ABSTRACT
Lithium-sulfur batteries (LSBs) have been increasingly recognized as a promising candidate for the next-generation energy-storage systems. This is primarily because LSBs demonstrate an unparalleled theoretical capacity and energy density far exceeding conventional lithium-ion batteries. However, the sluggish redox kinetics and formidable dissolution of polysulfides lead to poor sulfur utilization, serious polarization issues, and cyclic instability. Herein, sulfiphilic few-layer MoSSe nanoflake decorated on graphene (MoSSe@graphene), a two-dimensional and catalytically active hetero-structure composite, was prepared through a facile microwave method, which was used as a conceptually new sulfur host and served as an interfacial kinetic accelerator for LSBs. Specifically, this sulfiphilic MoSSe nanoflake not only strongly interacts with soluble polysulfides but also dynamically promotes polysulfide redox reactions. In addition, the 2D graphene nanosheets can provide an extra physical barrier to mitigate the diffusion of lithium polysulfides and enable much more uniform sulfur distribution, thus dramatically inhibiting polysulfides shuttling meanwhile accelerating sulfur conversion reactions. As a result, the cells with MoSSe@graphene nanohybrid achieved a superior rate performance (1091 mAh/g at 1C) and an ultralow decaying rate of 0.040 % per cycle after 1000 cycles at 1C.
ABSTRACT
The coronavirus disease 2019 (COVID-19) is a highly contagious and fatal disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In general, the diagnostic tests for COVID-19 are based on the detection of nucleic acid, antibodies, and protein. Among different analytes, the gold standard of the COVID-19 test is the viral nucleic acid detection performed by the quantitative reverse transcription polymerase chain reaction (qRT-PCR) method. However, the gold standard test is time-consuming and requires expensive instrumentation, as well as trained personnel. Herein, we report an ultrasensitive electrochemical biosensor based on zinc sulfide/graphene (ZnS/graphene) nanocomposite for rapid and direct nucleic acid detection of SARS-CoV-2. We demonstrated a simple one-step route for manufacturing ZnS/graphene by employing an ultrafast (90 s) microwave-based non-equilibrium heating approach. The biosensor assay involves the hybridization of target DNA or RNA samples with probes that are immersed into a redox active electrolyte, which are detectable by electrochemical measurements. In this study, we have performed the tests for synthetic DNA samples and, SARS-CoV-2 standard samples. Experimental results revealed that the proposed biosensor could detect low concentrations of all different SARS-CoV-2 samples, using such as S, ORF 1a, and ORF 1b gene sequences as targets. This microwave-synthesized ZnS/graphene-based biosensor could be reliably used as an on-site, real-time, and rapid diagnostic test for COVID-19. Supplementary Information: The online version contains supplementary material available at 10.1007/s42114-023-00630-7.
ABSTRACT
In this report, MoTe2 nanosheets were grown on highly conductive graphene support through a simple and ultrafast microwave-assisted chemical coupling and heating method to develop hybrid sulfur host materials for Li-S batteries. MoTe2 nanosheets with superb electrocatalytic activity combined with highly conductive graphene form a nano reservoir for containing elemental sulfur, intermediate polysulfide species, discharge product Li2S, and accelerating the electron transfer. Accordingly, the Li-S battery with the MoTe2@graphene@carbon cloth electrode exhibited a high initial discharge capacity of 1246 mAh g-1 at 0.2C for the first galvanostatic cycle, good cycle stability (98.7% capacity retention after 100 cycles at 0.2C) and superb rate performance. The synergistic effect of the chemical affinity and superior electrocatalytic capability of polar MoTe2, along with the effective physical confinement by graphene and free-standing carbon cloth, provides a promising way to design host materials to mitigate the shuttling effect in rechargeable Li-S batteries.
ABSTRACT
Li-ion battery (LIB) recycling has become an urgent need with rapid prospering of the electric vehicle (EV) industry, which has caused a shortage of material resources and led to an increasing amount of retired batteries. However, the global LIB recycling effort is hampered by various factors such as insufficient logistics, regulation, and technology readiness. Here, the challenges associated with LIB recycling and their possible solutions are summarized. Different aspects such as recycling/upcycling techniques, worldwide government policies, and the economic and environmental impacts are discussed, along with some practical suggestions to overcome these challenges for a promising circular economy for LIB materials. Some potential strategies are proposed to convert such challenges into opportunities to maintain the global expansion of the EV and other LIB-dependent industries.
ABSTRACT
The development of efficient electrocatalysts for hydrogen generation is an essential task to meet future energy demand. In recent years, molybdenum ditelluride (MoTe2) has triggered incredible research interests due to intrinsic nontrivial band gap with promising semi-metallic behaviors. In this work, 2D MoTe2 nanosheets have been synthesized uniformly on graphene substrate through ultra-fast microwave-initiated approach, that shows a superior hydrogen evolution in acidic medium with low overpotential (~150 mV), low activation energy (8.4362 ± 1.5413 kJ mol-1), along with a Tafel slope of 94.5 mV/decade. Interestingly, MoTe2/graphene exhibits the enhanced electrocatalytic stability during the long cycling test, resulting an increase in specific surface area of catalyst materials. Moreover, the results from periodic plane-wave density functional theory (DFT) indicate that, the best active sites are the corner of a Mo-atom and a critical bifunctional site comprised of adjacent Mo and Te edge atoms. Furthermore, the corresponding volcano plot reveals the near thermoneutral catalytic activity of MoTe2/graphene for hydrogen generation.