Preparation of carbon-coated hydroxyapatite nanorods from bovine bone and application in the photocatalytic N2/H2O synthesis of ammonia

Carbon-coated hydroxyapatite nanorods (HAp–C) were first synthesized using bovine bones from Urumqi as the carbon source. Ti³⁺-doped TiO₂ (Ti³⁺–TiO₂) was obtained via thermal reduction using NaBH₄. Ti³⁺–TiO₂ was hydrothermally deposited onto the surface of HAp–C, resulting in Ti³⁺–TiO₂/HAp–C formation. The photocatalytic N₂/H₂O ammonia synthesis performance of the prepared materials was investigated while analyzing their structure. HAp–C, a stable carbon material derived from bones, exhibits considerable photoluminescence under ultraviolet light. It serves as a substrate for the Ti³⁺–TiO₂ catalyst, reducing particle agglomeration and enhancing the photogenerated electron transfer rate. The presence of HAp–C further enhances the activation of Ti³⁺–TiO₂/HAp–C for N₂ adsorption and considerably increases its visible-light absorption compared to pure Ti³⁺–TiO₂. The 85%–Ti³⁺–TiO₂/HAp–C photocatalyst yielded 850.13 mol/(L·g cat.) of ammonia after 4 h of reaction during the photocatalytic N₂/H₂O ammonia synthesis, representing a 2.93-fold increase over the ammonia yield of pure Ti³⁺–TiO₂ under identical conditions.