Super retarding-flame wood

Wood, a sustainable and ubiquitous natural structural material, has been widely used in various fields. A bottleneck perplexing its applications is the inevitable flammability. Traditional anti-flammability methods, such as surface coating and internal decoration, still suffer from the possibility of wood combustion upon exposure to extreme flames, owing to the complexity imposed by the challenge to integrate the spatially localized flame retardants into the entire solid wood. Here, we develop a super retarding-flame wood, denoted as Surf-wood, that enables effective distribution of flame retardant metal salts in the hierarchical structures of wood cell walls through a facile molecular-scale cell wall engineering strategy. The Surf-wood exhibits a remarkable high limiting oxygen index of ∼100%, as well as 80% and 96% reduction in the peak of heat release rate and total smoke production compared with natural wood, suppresses combustion even when placed in harsh charcoal fire, and withstands 12 min-continuous burning at 1300 °C without structural collapse. This new material is scalable in production while maintaining the esthetics and other desirable properties of natural wood, which would open a new avenue for numerous functional applications.