In this work, we utilize the electrohydrothermal (EHT) approach, as a versatile synthesis approach, for fabricating MnO2-decorated Co3O4 (MnO2/Co3O4) composites for supercapacitor applications. This method leverages the strengths of both electrochemical deposition (ED) and hydrothermal (HT) synthesis, offering precise control and high efficiency. Co3O4 and MnO2 are potential candidates for electrode materials in energy storage systems due to their high theoretical capacity, biocompatibility, abundance in nature, and cost-effectiveness. Bimetallic oxide nanocomposites are highly attractive for supercapacitor applications due to integration of multiple redox-active centers with improved electrical conductivity, resulting in higher specific capacitance, improved rate capability, and superior cycling stability. Using EHT approach, hydrothermal conditions were applied in the first step while cobalt hydroxide layer was deposited on Ni foam substrate (NF). The resulting Co(OH)2/NF electrode was subsequently subjected to heat treatment to form the Co3O4/NF electrode. In the second step, the electrodeposition of MnO₂ was performed in the optimized EHT conditions by applying a constant cathodic potential, yielding the MnO2/Co3O4/NF electrode. Notably, MnO2/Co3O4/NF electrode exhibited an ultrahigh specific capacitance of 1207 F g-1 at a high current density of 6 A g-1, along with a 62% rate capability when the current density was increased from 6 to 25 A g-1. Besides, the electrode materials demonstrated excellent cycling stability and capacitance retention of almost 91% beyond 10,000 successive cycles. Furthermore, an asymmetric capacitor (ASC) was fabricated using MnO2/Co3O4/NF as positive electrode and 6 M of KOH as electrolyte to evaluate its electrochemical performance. The ASC device delivered an impressive energy and power densities of 54.8 Wh kg-1 and 44.14 kW kg-1, respectively. Our findings corroborate the superior capacitive performance of MnO2/Co3O4 electrode materials fabricated by an electrohydrothermal approach. 

Robust electrochemical sustainability of tailored high-performance nanocomposites is integral to advanced electrochemical energy conversion and storage (EECS) systems. Functions, such as nanoscale ionic-diffusion distance, electrocatalytic reactions, electrical conductivity, and fluid distribution, of transition metal dichalcogenide (TMD)-based nanostructures have been extensively designed and studied. However, challenges in materials selection, operational scalability, and design flexibility of TMD-incorporated metal-matrix composites (MMCs) consisting of non-noble metallic nanostructures and their originating TMD materials have scarcely been studied. Highlighting the effectiveness of emerging additive manufacturing techniques in sustainable energy supply and storage, laser powder bed fusion (L-PBF) can offer a directly added dual-functionality to fabricated complex multimaterial and TMD-incorporated MMC electrocatalytic electrodes. In this review, the characteristics of composite powder feedstock and optimizing process parameters are critically emphasized from another perspective to maintain a balance between mechanical robustness and enhanced electrochemical response. It is demonstrated how factors such as surface roughness, particle shape, and rheological characteristics of TMDs can influence the flowability of composite powder feedstock and the electrochemical performance of L-PBF-processed electrodes. The review further aims to contribute compiled information for use in the rapidly growing global market for advanced energy storage systems, underscoring the transformative potential of L-PBF and TMD-incorporated MMCs in modernizing the EECS components.

Reduced graphene oxide (rGO) is an ideal candidate in nanostructured metallic materials to enhance their electrochemical performance. However, few studies exist on the effects of rGO on the crystallographic, physical, and topological properties of co-electrodeposited Ni/rGO nanocomposites. In this study, the morphology and normalized electro-active specific surface (NESS) of a Ni/rGO nanocomposite were correlated with its crystal-lographic properties by varying the applied co-electrodeposition current density (0.01-0.1 A cm(-2)) and rGO concentration (0.5-2 mg mL(-1)). Tuning was done to achieve the best physical and electrochemical properties of the nanocomposite at alkaline (NaOH) conditions in terms of the highest NESS (12.3 x 10(-4)) and electro-active sensitivity (17.3 mu A mM(-1) cm(-2)) possible. The findings of the study show a possible approach to enhance the performance of electro-active components such as electrochemical devices, sensors, and actuators.

