Zhenhe Xu

Semiconductor and Metallic Core–Shell Nanostructures: Synthesis and Applications in Solar Cells and Catalysis

Nano-heterostructures have attracted great attention due to their extraordinary properties beyond those of their single-component counterparts. This review focuses on a specific type of hybrid structures: core-shell structures. In particular, we present and discuss the recent wet-chemical synthesis approaches for semiconductor and metallic core-shell nanostructures, and their relevant properties and potential applications in photovoltaics and catalysis, respectively.

Recent advancements in plasmon-enhanced promising third-generation solar cells

Abstract The unique optical properties possessed by plasmonic noble metal nanostructures in consequence of localized surface plasmon resonance (LSPR) are useful in diverse applications like photovoltaics, sensing, non-linear optics, hydrogen generation, and photocatalytic pollutant degradation. The incorporation of plasmonic metal nanostructures into solar cells provides enhancement in light absorption and scattering cross-section (via LSPR), tunability of light absorption profile especially in the visible region of the solar spectrum, and more efficient charge carrier separation, hence maximizing the photovoltaic efficiency. This review discusses about the recent development of different plasmonic metal nanostructures, mainly based on Au or Ag, and their applications in promising third-generation solar cells such as dye-sensitized solar cells, quantum dot-based solar cells, and perovskite solar cells.

Interfacial reaction-directed synthesis of a ceria nanotube-embedded ultra-small Pt nanoparticle catalyst with high catalytic activity and thermal stability

A catalyst based on ceria nanotube-embedded ultra-small Pt nanoparticles was synthesized by means of an interfacial reaction in the absence of any surfactant and without involving any separate surface modification process. When Ce(OH)CO3 nanorods and H2PtCl6 are introduced into a NaOH aqueous solution in sequence, a solid–liquid interfacial reaction between Ce(OH)CO3 and NaOH occurs. The formed Ce(OH)3 then deposits on the external surface of Ce(OH)CO3 nanorods. During the interfacial reaction, the negatively charged Pt species is expected to be electrostatically attracted to gradually formed Ce(OH)3 due to its positive charge, resulting in a uniform mixture of Pt species and Ce(OH)3. After removing residual Ce(OH)CO3 and hydrogen reduction, ceria nanotube-embedded Pt nanoparticle hollow composites were achieved. Due to the ultra-small size of catalytically active Pt nanoparticles and the close contact between Pt and ceria, the catalyst exhibits high catalytic activity toward CO oxidation and excellent thermal stability even at temperatures as high as 700 °C, suggesting that they also hold promise for higher temperature catalytic reactions.

Plasmonic Au Loaded Hierarchical Hollow Porous TiO2 Spheres: Synergistic Catalysts for Nitroaromatic Reduction

Plasmonic Au nanoparticle (NP)-loaded hierarchical hollow porous TiO2 spheres are designed and synthesized with the purpose of enhancing the overall catalytic activity by introducing the Au plasmonic effect into the system, where Au NPs themselves are catalytically active. The constructed nanohybrid exhibits both high activity in 4-nitrophenol reduction, compared to all of the previously reported Au-based catalysts, and high selectivity. The synergy of the inherent catalytic property of Au NPs and the plasmonic effect (mainly via hot electron transfer) under irradiation is confirmed by a series of control experiments. The specifically designed, porous hollow structure also greatly contributes to the good catalytic activity because it provides a large surface area, facilitates reactant adsorption, and hinders charge recombination. In addition, theoretical calculations reveal that such a structure also leads to an increase in light absorption of about 21% in the range of 400-800 nm with respect to a uniform water-TiO2 background featuring the same filling factor. This work provides insight into the rational design of plasmon-enhanced catalysts that will show their versatility in various electro-/photocatalysis.