A study on the mechanism for the interaction of light with noble metal-metal oxide semiconductor nanostructures for various photophysical applications

Abstract

Metal oxide semiconductors hold great promise for applications in energy conversion and storage, environmental remediation, optoelectronics, memory, light emission and other areas, but critical factors such as the high rate of charge-carrier recombination and limited light absorption have restricted more practical and viable applications. The remarkable ability of plasmonic noble metals to concentrate and scatter visible light has found a versatile potential in harvesting and converting solar energy. Plasmonic nanostructures of noble metals in combination with semiconductors offer a promising future for the next generation of energy needs. The overlap of the spectral range of the incident photon with absorbance wavelength of the semiconductor and the surface plasmon bands of the plasmonic metal provides a useful tool to predict the enhancement in optical and electrical properties of hybrid semiconductor-noble metal nanostructures. Here we make an attempt to comprehensively review the role of plasmonic noble metals in the enhanced functions for photocatalytic activity, photoenergy conversion in DSSCs, enhanced light emission and photochromatism. We mainly focus on the improvement of performance in TiO2 or ZnO in combination with noble metals on representative photophysical applications. The mechanism behind their interaction with light is discussed in detail in each section.

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

“…The charge density is redistributed and thus establishes a strong coulombic restoring force which results in the oscillation of charge density. The in phase oscillations (with the incident light) in this case can be compared to simple harmonic oscillator [154]. Further, these charge density oscillations decreased the dielectric constant of the surrounding matrix [155].…”

Study on Antibacterial Activity of Ag Nanometal-deposited TiO2Prepared by Sonochemical Reduction Method

“…또한 졸-겔 공정을 이용하여 금속염과 이산화티탄 전구체의 혼합물로부터 겔 형태의 중간체를 만들고 건조 및 강열, 그리고 최종 적으로 분쇄과정을 거쳐 나노분말 형태의 이산화티탄-메탈 복합체를 제조하기도 한다 [14,15]. 그러나 제조공정의 복잡함과 과량의 에너지 소비 등의 단점을 극복하기 위해서 최근에는 초음파환원법 혹은 광환 원법을 이용하여 나노사이즈의 귀금속 메탈(Au, Ag)을 이산화티탄 표 면에 도핑하는 방법이 많이 연구되고 있다 [4,[16][17][18][19] [20,21].…”

Plasmon Mediated Photocatalysis by Solar Active Ag/ZnO Nanostructures: Degradation of Organic Pollutants in Aqueous Conditions

“…The overall pictorial photocatalytic mechanism of degradation of MB in presence of Ag/ZnO under sunlight is shown in figure 15 [41]. The following reaction chain is the normal process [19,48]; Ag + hυ → Ag Additionally, in case of plasmonic photocatalyst (Ag/ZnO), intensive local electric field LSPR may create excitation of more electrons and holes and heat up the surrounding environment to increase the reaction rate and the mass transfer thereby polarizing the nonpolar molecules for better adsorption and absorption of pollutants with Ag/ZnO [30]. This local electric field may also have factored in better performance in the present study.…”