Plasmonic Metal Nanostructures as Efficient Light Absorbers for Solar Water Splitting

Abstract

The increasing use of traditional fossil fuels has led to serious environmental concerns, such as air pollution, global warming, and possible climate anomalies. For the purpose of sustaining economic growth, solar energy has become a considerably promising energy alternative to alleviate the energy crisis and environmental stress. [1] During the past few decades, photo-driven catalytic reactions have received widespread attention because of the ability of converting inexhaustible solar energy into available chemical energy, especially the clean hydrogen energy source. [2] However, the current photocatalyst materials are far from satisfactory and the actual catalytic performance is still insufficient for large-scale practical applications.Plasmonic metal (typically Au, Ag, Cu, and Al) nanoparticles (NPs) exhibit fantastic localized surface plasmon resonance (LSPR) property, which refers to the collective oscillation of free electrons around particles' surface when the incident light matches the resonant frequency of the collective electrons. [3] Through engineering the size, morphology, composition, and dielectric environment of NPs, LSPR properties can be customized to achieve optimized performances. Surface plasmon decays quickly, so the energy stored in the plasma can be released through far-field light scattering, nearfield electromagnetic field enhancement, and hot carrier generation. The strong interaction of plasmonic metal nanostructures with light makes them become commendable light absorber materials, and the absorbed energy can be efficiently transferred into the adjacent semiconductors or adsorbates. [4] Therefore, the introduction of plasmonic metal nanostructures into catalytic reactions provides a promising avenue to maximize the utilization of sunlight and facilitate the conversion from the inexhaustible solar energy into usable chemical energy. [5] In this review, we focus on the LSPR properties of plasmonic metal nanostructures and highlight recent research progress on the applications of plasmonic metal nanostructures in photocatalytic, photoelectrochemical (PEC) (electro-assisted photocatalytic), and photo-assisted electrocatalytic water splitting technologies, including the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In addition, the relevant structure design, mechanism exploration, and performance promotion are summarized and discussed. Finally, we put forward the perspectives and challenges in plasmon-enhanced catalysis, especially photo-assisted electrocatalysis, which has not been extensively studied at present but has significant research value. Overall, plasmonic photocatalysts hold great promises in the future and there is plenty of room to achieve the theoretically optimal catalytic performances.

Silver-Boosted WO3/CuWO4 Heterojunction Thin Films for Enhanced Photoelectrochemical Water Splitting Efficiency

“…The PRIET process involves the transfer of charge carriers in the plasmonic material to the semiconductor via an electric field or dipole–dipole interaction, without radiative loss. The efficiency of this transfer is determined by the overlap between the conduction band of the plasmonic metal and the semiconductor . Thus, LSPR-driven plasmonic electrons could preferentially transfer to the CB of WO 3 and CuWO 4 at the respective interfaces, and the plasmonic holes accumulate and prompt the water oxidation reaction.…”

“…The efficiency of this transfer is determined by the overlap between the conduction band of the plasmonic metal and the semiconductor. 58 Thus, LSPR-driven plasmonic electrons could preferentially transfer to the CB of WO 3 and CuWO 4 at the respective interfaces, and the plasmonic holes accumulate and prompt the water oxidation reaction. Consequently, the Ag-decorated WO 3 / CuWO 4 photoanode exhibited enhanced PEC performance due to the synergetic effect of LSPR-driven strong local electric field that enhances the photoabsorption ability, charge carrier injection, and heterojunction structure for effective charge carrier separation, thereby improving the overall PEC performance and making it a more viable option for large-scale applications.…”

Improving Wastewater Treatment by Triboelectric-Photo/Electric Coupling Effect

“…Photoelectric catalysis can be divided into two parts: electroassisted photocatalysis and photoassisted electrocatalysis (e.g., photoelectric-Fenton). , The photocatalyst is immobilized on an electrode as a photoanode. When sunlight irradiates the anode, electrons are excited from the valence band to the conduction band, and holes are generated in the valence band.…”

Photosensitization Efficiency Modulation of Atomically Precise Silver Nanoclusters for Photoelectrocatalysis

“…Atomically precise metal nanoclusters (NCs) featuring molecule-like discrete electronic structures have gained unprecedented attention because of their unique optical, optoelectronic, and catalytic properties. − Apart from these physical characteristics, metal NCs with a suitable highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap fulfill all fundamental criteria of photosensitizers, including light absorption over a broad range of solar spectra and a long excited state for charge transfer. − Therefore, metal NC-based photosystems demonstrate great potential for solar energy conversion. , …”