► Metal assisted chemical etching (MacEtch) is a wet but directional etching method. ► Aspect ratio and morphology depend on metal catalyst, semiconductor, and etchants. ► Si nanostructures with ...extremely high aspect ratio can be achieved by MacEtch. ► MacEtch also works for non-Si based semiconductors. ► MacEtch produced structures are promising for photovoltaic applications.
Metal assisted chemical etching (MacEtch) is a recently developed anisotropic wet etching method that is capable of producing high aspect ratio semiconductor nanostructures from patterned metal film. In this review article, we highlight the characteristics of MacEtch of silicon (Si) including controllability of the produced sidewall roughness, the inherent high aspect ratio, the weak crystal orientation dependence, impurity doping and solution concentration dependent porosity, as well as the applicability of MacEtch to non-Si based semiconductor materials including III–V compound semiconductors. Also reviewed are applications of MacEtch produced high aspect ratio Si nanostructures in photovoltaics, where the p–n junction can be in the planar Si tray, core–shell, or axial geometry, with nanowire, micropillar, or hole arrays serving as light trapping or carrier collection structures. The prospect of using MacEtch to improve the cost and efficiency of photovoltaic cells is discussed.
Glycosylation is one of the most common and important types of protein post-translational modifications in mammalian cells. To decode the protein glycosylation, it is highly important to enrich ...glycopeptides or separate glycans from complex biosamples. Hydrophilic interaction liquid interaction chromatography (HILIC) has inherent advantages in the separation of hydrophilic substances and glycopeptide enrichment. Conventional HILIC display unbiased binding with the hydrophilic solutes, leading to unsatisfactory enrichment selectivity for glycopeptides. In recent three years, many novel HILIC materials, including histidine, dipeptide, maltose, and amide-based ones, were developed and displayed either specific binding capacities toward sialylated glycopeptides, or substantially stronger retention toward neutral glycopeptides. Therefore, HILIC has grown up to be a high-efficiency method for collecting both glycosylation sites and glycan structural information simultaneously. In the review, recent breakthrough of HILIC materials applied to glycopeptide enrichment and glycan separation is summarized, and the future development tendency of the HILIC is suggested.
•We review recent advances in HILIC materials applied to glycopeptide enrichment and glycan separation.•The “hydrophilic subtraction” model is introduced as HILIC mechanisms.•Five categories of HILIC materials are classified.•The future development tendency of the HILIC is suggested.
Abstract
Graphene has inherent physical and chemical properties, but there are few reactive sites on the surface of graphene, and its use is limited. In the field of water treatment, especially in ...the adsorption treatment of heavy metals, it has shown great advantages and good development prospects. Dye wastewater is one of the more difficult industrial wastewaters to treat. Among various processes for removing dye wastewater, adsorption technology is considered to be the most promising method of water purification due to its fast, efficient, and low energy consumption characteristics. Molecular sieves have the characteristics of good adsorption selectivity, stable structure, easy regeneration, low price, and environmental protection. They are widely used as adsorbents. However, the adsorption efficiency of a single molecular sieve on organics is also low. In recent years, molecular sieve composite adsorption materials have begun to enter our field of vision. Hydrothermal treatment technology simply and quickly prepared composite materials with different graphene oxide content through chemical action, and studied the synergistic effect between the two composites on the adsorption performance of pollutants.
Exploring efficient and inexpensive oxygen evolution reaction (OER) electrocatalysts is of great importance for various electrochemical energy storage and conversion technologies. Ni-based ...electrocatalysts have been actively pursued because of their promising activity and earth abundance. However, the OER efficiency for most of the developed Ni-based electrocatalysts has been intrinsically limited due to their low electrical conductivity and poor active site exposure yield. Herein, we report metallic Ni3N nanosheets as an efficient OER electrocatalyst for the first time. The first-principles calculations and electrical transport property measurements unravel that the Ni3N is intrinsically metallic, and the carrier concentration can be remarkably improved with dimensional confinement. The EXAFS spectra provide solid evidence that the Ni3N nanosheets have disordered structure resultant of dimensional reduction, which then could provide more active sites for OER. Benefiting from enhanced electrical conductivity with metallic behavior and atomically disordered structure, the Ni3N nanosheets realize intrinsically improved OER activity compared with bulk Ni3N and NiO nanosheets. Our finding suggests that metallic nitride nanosheets could serve as a new group of OER electrocatalysts with excellent property.
