The high entropy alloy (HEA) nanoparticles have been prepared using cast cum cryo-milling process. In which, the Au, Ag, Pd, Pt and Cu (99.9 at. % pure, Alfa Aesar, USA) melted under argon environment to synthesize cast HEAs and afterwardcast HEA have been milled in cryomill for 6 hours. The detailed synthesis process can be found elsewhere. 1 The cryomilled powder (HEA nanoparticles) has been characterizedin order tothe crystalline phase, size, chemical homogeneity, composition, and catalyst activity. The X-ray diffraction recorded using Panalytical empyrean ( max =1.54056 A),and size of nanoparticles have been estimated using Transmission electron microscope (FEI, Technai G 2 , UT 20 operated at 200

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Two-dimensional (2D) materials from naturally occurring minerals are promising and possess interesting physical properties. A new 2D material "Ilmenene" has been exfoliated from the naturally occurring titanate ore ilmenite (FeTiO 3 ) by employing liquid phase exfoliation in a dimethylformamide solvent by ultrasonic bath sonication. Ilmenene displays a [001] orientation that is confirmed by transmission electron microscopy. Probable charge transfer excitation from Fe 2+ Ti 4+ to Fe 3+ Ti 3+ results in ferromagnetic ordering along with the antiferromagnetic phase accompanied by enhanced anisotropy due to surface spins. The 2D nature and band gap states help ilmenene form a heterojunction photocatalyst with titania nanotube arrays, capable of broad spectrum light harvesting and separating/transferring the photogenerated charges effectively for solar photoelectrochemical water splitting.

The study reports the optimized incorporation of pyridinic nitrogen in nitrogen-doped carbon nanotubes (CNTs) to realize effective Fe-N x centers throughout the framework. The study unveils nitrogen as a valuable asset to promote the homogeneous dispersion of Fe moieties throughout the CNT framework, which is a necessary component to institute uniform Fe-N x centers. In addition, pyridinic nitrogen causes disruption in strongly delocalized π-electrons, which impart electron-withdrawing nature in the carbon matrix, resulting in an anodic shift in oxygen reduction reaction (ORR) onset potential (E onset). The direct interaction of Fe-N x with O2, as evidenced by poisoning and computational studies, ensures the preferential inner sphere electron transfer mechanism. Despite the alkaline medium, the outer sphere electron transfer mechanism was muted, with suppressed HO2 – generation, preferential 4e– reduction pathways, and excellent cyclic stability. The study indicates the dependency of ORR half-wave potential on the electron transfer mechanism. The poisoning study unveils the direct involvement of Fe-N x electroactive centers in facilitating ORR in alkaline medium. It further indicates a noticable increase (up to ∼25%) in peroxide generationan unwanted ORR intermediateand concomitant reduction in average electron transfer no. per oxygen molecule.

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