Ball milling induced borophene flakes fabrication

Ewa Iwona Mijowska; Klaudia Natalia Zielinkiewicz; Daria Baranowska

doi:10.1039/d3ra02400h

Ball milling induced borophene flakes fabrication

Abstract

To fill the knowledge gap for borophene, as the youngest member of the two-dimensional (2D)
nanomaterials family, a facile, cost effective, scalable and reproducible fabrication route is still strongly
required. Among so far studied techniques the potential of pure mechanical processes such as ball
milling is not explored yet. Therefore, in this contribution, we explore the efficiency to exfoliate bulk
boron into a few-layered borophene induced by mechanical energy in the planetary ball mill. It was
revealed that the resulting flakes thickness and distribution can be controlled by (i) rotation speed (250–
650 rpm), (ii) time of ball-milling (1–12 hours), and mass loading of bulk boron (1–3 g). Furthermore, the
optimal conditions for the ball-milling process to induce efficient mechanical exfoliation of boron were
determined to be 450 rpm, 6 hours, and 1 g (450 rpm_6 h_1 g), which resulted in the fabrication of
regular and thin few-layered borophene flakes (∼5.5 nm). What is more, the mechanical energy induced
during ball-milling, and the heat generated inside, affected the structure of borophene resulting in
different crystalline phases. Besides being an additional and interesting discovery, it will also open up
opportunities to investigate the relevance between the properties and the emerging phase. Structures
labeled as b-rhombohedral, g-orthorhombic, s-B and the conditions under which they appear, have
been described. Therefore, in our study, we open a new door to obtain a bulk quantity of few-layered
borophene for further fundamental studies and practical potential assessment