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The primary objective of this study is to conduct a thorough examination of relativistic structures within the framework of f (ℛ ,) gravity, where ℛ is the Ricci scalar and is the trace of the energy–momentum tensor. We investigate the emerging characteristics of compact stars, focusing on the ℛ + 2 ξ model, where ξ is the coupling constant. In the initial sections of the paper, we concentrate on the examination of exact interior solutions involving perfect fluid. With this aim, we introduce the metric coefficient L = S (1 + 2 a r 2) d / 2 , where a and S are arbitrary constants to be computed from the matching conditions and d is a positive odd integer. It is worth noticing that we select a group of 10 significant compact stars from recent studies, namely, Vela X − 1 , EXO 1 7 8 5 − 2 4 8 , 4 U 1 8 2 0 − 3 0 , SMC X − 4 , Her X − 1 , PSR J 1 6 1 4 − 2 2 3 0 , PSR J 1 9 0 3 + 3 2 7 , Cen X − 3 , 4 U 1 5 3 8 − 5 2 and LMC X − 4. To investigate the viability of our model, we conduct various checks, including the analysis of energy density and pressure components, equilibrium, and energy conditions, stability analysis and the adiabatic index. An important part of this work provides the slowly rotating property of stars, accompanied by the derivation of the moment of inertia. The relationship of mass, energy density, radius and moment of inertia for stellar objects are observed. Our findings demonstrate that obtained results are physically acceptable and consistent with our considered model. [ABSTRACT FROM AUTHOR]

The urea oxidation reaction (UOR) is considered to be a replacement of the sluggish anodic oxygen evolution reaction (OER) in overall water-splitting. A three-dimensional (3D) nickel-containing metal-organic framework {[Ni II 2 (pdaa)(OH) 2 (H 2 O)] n (MOF 1) (where, H 2 pdaa = 1,4-phenylene diacetic acid) was investigated as a robust and highly efficient electrocatalyst for the UOR. MOF 1 comprised 1D nickel(ii) chains crosslinked through Ni 4 O 4 cubane units to form a 3D extended network. Dangling Ni⋯OH - groups were exposed in the MOF 1 structure, and could act as active catalytic centers for the UOR. MOF 1 required a very small onset potential of 1.18 V for urea oxidation in KOH (1 M) and urea (0.33 M) and had a low Tafel slope of 38.8 mV dec -1 (in contrast to 1.84 V for the oxygen evolution reaction). The overpotential required to attain a catalytic current density of 10 mA cm -2 was 1.24 V, which is much lower than that for many materials. Controlled potential electrolysis, powder X-ray diffraction, and X-ray photoelectron spectroscopy affirmed the physicochemical integrity of the catalyst over a 17 h test reaction. This work not only addresses the problem of urea contamination, it also helps to utilize it in an energy-conversion process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)