Boron-doped and defect-engineered graphene aerogels are prepared using triphenyl boron as a boron precursor and subsequent heat treatments. The boron chemistry and concentration in the graphene lattice are found to be highly dependent on the temperature used to activate boron. At 1500 °C, boron is incorporated at 3.2 atom % through a combination of B–C, B–N, and B–O bonds. At 1750 °C, the boron concentration decreases to 0.7 atom % and is predominantly incorporated through B–N bonding. Higher temperatures result in complete expulsion of boron from the lattice, leaving behind defects...