A novel CoN4-driven self-assembled molecular engineering for oxygen reduction reaction

The poor kinetics of oxygen reduction reaction (ORR) invites a quest for the development of low-cost and efficient non-Pt electrocatalysts for fuel cells. Herein, a nanocomposite (g-[Co₂N₈]) was synthesized by coordination assembly of CoN₄ macrocyclic moieties on graphene surface. The CoN₄ macrocyclic complex was characterized by UV–Vis, FT-IR, Mass, ¹H NMR and ¹³C NMR spectral studies, whereas UV–Vis, FT-IR, and Mass spectral, Raman, XRD and TEM studies were utilized to characterize the nanocomposite g-[Co₂N₈]. The results suggested that [CoN₄] units are present in self-assembled [Co₂N₈] species. Further, the nanocomposite g-[Co₂N₈] was examined for ORR activity by employing cyclic and linear sweep voltammetry and found that the formal potential (E_1/2) of g-[Co₂N₈] (+0.90 V) was more positive than 20% Pt/C (+0.86 V), indicating a remarkable ORR performance of g-[Co₂N₈] in comparison to 20% Pt/C, followed by 4e-mechanism. Moreover, the nanocomposite (g-[Co₂N₈]) displayed better ORR activity in comparison to [CoN₄] complex which can be attributed to the synergistic incorporation of endo and exo N₄–Co²⁺ moieties in the [Co₂N₈] species. In addition, g-[Co₂N₈] electrocatalyst exhibited a comparable stability to 20% Pt/C catalyst after 5000 cycles. This work will help to design multi-metallic coordination polymers with similar or different metal ions in N₄-arrangement for various energy related electrocatalysis.     

Space bricks: From LSS to machinable structures via MICP

In this work, we show that Microbial Induced Calcite Precipitation (MICP) can be used for making consolidated structures – space bricks – using lunar soil simulant (LSS). Sporosarcina pasteurii was used as a bacterial strain to initiate MICP process via ureolytic pathway. An admixture of a naturally occurring biopolymer (guar gum) and a structural reinforcement material (glass fibre) was used to enhance the mechanical properties of the bio-consolidated bricks. When supplemented with guar gum, the compressive strength of the resulting bricks was found to be significantly higher – by nearly six-fold – making them comparable to commercially used mud bricks. The addition of glass fibre reduced this strength a little, but had the benefit of making the space bricks machinable on a conventional lathe. This latter fact enabled the fabrication of precise and free-form shapes post-consolidation, without the need for specialized casting molds or dies. Details of the MICP process were investigated using field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses. The route demonstrated here holds great potential for making strong structures in extra-terrestrial habitats, while adhering to the principles of in situ resource utilization.     

Magnetically recoverable nanocatalyst based on N-heterocyclic ligands: efficient treatment of environmental pollutants in aqueous media

Clean Technologies and Environmental Policy - The fabrication of aminotetrazole–palladium(II) complex immobilized on silica-encapsulated Fe3O4 magnetic nanoparticles is described with full...     

Entropy generation analysis on forced and free convection flow in a vertical porous channel with aligned magnetic field and Navier slip

The entropy generation rate in a vertical porous channel with injection and suction walls and a uniform magnetic field provided at an angle $\xi$ to the flow direction is studied using an analytical perturbation technique in the presence of Navier slip and buoyancy force. The momentum and energy equations were solved for exemplary values of fluid convection's physical characteristics. Important parameters' impacts on adequate numbers are graphically portrayed and conveyed.