High-Performing Quasi-2D Perovskite Photodetectors with Efficient Charge Transport Network Built from Vertically Orientated and Evenly Distributed 3D-Like Phases

Quasi-two-dimensional (Q-2D) perovskites are emerging as one of the most promising materials for photodetectors. However, a significant challenge to Q-2D perovskites for photodetection is their insufficient charge transport ability, which is mainly attributed to their hybrid low-dimensional n-phase structure. This study demonstrates that evenly-distributed 3D-like phases with vertical orientation throughout the film can greatly facilitate charge transport and suppress charge recombination, outperforming the prevalent phase structure with a vertical dimension gradient. Based on such a phase structure, a Q-2D Ruddlesden−Popper perovskite self-powered photodetector achieving a combination of exceptional figures-of-merit is realized, including a responsivity of 0.45 AW⁻¹, a peak specific detectivity of 2.3 × 10¹³ Jones, a 156 dB linear dynamic range, and a rise/fall time of 2.89 µs/1.93 µs. The desired phase structure is obtained by utilizing a double-hole transport layer (HTL), combining hydrophobic PTAA and hydrophilic PEDOT: PSS. Besides, the dependence of the hybrid low-dimensional phase structure is also identified on the surface energy of the buried HTL substrate. This study gives insight into the correlation between Q-2D perovskites’ phase structure and performance, providing a valuable design guide for Q-2D perovskite-based photodetectors.     

Significant effect of TiF3 on the performance of 2NaAlH4+Ca(BH4)2 hydrogen storage properties

Titanium fluoride (TiF₃) is doped into the reactive hydride composite of 2NaAlH₄ + Ca(BH₄)₂ by ball milling to enhance the hydrogen storage properties of the composite system. NaAlH₄ and Ca(BH₄)₂ phases were fully transformed to Ca(AlH₄)₂ and NaBH₄ phases after the ball-milling process (6 h). Four major stages were discovered in the undoped and TiF₃-doped system, which is corresponding to; (i) Ca(AlH₄)₂, (ii) CaAlH₅, (iii) CaH₂ and (iv) NaBH₄, respectively. The addition of TiF₃ to the studied composite resulted in both reduced decomposition temperature and enhanced sorption kinetics compared with the undoped composite. The onset desorption temperature was reduced from 125 °C to 60 °C for the first stage in the TiF₃-doped composite, compared with the undoped composite. From differential scanning calorimetry analysis, the decomposition temperature for all stages has shifted to a lower temperature after doping with TiF₃. The activation energy has greatly reduced by 63.6 and 21.9 kJ/mol for CaAlH₅ and NaBH₄ stages, respectively, as compared with the undoped 2NaAlH₄ + Ca(BH₄)₂ composite. During the dehydrogenation process, the formation of new active species of Al₃Ti together with CaF₂ played a vital role in accelerating the reactions in 5 wt% TiF₃ doped to the studied composite system.     

Ion-exchange synthesis of Co-functionalized titanate nanotubes and their application in electrochemical capacitors

Co-functionalized titanate nanotubes (Co-Ti-NTs) were successfully synthesized by means of an ion-exchange reaction. In contrast to the pristine titanate nanotubes (Ti-NTs), Co-Ti-NTs retained rich porous channels and owned even larger specific surface area and better electronic conductivity, which rendered electrons and OH^? ions easily contact the Co species uniformly distributed on their surfaces for energy storage at high rates. The Co-Ti-NTs delivered a specific capacitance (SC) of 124 F g^?1 at 0.4 A g^?1, and a SC degradation of ca. 7% after 1500 continuous cycling at 3 A g^?1, indicating that the Co-Ti-NTs were good candidates and/or even good supports for other electroactive materials for supercapacitors application.     

State-of-charge determination of lead-acid batteries using wire-wound coils

Non-intrusive monitoring of the state-of-charge of sealed lead-acid batteries using wire-wound coils is described. Coils were attached to the plastic case of the batteries, adjacent to the negative end plate, and excited using ac current at 10 kHz. As the batteries were cycled, the inductance of the coils tracked the change in metallic content of the end plates. Data is presented for different discharge rates and temperatures. A variation of the technique is also described that uses less expensive equipment to measure the voltage drop across the coil, rather than inductance.     

