Neighboring Platinum Atomic Sites Activate Platinum-Cobalt Nanoclusters as High-Performance ORR/OER/HER Electrocatalysts.

The rational design of efficient and multifunctional electrocatalysts for energy conversion devices is one of the major challenges for clean and renewable energy transition. Herein, the local electronic structure of cobalt-platinum nanoclusters is regulated by adjacent platinum atomic site encapsulated in N-doped hollow carbon nanotubes (PtSA -PtCo NCs/N-CNTs) by pyrolysis of melamine-orientation-induced zeolite imidazole metal-organic frameworks (ZIF-67) with thimbleful platinum doping. The introduction of melamine can reactivate adjacent carbon atoms and initiate the oriented growth of nitrogen-doped carbon nanotubes. The systematic analysis suggests the significant role of thimbleful neighboring low-coordinated Pt─N2 in altering the localized electronic structure of PtCo nanoclusters. The optimized PtSA -PtCo NCs/N-CNTs-900 exhibit excellent hydrogen evolution reaction (HER)/oxygen evolution reaction (OER)/oxygen reduction reaction (ORR)/ catalytic performance reaching the current density of 10 mA cm-2 in 1 m KOH under the low 47 (HER) and 252 mV (OER) overpotentials, and a high half-wave potential of 0.86 and 0.89 V (ORR) in 0.1 m KOH and 0.1 m HClO4 , respectively. Remarkably, the PtSA -PtCo NC/N-CNT-900 also presents outstanding catalytic performances toward water splitting and rechargeable Zn-air batteries. The theoretical calculations reveal that optimal regulation of the electronic structure of PtCo nanoclusters by thimbleful neighboring Pt atomic reduces the reaction energy barrier in electrochemical process, facilitating the ORR/OER/HER performance.

Reduced electric field and gas temperature effects on chemical product dynamics in air surface dielectric barrier discharges: from macro-physical parameters to micro-chemical mechanisms.

To gain insights into the mechanisms of plasma chemical product interactions, the dynamic changes of the surface dielectric barrier discharge (SDBD) products are experimentally related to the reduced electric field and gas temperature. The higher applied voltage and frequency cause faster product changes from the O3-containing to the O3-free state, while raising the electron energy and gas temperature. The electron energy affects the electron collision reactions and the production of various reactive species, steering the chemical reactions towards the predominant production of NO over O3. The gas temperature affects the generation and quenching rates of the key products. Collectively, this work bridges macro-physical parameters and micro-chemical mechanisms through the electron energy and gas temperature effects, and contributes to better understanding of the physico-chemical processes in low-temperature plasmas.

Rational synthesis of methylsilsesquioxane aerogels addressing thermal load and compression recovery issues in Li-ion batteries.

Li-ion batteries suffer from two key safety issues: thermal overload and compression recovery, which may lead to flammability and mechanical failure. Silica aerogels are promising solutions to both these issues owing to their excellent thermal stability and tailored mechanical properties. However, finding the optimum sol composition in sol-gel-based aerogel synthesis is needed to address these issues at industry-relevant scales. Here, we propose an innovative approach to determine the optimum sol composition for methylsilsesquioxane (MSQ) aerogel sheets, which is based on the mechanisms of the effects of molar ratios of hydrolysis water and isopropyl alcohol (IPA) to methyltrimethoxysilane (MTMS) on the physical properties of MSQ aerogel sheets and according to the ternary contour distribution of their properties. The synthesized MSQ aerogels exhibited a soft, light, and powderless texture and featured superhydrophobic properties (150.2°), low thermal conductivity of 33.6 mW/(m·K), high thermal stability temperature in nitrogen atmosphere at 479.3 °C and moderate short-term (<6 h) service temperature of 120.0 °C. Significantly, the structural stability and elasticity of the aerogels surpassed the current state-of-the-art, showing recovery to 81.3 % of the original thickness and 85.2 % of the original stress after being subjected to 400 cycles of high-speed and high-strain consecutive compression, respectively. These excellent properties make the MSQ aerogel sheets promising for applications in thermal load and compression recovery management of diverse energy storage devices, including batteries for next-generation electric vehicles.

MoS2 nanosheets on plasma-nitrogen-doped carbon cloth for high-performance flexible supercapacitors.

With the surging demand for flexible and portable electronic devices featuring high energy and power density, the development of next-generation lightweight, flexible energy storage devices is crucial. However, achieving the expected energy and power density of supercapacitors remains a great challenge. This work reports a facile plasma-enabled method for preparing supercapacitor electrodes made of MoS2 nanosheets grown on flexible and lightweight N-doped carbon cloth (NCC). The MoS2/NCC presents an outstanding specific capacitance of 3834.28 mF/cm2 at 1 mA/cm2 and energy density of 260.94 µWh/cm2 at a power density of 354.48 µW/cm2. An aqueous symmetric supercapacitor fitted with two MoS2/NCC electrodes achieved the maximum energy density of 138.12 µWh/cm2 and the highest power density of 7,417.33 µW/cm2, along with the excellent cycling stability of 83.3 % retention over 10,000 cycles. The high-performance energy storage ASSSs (all-solid-state supercapacitors) are demonstrated to power devices in both rigid and flexible operation modes. This work provides a new perspective for fabricating high-performance all-solid-state flexible supercapacitors for clean energy storage.

