Ga4B2O9: an efficient borate photocatalyst for overall water splitting without cocatalyst

Area of Science:

• Materials Science
• Photocatalysis
• Inorganic Chemistry

Background:

• Borates are recognized for optical properties, but their photocatalytic potential remains underexplored.
• Gallium (Ga)-based oxides and sulfides are promising for photocatalysis due to Ga(3+)'s electronic structure.
• Ga4B2O9, with its high Ga/B ratio and 3D network, was investigated as a potential photocatalyst.

Purpose of the Study:

• To synthesize and evaluate Gallium Borate (Ga4B2O9) as a novel photocatalyst.
• To compare the photocatalytic activity of Ga4B2O9 prepared by different methods.
• To assess the efficiency of Ga4B2O9 in UV-light-driven water splitting.

Main Methods:

• Crystalline Ga4B2O9 synthesized using hydrothermal (HY), sol-gel (SG), and high-temperature solid-state reaction (HTSSR) methods.
• Characterization of synthesized Ga4B2O9 materials.
• Evaluation of photocatalytic activity for hydrogen (H2) and oxygen (O2) evolution from pure water under UV irradiation.

Main Results:

• Hydrothermal synthesis yielded micrometer single crystals (HY-Ga4B2O9) with poor UV activity due to rapid photoexciton recombination, requiring Pt loading.
• Sol-gel (SG) and HTSSR methods produced Ga4B2O9 with nanostrip morphology, facilitating charge carrier transport.
• SG- and HTSSR-derived Ga4B2O9 exhibited significant intrinsic UV-light photocatalytic activity for water splitting (e.g., 118 μmol/h/g H2, 58 μmol/h/g O2), outperforming P25 TiO2.

Conclusions:

• The synthesis method critically influences Ga4B2O9's photocatalytic performance.
• Nanostructured Ga4B2O9 prepared by SG and HTSSR methods are effective, self-sufficient UV photocatalysts for water splitting.
• Ga4B2O9 presents a promising new class of materials for photocatalytic applications.