Hang Yu

Bio: Hang Yu is an academic researcher from North China Electric Power University. The author has contributed to research in topics: Silicon & Etching (microfabrication). The author has an hindex of 8, co-authored 15 publications receiving 214 citations.

Effective light trapping enhancement by plasmonic Ag nanoparticles on silicon pyramid surface

Abstract: Plasmonic Ag nanoparticles were deposited on the silicon pyramid structures to further reduce surface reflectance. Compared with the bare silicon pyramid surface, a dramatic reflectance reduction around 380 nm was observed and the weighted average surface reflectance from 300 nm to 1100 nm could be reduced about 3.4%. By a series of designed experiments combined with Mie theory calculations, the influences of the size, shape and density distribution of Ag nanoparticles on the surface reflectance reduction were investigated in detail. This study shows a practicable method to improve light trapping for the application to solar cells.

Hydrothermal Synthesis of Anatase TiO2 Nanoflowers on a Nanobelt Framework for Photocatalytic Applications

Abstract: Anatase titanium dioxide (TiO2) nanoflowers were fabricated on rutile TiO2 nanobelts through a simple hydrothermal synthesis. The architecture of the composite nanostructures was composed of a rutile nanobelt framework with anatase nanoflowers. The novel TiO2 composite nanostructures exhibit higher photocatalytic activity for organic pollutants relative to TiO2 nanobelts and commercially available nanoparticles (P25). This enhanced photocatalytic activity is primarily a result of complex crystal nanostructures that enhance the carrier transport along the nanobelt framework. The results indicate that this novel TiO2 nanostructure has superior photocatalytic properties, which demonstrates its potential as a new photocatalyst material.

Electrodeposition of Ag nanosheet-assembled microsphere@Ag dendrite core–shell hierarchical architectures and their application in SERS

Abstract: Ag core–shell hierarchical microstructures, with nanosheet-assembled microspheres as the core and dendrites coated on the surface, have been synthesized by electrodeposition. The growth mechanisms of these Ag microstructures have been systematically investigated through time-dependent morphological evolution. A transformation stage from the microspheres to the dendrites was found in the morphological evolution of Ag core–shell hierarchical microstructures, which was affected by the deposition time and voltage. Therefore, we obtained various Ag core–shell hierarchical microstructures, with adjustable ratios of the microsphere cores to the dendrite shells, by controlling the deposition voltage. Furthermore, the Ag core–shell hierarchical microstructures exhibit excellent surface-enhanced Raman scattering (SERS) ability, showing great potential as effective SERS substrates.

A review of one-dimensional TiO2 nanostructured materials for environmental and energy applications

Abstract: One-dimensional TiO2 (1D TiO2) nanomaterials with unique structural and functional properties have been extensively used in various fields including photocatalytic degradation of pollutants, photocatalytic CO2 reduction into energy fuels, water splitting, solar cells, supercapacitors and lithium-ion batteries. In the past few decades, 1D TiO2 nanostructured materials with a well-controlled size and morphology have been designed and synthesized. Compared to 0D and 2D nanostructures, more attention has been paid to 1D TiO2 nanostructures due to their high aspect ratio, large specific surface area, and excellent electronic or ionic charge transport properties. In this review, we present the crystal structure of TiO2 and the latest development on the fabrication of 1D TiO2 nanostructured materials. Besides, we will look into some critical engineering strategies that give rise to the excellent properties of 1D TiO2 nanostructures such as improved enlargement of the surface area, light absorption and efficient separation of electrons/holes that benefit their potential applications. Moreover, their corresponding environmental and energy applications are described and discussed. With the fast development of the current economy and technology, more and more effort will be put into endowing TiO2-based materials with advanced functionalities and other promising applications.

Surface and Interface Engineering of Electrode Materials for Lithium‐Ion Batteries

Abstract: Lithium-ion batteries are regarded as promising energy storage devices for next-generation electric and hybrid electric vehicles. In order to meet the demands of electric vehicles, considerable efforts have been devoted to the development of advanced electrode materials for lithium-ion batteries with high energy and power densities. Although significant progress has been recently made in the development of novel electrode materials, some critical issues comprising low electronic conductivity, low ionic diffusion efficiency, and large structural variation have to be addressed before the practical application of these materials. Surface and interface engineering is essential to improve the electrochemical performance of electrode materials for lithium-ion batteries. This article reviews the recent progress in surface and interface engineering of electrode materials including the increase in contact interface by decreasing the particle size or introducing porous or hierarchical structures and surface modification or functionalization by metal nanoparticles, metal oxides, carbon materials, polymers, and other ionic and electronic conductive species.

Exceeding the limit of plasmonic light trapping in textured screen-printed solar cells using Al nanoparticles and wrinkle-like graphene sheets

Abstract: The solar cell market is predominantly based on textured screen-printed solar cells. Due to parasitic absorption in nanostructures, using plasmonic processes to obtain an enhancement that exceeds 2.5% of the short-circuit photocurrent density is challenging. In this paper, a 7.2% enhancement in the photocurrent density can be achieved through the integration of plasmonic Al nanoparticles and wrinkle-like graphene sheets. For the first time, we experimentally achieve Al nanoparticle-enhanced solar cells. An innovative thermal evaporation method is proposed to fabricate low-coverage Al nanoparticle arrays on solar cells. Due to the ultraviolet (UV) plasmon resonance of Al nanoparticles, the performance enhancement of the solar cells is significantly greater than that from Ag nanoparticles. Subsequently, we deposit wrinkle-like graphene sheets over the Al nanoparticle-enhanced solar cells. Compared with planar graphene sheets, the bend carbon layer also exhibits a broadband light-trapping effect. Our results exceed the limit of plasmonic light trapping in textured screen-printed silicon solar cells. The performance of screen-printed silicon solar cells can be enhanced by aluminium nanoparticles. Xi Chen and co-workers from the Swinburne University of Technology in Australia report that light scattering effects can increase a solar cell’s short-circuit photocurrent density by up to 6.3%. Aluminium nanoparticles are advantageous because their Fano resonance, unlike those of gold or silver nanoparticles, falls in the ultraviolet wavelength band. This means that detrimental Fano interference effects between scattered and unscattered light can be avoided within the solar cell’s spectral range of operation. The addition of wrinkle-like graphene sheets further improves the photocurrent to 7.3% beyond that of an unmodified screen-printed cell.

Review of porous silicon preparation and its application for lithium-ion battery anodes

Abstract: Silicon is of great interest for use as the anode material in lithium-ion batteries due to its high capacity. However, certain properties of silicon, such as a large volume expansion during the lithiation process and the low diffusion rate of lithium in silicon, result in fast capacity degradation in limited charge/discharge cycles, especially at high current rate. Therefore, the use of silicon in real battery applications is limited. The idea of using porous silicon, to a large extent, addresses the above-mentioned issues simultaneously. In this review, we discuss the merits of using porous silicon for anodes through both theoretical and experimental study. Recent progress in the preparation of porous silicon through the template-assisted approach and the non-template approach have been highlighted. The battery performance in terms of capacity and cyclability of each structure is evaluated.