Methods of manufacturing nano-engineered carbon materials, such as carbon aerogels and carbon xerogels, and methods of manufacturing precursor solutions and sol-gels for making the same are provided. A method for manufacturing a precursor solution comprises programmed-addition of a cross-linking agent to a component mixture comprising a resorcinol compound. A method for manufacturing a sol-gel comprises subjecting a precursor solutions to at least one heat treatment. Methods for producing nano-engineered carbon materials from precursor solutions and sol-gels are also provided. Methods for using the nano-engineered carbon materials are also disclosed. The resulting nano-engineered carbon materials can be useful in a range of products including, supercapacitor applications, high-surface-area electrodes, fuel cells, and desalination systems.