  The thermal transport properties of biphenylene network (BPN), a novel sp2
-hybridized two-dimensional allotrope of carbon atoms recently realized in
experiments [Fan et al., Science, 372 852-856 (2021)], are studied using the
density functional theory-driven solution of the Boltzmann transport equation.
The thermal transport in BPN is anisotropic and the obtained thermal
conductivities are more than an order of magnitude lower than that in graphene,
despite similar sp2-hybridized planar-structure of both allotropes. The lower
thermal conductivity in BPN is found to originate from enhanced anharmonicity
which in turn is a result of reduced crystal symmetry of BPN.