A review on reactive oxygen species (ROS)-inducing nanoparticles activated by uni- or multi-modal dynamic treatment for oncotherapy.

Cancer seriously threatens human health. As compared to normal tissue cells, tumor cells are generally more susceptible to oxidative stress and accumulate higher concentrations of reactive oxygen species (ROS). Accordingly, nanomaterials-based therapies that boost intracellular ROS generation have recently been effective in targeting and eliminating cancer cells by causing programmed death. This review presents a comprehensive analysis of ROS-generation induced by nanoparticles and critically examines the associated therapies which can be categorized as uni-modal (chemodynamic therapy, photodynamic therapy, sonodynamic therapy) and multi-modal (uni-modal therapy + chemotherapy, uni-modal therapy + uni-modal therapy) therapies. Comparison of the relative tumor volume ratio between the experimental and initial tumor volumes shows that multi-modal therapy significantly outperformed other treatments. However, the limitations of multi-modal therapy are in the difficulties of materials preparation and sophisticated operation protocols, thus limiting its applications in clinical practice. As an emerging treatment modality, cold atmospheric plasma (CAP) is a reliable source of ROS, light, and electromagnetic fields that can be used to implement multi-modal treatments in a simple setting. Therefore, the field of tumor precision medicine is expected to increasingly benefit from these promising and rapidly emerging multi-modal therapies based on ROS-generating nanomaterials and reactive media such as CAPs.

Capacitative deionization using commercial activated carbon fiber decorated with polyaniline.

Capacitive deionization (CDI) has become a promising technology for water desalination due to its remarkable advantages including low operation cost, no secondary pollution and high rate of ion recovery. However, the majority of commercial CDI electrode materials are carbonaceous materials such as activated carbon with limited capacitance and high charge transfer resistance, which significantly hinders the wide application of CDI. Herein, we demonstrate a N-doped carbonaceous CDI electrode with a maximum ion electrosorption capacity of 19.9 mg/g, a low charge transfer resistance (1.17 Ω) and a robust regeneration performance (2800 min for 28 circles). The N-doped carbonaceous CDI electrode is the commercial activated carbon fiber (ACF) decorated with polyaniline (PANI) (ACF/PANI) electrode fabricated by in-situ electrochemical polymerization. The ACF/PANI electrode was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The pseudocapacitance of ACF/PANI electrode significantly contributed to the effectively improved CDI performance that 90.0% of sodium storage was attributed to the capacitive process and the unique porous structure of ACF/PANI electrode contributed to the other 10.0% diffusion-controlled capacity.

Recent advances in plasma modification of 2D transition metal dichalcogenides.

Two-dimensional (2D) transition metal dichalcogenide (TMDC) materials have recently attracted great interest because of their tantalising prospects for a broad range of applications including electronics, optoelectronics, and energy storage. Unlike bulk materials, the device performance of atomically thin 2D materials is determined by the interface, thickness and defects. Plasma processing is very effective for diverse modifications of nanoscale 2D TMDC materials, owing to its uniquely controllable, effective processes and energy efficiency. Herein, we critically discuss selected recent advances in plasma modification of 2D TMDC materials and their optical and electronic (including optoelectronic) properties of relevance to applications in hydrogen production, gas sensing and energy storage devices. Challenges and future research opportunities in the relevant research field are presented. This review contributes to directing future advances of plasma processing of TMDC materials for targeted applications.

Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth.

Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma.

Synergistic Effect of Atmospheric-pressure Plasma and TiO2 Photocatalysis on Inactivation of Escherichia coli Cells in Aqueous Media.

Atmospheric-pressure plasma and TiO2 photocatalysis have been widely investigated separately for the management and reduction of microorganisms in aqueous solutions. In this paper, the two methods were combined in order to achieve a more profound understanding of their interactions in disinfection of water contaminated by Escherichia coli. Under water discharges carried out by microplasma jet arrays can result in a rapid inactivation of E. coli cells. The inactivation efficiency is largely dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2, He and air microplasma arrays, O2 microplasma had the highest activity against E. coli cells in aqueous solution, and showed >99.9% bacterial inactivation efficiency within 4 min. Addition of TiO2 photocatalytic film to the plasma discharge reactor significantly enhanced the inactivation efficiency of the O2 microplasma system, decreasing the time required to achieve 99.9% killing of E. coli cells to 1 min. This may be attributed to the enhancement of ROS generation due to high catalytic activity and stability of the TiO2 photocatalyst in the combined plasma-TiO2 systems. Present work demonstrated the synergistic effect of the two agents, which can be correlated in order to maximize treatment efficiency.

Energy efficiency in nanoscale synthesis using nanosecond plasmas.

We report a nanoscale synthesis technique using nanosecond-duration plasma discharges. Voltage pulses 12.5 kV in amplitude and 40 ns in duration were applied repetitively at 30 kHz across molybdenum electrodes in open ambient air, generating a nanosecond spark discharge that synthesized well-defined MoO3 nanoscale architectures (i.e. flakes, dots, walls, porous networks) upon polyamide and copper substrates. No nitrides were formed. The energy cost was as low as 75 eV per atom incorporated into a nanostructure, suggesting a dramatic reduction compared to other techniques using atmospheric pressure plasmas. These findings show that highly efficient synthesis at atmospheric pressure without catalysts or external substrate heating can be achieved in a simple fashion using nanosecond discharges.