Most recently, much attention has been devoted to 1T phase MoS2 because of its distinctive phase‐engineering nature and promising applications in catalysts, electronics, and energy storage devices. ...While alkali metal intercalation and exfoliation methods have been well developed to realize unstable 1T‐MoS2, but the aqueous synthesis for producing stable metallic phase remains big challenging. Herein, a new synthetic protocol is developed to mass‐produce colloidal metallic 1T‐MoS2 layers highly stabilized by intercalated ammonium ions (abbreviated as N‐MoS2). In combination with density functional calculations, the X‐ray diffraction pattern and Raman spectra elucidate the excellent stability of metallic phase. As clearly depicted by high‐angle annular dark‐field imaging in an aberration‐corrected scanning transmission electron microscope and extended X‐ray absorption fine structure, the N‐MoS2 exhibits a distorted octahedral structure with a 2a
0 × a
0 basal plane superlattice and 2.72 Å Mo–Mo bond length. In a proof‐of‐concept demonstration for the obtained material's applications, highly efficient photocatalytic activity is achieved by simply hybridizing metallic N‐MoS2 with semiconducting CdS nanorods due to the synergistic effect. As a direct outcome, this CdS:N‐MoS2 hybrid shows giant enhancement of hydrogen evolution rate, which is almost 21‐fold higher than pure CdS and threefold higher than corresponding annealed CdS:2H‐MoS2.
Gram‐scale aqueous synthesis of 1T‐MoS2
, highly stabilized by intercalated ammonium ions, is demonstrated. In combination with X‐ray absorption spectra and atomic structure observations, the correlation between microstructure and stable metallic phase is revealed, agreeing with density functional calculations. More interestingly, highly efficient hydrogen evolution is achieved by hybridizing the 1T‐MoS2 with semiconducting CdS nanorods.
III-V semiconductors, especially InAs, have much higher electron mobilities than Si and have been considered as promising candidates for n-channel materials for post-Si low-power CMOS logic ...applications. Combined with the inherent 3-D structure that enables the gate-all-around (GAA) geometry for superb gate electrostatic control, III-V nanowire (NW) MOSFETs are well positioned to extend the scaling beyond Si. This paper attempts to provide a review of the growth and fabrication approaches (both bottom-up and top-down), and the state-of-the-art device performance of III-V NW GAA MOSFETs, as well as an outlook of their scaling potential.
As a promising candidate for low‐cost and environmentally friendly thin‐film photovoltaics, the emerging kesterite‐based Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have experienced rapid advances over the ...past decade. However, the record efficiency of CZTSSe solar cells (12.6%) is still significantly lower than those of its predecessors Cu(In,Ga)Se2 (CIGS) and CdTe thin‐film solar cells. This record has remained for several years. The main obstacle for this stagnation is unanimously attributed to the large open‐circuit voltage (VOC) deficit. In addition to cation disordering and the associated band tailing, unpassivated interface defects and undesirable energy band alignment are two other culprits that account for the large VOC deficit in kesterite solar cells. To capture the great potential of kesterite solar cells as prospective earth‐abundant photovoltaic technology, current research focuses on cation substitution for CZTSSe‐based materials. The aim here is to examine recent efforts to overcome the VOC limit of kesterite solar cells by cation substitution and to further illuminate several emerging prospective strategies, including: i) suppressing the cation disordering by distant isoelectronic cation substitution, ii) optimizing the junction band alignment and constructing a graded bandgap in absorber, and iii) engineering the interface defects and enhancing the junction band bending.
Cation substitution is one of the most promising solutions to overcome the large open‐circuit voltage (VOC) deficit in kesterite solar cells. This deficit is attributed to cation disorder and associated band tailing, unpassivated interfaces, and undesirable energy band alignment. Recent efforts and strategies are considered to overcome the VOC limit of kesterite solar cells using various cation substitution methods.
Designing advanced electrocatalysts for hydrogen evolution reaction is of far-reaching significance. Active sites and conductivity play vital roles in such a process. Herein, we demonstrate a ...heteronanostructure for hydrogen evolution reaction, which consists of metallic 1T-MoS2 nanopatches grown on the surface of flexible single-walled carbon nanotube (1T-MoS2/SWNT) films. The simulated deformation charge density of the interface shows that 0.924 electron can be transferred from SWNT to 1T-MoS2, which weakens the absorption energy of H atom on electron-doped 1T-MoS2, resulting in superior electrocatalytic performance. The electron doping effect via interface engineering renders this heteronanostructure material outstanding hydrogen evolution reaction (HER) activity with initial overpotential as small as approximately 40 mV, a low Tafel slope of 36 mV/dec, 108 mV for 10 mA/cm2, and excellent stability. We propose that such interface engineering could be widely used to develop new catalysts for energy conversion application.
We have developed methods for creating microscale inorganic light-emitting diodes (LEDs) and for assembling and interconnecting them into unusual display and lighting systems. The LEDs use ...specialized epitaxial semiconductor layers that allow delineation and release of large collections of ultrathin devices. Diverse shapes are possible, with dimensions from micrometers to millimeters, in either flat or "wavy" configurations. Printing-based assembly methods can deposit these devices on substrates of glass, plastic, or rubber, in arbitrary spatial layouts and over areas that can be much larger than those of the growth wafer. The thin geometries of these LEDs enable them to be interconnected by conventional planar processing techniques. Displays, lighting elements, and related systems formed in this manner can offer interesting mechanical and optical properties.
PDF
