  Topological insulators hold great potential for efficient information
processing and storage. Using density functional theory calculations, we
predict that a honeycomb lead monolayer can be stabilized on the Al2O3 (0001)
substrate and becomes topologically non-trivial with a sizeable band gap (~0.27
eV). Furthermore, we propose to use hexagonal boron-nitride (h-BN) monolayer as
a protection for the topological states of Pb/Al2O3 and Sn/Al2O3. Our findings
suggest new possibilities for designing and protecting two-dimensional TIs for
practical applications.
