(1) Non metallic doped carbon based materials
Introducing heteroatoms into carbon materials can regulate the electronic structure distribution of the carbon skeleton and achieve functionalization of the carbon material surface, making it an effective means of controlling the electrocatalytic performance of carbon materials. Due to the difference in electronegativity between heterogeneous heteroatoms and carbon atoms, introducing heteroatoms into a carbon substrate can cause a rearrangement of the charge density and electron cloud of the carbon lattice, endowing carbon materials with new physical and chemical properties. The atomic size, electronegativity, and outer electron number of non-metallic heteroatoms are the main factors affecting the doping effect. By selecting and changing the type and content of doping atoms, carbon materials can be effectively modified. Commonly used heteroatoms for carbon material modification include boron (B), nitrogen (N), oxygen (O), phosphorus (P), sulfur (S), etc. The doping of different heteroatoms and the synergistic effect between heteroatoms will have different effects on the improvement of catalytic performance of carbon materials.
(2) Transition metal and its compound doped carbon based materials
In addition to doping carbon materials with non-metallic atoms, metal elements can also be used to modify carbon materials to enhance their catalytic activity. Due to their relatively abundant content and low price on Earth, transition metals are an easily obtainable raw material. The most common non precious metals used for doping carbon materials include transition metals such as iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). By selecting components, controlling morphology, and adjusting the existence state of transition metals, various transition metal carbon based materials can be developed. Due to the strong interaction between metals and carbon substrates, as well as the high conductivity of carbon materials themselves, transition metal carbon based materials exhibit enhanced electrocatalytic activity and have broad application prospects in various fields.