In recent years, spinel-structured transition-metal oxide ZnMn₂O₄ has attracted attention as a low-cost anode material with high lithium-ion storage capacity. However, its practical application is limited by poor intrinsic electrical conductivity, sluggish reaction kinetics, and large volume changes during repeated lithiation and delithiation, leading to unstable cycling behavior. Although several strategies have been explored to improve cyclic stability, many reported systems still suffer from limited rate performance, multistep synthesis routes, and an incomplete understanding of nitrogen-doped graphene oxide (N-rGO)-induced interfacial effects. In this work, hybrid ZnMn₂O₄/N-rGO nanocomposites with controlled graphene oxide additions of 20 and 30 wt% were synthesized via a simple one-pot hydrothermal route, enabling intimate oxide–N-rGO interfacial contact. Structural, microscopic, and X-ray photoelectron spectroscopy analyses confirmed the formation of phase-pure tetragonal ZnMn₂O₄ nanoparticles uniformly distributed on the N-rGO framework. XPS revealed a redistribution of nitrogen bonding configurations at higher GO loading, with increased graphitic nitrogen contribution that may enhance electronic conductivity, while pyridinic and pyrrolic nitrogen species provide interfacial active sites. Brunauer-Emmett-Teller analysis showed that increasing GO content enhanced the specific surface area and pore volume while preserving mesoporous architecture. The ZnMn₂O₄/N-rGO nanocomposite containing 30 wt% graphene oxide (ZMO-30) delivered a reversible discharge capacity of 859.02 mAh g^-1 after 100 cycles at 100 mA g^-1 with superior rate performance and reduced charge-transfer resistance, demonstrating the beneficial role of oxide–N-rGO interfacial engineering in improving the kinetics and durability of ZnMn₂O₄ anodes.

Molybdenum disulfide (MoS ₂) has emerged as a promising electrocatalyst for the electrochemical reduction of CO ₂, primarily yielding carbon monoxide. However, product selectivity is known to be highly sensitive to structural features such as edge termination and defect density. In this work, we report the formation of higher hydrocarbons (C ₂+ products) enabled by the presence of inherent sulfur vacancies in MoS ₂ when combined with various ionic liquids as co-catalysts. While MoS ₂ has traditionally shown limited hydrocarbon output, our findings demonstrate for the first time that native defect sites, interacting synergistically with the electrolyte environment, can facilitate the production of significant amounts of C ₂+ species. These results provide new insights into defect-mediated catalytic pathways and highlight the importance of electrolyte design in tuning product distribution during CO ₂ electroreduction.

Silicon is a promising alternative to the conventional graphite anodes due to its high theoretical capacity and favorable lithiation potential for lithium-ion batteries (LIBs) with liquid as well as solid-state electrolytes. However, lithiation-induced extreme volume change causes severe mechanochemical deformation and continuous formation of solid-electrolyte interphase leads to cell failure. One of the strategies to mitigate this problem is alloying silicon with a suitable element that can alter the surface electrochemistry and/or lithiation pathways, and acts as mechanical buffer. Nonetheless, these benefits come with a compromise on the specific capacity, which strongly influences the mass loading of the electrodes, highlighting the need to deconvolute the intertwined influence of composition and mass loading when designing high performance electrodes. In this work, we systematically studied the influence of composition and mass loading in monolithic amorphous silicon and non-stoichiometric silicon nitride (SiN_x) electrodes on their electrochemical performance as LIB anodes. The incorporation of nitrogen in the electrode matrix clearly improves the electrochemical stability at the expense of reduced specific capacity, while higher mass loading accelerates capacity fading, most critically in amorphous silicon electrodes. Postmortem analysis reveals that such capacity fading in the electrodes with higher mass loading can be related to delamination due to evolved tensile stress during the charge–discharge cycle. Yet, nitrogen-rich SiN_x monolithic electrodes accommodate strain more effectively. These findings demonstrate that while pristine Si delivers high specific capacity and long-term stability in thin films, thicker (>1 µm) monolithic electrodes benefit from higher nitrogen content in SiN_x, which provides more stable cycling and sustained capacity.

