The growing demand for sustainable energy solutions highlights the need for advancements in electrocatalysts for direct methanol fuel cells (DMFCs). This study introduces a novel approach to enhance the efficiency and durability of nickel sulfide (NiS) catalysts. We developed a hierarchically porous structure integrated with reduced graphene oxide (rGO) on a nickel foam substrate. Using a dynamic hydrogen bubble template (DHBT) technique, we created a porous nickel scaffold. We then electrodeposited graphene oxide and NiS onto this scaffold, resulting in a hybrid structure termed NiS-rGO-Ni/NF. Characterization through SEM, XRD, and XPS confirmed that the catalyst has a highly porous structure with uniformly distributed Ni₃S₂ and Ni₃S₄ phases. The NiS-rGO-Ni/NF catalyst showed significant improvements over conventional NiS/NF. It achieved a peak current density of 84.10 mA/cm² in the presence of 0.1 M methanol, compared to 30.32 mA/cm² with NiS/NF. This enhancement is due to the porous nickel layer created using DHBT and the integration of rGO. Additionally, the NiS-rGO-Ni/NF catalyst demonstrated superior reaction kinetics, evidenced by a decrease in the Tafel slope from 204 mV/dec to 122 mV/dec. It also exhibited a remarkable increase in the electrochemically active surface area, reaching 179 cm² compared to 22 cm² for NiS/NF. These improvements in surface area and kinetics contribute to its excellent stability, with the catalyst maintaining consistent performance over 20 h of continuous operation. These results underscore the effectiveness of the NiS-rGO-Ni/NF catalyst in methanol oxidation and its potential for more efficient and stable electrochemical applications.

Nowadays, scientists are increasingly focused on finding new efficient 2D materials for hydrogen storage due to their large specific surface area, exceptional physisorption properties, and high gravimetric capacity. In this respect, we have analyzed the potential of new 2D orthorhombic (o)-B₂CN and o-B₂C₂ materials as lightweight solid mediums for hydrogen storage, employing lithium decoration through density functional theory (DFT) calculations. Both materials were found to be conductive and demonstrated excellent mechanical, dynamical and thermal stability. The binding energies of lithium adatoms to the monolayers during the decoration process were found to be −3.38 and −3.72 eV for o-B₂CN and o-B₂C₂, respectively. These values indicate strong interactions with both substrates and the lack of lithium clustering given that they are higher than its cohesive energy (−1.63 eV). The lithium decoration technique significantly improves the adsorption of H₂ molecules on both materials, where each system adsorbs 32 molecules with an average adsorption energy of 0.25 and 0.23 eV for 32H₂@8Li-B₂CN and 32H₂@8Li-B₂C₂, respectively, along with excellent gravimetric capacities of 12.87 and 13.29 wt% and desorption temperatures of 186 and 171 K. To assess dynamical stability, AIMD calculations were conducted on fully loaded H₂ systems at temperatures of 100, 200, 400 and 500 K, demonstrating complete H₂ desorption and confirming the reversibility of both systems. A radial distribution function (RDF) analysis was conducted to examine the thermal effects on Li–H atomic correlations and assess the stability of hydrogen adsorption at different temperatures. Based on these results, it can be concluded that Li-decorated o-B₂CN and o-B₂C₂ show considerable potential for hydrogen storage applications.

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 development of stable, non-toxic, and high-efficiency perovskite materials is critical for advancing next-generation photovoltaic technologies. While numerous halide double perovskites have been explored, many suffer from indirect band gaps or limited optoelectronic tunability. In this work, we employ first principles calculations to investigate the structural, electronic, and optical characteristics of the rubidium-based double perovskite Rb₂NaTlBr₆. Our results reveal that the compound exhibits a direct band gap of 1.869 eV, along with strong, dynamic and thermodynamic stability. Notably, the application of tensile strain engineering systematically reduces the band gap to 1.374 eV, placing it within the optimal range for solar absorption and significantly enhancing its optoelectronic response. The material also demonstrates high absorption coefficients and favorable carrier effective masses. Importantly, the spectroscopic limited maximum efficiency (SLME) reaches 33% under 5% tensile strain, underscoring its photovoltaic potential. The findings suggest that strain engineered Rb₂NaTlBr₆ is promising, lead-free candidate for high-efficiency solar energy applications.

