Utilizing inexhaustible solar energy to split water into oxygen and clean hydrogen energy is an ideal solution for addressing the increasingly severe energy and environmental issues. This study aims to develop a composite photocatalyst based on titanium dioxide semiconductors for the efficient use of solar energy. Gold nanoclusters, novel sub-nanomaterials with atomic precision, exhibit molecular-like properties due to the quantum size effect. By loading them onto titanium dioxide materials as photosensitizers, the electrons in the Highest Occupied Molecular Orbital (HOMO) can be easily excited to higher energy levels under light illumination and injected into the CB of TiO₂. This research explores the combination of gold nanoclusters with wide bandgap semiconductors, represented by tit...[ Read more ]

Utilizing inexhaustible solar energy to split water into oxygen and clean hydrogen energy is an ideal solution for addressing the increasingly severe energy and environmental issues. This study aims to develop a composite photocatalyst based on titanium dioxide semiconductors for the efficient use of solar energy. Gold nanoclusters, novel sub-nanomaterials with atomic precision, exhibit molecular-like properties due to the quantum size effect. By loading them onto titanium dioxide materials as photosensitizers, the electrons in the Highest Occupied Molecular Orbital (HOMO) can be easily excited to higher energy levels under light illumination and injected into the CB of TiO₂. This research explores the combination of gold nanoclusters with wide bandgap semiconductors, represented by titanium dioxide, for photoelectrochemical water splitting hydrogen production and designs. It optimizes several loading schemes for gold nanoclusters and titanium dioxide.

In this study, four types of gold nanoclusters protected by glutathione ligands and reduced by carbon monoxide were precisely prepared and loaded onto titanium dioxide photoelectrodes and compared to bare TiO₂, the composite photoelectrode loaded with Au₁₈(GSH)₁₅ gold nanoclusters exhibited up to 294 times enhanced photo response under visible light. Based on this, to maintain the stability of gold nanocluster loading, titanium dioxide nanotubes were chosen as substrates, and the hierarchical structure of Nafion/AuNCs/PEI was constructed for the first time to enhance significantly the stability of gold nanoclusters on titanium dioxide and the carrier separation ability of the photoelectrode. Porous metal-organic frameworks MIL-125(Ti) and its amino-functionalized product NH₂-MIL-125(Ti) possess near-semiconductor photo response capabilities, emerging as a new star in the field of photocatalysis. Using these MOF materials as loading media for gold nanoclusters, they displayed excellent photocatalytic abilities under visible light. In addition, this project explores for the first time the photo absorption capabilities of X-MIL-125 materials functionalized with methyl (CH₃-), thiol (SH-), bromo (Br-), hydroxyl (OH-), and fluoro (F-) groups and their photocatalytic abilities after combining with gold nanoclusters. In order to achieve better electron transport, SH-MIL-125(Ti) and NH₂-MIL-125(Ti) materials were loaded in situ on the titanium dioxide nanorods electrode, and the heterojunctions formed promoted carrier separation. The nanostructure on the surface of the composite electrode provides a good loading site for the gold nanoclusters, showing an efficient photoelectrochemical water decomposition ability under visible light.

This study provides schemes and technical support for optimizing the utilization of solar energy by noble metal clusters in wide bandgap semiconductors and their application in photocatalytic hydrogen production.