Electrochemical CO₂ reduction (CO₂R) to chemicals and fuels has made tremendous progress since the introduction of gas diffusion electrodes (GDEs) to overcome mass-transfer limitations and enable industrial-scale current densities. The advancement in the field, however, has come with new challenges that are related to the stability and degradation of the GDE due to flooding issues, which currently hinder the scale-up. Here, we investigated the effect of six different binding materials (Nafion, polytetrafluoroethylene, Fumion, Pention, poly(vinyl alcohol), and polypyrrole) on the stability and performance of Ag-based GDEs for CO₂R to CO in alkaline media. All binders show a decrease in the Faraday efficiency (FE) of CO and increase in hydrogen evolution reaction over time. The most hydrophilic GDE based on polypyrrole can uphold a higher FE of CO for longer times, which is contrary to a common belief that low wettability is required for long-term stability. By using a range of tools (SEM-EDX, SEM-FIB, X-ray diffraction, and contact angle measurements) for the postelectrolysis characterization of the GDEs, we show that the performance loss is related to flooding, bi(carbonate) precipitation, and catalyst agglomeration. These results contribute to a better understanding of the stability issues in GDE-based CO₂ electrolyzers.

In the search for effective high-tech materials for energy conversion and storage devices, spinel-structured nickel ferrite (NiFe₂O₄) has been identified as a promising anode material for lithium-ion batteries (LIBs). However, the influence of different morphologies and surface properties of NiFe₂O₄ nanoparticles on battery performance is hardly addressed. To understand the effect of different morphologies and surface properties on the lithium-ion storage performance, NiFe₂O₄ nanoparticles were synthesized through four different synthesis conditions: NFO-S, NFO-U, NFO-G, and NFO-C. The formation of polycrystalline inverse spinel NiFe₂O₄ was confirmed through XRD, FTIR, and Raman spectroscopy. The morphologies of the obtained samples were studied using FESEM, and it was found that the four different synthesis conditions employed here enabled us to obtain NiFe₂O₄ with four different morphologies. The surface chemistry, surface area and porosity of the NiFe₂O₄ samples were respectively characterized using XPS and BET. The electrochemical performance of the four NiFe₂O₄ samples as anode material was studied by fabricating lithium-ion half-cells. NiFe₂O₄ sample obtained from surfactant-free synthesis condition (NFO-S) displayed a high initial discharge and charge capacity of 2258 mAh/g and 1815 mAh/g, respectively at the current density of 100 mA/g. Even after 100 cycles, NFO-S showed a better discharge capacity of 116 mAh/g at the current density of 100 mA/g, compared to the other samples studied here. The observed higher capacity of the NFO-S sample is attributed to the higher surface area (40.8 m²/g) and pore volume (0.190 cm³/g). The NiFe₂O₄ sample prepared with cationic CTAB surfactant (NFO-C) showed better cyclic stability with a stable coulombic efficiency of 98.5% at the 100th cycle, mainly attributed to its nanocube morphology with lower surface area (16.1 m²/g) and pore volume (0.087 cm³/g).

Optimizing the deposition parameters in the fabrication of passivating contacts for crystalline silicon solar cells is critical for improving efficiency. This study explored the influence of varying RF power of Plasma-Enhanced Chemical Vapor Deposition (PECVD) on the quality of hydrogenated intrinsic amorphous silicon ( a-Si:H) films. The aim is to manufacture in-situ phosphorous-doped poly-Si/SiO_x/c-Si passivating contacts with a-Si:H as buffer layer between the tunnelling oxide and the n-type poly-Si. The microstructure factor of our intrinsic layers increases from 0.176 to 0.804, that is from higher to lower film density, as the RF power increases from 5 W to 55 W. Analysis using X-ray Photoelectron Spectroscopy and Optical Microscopy indicates that the Si content in SiO_x is correlated with the formation of pinholes. Our detailed analysis showed that varying the RF power when depositing a-Si:H contacting layer is crucial in altering both the Si⁴⁺ content in SiO_x and the pinhole density, due to the interplay between the plasma etching and the buffering effects during of the a-Si:H layer growth. Notably, the sample processed with 25 W exhibited the maximum pinhole density, the lowest Si⁴⁺ content in SiO_x and the deepest phosphorus in-diffusion, potentially yielding superior results in passivation quality and contact resistivity under optimized PECVD conditions.

