Phosphorus-containing carbons: Preparation, properties and utilization

Heteroatom doping of carbon materials modifies their chemical and electronic properties. Phosphorus-containing carbon materials are reviewed by focusing on their preparation, properties and applications. The preparation methods include carbonization of carbon precursors with phosphorus compounds, modification of already prepared carbons and deposition of carbon and phosphorus from the gas phase. Phosphorus in carbons occurs mainly bound to oxygen, even in carbons obtained using oxygen-free compounds. The most common structure is pentavalent tetra-coordinated phosphorus as in phosphates; however, some P–O bonds may be replaced with P–C bonds. Phosphorus species bind to the active sites of carbon rendering stability to P-containing carbons. This defines the properties of P-containing carbons: hydrophilic acid surface and chemical stability, which are beneficial in a wide range of technologically important applications. P-containing carbons show a high adsorption capacity for metal ions and organic molecules with basic nature. P-species of acidic nature impart carbon a catalytic activity in diverse reactions useful in the production of commodity chemicals and biomass transformation. P-species alter the optical properties of carbons suitable in photovoltaics, photocatalysis or bioimaging. Finally, P-species make carbons suitable for many electrochemical applications like energy storage (EDLC, Li-ion batteries) or in fuel cells.