Boosting Photocatalytic Hydrogen Production by MOF‐Derived Metal Oxide Heterojunctions with a 10.0 % Apparent Quantum Yield

• Published in: Angewandte Chemie 2024-10, Vol.136 (42), p.n/a
• Main Authors: Musa, Emmanuel N., Yadav, Ankit K., Smith, Kyle T., Jung, Min Soo, Stickle, William F., Eschbach, Peter, Ji, Xiulei, Stylianou, Kyriakos C.
• Format: Article
• Language: English
• Subjects: Catalytic activity; Drinking water; Electron transfer; Fossil fuels; Fuel combustion; Heterojunctions; Hydrogen; Hydrogen evolution; Hydrogen production; Indium oxides; Metal oxides; Metal-organic frameworks; Metals; Photocatalysis; Porosity; Pyrolysis; Quantum efficiency; Rivers; Ruthenium oxide; Surface properties; Sustainable energy; Synergistic effect; Titanium dioxide; Water analysis; Water resources; Water sampling; Zinc oxide
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202405681

Photocatalytic hydrogen production offers an alternative pathway to establish a sustainable energy economy, utilizing the Earth's natural sunlight and water resources to address environmental concerns associated with fossil fuel combustion. While numerous photoactive materials exhibit high potential for generating hydrogen from water, the synergy achieved by combining two different materials with complementary properties in the form of heterojunctions can significantly enhance the rate of hydrogen production and quantum efficiency. Our study describes the design and generation of the metal–organic framework‐derived (MOF) metal oxide heterojunction herein referred to as RTTA, composed of RuO2/N,S‐TiO2. The RuO2/N,S‐TiO2 is generated through the pyrolysis of MOFs, Ru‐HKUST‐1, and the amino‐functionalized MIL‐125‐NH2 in the presence of thiourea. Among the various RTTA materials tested, RTTA‐1, characterized by the lowest RuO2 content, exhibited the highest hydrogen evolution rate, producing 10,761 μmol ⋅ hr−1 ⋅ g−1 of hydrogen with an apparent quantum yield of 10.0 % in pure water containing glycerol. In addition to RTTA‐1, we generated two other MOF‐derived metal oxide heterojunctions, namely ZTTA‐1 (ZnO/N,S‐TiO2) and ITTA‐1 (In2O3/N,S‐TiO2). These heterojunctions were tested for their photocatalytic activity, leading to apparent quantum yields of 0.7 % and 0.3 %, respectively. The remarkable photocatalytic activity observed in RTTA‐1 is thought to be attributed to the synergistic effects arising from the combination of metallic properties inherent in the metal oxides, complemented by the presence of suitable band alignment, porosity, and surface properties inherited from the parent MOFs. These properties enhance electron transfer and restrict hole movement. The photocatalytic efficiency of RTTA‐1 was further demonstrated in actual water samples, producing hydrogen with a rate of 8,190 μmol ⋅ hr−1 ⋅ g−1 in tap water, and 6,390 μmol ⋅ hr−1 ⋅ g−1 in river water. The pyrolysis of Ti(IV)‐ and Ru(II/III)‐based MOFs results in the formation of metal oxide heterojunctions, which exhibit photocatalytic activity for water reduction and hydrogen generation, achieving an apparent quantum yield of 10.0 %.