2D materials, characterized by their extensive surface area and customizable chemical and electronic properties, offer compelling advantages as advanced materials. These unique attributes pave the way for the development of next-generation electronics and optoelectronics, photo- and electro-catalysis, energy storage and conversion devices, and sensors. The most prominent and commonly available 2D transition metal dichalcogenide, molybdenum disulfide (MoS₂), has already shown its potential for advanced applications. However, its relatively unfavorable electronic structure and limited intrinsic conductivity lower its suitability for applications that require high conductivity, such as electrocatalysts. One way to enhance its conductivity is by electrochemically intercalating alkali metal ions, e.g., Na⁺ and K⁺, into its layered structure, potentially adjusting its electronic structure. Here, we present a comprehensive investigation into the atomic-scale intercalation mechanism using molecular dynamics simulations, complemented by experimental analysis of structural and electronic properties at the macro scale through various characterization techniques. It is demonstrated that the hydration shell of ions serves as an energy barrier to intercalation as it undergoes a structural change during the intercalation. When alkali metal ions are intercalated into MoS₂, they introduce more defects and enhance conductivity. Notably, these effects are more pronounced for potassium than for sodium.

The increasing concentration of CO2 is a serious concern for the environment. Electrochemical conversion of CO2 into valuable products, including fuels, offers a viable solution and helps close the carbon-neutral cycle. Metal-organic framework (MOF) composites, due to their high porosity, large surface area, and significant chemical tunability, are considered to be a promising class of catalyst materials for the CO2 reduction reaction (CO2RR). This chapter focuses on the fundamentals of CO2RR and mechanism of the reaction followed by discussing the recent advancements in MOF composite electrocatalysts for CO2RR including MOF-supported electrocatalysts, conductive-supported MOF composites, graphene and carbonous MOF composites, MOF-MXenes, MOF-polymers, and polyoxometalate.

The development of advanced catalysts with innovative nanoarchitectures is critical for addressing energy and environmental challenges such as the electrochemical CO₂ reduction reaction (CO₂ RR). Herein, the synthesis of an innovative copper–sulfur planar structure, Cu–S–BDC, within a metal–organic framework (MOF) catalyst is presented, which demonstrates 100% selectivity toward formate as the sole carbon product. Structural analysis and surface characterizations reveal that Cu–S–BDC exhibits quasi-2D inorganic building units, with Cu bonded to two S-CH (Formula presented.) groups and one BDC linker, while carboxylate groups adopt a bridging coordination mode. This unique arrangement not only imparts remarkable structural stability but also enhances the electronic properties of the MOF, as evidenced by a narrow bandgap of 1.203 eV that facilitates efficient charge transfer and increased electrochemical current density in CO (Formula presented.) RR. Notably, it offers a Faradaic efficiency of 92% for formate at an overpotential as low as −0.4 V versus the reversible hydrogen electrode (RHE) in an aqueous electrolyte of 1 m KOH, as well as a current density of −25.8 mA cm² at −0.9 V versus RHE, averaged over 24 h of electrolysis. This study highlights a fresh perspective in the field of MOF electrocatalysts by demonstrating that engineering the metal coordination environment can significantly enhance the electronic properties and consequently improve the electrocatalytic performance of these materials.

