As renewable energy is becoming a crucial energy source to meet the global demand, electrochemical energy storage devices become indispensable for efficient energy storage and reliable supply. The electrode material is the key factor determining the energy storage capacity and the power delivery of the devices. Carbon-based materials, specifically graphite, activated carbons etc, are extensively used as electrodes, yet their low energy densities impede the development of advanced energy storage materials. Decoration by nanoparticles of metals, metal oxides, nitrides, carbides, phosphides, chalcogenides and bimetallic components is one of the most promising and easy-to-implement strategies to significantly enhance the structural and electronic properties, pore refinement, charge storage and charge-transfer kinetics of both pristine and doped carbon structures, thereby making their performance promising for next-generation energy storage devices. Structuring the materials at nanoscale is another probable route for better rate performance and charge-transfer kinetics. This review covers the state-of-art nanoparticle decorated nanocarbons (NCs) as materials for battery anode, metal-ion capacitor anode and supercapacitor electrode. A critical analysis of the elemental composition, structure, associated physico-chemical properties and performance relationships of nanoparticle-decorated NC electrodes is provided as well to inform the future development of the next-generation advanced energy storage materials and devices.

Among post-lithium ion battery technologies, rechargeable chemistries with Zn anodes bear notable technological promise owing to their high theoretical energy density, lower manufacturing cost, availability of raw materials and inherent safety. However, Zn anodes, when employed in aqueous electrolytes, suffer from hydrogen evolution, passivation, and shape changes. Alternative electrolytes can help tackle these issues, preserving the green and safe characteristics of aqueous-based ones. Deep eutectic solvents (DESs) are promising green and low-cost non-aqueous solvents for battery electrolytes. Specifically, the cycling of Zn anodes in DESs is expected to be reversible, chiefly owing to their dendrite-suppression capability. Nevertheless, apart from a few studies on Zn plating, insight into the cathodic–anodic electrochemistry of Zn in DESs is still very limited. In view of developing DES-based battery electrolytes, it is crucial to consider that a potential drawback might be their low ionic conductivity. Water molecules can be added to the eutectic mixtures by up to 40% to increase the diffusion coefficient of the electroactive species and lower the electrolyte viscosity without destroying the eutectic nature. In this study, we address the electrochemistry of Zn in two different hydrated DESs (ChU and ChEG with ~30% H₂O). Fundamental electrokinetic and electrocrystallization studies based on cyclic voltammetry and chronoamperometry at different cathodic substrates are completed with a galvanostatic cycling test of Zn|Zn symmetric CR2032 coin cells, SEM imaging of electrodes and in situ SERS spectroscopy. This investigation concludes with the proposal of a specific DES/H₂O/ZnSO₄-based electrolyte that exhibits optimal functional performance, rationalized on the basis of fundamental electrochemical data, morphology evaluation and modeling of the cycling response.

In pulsed laser deposition, along the traditionally exploited deposition on the front‐side of the plasma‐plume, a coating forms on the surface of the target as well. For reproducibility, this residue is usually cleaned and discarded. Here we instead investigate the target‐side coated materials and employ them as a binder‐free supercapacitor electrode. The ballistic‐aggregated, target‐side nanofoam is compact and features a larger fraction of sp²‐carbon, higher nitrogen content with higher graphitic‐N and lower oxygen content with fewer COOH groups than that of diffusive‐aggregated conventional nanofoams. They are highly hydrogenated graphite‐like amorphous carbon and superhydrophilic. The resulting symmetric micro‐supercapacitor delivers higher volumetric capacitance of 522 mF/cm³ at 100 mV/s and 104 % retention after 10000 charge‐discharge cycles over conventional nanofoam (215 mF/cm³ and 85 % retention) with an areal capacitance of 134 μF/cm² at 120 Hz and ultrafast frequency response. Utilizing the normally discarded target‐side material can therefore enable high performing devices while reducing waste, cost and energy input per usable product, leading towards a greater sustainability of nanomaterials synthesis and deposition techniques.

Manganese, showing stable oxidation states spanning from +2 to +7, gives rise to a variety of oxides ($\mathrm{Mn}{\mathrm{O}}_x$) whose exploitation in several technological fields, such as energy conversion and storage, catalysis, sensing, and environmental and biomedical engineering, is highly promising. Nevertheless, the chemical complexity and the structural richness of $\mathrm{Mn}{\mathrm{O}}_x\text{—}\mathrm{involving}$ mixed-valence and metastable species—make the correct identification by Raman spectroscopy challenging, further complicated by the laser sensitivity, poor Raman activity, and conflicting literature scenario. Moreover, a careful optimization of the material in terms of phase, structure, and morphology is highly desirable in view of the final application, where precise control over the materials properties is essential. In this paper, we discuss the capability of room-temperature pulsed laser deposition (PLD) followed by postdeposition thermal treatments to successfully grow engineered and pure $\mathrm{Mn}{\mathrm{O}}_x$ thin films, whose phase and morphology at the nanoscale can be totally decoupled and independently optimized. The detailed Raman characterization of these films enabled a clear identification of specific $\mathrm{Mn}{\mathrm{O}}_x$ phases and poses the basis for the rationale of the $\mathrm{Mn}{\mathrm{O}}_x$ Raman spectra. Starting from the same MnO PLD target, we obtained five different $\mathrm{Mn}{\mathrm{O}}_x$ phases (i.e., MnO, ${\mathrm{Mn}}_3{\mathrm{O}}_4, {\mathrm{Mn}}_2{\mathrm{O}}_3$, amorphous $\mathrm{Mn}{\mathrm{O}}_2$, and $\alpha \text{−}\mathrm{Mn}{\mathrm{O}}_2$) with tailored and tunable degree of porosity and crystallinity, by modulating process parameters like the ${\mathrm{O}}_2$ deposition partial pressure (vacuum to 100 Pa), the type of substrate, and the annealing temperature ($300-900{}^{\circ }\mathrm{C}$) and atmosphere (air/vacuum). The Raman spectroscopy reliability of the $\mathrm{Mn}{\mathrm{O}}_x$ phase assignment was assessed by thoroughly investigating the impact of the exciting laser power, and it was further validated by energy-dispersive x-ray spectroscopy, x-ray photoemission spectroscopy, and x-ray diffraction, providing additional insight into the compositional properties and the crystalline structure.