  The design of novel devices with specific technical interests through
modulating structural properties and bonding characteristics promotes the
vigorous development of materials informatics. Herein, we propose a synergy
strategy of component reconstruction by combining geometric configuration and
bonding characteristics. With the synergy strategy, we designed a novel
two-dimensional (2D) graphene-like borides, e.g. g-B3N5, which possesses
counter-intuitive ultra-low thermal conductivity of 21.08 W/mK despite the
small atomic mass. The ultra-low thermal conductivity is attributed to the
synergy effect of electronics and geometry on thermal transport due to the
combining reconstruction of g-BN and nitrogene. With the synergy effect, the
dominant acoustic branches are strongly softened, and the scattering absorption
and Umklapp process are simultaneously suppressed. Thus, the thermal
conductivity is significantly lowered. To verify the component reconstruction
strategy, we further constructed g-B3P5 and g-B3As5, and uncovered the
ultra-low thermal conductivity of 2.50 and 1.85 W/mK, respectively. The synergy
effect and the designed ultra-low thermal conductivity materials with
lightweight atomic mass cater to the demand for light development of momentum
machinery and heat protection, such as aerospace vehicles, high-speed rail,
automobiles.
