Development of Strong Visible-Light-Absorbing Cyclometalated Iridium(III) Complexes for Robust and Efficient...

Area of Science:

• Inorganic Chemistry
• Photochemistry
• Materials Science

Background:

• Common iridium(III) complexes exhibit weak light absorption, limiting their use as photosensitizers in photocatalytic hydrogen generation.
• Developing efficient photosensitizers is crucial for advancing light-driven water splitting technologies.

Purpose of the Study:

• To synthesize novel cyclometalated iridium(III) complexes with enhanced light absorptivity for photocatalytic hydrogen production.
• To investigate the effect of electron-donating substituents on the performance of iridium(III) photosensitizers.

Main Methods:

• Synthesis of a series of cyclometalated iridium(III) complexes (Ir1-Ir5) incorporating electron-donating moieties like carbazole and triphenylamine derivatives.
• Evaluation of the complexes as photosensitizers in a three-component photocatalytic system for hydrogen generation using platinum nanoparticles as catalysts.
• Characterization of photocatalytic performance, including turnover number (TON), turnover frequency (TOF), activity, and apparent quantum yield (AQY).

Main Results:

• Complex Ir4, featuring a 4,4'-dimethoxytriphenylamine moiety, exhibited the highest performance with a TON of 12,300 and an initial AQY of 9.59% under blue LED irradiation.
• The synthesized iridium(III) complexes demonstrated stable and efficient photocatalytic hydrogen production over 105 hours.
• The study highlights the superior performance of triphenylamine-based iridium(III) photosensitizers in light-driven water splitting.

Conclusions:

• Electron-donating substituents, particularly triphenylamine derivatives, significantly enhance the light absorption and photocatalytic activity of iridium(III) complexes.
• The developed iridium(III) complexes show great potential as efficient and stable photosensitizers for photocatalytic hydrogen generation from water.
• This research sets a new benchmark for photocatalytic systems using iridium(III) complexes with platinum nanoparticles, achieving the highest reported TON.