Selective laser melting (SLM) based processing of Mo-based samples is challenging due to solidification cracking. We here demonstrate that the addition of 2 wt% MoS2 to the Mo feedstock markedly improves crack mitigation of SLM-processed Mo/MoS2/Mo2S3 composite micro-lattice structures (SLM-Mo/ Mo(x)S(x+1)). Crack inhibition is suggested to be a result of Mo2S3 formation, decreased lattice strain (0.04 4%), and a decrease in accumulated residual stresses. The increased values of polarization resistance from 42.3 and 19.2 kU cm2 to 437 and 78.2 kU cm2, respectively verified the hindering effect of the composition on stress corrosion cracking (SCC) and surface oxidation cracking. However, an increased corrosion current density, from 1.22 to 10.2 mA/cm2, and cathodic Tafel constant, from 175 to 260.5 mV, confirmed the decreased polarization resistance and occurrence of different types of corrosion such as SCC and pitting. The strategy to add 2 wt% MoS2 to the Mo feedstock enables the fabrication of hightemperature micro-lattice structure components with improved corrosion resistance properties applicable in e.g., electronic, power semiconductor heat sinks, offshore-, aerospace-, defense-, or particularly novel sodium-ion energy storage applications.

Investigation of next-generation manufacturing methods for the processing of functional materials and offering products with improved performance/functionalities has always been a challenge in terms of energy efficiency, cost-effectiveness, and eco-friendliness. Additive manufacturing (AM) attributes to rapid prototyping techniques that provide new opportunities to test new concepts and design complex 3D structures from metals, ceramics, and composites. Moreover, as a well-known transition metal dichalcogenide, Molybdenum disulfide (MoS2) is a two-dimensional (2D) material with outstanding electrochemical, physical, and mechanical properties that make it a potential candidate for energy storage electrodes via intercalation of different H+, Li+, Na+, and K+ cations. In this review, we discuss the existing conventional MoS2-processing methodologies and compare them with the novel additive manufacturing processes (especially laser-based powder bed fusion). The authors are convinced that the processing of prominent MoS2-based functional structures by the novel additive manufacturing processes can provide complex structures for different electrochemical applications, particularly for energy conversion/ storage systems.

MoS2-based nanocomposites have been widely processed by a variety of conventional and 3D printing techniques. In this study, selective laser melting (SLM) has for the first time successfully been employed to tune the crystallographic structure of bulk MoS2 to a 2H/1T phase and to distribute Mo2S3 nanoparticles in-situ in MoS2/Mo2S3 nanocomposites used in electrochemical energy conversion/storage systems (EECSS). The remarkable results promote further research on and elucidate the applicability of laser-based powder bed processing of 2D nanomaterials for a wide range of functional structures within, e.g., EECSS, aerospace, and possibly high-temperature solid-state EECSS even in space.

Relying on the reduction of oxygenated functional groups of graphene oxide, the engineering of the morphology of Ni-based reduced graphene oxide (Ni-rGO) nanocomposite was carried out via galvanostatic electrochemical co-deposition by changing the current density in a range of 0.001-0.01 A.cm(-2) and loading of 2 g.L-1 of graphene oxide. The morphology has been converted to a porous, rough, and three-dimensional (3D) form by significant incorporation and simultaneous reduction of GO into the structure of Ni-rGO nanocomposite film. Study on 3D morphology by SEM, FT-IR, XRD, and Raman confocal spectroscopy approved simultaneously reduction of oxygenated functional groups. Moreover, we have discussed the impact of rGO incorporated in the structure of Ni-rGO nanocomposite onto the creation of porous 3D-morphology and the enhancement of the electroactive specific surface. This new fascinating mechanism and structure can lead to the enhancement of electroactive components in electrochemical sensors and energy conversion-storage systems.