Silver nanoplatelets prove efficient photosensitizers

Using solar power in photosensitization has proven effective for reducing the carbon-based energy previously used in photocatalytic and photovoltaic processes. Because of their high light absorption and potential for efficient injection of excited electrons, noble metal nanomaterials are often used as photosensitizers.

Fang et al. directly measured the rate of electron injection from silver nanoplatelets to nanotubes of the semiconductor titanium dioxide. To understand the mechanisms of the enhanced photocatalytic efficiency of silver nanoplatelets as photosensitizers, they studied the dynamics of the electrons at the metal-semiconductor interface.

Compared to spherical nanoparticles, the flat, disc-like nanoplatelets had the highest surface area in contact with the semiconductor, resulting in the fastest electron injection rate. Using transient IR absorption, the researchers determined the photo-induced electron injection rate for silver to titanium dioxide was 13 femtoseconds.

“These results, combined with the fact that silver is a strong light absorber, show that silver nanoplatelets are excellent sunlight absorbing materials to be used in photocatalytic and photovoltaic devices,” said co-author Hai-Lung Dai.

Common speculation is that larger semiconductor nanoparticles produce a longer excited-electron lifetime. Future research in this field will focus on understanding the effects of particle size on the lifetime of these excited electrons.

“Eventually, this ongoing study combined with our current published work will provide the best set of guidance on designing the size and shape of the nanomaterials for most efficient photocatalytic and photovoltaic devices,” said Dai.

Source: “Ag nanoplatelets as efficient photosensitizers for TiO₂ nanorods,” by Hui Fang, Michael J. Wilhelm, Jianqiang Ma, Yi Rao, Danielle L. Kuhn, Zachary Zander, Brendan G. DeLacy, and Hai-Lung Dai, Journal of Chemical Physics (2022). The article can be accessed at https://doi.org/10.1063/5.0074322 .

This paper is part of the Transport of Charge and Energy in Low-Dimensional Materials Collection, learn more here .