Sub-nanometer Co₃O₄ clusters anchored on TiO₂(B) nano-sheets: Pt replaceable Co-catalysts for H₂ evolution

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Cobalt-based cocatalysts are cost-effective alternatives to noble metals.
• Current cobalt cocatalysts suffer from low efficiency due to limited active sites.
• Maximizing active sites through small cluster dispersion is crucial for enhanced performance.

Purpose of the Study:

• To synthesize sub-nanometer cobalt oxide (Co3O4) clusters anchored to 2D ultrathin titanium dioxide (TiO2(B)) nanosheets.
• To investigate the impact of cluster size on the electronic properties and heterojunction band structure.
• To evaluate the performance of the synthesized material as a cocatalyst for the hydrogen evolution reaction (HER).

Main Methods:

• Synthesis of sub-nanometer Co3O4 clusters on ultrathin TiO2(B) nanosheets.
• Characterization of electronic properties (conduction type) and heterojunction band structure (Type II to Type I transition).
• Evaluation of photocatalytic activity for HER and stability testing.

Main Results:

• Reducing Co3O4 cluster size to sub-nanometer scale altered its conduction type from P-type to N-type.
• The heterojunction band structure shifted from Type II to Type I with decreasing cluster size.
• Optimized band matching facilitated electron transfer, reducing Co ions to metallic Co, enhancing HER efficiency and stability.

Conclusions:

• Sub-nanometer Co3O4 clusters on TiO2(B) nanosheets represent a highly efficient cocatalyst for HER.
• The observed electronic and structural changes are key to achieving performance comparable to platinum.
• This work highlights the potential of precisely controlled nanostructures for advanced catalytic applications.