No abstract

Here, the modification of screen‐printed carbon electrodes (SPCEs) with 3D nanostructured multi‐walled carbon nanotube‐sponge (MWCNT‐Spng) and graphene foam along with their impact on analytical performance was reported. The bare and modified SPCE electrodes were imaged and characterized using scanning electron microscopy, energy dispersive and electrochemical impedance spectroscopy. The modified electrodes were tested for electrochemical detection of dopamine (DA) and a significant improvement was observed in terms of both limit of detection (LOD) and sensitivity as compared to bare SPCE. MWCNT‐Spng‐AuNPs/SPCE demonstrated the highest analytical performance for DA. It was also tested for enzyme‐free glucose detection, in which case it demonstrated an LOD of 4.96 μM and a sensitivity of 526 μA/mM⋅cm2, along with a good selectivity for glucose.

No abstract

No abstract

The growing energy use of modern societies has created a major need for better approaches to not only the production and management of energy, but also its storage. As they have high energy density and cyclability lithium-ion batteries (LIBs) serve currently as the secondary rechargeable battery systems for portable devices and electric vehicles (EVs). However, there are weight and volume constraint for the LIB systems especially for vehicle applications due to the limited space and energy consumption. Energy density limitation of LIBs is the main drawback for successful commercialization of EVs because of its direct effect on the vehicle's driving range, so enhancing the negative and positive electrodes by increasing their capacities and operating voltage is the best approach to improve the electro chemical performance of LIBs. Lithium rich layered oxides, which are solid solutions between layered Li[Li1/3Mn2/3]O2 (commonly designated as Li2MnO3) and layered Li[Mn1-y-zNiyCoz]O2, have been comprehensively studied as next generation cathode materials as they show much higher specific capacity (∼250 mAh/g) and operating voltage (>4.5) compared to the commercial cathodes. One of the defining characteristics of lithium-rich layered oxides (LLOs) is that they exhibit a unique first charge profile. The first charge profile can be divided into two regions, the sloping (below 4.5 V) and plateau regions (above 4.5 V), depending on the mechanism of oxidation during lithium-ion extraction. However, increase in voltage results O2 release from Li2MnO3 structure in the form of LiO2. This mechanism is one of the crucial drawbacks for Li-rich cathodes that results in huge capacity fade during cycles because of the structural change that occurs in Li2MnO3 phase (at high voltages). Therefore, in this study, different upper voltage limits (4.2-4.8 V) are investigated for Li[Li0,2Mn0,54Ni0,13Co13]O2 in order to analyze and optimize the capacity retention.