Photocatalytic water splitting represents a promising approach for sustainable hydrogen production, with two-dimensional Janus materials offering unique advantages through intrinsic electric fields that enhance charge separation. We present a comprehensive first-principles investigation of Janus AlXY₂ (X = Ga, In; Y = S, Se, Te) monolayers using density functional theory and ab initio molecular dynamics simulations. All six systems exhibit excellent structural, thermal, and mechanical stability with HSE06 bandgaps of 2.029–2.969 eV suitable for UV-light absorption. The asymmetric structure generates strong intrinsic electric fields of 5.391–6.437 V perpendicular to the monolayer plane, significantly enhancing photogenerated charge carrier separation. While pristine monolayers show poor hydrogen evolution reaction (HER) activity with Gibbs free energies of 1.937–2.371 eV, strategic introduction of metal vacancies dramatically improves performance, reducing ΔG_H values to −0.371 to ＋0.607 eV and approaching optimal catalytic conditions. These findings demonstrate the potential of defect-engineered 2D Janus AlXY₂ materials for efficient photocatalytic hydrogen production.

The development of novel anode materials with superior electrochemical performance is imperative for advancing next-generation high-performance rechargeable batteries beyond current limitations. In this study, it presents a 2D o-Al₂C₂ monolayer as a promising lightweight candidate for lithium and sodium–ion battery systems, based on the density functional theory investigations and ab initio molecular dynamics (AIMD) simulations. Our comprehensive investigation demonstrates that the o-Al₂C₂ monolayer exhibits remarkable stability with a cohesive energy of −5.30 eV atom⁻¹ and maintains its structural integrity at room temperature during extended AIMD simulations. The o-Al₂C₂ monolayer demonstrates exceptional electrochemical characteristics for Li and Na storage: theoretical specific capacities of 3780.42 and 3436.75 mA h g⁻¹, optimal average open circuit voltages of 0.81 and 0.67 V, and favorable diffusion barriers of 0.62 eV and 0.31 eV, respectively. These performance metrics significantly surpass those of conventional graphite (372 mA h g⁻¹) and other recently reported 2D anode materials, establishing o-Al₂C₂ as an exceptionally promising candidate for next-generation energy storage applications. Hence, this current theoretical investigation suggests that the o-Al₂C₂ monolayer holds significant potential for future experimental studies in lithium and sodium storage applications for LIB and NIB systems.

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.

Solar cells are expected to become one of the dominant electricity generation technologies in the coming decades. Developing high-performance absorbers made from thin materials is a promising pathway to improve efficiency and reduce cost, accelerating the widespread adoption of these photovoltaic cells. In the present work, we have systematically investigated the 2D MoSi₂N₄/Arsenene van der Waals (vdW) heterostructure, which exhibits a type-II band alignment with an indirect band gap semiconductor (1.58 eV), that can effectively separate the photogenerated electron–hole (e⁻–h⁺) pairs. Compared to the isolated MoSi₂N₄ and Arsenene monolayers, the optical absorption strength can be significantly enhanced in MoSi₂N₄/Arsenene vdW heterostructure (in the order of ∼10⁵ cm⁻¹ in the visible region). The calculated optical absorption gaps are 2.12 eV (Arsenene) and 1.76 eV (MoSi₂N₄), with excitonic binding energies of 0.05 eV for arsenene and 0.48 eV for MoSi₂N₄, indicating that both materials can effectively form excitons and separate charges. Moreover, we found a high spectroscopic limited maximum efficiency of 27.27% for the MoSi₂N₄/Arsenene vdW heterostructure, which is relatively higher compared to previously reported 2D heterostructures. Ab-initio molecular dynamics (AIMD) simulations at 300 K, 600 K, and 900 K were conducted to evaluate the thermal stability of the MoSi₂N₄/Arsenene heterostructure. Simulations in the presence of water and NO₂ at 300 K were also performed to assess its resilience to humidity and pollutants. The results suggest strong stability under harsh environmental conditions. Our findings demonstrate that the 2D MoSi₂N₄/Arsenene vdW heterostructure is an excellent candidate for both photovoltaic device applications and optoelectronic nanodevices.

