RESUMEN
Organophosphorus nerve agents are toxic compounds that disrupt neuromuscular transmission by inhibiting the neurotransmitter enzyme, acetylcholinesterase, leading to rapid death. A hybrid composite was synthesized using a hydrothermal process for the early detection of dimethyl methyl phosphonate (DMMP), a simulant of the G-series nerve agent, sarin. Quartz crystal microbalance (QCM) and surface acoustic wave (SAW) sensors were used as detectors. Nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs), cobalt oxide (Co3O4), and N-MWCNT@Co3O4 were compared to detect DMMP concentrations of 25-150 ppm. At 25 ppm, the differential frequencies (Δf) of the N-MWCNT, Co3O4, and N-MWCNT@Co3O4 sensors were 5.8, 2.3, and 99.5 Hz, respectively. The selectivity results revealed a preference for the DMMP rather than potential interference. The coefficients of determination (R2) of the N-MWCNT, Co3O4, and N-MWCNT@Co3O4 sensors for detecting 25-150 ppm DMMP were 0.983, 0.986, and 0.999, respectively. The response times of the N-MWCNT, Co3O4, and N-MWCNT@Co3O4 sensors for detecting 100 ppm DMMP were 25, 27, and 34 s, respectively, while the corresponding recovery times were 85, 105, and 181 s. The repeatability results revealed the reversible adsorption and desorption phenomena for the fixed DMMP concentration of 100 ppm. These unique findings show that synthesized materials can be used to detect organophosphorus nerve agents.
RESUMEN
The use of water-soluble, abundant biopolymers as binders for lithium-ion positive electrodes is explored because it represents a great step forward towards environmentally benign battery processing. However, to date, most studies that employ, for instance, carboxymethyl cellulose (CMC) as a binder have focused on rather low electrode areal loadings with limited relevance for industrial needs. This study concerns the use of natural guar gum (GG) as a binding agent for cobalt-free, high-voltage LiNi0.5 Mn1.5 O4 (LNMO), which realizes electrodes with substantially increased areal loadings, low binder content, and greatly enhanced cycling stability. Co-crosslinking GG through citric acid with CMC allows for an enhanced rate capability and essentially maintains the beneficial impact of using GG as a binder rather than CMC only. Lithium-ion full cells based on water-processed LNMO and graphite electrodes provide a remarkably high cycling stability with 80 % capacity retention after 1000â cycles at 1 C.