In-situ incorporation of metal phytates for green and highly efficient flame-retardant wood with excellent smoke-suppression property

Phytic acid (PA) have attracted rapidly growing attention as a bio-based and effective flame retardant for cellulosic materials. However, they produce much toxic smoke during the combustion, which severely threats human life. To address this problem, in this work, metal phytates were in-situ incorporated into the wood matrix via a simple two-step approach to fabricate green and highly efficient flame-retardant wood (PM-W, M = Cu, Fe, Zn, and Mg) with excellent smoke-suppression property. PCu-W exhibits 44.77 % and 91.98 % smaller total heat release and total smoke production than W, respectively, with a weight percent gain of only 13.06 %, outperforming most of its previous counterparts. The improvements can be mainly ascribed to the significant dual-charring effect of metal phytates, and the catalytic graphitizing effect of metallic species on the char residue. The high-quality char layer act as an efficient isolating barrier to restrict the emission of smoke. Moreover, PCu-W shows superior performances to other PM-Ws owing not only to the stronger Lewis acidity of Cu 2+ , but also to the lower nitrogen solubility of metallic Cu, which increased the nitrogen content in the graphitic structure and accordingly enhanced the stability of the char. This work provides guidelines for designing green and safer strategy to address the fire hazard of wood or other cellulosic materials by PA-derived flame retardants. • Metal phytates were in-situ incorporated into wood matrix via a facile method. • PM-Ws have outstanding flame retardancy and smoke suppression performance. • The improvement is ascribed to dual-charring and catalytic graphitizing effects. • Smoke-suppression performance of PCu-W outperforms other PM-Ws.