Johannes Binder1,Aleksandra Dabrowska1,Mateusz Tokarczyk1,Katarzyna Ludwiczak1,Rafal Bozek1,Grzegorz Kowalski1,Roman Stepniewski1,Andrzej Wysmolek1
Faculty of Physics, University of Warsaw1
Johannes Binder1,Aleksandra Dabrowska1,Mateusz Tokarczyk1,Katarzyna Ludwiczak1,Rafal Bozek1,Grzegorz Kowalski1,Roman Stepniewski1,Andrzej Wysmolek1
Faculty of Physics, University of Warsaw1
Hydrogen is an important building block in global strategies toward a future green energy system. To make this transition possible, intense scientific efforts are needed, also in the field of materials science. Hexagonal boron nitride (h-BN) is a very promising candidate for such applications, as it has been demonstrated that micrometer-sized flakes are excellent barriers to molecular hydrogen. However, it remains an open question whether large-area layers fabricated by industrially relevant methods preserve such promising properties.<br/><br/>We address this issue and show results on the growth of epitaxial h-BN on 2-inch sapphire wafers by metalorganic vapour-phase epitaxy (MOVPE) [1-5], which is currently regarded as one of the most promising growth techniques. This technique allows to grow hBN layers, with thicknesses of tens of nm [1,3], and can serve as a substrate for the direct growth of van der Waals heterostructures on the wafer-scale [4].<br/><br/>In this work, we show that electron-beam-induced splitting of water creates hBN bubbles that effectively store molecular hydrogen for weeks [5]. The bubble formation can be observed in-situ in a scanning electron microscope, giving us the unique possibility to visualize the hydrogen generation process. Raman spectroscopy proves the presence of molecular hydrogen and experiments with heavy water provide evidence that hydrogen generation is triggered by the radiolysis of water captured at the van der Waals interface. By performing a stress test we could also demonstrate that H<sub>2</sub> remains in the bubble even after extreme wear and deformation (over 500 cycles of deflation and inflation by changing the ambient pressure), highlighting the suitability of our large-area epitaxial material for possible hydrogen storage applications.<br/><br/>Our findings show that epitaxial h-BN by MOVPE is not only a potential candidate for the growth of large-area van der Waals heterostructures and hydrogen storage but also holds promise for the development of unconventional hydrogen production schemes [5].<br/><br/><u>References:</u><br/>[1] M. Tokarczyk, A. K. Dabrowska, G. Kowalski, R. Bozek, J. Iwanski, J. Binder, R. Stepniewski, A. Wysmolek <i>2D Materials</i> <b>10</b>, 025010 (2023)<br/>[2] K. P. Korona, J. Binder, A. K. Dabrowska, J. Iwanski, A. Reszka, T. Korona, M. Tokarczyk, R. Stepniewski, A. Wysmolek <i>Nanoscale</i> <b>15</b>, 9864 (2023)<br/>[3] A. K. Dabrowska, M. Tokarczyk, G. Kowalski, J. Binder, R. Bozek, J. Borysiuk, R. Stepniewski, A. Wysmolek <i>2D Materials</i> <b>8</b>, 015017 (2021)<br/>[4] K. Ludwiczak, A. K. Dabrowska, J. Binder, M. Tokarczyk, J. Iwanski, B. Kurowska, J. Turczynski, G. Kowalski, R. Bozek, R. Stepniewski, W. Pacuski, A. Wysmolek <i>ACS Appl. Mater. Interfaces</i> <b>13</b>, 47904 (2021)<br/>[5] J. Binder, A. K. Dabrowska, M. Tokarczyk, K. Ludwiczak, R. Bozek, G. Kowalski, R. Stepniewski, A. Wysmolek <i>Nano Letters</i> <b>23</b>, 1267−1272 (2023)