Light-Off in Plasmon-Mediated Photocatalysis.

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Plasmon-mediated photocatalysis involves complex light-induced reaction pathways.
• Differentiating photothermal heating from hot carrier injection is experimentally difficult.
• Understanding these mechanisms is crucial for optimizing catalytic efficiency.

Purpose of the Study:

• To differentiate photothermal rate enhancement from other light-induced channels in plasmon-mediated photocatalysis.
• To investigate the role of temperature control in CO oxidation over Pd and AuPd catalysts.
• To provide insights into experimental strategies for distinguishing catalytic mechanisms.

Main Methods:

• Utilized nanofabricated palladium (Pd) and gold-palladium (Au50Pd50) alloy catalysts.
• Performed CO oxidation reactions under varying photon fluxes.
• Measured reaction rates and correlated them with catalyst operating position on the light-off curve in the dark.

Main Results:

• Photothermal rate enhancement varied by up to three orders of magnitude for identical photon flux.
• The observed photothermal effect was primarily controlled by the catalyst's operating temperature along the light-off curve.
• Temperature fluctuations and gradients significantly influence photothermal enhancement and mechanism interplay.

Conclusions:

• Photothermal heating is a dominant factor in CO oxidation rates, highly sensitive to temperature.
• Precise temperature control is essential for accurately distinguishing between photothermal and hot electron effects.
• Experimental designs must account for temperature gradients to reliably analyze photocatalytic mechanisms.