X-ray photoelectron spectroscopy studies of indium-tin-oxide treated via oxygen plasma immersion ion implantation

Surface modification was performed on the indium-tin-oxide (ITO) thin films by oxygen inductive coupling plasma (O-ICP) and oxygen plasma immersion ion implantation (O-PIII). The electronic states of ITO surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The observed peak shifts of O 1s, In 3d5/2 and Sn d5/2 core levels showed that the work function of ITO can be further enhanced by O-PIII treatment, compared with that of untreated and O-ICP treated surfaces. The deconvolution of O 1s spectrum and calculation of stoichiometry showed that the work function improvement should be attributed to the increase of effective oxygen content, namely, the elimination of oxygen vacancies. In addition, the measurement of Kelvin probe confirmed that an increment of the ITO work function by 1.1 eV was obtained on O-PIII treated sample and the results sustained our proposal

Electrical characteristics of monofilaments in dielectric barrier discharge plasma jets at atmospheric pressure

Electrical characteristics of monofilaments in dielectric barrier discharge plasma jets were investigated at atmospheric pressure. It is found that the shapes of monofilaments, the discharge current, the number of discharges, the breakdown voltage and the input power are dependent not only on the Ar flow rate but also on the applied voltage and exhibit complicated behaviors. Especially, the discharge current is irregular and has the oscillating pulses with positive and negative polarities. The influence of wall charges on the above parameters was discussed

Reconfigurable Amplitude-Phase-Coding Metasurface with Flexible Beamforming Capability

Recently, reconfigurable coding metasurfaces have attracted extensive attention due to their dynamic and flexible manipulation of electromagnetic (EM) waves, making them an effective solution to connect physical reality and information science. Nevertheless, most previously reported reconfigurable metasurfaces suffer from limited applications, as they solely possess either phase or amplitude modulation. In this article, we propose a reconfigurable coding metasurface that can regulate both phase and amplitude response independently. In the field of the metasurface, the phase response can tailor the wavefronts, and the amplitude response can adjust the redistribution of the energy of the EM waves. Specifically, by integrating a PIN diode into the meta-atom and controlling its bias voltage, the reflection phase can be switched between two opposite phases with a phase difference of about 180°, and the reflection amplitude can be manipulated from 0.02 to 0.98 continuously at 11 GHz. The unit element consists of simple multi-layer structures, reducing its production cost and processing difficulty. By loading 1-bit phase code and multi-bit amplitude code to each unit element severally, this metasurface can modulate the distribution of reflected EM waves in two-dimensional (2-D) space while simultaneously suppressing the sidelobes for any quantity of scattered beams over a wide operating band ranging from 10.5 to 11.5 GHz. This metasurface exhibits promising potential for manipulating the distribution of EM wave energy and shaping of EM beams, which can be expected to facilitate wireless communication technology

Selective Recovery of Lithium from Spent Lithium-Ion Batteries by Coupling Advanced Oxidation Processes and Chemical Leaching Processes

Traditional technologies for the recycling of spent lithium-ion batteries (LIBs) mainly focus on reductive leaching, which often leads to total leaching rather than selective leaching of metals. As a result, loss of valuable metal ions, particularly Li+, occurs in subsequent extraction processes, causing low recycling efficiency of valuable metals. Inspired by the oxidede-lithiation process in materials science, here, advanced oxidation processes (AOPs) are first introduced to selectively recover Li from spent LIBs during hydrometallurgical leaching (oxidative leaching), and a high Li recovery rate is achieved with an extremely high slurry density. In AOPs, the sulfate radical (SO4 center dot-) and hydroxyl radical (HO center dot), which have high oxidation potentials, are in situ generated by heat-activated persulfate to prevent the leaching of Co2+ and Mn2+ and, simultaneously, promote the leaching of Li. Besides, chemical leaching processes are coupled with AOPs to enhance the leaching of Li for the incomplete delithiation of AOPs. Through the selective recovery, the extraction process of Li is drastically shortened. A lithium-rich solution (18.2 g/L of Lit), which is available to directly prepare qualified lithium products, can be obtained in only two steps. The reaction mechanisms between AOPs and spent LIBs are also comprehensively investigated. In the end, the loss of Li is only 2.06% in the purification processes, leading to a high recycling efficiency of Li. Li2CO3 with a purity of 99.0% was obtained. Furthermore, the introduction of AOPs for selective extraction of metals will not only show its significant value in the waste recycling field but also in the mineral resource utilization

Direct preparation of efficient catalyst for oxygen evolution reaction and high-purity Li2CO3 from spent LiNi0.5Mn0.3Co0.2O2 batteries

The recovery of waste lithium-ion batteries (LIBs) is an intensively studied worldwide because of environmental pollution and the risk of undersupply of a strategic raw material. Traditional technologies have poor selectivity for lithium recovery from waste LIBs. Metallic Ni, Co, and Mn are usually recovered by leaching, precipitation, and solvent extraction. These recycling methods are costly and have a long recycling route and high potential for secondary waste generation. In this paper, a mechanochemical activation approach was proposed for the selective recycling of lithium and recovery of Ni0.5Mn0.3Co0.2(OH)2 from spent LiNi0.5Mn0.3Co0.2O2 batteries. The leaching efficiency and Li selectivity were found to be 95.10% and 100%, respectively. The structure of Ni0.5Mn0.3Co0.2(OH)2 was investigated using various characterisation techniques. The selective reaction mechanism of mechanochemical activation was identified. High-purity Li2CO3 (99.96 wt%) was obtained. Electrochemical tests showed that the performance of Ni0.5Mn0.3Co0.2(OH)2 was comparable to that of a commercial oxygen evolution reaction catalyst (IrO2). This research demonstrates an effective and shorter route from waste to a functional material during recycling spent LIBs that incorporates the principles of green chemistry and shows great potential for practical application

Systematic study on size and temporal dependence of micro-LED arrays for display applications

Micro-LEDs are one of the most promising candidates for next-generation displays, yet they are inconvenienced by the efficiency reduction induced by the sidewall defects when pursuing further scaled-down device dimensions. We have systematically investigated both the size and temporal dependence of micro-LEDs. Micro-LED arrays with a mesa size ranging from 7 to 100 μm were prepared for display purposes. The luminance and external quantum efficiency (EQE) were measured and discussed. Surprisingly, micro-LED arrays with a smaller mesa size exhibit a higher EQE under 100 ns pulse duration operation when compared with longer pulse duration operations. Under certain short-pulsed excitation, a 7 7 7 μm2 micro-LED array even exhibits a >20% higher EQE as compared to the direct current (DC) or the long duration pulse operation condition.We thus concluded that the notorious efficiency reduction induced by sidewall defects in small-sized micro-LED arrays could be significantly reduced by applying short-pulse voltages