Hot Carrier Chemistry

This special issue on Hot Carrier Chemistry, guest edited by Professor Toshiharu Teranishi, aims to introduce the recent advances in the understanding of hot carrier behaviors in metal and semiconductor nanostructures and the creation of efficient hot carrier conversion systems. Photoenergy conversion systems using solar light are promising alternative energy technologies of the future. Light-induced hot carrier generation in metal and semiconductor nanostructures is key for photoenergy conversion processes, including photocatalytic and photochemical processes and photoelectric conversion processes. Metal (including heavily doped semiconductor) and semiconductor nanostructures have a big advantage in tuning the light absorption wavelength in the visible-to-infrared region. To understand and control the hot carrier behavior is quite important for efficient photoenergy conversion using whole solar light energy. In particular, localized surface plasmon resonance (LSPR)-induced photoenergy conversion is causing a paradigm shift in both fundamental science and industry for solar-energy utilization, because the LSPR band can be tuned over a wide spectral range by changing the carrier density, morphology, and so on, enabling solar energy utilization from ultraviolet to infrared regions. As hot carrier transfer competes with ultrafast relaxation via carrier scattering with timescales of just hundreds of femtoseconds and recombination after the charge separation completes in picoseconds region, it is challenging to achieve sufficient extraction of hot carriers for practical applications from the kinetic perspective. This special issue on “Hot Carrier Chemistry” includes two Minireviews and eight Full Papers and aims to introduce the recent advances in the understanding of hot carrier behaviors in metal and semiconductor nanostructures and the creation of efficient hot carrier conversion systems. As an example of LSPR-induced hot carrier transfer, Cao et al. investigate the hot-electron transfer efficiency under modal strong coupling conditions in an Au nanoparticles/TiO2/Au film structure. Kao et al. show the accumulation of positive charges in the TiO2/Au photoelectrode coated with Ni(OH)2 or CrOx by using plasmon-induced charge separation. Nanostructures that couple localized plasmon mode with multi-reflection mode and/or cavity resonator mode are proposed by Yanagiya et al. As an example of LSPR-based SERS applications, Banchelli et al. propose dot arrays of assembled Ag nanowires for spot-on SERS detection of biomolecules. Efficient passivation of Ag nanowires is described by Plissonneau et al. by means of in-situ total-internal-reflection SERS. Dai et al. demonstrate the significant improvement of reaction rate and product selectivity of nitrobenzene reduction by the use of photoexcited hot electrons in Rh nanocrystals. Important hot carrier behaviors in semiconductor nanocrystals (quantum dots) are also discussed. Singhal and Ghosh review the details of the hot charge carriers in semiconductor quantum dots for applications in different technologically relevant areas. The multiple-exciton harmonic quantum coherence in PbS quantum dots has been reviewed by Tahara and Kanemitsu by means of coherent spectroscopy. Photoelectrochemical properties of ZnTe–AgInTe2 solid solution nanocrystals enhanced by the hot hole transfer are described by Kameyama et al. Choi et al. describe the performance enhancement of p-i-n perovskite solar cells by incorporating two-dimensional WSe2 into PEDOT:PSS. I hope that you enjoy the articles in this special issue and that many researchers pay attention to this field for the development of hot carrier chemistry in light of both academic and practical points of view. Toshiharu Teranishi received his B.S. from The University of Tokyo in 1989. In 1994, he obtained his Ph.D. degree in chemistry from The University of Tokyo under the direction of Prof. Naoki Toshima. During 1994-2004, he worked on precise synthesis and two-dimensional assembly of metal nanoparticles as an assistant professor and an associate professor at Japan Advanced Institute of Science and Technology. In 2004, he moved to Tsukuba University as a full professor, and moved to Kyoto University in 2011. He is on the advisory editorial board of ChemNanoMat and editorial board of Chem. Sci. His current research interests include precise structural control of inorganic nanomaterials and structure-specific functions for high-performance devices and photo-energy conversion. He is a vice president of the Society of Nano Science and Technology, Japan, and an associate member of Science Council of Japan.