In this work, uniform hierarchical mesoporous 3D-urchin-like Bi2S3@2D-nanosheet g-C3N4 was synthesized via a superficial hydrothermal method. The prepared pristine Bi2S3, g-C3N4, and 3D-Bi2S3@2D-g-C3N4 composite samples were extensively studied for their electrochemical performance and exhibited superior battery-type behaviors. The results highlight that the optimized 3D-Bi2S3@2D-g-C3N4 composite sample exhibits a high areal capacity of 41.53 μA h/cm2 at 1 mA/cm2 and a good rate capability of 62.77% along with a remarkable capacity retention of 94.86% after 5000 cycles. The improved performance can be attributed to the good beneficial features of the synergistic effect, mesoporous structure, and lower dissolution. It offers a higher specific surface area, enriches electroactive sites, increases electronic/ionic conductivities, and reduces the interfacial resistance. Furthermore, the solid-state symmetric supercapacitors (SSCs) were assembled by two similar electrodes of 3D-Bi2S3@2D-g-C3N4 sandwiched between the KOH and PVA gel electrolyte. The fabricated SSC device provides a high areal capacity of 25.40 μA h/cm2 at 1 mA/cm2. Furthermore, the SSC delivers a maximum power density of 1495 μW/cm2 and an energy density of 3.17 μW h/cm2 with a good cyclic retention of 83.84% after 7500 cycles. This work also demonstrates the practical applicability of realizing red-light-emitting diodes by interconnecting two SSCs in series.

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Magnetocrystalline anisotropy is a crucial parameter that determines the suitability of magnetic material in a wide range of emerging applications. The law‐of‐approach‐to‐saturation (LAS), utilized to obtain the magnetocrystalline anisotropy from hysteresis loops, is not satisfactory for materials with cubic anisotropy as they are two orders higher than the bulk value. Herein, a modified formulation to LAS is presented, where the reduction in effective magnetic anisotropy (K) values due to Fe oxide phases in Fe particles over wide size ranges is accounted. The value of K decreases from 4.2 × 104 J m−3 for the Fe particles of average size 210 nm to 1.2 × 104 J m−3 for the 20 nm particles due to the increase in the iron oxide fraction with size reduction. The effective magnetic anisotropy obtained from the modified LAS has been validated from the ferromagnetic resonance studies for particles of the smallest size.

The magnetic moment and the Curie temperature of the NiCu alloy decrease to a large extent with Cu. A Ni60Cu40 alloy with Fe substitutions up to 2 at% using a polyol‐mediated synthesis process resulting in enhanced magnetic properties is obtained. The Ni60Cu39Fe1 and Ni60Cu38Fe2 alloys show fcc phase with the Curie temperatures of 237 and 266 K, respectively. The room temperature magnetization measurement shows paramagnetic behavior, whereas, at 15 K, the 1 at% Fe‐substituted alloy exhibits a saturation magnetization of 20 emu g−1 that increases by 25% with 2 at% Fe. The positive slope in the Arrott plot confirms the second‐order phase transition in the alloys. The maximum magnetic entropy change (MCE) is observed as 0.101 J kg−1 K−1 for the Ni60Cu39Fe1 alloy with the peak temperature of 238 K in an applied magnetic field of 0.5 T. The critical exponent (β) calculated using the MCE method is in the range of 0.576(3)–0.587(3) for the alloys, whereas the values obtained using the Kouvel‐Fisher (KF) method are 0.523(3)–0.565(2). The extracted β values are slightly greater than the mean‐field model suggesting clustering behavior in the alloys.