Phase Transition of Two-Dimensional β-Ga₂O₃ Nanosheets from Ultrathin γ-Ga₂O₃ Nanosheets and Their Photocatalytic Hydrogen Evolution Activities

Abstract

Monoclinic β-Ga 2 O 3 nanosheets hold great potential applications in electronic, optical, and photocatalytic fields. In this study, two-dimensional β-Ga 2 O 3 nanosheets were successfully fabricated through a simple crystalline phase transition from the as-prepared ultrathin γ-Ga 2 O 3 nanosheets. The photocatalytic hydrogen evolution reaction under UV light irradiation was achieved on the two kinds of photocatalysts. However, β-Ga 2 O 3 with a higher crystallinity shows a lower photocatalytic activity in comparison with γ-Ga 2 O 3 . The average apparent quantum yield is calculated to be 0.29% for β-Ga 2 O 3 nanosheets and 1.82% for γ-Ga 2 O 3 . More efficient separation and transfer rates of photogenerated carriers and larger specific areas were found in γ-Ga 2 O 3 . On the basis of the analysis of the structures of γ-Ga 2 O 3 and β-Ga 2 O 3 , it is proposed that the disordered or defective structure contributes to the improvement of photocatalytic activity to some extent. Therefore, it is significant to develop the photocatalyst with a stable structure and a certain number of defects at the same time.

High Shear in Situ Exfoliation of 2D Gallium Oxide Sheets from Centrifugally Derived Thin Films of Liquid Gallium

“…The Ga 2p3/2 and Ga 2p1/2 peaks are positioned at 1145.03 eV and 1118.13 eV respectively for bulk gallium with a shift by 0.75 eV to a higher binding energy associated with the Ga-O bonding in Ga2O3 [21].…”

“…A number of 2D materials that have recently emerged including transition metal dichalcogenides (TMDs), layered metal oxides, 2D inorganic compounds, hexagonal boron nitride (h-BN), layered double hydroxides (LDHs), black phosphorus (BP) and other elemental main group metals and metalloids [5][6][7][8][9][10][11][12][13][14][15]. 2D-nanomaterials derived from liquid metals and/or eutectic melts of the metals, in particular, are envisaged to break new barriers, offering unique properties and potential in applications [16][17][18][19][20][21][22][23]. In addition, it is a significant advantage that any development as such needs to incorporate the principles of green chemistry to minimise the likelihood of any downstream issues, including adverse effects on the natural environment, with the process being readily scalable.…”

Aero-Ga2O3 Nanomaterial Electromagnetically Transparent from Microwaves to Terahertz for Internet of Things Applications

“…While both nitride and oxide phases co-exist after the thermal step at T = 800°C in air for 1 h (both reflection peaks sets for wurtzite GaN and monoclinic Ga 2 O 3 are found in the diffraction pattern), only reflections from the oxide remain after annealing at T = 950°C. Formation of monoclinic Ga 2 O 3 in thin structures was already observed for annealing temperatures as low as 750 °C [ 15 ].…”

CuO-Ga2O3 Thin Films as a Gas-Sensitive Material for Acetone Detection

“…There are several polymorphs of Ga 2 O 3 [54], such as the rhombohedral (α-Ga 2 O 3 ), monoclinic (β-Ga 2 O 3 ), defective spinel (γ-Ga 2 O 3 ), cubic (δ-Ga 2 O 3 ), and orthorhombic (ε-Ga 2 O 3 ) structure, among which the most chemical and thermal stable under ambient conditions is β-polymorph [55]. Moreover, the various forms of low-dimensional crystalline Ga 2 O 3 , including nanowires (NWs) [56,57], nanobelts (NBs) [58], and nanosheets (NSHs) [59], are the subject of research. Ga 2 O 3 is an n-type semiconductor with an ultrawide-bandgap in the range of 4.2-5.3 eV [54,60,61].…”