Titanium dioxide (TiO₂) has been widely used as a photocatalyst in CO₂ reduction reaction (CO₂RR) due to its low cost, high stability, and strong absorption in the close-to-visible ultra-violet (UV) range. However, TiO₂ films suffer from poor selectivity in CO₂ reduction due to their unfavorable electronic properties. In this work, we address this challenge by fabricating ultra-thin (14 nm) defective TiO₂ films (TiO₂-DTF) to enhance the selectivity of CO₂RR towards formate. TiO₂ sol was prepared using a facile and reproducible sol-gel method and directly deposited onto the surface of the electrode, forming a uniform, ultra-thin TiO₂ layers with a high number of defects. The activity of the TiO₂-DTF catalyst was studied in both photochemical and photoelectrochemical CO₂RR, indicating that the applied potential increases both the yield and selectivity of CO₂RR to formate. The TiO₂-DTF photocathode exhibited remarkable formate production during CO₂ reduction, achieving exceptional Faradaic efficiencies of up to 45 %. To elucidate the mechanism of photoelectrochemical CO₂RR on TiO₂-DTF, an in-situ attenuated total reflection Fourier-transform infrared spectroscopy (in-situ ATR-FTIR) was used and experimental results were supported by density functional theory (DFT) calculations. This study demonstrates that ultra-thin highly defective TiO₂ film, prepared using the cost-effective and environmentally friendly sol-gel method, can be used as photoelectrocatalyst for CO₂ reduction.

The search for non-toxic alternatives to hexavalent chromium based corrosion inhibitors requires a comprehensive understanding of the factors critical to effective corrosion protection. Key considerations include the evolution of corrosion inhibition with inhibitor concentrations and exposure times, the inhibition efficacy in the presence and following absence of inhibitors, and the stability of inhibition upon polarisation. In our electrochemical comparison of promising organic molecules with sodium dichromate, we found that even top-performing candidates can lead to premature conclusions if such critical factors are overlooked. While organic molecules can match the inhibition performance of chromates under specific conditions, this can be misleading when considering concentration, time, and polarisation dependent behaviour. Initial high performance can also be deceptive in dynamic environments, as we observed that the inhibition provided by most organic molecules drastically decreases when the inhibitor is absent in the electrolyte. These observations call for broader comprehensive inhibitor robustness studies that take into account factors including time, concentration, stability, and polarisation effects in inhibitor efficacy analysis.

Titanium surfaces featuring high-aspect ratio (HAR) nanopillars can have antimicrobial and osteogenic properties. Nevertheless, the impact of these surfaces on immune cells and their potential for immunomodulation remain unclear. In this study, the effects of HAR titanium nanopillars produced by dry-etching (DETi) on the response of unstimulated (M0) and pro-inflammatory (M1) murine macrophages (J774A.1) have been explored. The findings revealed changes in the morphology and crystallinity of the DETi nanopillars along their height. After 48 h of culture, both M0 and M1 stimulated macrophages displayed a more elongated morphology, a smoother cell surface, and shorter cellular protrusions on the more hydrophilic and rough DETi surfaces. Furthermore, DETi surfaces induced polarization of M0 cells towards M2 phenotypes, whereas M1 stimulated cells showed M2-like elongated morphologies while maintaining a stronger pro-inflammatory response to DETi surfaces relative to the glass control. The findings indicate that the DETi surfaces can induce morphological changes in macrophages and specific immunomodulatory effects depending on their initial phenotype, highlighting the potential of such biomaterials to incorporate an immunomodulatory biofunctionality next to the osteogenic and bactericidal ones.

The dream corrosion inhibitor would work for every substrate–environment combination, and the protection would be sustained indefinitely with an irreversible barrier layer when exposed to aggressive and changing environmental conditions. However our prior electrochemical experiments on AA2024-T3 have shown that despite the initial inhibition, all of the tested molecules had reversible bonds that limit their inhibition performance and applicability in dynamic environments, with the exception of 3-amino-1,2,4-triazole-5-thiol, which still showed 42% inhibition efficiency after being exposed to 0.1M NaCl only for three days. To our knowledge, this is the first mechanistic study that explains the origin of such quasi-sustained inhibition by an organic molecule under dynamic and aggressive conditions relevant to aerospace alloys. Potentiodynamic polarization, atomic force microscopy and scanning Kelvin probe force microscopy (AFM/SKPFM), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) complemented by density functional theory (DFT) calculations were used to identify the molecular mechanism responsible for the quasi-stable adsorption provided by 3-amino-1,2,4-triazole-5-thiol. Our findings suggest that a sulphatization of the Al-(hydr)oxide is the key contributor to the quasi-sustained corrosion inhibition. Sustained molecule adsorption over intermetallics in trace amounts was also observed, but their presence was insufficient to inhibit corrosion.