• Energy Research

Supercapacitors have gained prominence as a cutting‐edge energy storage technology. However, the performance of conventional transition metal oxide electrodes is hindered by their poor electrical conductivity, insufficient ion‐accessible surface area, and complex synthesis processes. Herein, a firsthand demonstration of carbon doping in a crystalline NiCuMn trimetallic alloy, followed by dealloying in an oxygen‐rich environment, is presented. This process produces a highly uniform, 3D flaky nanoporous microstructure with exceptional electrochemical energy storage capabilities. The synthesized electrode demonstrates a remarkable specific capacitance of 1835 F cm−3 at an ultrahigh current density of 10 A cm−3 along with an excellent rate capability of ≈62%. In contrast, the carbon‐free NiCuMn alloy shows 900 F cm−3 capacitance with only 35% retention under similar test conditions. A symmetric supercapacitor showcases an impressive energy density of 120.4 Wh L−1 at a power density of 850 W L−1. It also exhibits remarkable rate capability of ≈50% and excellent cyclic stability, maintaining 96.5% of its capacity after 10000 cycles. The exceptional performance of the developed electrode is attributed to its carbon‐doped unique hierarchical microstructure that ensures efficient and rapid charge transport due to large surface area and high electrical conductivity.

Abstract In present work, we investigated the tribological behavior of the high entropy alloy (HEA) claddings under different degrading environments viz, slurry erosion-corrosion, liquid impingement erosion, electrochemical corrosion, and sliding wear. The HEA claddings were developed by varying Al fraction (AlxCoCrFeNi) (x = 0.1 to 3) using microwave processing. The claddings were composed of cellular structure with intermetallic phases segregated in the intercellular region. Variation in Al content showed significant influence on the microstructure and mechanical properties. The hardness of the claddings increased with an increase in Al fraction with a maximum value of 624 HV observed for the cladding containing three molar Al. Correspondingly, the fracture toughness showed an opposing trend. All claddings showed better wear resistance than SS316L with equimolar composition outperforming other counterparts. The equimolar HEA cladding showed 3 to 23 times higher wear resistance compared to SS316L steel depending upon test conditions. Inimitable wear resilience of the equimolar composition was attributed to its high hardness and strain-hardening ability. Surface morphologies of the tested claddings indicated the presence of ductile-brittle mixed damage modes. The tested surfaces showed numerous pits and cracks with delaminated secondary phase. Presence of groves and signs of delamination were also observed in case of sliding wear. The results of the present work show that microwave synthesized equimolar HEAs can effectively counter different tribological forms.

Ni‐based binary alloy compositions are considered promising materials for energy storage and catalysis applications. Herein, a highly simplistic and efficient technique is reported for synthesizing NiMn hybrid oxyhydroxides as a bifunctional electrode for flexible supercapacitors and an efficient oxygen evolution reaction (OER) catalyst. The synthesis approach involves Ni and Mn coelectrodeposition under a controlled oxygenated environment over a flexible stainless‐steel substrate. The developed electrodes exhibit an excellent specific capacitance of 633.54 F g−1 at a current density of 1 A g−1, matching one of the best‐reported values in the literature. A symmetric device demonstrates a remarkable energy density of 45 Wh kg−1 at a power density of 181.22 W kg−1. The device shows an excellent cyclic stability of 89.5% after 10 000 cycles. In addition, the NiMn oxyhydroxide electrode showed a remarkable performance in OER with overpotential values of only 282 and 312 mV at 500 and 1000 mA cm−2 current density, surpassing many well‐reported studies in the literature. The current study provides a facile and efficient strategy for synthesizing bifunctional electrodes for high‐performance energy storage devices and catalysts for OERs.

Abstract The deterioration of fluid machines due to slurry and cavitation erosion significantly impairs their serviceability. In the present work, we investigated the influence of deep cryogenic treatment (DCT) on the slurry and cavitation erosion resistance of WC-10Co-4Cr coatings developed using the detonation spraying technique. For comparison, hydroturbine steels and other conventional (Alumina and Stellite 6) coatings were also investigated. All thermal spray coatings showed typical lamellar structure along with the presence of pores and splat boundaries. Among all the coatings, the WC-10Co-4Cr showed the highest slurry (up to 15 times) and cavitation (2 times) erosion resistance owing to high hardness and fracture toughness. Post DCT, the WC-10Co-4Cr coating showed further improvement due to reduced porosity and improved hardness without decrement in fracture toughness. As a result, the DCT coating showed 1.5 to 4.2 times improved slurry erosion resistance than the as-sprayed counterpart, along with 1.6 times higher cavitation erosion resistance. The improved tribological performance of the coating after DCT is associated with enhanced hardness due to the presence of nano precipitates and densification as analyzed using electrochemical techniques. The topological analysis of the eroded surfaces indicated micro-cutting, micro-cracking, and delamination as the primary mechanism controlling the erosion behavior of the coatings.