming to stimulate more competent applications. Heteroatom doping can alter the physicochemical and electronic properties of graphene. Tailoring graphene properties by interacting molecules, which either donate or withdraw free electrons, has been demonstrated in many studies and discussed in recent review articles. Herein, we focus the discussion on the doping of graphene with various heteroatoms (oxygen, boron, nitrogen, phosphor, sulfur, etc.), i.e., the graphitic carbon atoms are substituted or covalently bonded by foreign atoms. Although several review articles focusing on specific dopants or particular applications have been published, a more comprehensive and comparative review on this important and quickly evolving topic is necessary. In this article, the synthesis methods, properties and applications of graphene materials doped with various heteroatoms are reviewed extensively. We aim to cover the latest developments, underscore physical mechanisms, highlight unique application-specific advantages conferred by doping, and provide insightful comparison between doped and pristine graphene, different synthesis routes, different dopant atoms, and different doping configurations. Table 1 Summary of graphene doping techniques 2.1 In situ doping 2.1.1 Chemical vapor deposition (CVD). Many CVD methods have been developed to synthesize large, continuous, defect-free, single- or few-layered graphene films. The catalytic growth mechanism makes it a convenient route to dope heteroatoms during the formation of graphene films, particularly to incorporate heteroatoms directly into the graphitic carbon lattices. A large variety of methods have already been developed for the synthesis of graphene materials, from which various doping strategies could be derived. The current methods for heteroatom doping can be categorized into in situ approaches and post-treatment approaches. In situ approaches, which simultaneously achieve graphene synthesis and heteroatom doping, include chemical vapor deposition (CVD), ball milling, and bottom-up synthesis. Post-treatment methods include wet chemical methods, thermal annealing of graphene oxides (GO) with heteroatom precursors, plasma and arc-discharge approaches. In this section, these