All-solid-state lithium secondary batteries using a layer-structured LiNi0.5Mn0.5O2 cathode material

All-solid-state cells of In/LiNi_0.5Mn_0.5O₂ using a superionic oxysulfide glass with high conductivity at room temperature of 10⁻³ S cm⁻¹ as a solid electrolyte were fabricated and the cell performance was investigated. Although a large irreversible capacity was observed at the 1st cycle, the solid-state cells worked as lithium secondary batteries and exhibited excellent cycling performance after the 2nd cycle; the cells kept charge–discharge capacities around 70 mAh g⁻¹ and its efficiency was almost 100%. This is the first case to confirm that all-solid-state cells using manganese-based layer-structured cathode materials work as lithium secondary batteries.     

Investigation of the effects of SPEEK and its clay composite membranes on the performance of Direct Borohydride Fuel Cell

In this study, composite cation exchange membranes (CEM) were developed. With the experience from widely studied proton exchange membrane fuel cells (PEMFC), sulfonated polyether ether ketone (SPEEK) was prepared to be a more effective and cheaper ionomer alternative to the industry standard Nafion ®. SPEEK polymer membrane can reach sufficient ionic conductivities but have some mechanical and chemical stability problems (at a high degree of sulfonations (DS)). Therefore, in order to optimize the membrane, composite mixing with a well-known organic/inorganic clays called Cloisite® 15A, Cloisite ® 30B and MMT were used. Test cells for both single-cell and conductivity were designed and constructed. The ionic conductivity cell was different than the ones used in most studies, measuring conductivity in-plane with 4 probes using EIS. The membranes were characterized for their proton conductivity with electrochemical impedance spectroscopy (EIS), for DS with H NMR, water uptake, and fuel cell performance tests. First results showed that the acidic sulfonic groups of SPEEK interacted with organic/inorganic clays and as a result of partial barrier the ionic conductivity was decreased but power densities were increased. SPEEK-Cloisite® 30B composite membrane has given 40 mW/cm² power density value which is higher than pure SPEEK membrane (35 mW/cm²). The proton conductivities of the final composite membranes were close to bare SPEEK membranes which are 0,065 and 0,075 S/cm for SPEEK-Cloisite ® 30B and pristine SPEEK, respectively.     

Investigation of the performance of a direct borohydride fuel cell with low Pt/C catalyst loading under different operating conditions

Fuel cells are promising alternative energy converters in terms of preventing pollution, efficiency, and noise. Direct borohydride fuel cells (DBFCs) which are defined as a sub-class of polymer electrolyte membrane fuel cells (PEMFCs) and direct liquid fuel cells (DLFC) have increased attention recently since they offer a solution for hydrogen storage problem. However, the commercialization of DBFC is hindered by the need of high platinum loadings. Therefore, reducing the platinum content is crucial to develop cost-effective DBFC without compromising performance. This research focuses on the effects of operational parameters on the DBFC performance with low level Pt/C catalyst loading (anode: 0.32 mg/cm², cathode: 0.36 mg/cm²). The gas diffusion electrode was prepared by spray-coating technique. The peak power density of 19.95 mW/cm² was obtained at 80 ^°C when 1 mL/min was used as a flow rate of fuel.     

Electrochemical behavior of potentiodynamically deposited cobalt oxyhydroxide (CoOOH) thin films for supercapacitor application

In the present study, we report, for the first time, the synthesis of cobalt oxyhydroxide thin films on inexpensive stainless steel substrate using potentiodynamic electrodeposition method. These films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) techniques. The orthorhombic crystal structure was revealed by the X-ray diffraction study. The FT-IR spectrum confirmed the formation of cobalt oxyhydroxide. The SEM studies showed the nanoflakes-like morphology with an average thickness of 100 nm. The cyclic voltammetry study of the cobalt oxyhydroxide films in 1 M KOH showed maximum specific capacitance of 449 F g^?1 at scan rate of 5 mV s^?1.     

YAG晶体在软X射线荧光靶探测器中的应用

荧光靶探测器是同步辐射光源光束位置定位的重要设备之一,本文在96 500 eV软X射线内对CVD金刚石薄片和Ce:YAG晶体薄片进行光致发光亮度的测试,观察到Ce:YAG在该能量段的发光亮度比金刚石高,完成了上海光源软X射线荧光靶探测器靶材的实验研究与探测器的设计;同时给出了YAG晶体荧光靶探测器在线使用时观察到的相干光的衍射图像。