In this study, we report the quantum-mechanical characterization of two novel alpha- and beta-type 2D pure boron sheets, i.e., alpha(6)- and beta(14)-sheets, constructed from the experimentally available B-36 and B-35 building blocks. Ten isomeric configurations were located. Using the calculated binding energies, the thermodynamic stability of these structures was considered in detail. Additionally, we calculated the work functions of alpha(6)- and beta(14)-sheets. The results clearly demonstrate that their work functions (approximately 4.6 eV) are the highest among all of the reported mixed triangular-hexagonal type 2D boron sheets and are very similar to that of graphene. (C)2016 Elsevier B.V. All rights reserved.