Two new Cu-based borate catalysts with cubic supramolecular cages for efficient catalytic hydrogen evolution

Area of Science:

• Materials Science
• Catalysis
• Renewable Energy

Background:

• Developing efficient and cost-effective water reduction catalysts (WRCs) is crucial for renewable energy technologies.
• Copper-based borates represent a promising class of materials for catalytic applications.

Purpose of the Study:

• To synthesize novel copper-based borate catalysts with cubic supramolecular cages.
• To investigate the photocatalytic activity of these new WRCs.
• To understand the influence of counter cation atomic radius on catalytic performance.

Main Methods:

• Hydrothermal synthesis of two new Cu-based borate catalysts: H2Na2K2[(μ4-O)Cu4@B20O32(OH)8]·21H2O (1) and H2Rb1.6K2.4[(μ4-O)Cu4@B20O32(OH)8]·15H2O (2).
• Photocatalytic evaluation of WRCs using [Ir(ppy)2(dtbbpy)][PF6] as a photosensitizer and triethanolamine (TEOA) as a sacrificial electron donor.
• Density Functional Theory (DFT) calculations to support experimental findings.

Main Results:

• Successful synthesis of two novel cubic supramolecular copper-borate structures.
• Demonstrated photocatalytic activity of the synthesized copper complexes as WRCs.
• Identified the central borate core [(μ4-O)Cu4@B20O32(OH)8] as the active site.
• Established that increasing counter cation atomic radius (Na to Rb) decreases photocatalytic activity.
• Experimental results align with DFT predictions.

Conclusions:

• The synthesized Cu-based borates are effective water reduction catalysts.
• The atomic radius of the counter cation is a critical factor influencing photocatalytic activity.
• This research expands Cu-based borate chemistry and provides guidance for designing advanced borate materials for energy and environmental applications.