Md. Tariqul Islam

Green synthesis of gold nanoparticles reduced and stabilized by squaric acid and supported on cellulose fibers for the catalytic reduction of 4-nitrophenol in water

We report a simple, fast, and green method to produce gold nanoparticles (AuNPs) that are reduced and stabilized by sodium squarate in water and easily attach to cellulose fibers. The AuNPs and its nanocomposites with cellulose fibers exhibited excellent catalytic activity for the reduction of 4-nitrophenol (4-NP) with NaBH4. A glass column was packed with the nanocomposites and used for the continuous catalytic reduction of 4-NP with NaBH4 and demonstrated to be used multiple times (20×) without loss of catalytic activity.

High-performance porous carbon/CeO2 nanoparticles hybrid super-capacitors for energy storage

Increasing demand for energy storage devices has propelled researchers for developing efficient super-capacitors (SC) with long cycle life and ultrahigh energy density. Carbon-based materials are commonly used as electrode materials for SC. Herein we report a new approach to improve the SC performance utilizing porous carbon /Cerium oxide nanoparticle (PC-CON) hybrid as electrode material synthesized via low temperature hydrothermal method and tetraethyl ammonium tetrafluroborate in acetonitrile as organic electrolyte. Through this approach, charges can be stored not only via electrochemical double layer capacitance (EDLC) from PC but also through pseudo-capacitive effect from CeO2 NPs. The excellent electrode-electrolyte interaction due to the electrochemical properties of the ionic electrolyte provides a better voltage window for the SC. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) measurements were used for the initial characterization of this PC/CeO2 NPs hybrid material system. Electrochemical measurements of SCs was performed using a potentio-galvanostat. It is found that the specific capacitance was improved by 30% using PC-CON system compared with pristine PC system.

Green synthesis of gold, silver, platinum, and palladium nanoparticles reduced and stabilized by sodium rhodizonate and their catalytic reduction of 4-nitrophenol and methyl orange

Sodium rhodizonate was used as a bifunctional reducing as well as stabilizing agent for the single step synthesis of gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) nanoparticles (NPs) in water. Transmission electron microscopy analysis revealed that Pt, Au, Ag, and PdNPs have average core diameters of about 2, 8, 26, and 39 nm, respectively. The ability of these nanoparticles towards the catalytic reduction of 4-nitrophenol (4-NP) with sodium borohydride (NaBH4) and the dual-catalytic oxidation of formic acid followed by the reduction of methyl orange (MO) was studied. The apparent rate constants (kapp) of the catalytic reduction of 4-NP in the presence of Ag, Au, Pt, and PdNPs were calculated to be 2.1482, 1.1167, 1.088 × 10−1, and 1.65 × 10−2 min−1, respectively. However, for the dual-catalytic oxidation of formic acid followed by the reduction of MO, the kapp values were calculated to be 4.145, 1.25 × 10−2, 6.7 × 10−3, and 9.0 × 10−5 for the Pt, Pd, Au, and AgNPs, respectively.

Adsorption of methylene blue and tetracycline onto biomass-based material prepared by sulfuric acid reflux

The adsorptive removal of environmental pollutants is an effective method for the treatment of contaminated water. Thus, the preparation of adsorbents from low-cost, readily available, and renewable resources has garnered immense attention in recent years. In this study, a facile one-step method for the preparation of a high-capacity adsorbent is demonstrated by refluxing pine cones in concentrated sulfuric acid. With sulfuric acid reflux, the pine cones undergone carbonization as well as functionalization with sulfonic acid groups. The adsorbent demonstrated high adsorption capacity for two emerging organic pollutants, methylene blue (MB) and tetracycline (TC). Different variables such as pH, temperature, contact time, and initial concentration of the pollutants were analyzed and showed that the adsorption capacity for MB increased in a basic pH and vice versa for TC. Also, the elevated temperature favored the adsorption for both MB and TC. The maximum adsorption capacity was found to be 1666.66, and 357.14 mg g−1 for MB and TC, respectively. In comparison to the pristine pine cone, the sulfuric acid treated pine cone demonstrated an extraordinary improvement in the adsorption capacity. The adsorption of MB and TC was performed from the tap water matrix and similar adsorption capacities were found. A packed glass column was also prepared to demonstrate the adsorption of MB from tap water under flow conditions.

Porous carbon/CeO2 composites for Li-ion battery application

Development of new materials hold the key to the fundamental progress in energy storage systems such as Li-ion battery, which is widely used in modern technologies because of their high energy density and extended cycle life. Among these materials, porous carbon is of particular interest because it provides high lithiation and excellent cycling capability by shortening the transport length for Li+ ions with large electrode/electrolyte interface. It has also been demonstrated that transition metal oxide nanoparticle can enhance surface electrochemical reactivity and increase the capacity retention capability for higher number of cycles. Here we investigate porous carbon/ceria (CeO2) nanoparticles composites as an anode material. The high redox potential of ceria is expected to provide a higher potential window as well as increase the specific capacity and energy density of the system. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) is used for material characterization, while battery analyzer is used for measuring the electrochemical performance of the battery.