Self-Constructed Multiple Plasmonic Hotspots on an Individual Fractal to Amplify Broadband Hot Electron Generation

Abstract

Plasmonic nanoparticles are ideal candidates for hot-electron-assisted applications, but their narrow resonance region and limited hotspot number hindered the energy utilization of broadband solar energy. Inspired by tree branches, we designed and chemically synthesized silver fractals, which enable self-constructed hotspots and multiple plasmonic resonances, extending the broadband generation of hot electrons for better matching with the solar radiation spectrum. We directly revealed the plasmonic origin, the spatial distribution, and the decay dynamics of hot electrons on the single-particle level by using ab initio simulation, dark-field spectroscopy, pump–probe measurements, and electron energy loss spectroscopy. Our results show that fractals with acute tips and narrow gaps can support broadband resonances (400–1100 nm) and a large number of randomly distributed hotspots, which can provide unpolarized enhanced near field and promote hot electron generation. As a proof-of-concept, hot-electron-triggered dimerization of p-nitropthiophenol and hydrogen production are investigated under various irradiations, and the promoted hot electron generation on fractals was confirmed with significantly improved efficiency.

Boride-derived oxygen-evolution catalysts

“…As shown in linear sweep voltammetry (LSV, Fig. 4a ) curves, the overpotential of NiFe-Boride catalyst at 10 mA/cm 2 , 34 and without iR compensation is 167 mV. This is lower than the 200 mV and 189 mV obtained for sol-gel NiFe and IrO 2 , respectively (Supplementary Table 4 ).…”

Ultra-small-sized multi-element metal oxide nanofibers: an efficient electrocatalyst for hydrogen evolution

“…Alternatively, in photoelectrochemical (PEC) cells, electricity generated from a solar cell can be utilized to drive electrochemical transformations. [2][3][4] The real potential of water splitting is much higher than the theoretical potential value (1.23 V). 5 A key factor to realize highefficiency water splitting systems is the development of highly active, stable, and low-cost electrocatalysts for the hydrogen evolution reaction (HER).…”

“…Solardriven water electrolysis can produce hydrogen economically and environmentally, therefore the combination between the solar cell and water electrolyzer is particularly rational. Alternatively, in the photoelectrochemical (PEC) cells, electricity generated from a solar cell can be utilized to drive electrochemical transformations [2][3][4].…”

“…Alternatively, in photoelectrochemical (PEC) cells, electricity generated from a solar cell can be utilized to drive electrochemical transformations. 2–4…”

Aluminum Cayley trees as scalable, broadband, multiresonant optical antennas

“…This unprecedented range of tunability is experimentally evidenced using electron energy loss spectroscopy (EELS), a powerful tool allowing us to simultaneously obtain a spectrum analogous to an unpolarized optical extinction spectrum ( 25 ) and perform a spatial mapping of the resonances with nanoscale resolution ( 26 ). As such, EELS is well suited to the experimental study of optical antennas and has been applied to the characterization of antennas of various geometries ( 14 , 17 , 18 , 27 ), including fractals ( 24 , 28 , 29 ). In order to unveil all the electromagnetic resonances sustained by the Al Cayley trees, it is necessary to probe the mid-IR regime.…”