Irregularly Shaped Zn_0.6Mn_2.4O₄ Nanoparticles for Supercapacitors and Nitroaromatics Detection

Abstract

This work reports a coordination polymer-derived nanosized Zn0.6Mn2.4O4 as the electrode material for supercapacitor and sensing material for nitroaromatics in an aqueous medium. A bimetallic coordination polymer of formula {(H2pip)3[Zn x Mn(3–x)(pydc-2,5)6(H2O)3]·6H2O} {where x = 0.6}, 1, was prepared through a hydrothermal process and utilized as a template. The structural information and phase information of 1 were examined by comparing the PXRD pattern of the compound with that of the pure Mn-based compound, 1a, simulated from the single-crystal X-ray data. Zn0.6Mn2.4O4 nanoparticles were synthesized by calcining the bimetallic coordination polymer, 1, at 350 °C for 1 h. The as-obtained Zn0.6Mn2.4O4 nanoparticles were thoroughly identified using PXRD, TEM, and EDX analyses. Scherrer’s formula gives the average particle size of about 25 nm for Zn0.6Mn2.4O4. Nanostructured Zn0.6Mn2.4O4 was operated as a pseudocapacitor electrode in 2 M KOH solution, which shows a specific capacitance of 1334 F g–1 at a scan rate of 5 mV s–1 in a three-electrode cell configuration. CV study exhibits long-term cycling performance with 90.5% retention of its original capacitance after 1500 cycles. On the other hand, upon excitation at 295 nm, the aqueous dispersion of nanosized Zn0.6Mn2.4O4 displays a strong emission peak centered at 410 nm and was utilized to trace a very low concentration of nitroaromatics in the water medium. Among the nitroaromatics, the addition of 50 μM of TNP quenches around 90% of the luminescence intensity of the aqueous suspended Zn0.6Mn2.4O4. The observed detection limit for TNP is 70 ppb. This outstanding sensitivity of Zn0.6Mn2.4O4 nanoparticles toward nitroaromatics inspired us to use it as a nitroaromatics detector. These results demonstrate that the nanostructured Zn0.6Mn2.4O4 could be a potential supercapacitor as well as a nitroaromatics detector with striking sensitivity for commercial purposes.

Morphology Controlled Synthesis of Heteroatom-Doped Spherical Porous Carbon Particles Retaining High Specific Capacitance at High Current Density

“…Apart from that, the Nyquist plot of CPSM-900 in the low frequency region is linear with a greater slope as compared to the other carbon samples, which supports its lowest ion diffusion resistance . Thus, both the appearance of a semicircle with smaller diameter (in the high frequency region) and a linear plot with greater slope (in the low frequency region) indicate the good capacitive behavior of CPSM-900 …”

“…62 Thus, both the appearance of a semicircle with smaller diameter (in the high frequency region) and a linear plot with greater slope (in the low frequency region) indicate the good capacitive behavior of CPSM-900. 63 It has been found from XPS analysis that nitrogen is present in the structures of the carbonized samples, and they exist primarily in three different forms; these are pyrrolic, pyridinic, and pyridonic types of nitrogen. Their amounts in the samples vary with the temperature of pyrolysis, but all three forms are found to exist.…”

CuMn2O4 Spinel Nanoflakes for Amperometric Detection of Hydrogen Peroxide

“…Recently, nonenzymatic electrochemical sensors constructed from nanometal oxides have become a fascinating research topic in H 2 O 2 detection because of their low cost, easy preparation, rapid sensitivity, and high stability. , Especially, compared to single metal oxides, spinel AB 2 O 4 oxides contain two variable valence transition metals, and their synergism can effectively reduce the activation energy of charge transfer and promote the internal electron transfer rate. Meanwhile, the inherent redox coupling also increases the active sites to capture H 2 O 2 molecules, further promoting its catalytic reduction reaction on the electrode surface. − At present, most reported spinel AB 2 O 4 oxides have shown excellent electrochemical detection to H 2 O 2 in 0.1–0.3 M NaOH solution. − This is mainly because that B-site metal ions with a high oxidation state can serve as an oxidant to effectively promote the redox reaction of H 2 O 2 in the above strong alkaline solution . In contrast, the spinel oxide-based electrochemical sensors for detecting H 2 O 2 in near-neutral conditions or physiological environments (such as phosphate buffer solution (PBS)) have the defects of high detection limit and low sensitivity except for the NiCo 2 O 4 nanoparticles reported in 2020, which limit their practical applications in detecting trace H 2 O 2 in foods and nanomolar-level H 2 O 2 in cells.…”

Nanoemulsion Technique for the Syntheses of N-Doped Porous Carbon Nanospheres and Their Application in Energy Storage Devices

“…The higher the slope of the curve, the higher the electron transport. 53,54 The equivalent circuit for all of these EIS measurements is shown in Figure 11b. It consists of the solution resistance (R s ) in series, charge transfer resistance (R ct ), along with capacitance (C s1 ), and Warburg impedance (W) in parallel and again capacitance (C s2 ) in series.…”

“…, a semicircular part at a high-frequency range which corresponds to the ion diffusion through the electrode/electrolyte interface, a steeper region at an intermediate frequency reflecting the ion penetration through pore channels, and a linear part at a low-frequency region due to ion diffusion and transport at the electrolyte interface. The higher the slope of the curve, the higher the electron transport. , The equivalent circuit for all of these EIS measurements is shown in Figure b. It consists of the solution resistance ( R s ) in series, charge transfer resistance ( R ct ), along with capacitance ( C s1 ), and Warburg impedance ( W ) in parallel and again capacitance (C s2 ) in series.…”