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Unmodified and modified Haloxylon recurvumplant stems (HRS) were studied as new sorbents for the removal of Acid Blue 25 dye (AB25) from synthesized dye solutions. Characterization of the pristine and dye-loaded adsorbents by Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM–EDX), and nitrogen adsorption techniques indicated that the chemical and physical properties of the surfaces of the HRS samples were strongly influenced by the modifying agents. Moreover, the modified biomass showed great potential for binding AB25 at relatively low pH (a pH of 2), with sorption parameters that could be optimized by using batch adsorption techniques. The AB25 sorption behaviour varied with the modification technique; untreated HRS and HRS modified with phosphoric acid (MHRS-H3PO4) exhibited pseudo-first-order sorption kinetics, whereas when HRS was modified with either urea or nitric acid (MHRS-U and MHRS-HNO3respectively), then pseudo-second-order sorption kinetics was observed. Intra-particle and liquid film diffusion models were used to describe the mechanisms of dye sorption and to identify the rate-determining steps in each case. The adsorption and desorption rates were determined using the Elovich model. The AB25 equilibrium sorption data most convincingly fitted to the Langmuir sorption isotherm for HRS and MHRS-H3PO4biomass samples. By contrast, the Freundlich sorption isotherm provided a better fit to the equilibrium sorption process of AB25 on MHRS-U and MHRS-HNO3. The binding energies could be calculated by applying the Dubinin-Radushkevich (D-R) model. The maximum adsorption capacities of the materials were found to be 16.22 mg g−1(HRS), 22.94 mg g−1(MHRS-U), 21.10 mg g−1(MHRS-HNO3), and 24.04 mg g−1(MHRS-H3PO4) at the optimized conditions. The results of the studies herein suggest that HRS-H3PO4is the most effective environmentally-friendly material for AB25 sorption under the experimental conditions applied.

Quantum dot light-emitting diodes (QLEDs) are an emerging class of optoelectronic devices with a wide range of applications. However, there still exist several drawbacks preventing their applications, including long-term stability, electron leakage, and large power consumption. To circumvent the difficulties, QLEDs based on a self-assembled hole transport layer (HTL) with reduced device complexity are proposed and demonstrated. The self-assembled HTL is prepared from poly[3-(6-carboxyhexyl)thiophene-2,5-diyl] (P3HT-COOH) solution in N,N-dimethylformamide (DMF) forming a well-ordered monolayer on an indium-tin-oxide (ITO) anode. The P3HT-COOH monolayer has a smaller HOMO band offset and a sufficiently large electron barrier with respect to the CdSe/ZnS quantum dot (QD) emission layer, and thus it is beneficial for hole injection into and electron leakage blocking from the QD layer. Interestingly, the QLEDs exhibit an excellent conversion efficiency (97%) in turning the injected electron–hole pairs into light emission. The performance of the resulting QLEDs possesses a low turn-on voltage of +1.2 V and a maximum external quantum efficiency of 25.19%, enabling low power consumption with high efficiency. Additionally, those QLEDs also exhibit excellent long-term stability without encapsulation with over 90% luminous intensity after 200 days and superior durability with over 70% luminous intensity after 2 h operation under the luminance of 1000 cd m–2. The outstanding device features of our proposed QLEDs, including low turn-on voltage, high efficiency, and long-term stability, can advance the development of QLEDs toward facile large-area mass production and cost-effectiveness.

Multilevel and flexible nonvolatile memory (NVM) is a promising candidate for data storage in next-generation devices but its high bias and low mobility of conducting channels are often its drawbacks. In this study, we demonstrate a low bias of smaller than 0.1 V and a high-mobility graphene layer as a conducting channel for flexible optoelectronic NVM based on a composite thin film of indium-based MOF-derived InCl3and 4,4-oxydiphthalic anhydride (odpta), Na[In3(odpt)2(OH)2(H2O)2](H2O)4, and reduced graphene oxide (rGO). The optoelectronic NVM device can be encoded and erased optically by ultraviolet (UV) light and visible light, respectively. Our device also achieves memory states over 192 (6-bit storage) distinct levels, which can emerge as mass data storage. It also shows an excellent endurance of write–erase cycles under irradiation with a laser of varying wavelengths, the mechanical stability of more than 1000 bending cycles, and stable retention for longer than 10 000 s. These results open an alternative route for developing low bias and innovative optoelectronic technologies.

Supercapacitors have emerged as the most integral energy devices due to their unexampled countenance like high power and energy density, long cyclic life and environmentally friendly nature. Electrode materials play a critical role in determining the supercapacitor performance. Due to their rich valence states, excellent redox properties and high energy density, transition-metal oxides have demonstrated to be promising candidates for high performance supercapacitors, however, the relatively low conductivity limits their applications. Therefore, incorporating with carbon-based materials or conductive polymers is a promising strategy to further improve the performance of transition-metal oxide based supercapacitors. Here in, we have a comprehensive review on the advances and progress of transition-metal oxides materials applied in supercapacitors, such as copper oxide (CuO), nickel oxide (NiO), cobalt oxide (Co3O4), zinc oxide (ZnO), manganese dioxide (MnO2), iron oxide (Fe2O3, Fe3O4, FeO), and their composites incorporated with carbon-based materials or conductive polymers. Finally, the current challenges and future perspectives of these electrode materials for supercapacitors have been summarized and anticipated.

Supercapacitors play a vital role in the storage of energy devices and in systems that assist in energy conversion. Currently, researchers focus on developing advanced materials to improve overall performance of the supercapacitors, and extensive efforts have been made towards scientific and technological advancements. The continuous progress towards composite materials hold enormous potential to circumvent present limitations, such as better architecture design of the materials to make it more durable, long cycle life, higher energy density, higher power density and better stability as well as being environment friendly to combat climate change. To address these limitations, the scope of advance electrode materials composed of copper nanostructures for the supercapacitor applications has been concentrated on this review. Apart from the versatile nature of copper oxide, it can be easily mixed with polarized liquids and polymers, thereby has very stable physical and chemical properties. We highlighting the numerous copper oxide hybrid metal oxide electrodes available to develop such supercapacitors. Consequent sections covered recent studies on composite nanostructures and electrodes based on copper oxide combined with organic compounds. Furthermore, we concluded the review and presented the challenges and prospects of this promising field.