Engineering Reaction Kinetics by Tailoring the Metal Tips of Metal–Semiconductor Nanodumbbells

5 years ago

Engineering Reaction Kinetics by Tailoring the Metal Tips of Metal–Semiconductor Nanodumbbells

Ki Min Nam, Hyunjoon Song, Seon Joo Lee, Dahyi Jeong, Sang Kyu Kim, Dong-gu Kang, Ji Yong Choi

Semiconductor–metal hybrid nanostructures are one of the best model catalysts for understanding photocatalytic hydrogen generation. To investigate the optimal structure of metal cocatalysts, metal–CdSe–metal nanodumbbells were synthesized with three distinct sets of metal tips, Pt–CdSe–Pt, Au–CdSe–Au, and Au–CdSe–Pt. Photoelectrochemical responses and transient absorption spectra showed that the competition between the charge recombination at the metal–CdSe interface and the water reduction on the metal surface is a detrimental factor for the apparent hydrogen evolution rate. For instance, a large recombination rate (k_rec) at the Pt–CdSe interface limits the quantum yield of hydrogen generation despite a superior water reduction rate (k_WR) on the Pt surface. To suppress the recombination process, Pt was selectively deposited onto the Au tips of Au–CdSe–Au nanodumbbells in which the k_rec was diminished at the Au–CdSe interface, and the large k_WR was maintained on the Pt surface. As a result, the optimal structure of the Pt-coated Au–CdSe–Au nanodumbbells reached a quantum yield of 4.84%. These findings successfully demonstrate that the rational design of a metal cocatalyst and metal–semiconductor interface can additionally enhance the catalytic performance of the photochemical hydrogen generation reactions.

Publisher URL: http://dx.doi.org/10.1021/acs.nanolett.7b02582

DOI: 10.1021/acs.nanolett.7b02582