Two-dimensional (2D) Janus monolayers, distinguished by their intrinsic vertical electric fields, emerge as highly efficient and eco-friendly materials for advancing the field of hydrogen evolution reactions (HER). In this study, we explore, for the first time, the potential viability of the oxygenation phase of two-dimensional Janus transition metal dichalcogenides MoOX (X = S, Se, and Te) monolayers as an exceptionally efficient photocatalyst for hydrogen production. Based on first-principles computations, we demonstrate that all three monolayers exhibit semiconductor behavior, characterized by a band gap ranging from 0.66 to 1.55 eV. This narrow band gap renders the proposed materials highly efficient at absorbing light within the visible region. Excitingly, the introduction of an electrostatic potential difference ΔΦ has granted us the ability to surpass the conventional bandgap limit (E_g≥1.23). Consequently, all monolayers exhibit favorable band alignment with respect to the vacuum level. Moreover, the calculated solar-to-hydrogen efficiency for the envisaged monolayer exceeds the established theoretical limit. Particularly, the MoOTe monolayer emerges as an infrared-light-driven photocatalyst, demonstrating a remarkable solar-to-hydrogen efficiency limit of up to 25,21% when considering the entire solar spectrum. A thorough examination of the Gibbs free energy differences across these monolayers has revealed that the values during the oxygenation phase are significantly smaller and approach the optimum, in contrast to the parental two-dimensional Janus transition metal dichalcogenides. Our results conclusively establish that the proposed materials exhibit exceptional efficiency as photocatalysts for hydrogen evolution reactions. Notably, their efficacy is demonstrated even in the lack of co-catalysts or sacrificial agents.

Lithium–sulfur (Li–S) batteries, renowned for their potential high energy density, have attracted attention due to their use of earth-abundant elements. However, a significant challenge lies in developing suitable materials for both lithium-based anodes, which are less prone to lithium dendrite formation, and sulfur-based cathodes. This obstacle has hindered their widespread commercial viability. In this study, we present a novel sulfur host material in the form of a two-dimensional semiconductor boron nitride framework, specifically the 2D orthorhombic diboron dinitride (o-B2N₂). The inherent conductivity of o-B2N₂ mitigates the insulating nature often observed in sulfur-based electrodes. Notably, the o-B2N₂ surface demonstrates a high binding affinity for long-chain Li-polysulfides, leading to a significant reduction in their dissolution into the DME/DOL electrolytes. Furthermore, the preferential deposition of Li2S on the o-B2N₂ surface expedites the kinetics of the lithium polysulfide redox reactions. Additionally, our investigations have revealed a catalytic mechanism on the o-B2N₂ surface, significantly reducing the free energy barriers for various sulfur reduction reactions. Consequently, the integration of o-B2N₂ as a host cathode material for Li–S batteries holds great promise in suppressing the shuttle effect of lithium polysulfides and ultimately enhancing the overall battery performance. This represents a practical advancement for the application of Li–S batteries.

This study aims to identify photo-/electrocatalysts that can enhance the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR), which are of utmost importance in electro-/photochemical energy systems, such as solar energy, fuel cells, water electrolyzers, or metal-air batteries. Our study focused on investigating the 2D Ge₂Se₂P₄ monolayer and found that it exhibits a bifunctional photocatalyst with a very high solar-to-hydrogen efficiency. The two-dimensional (2D) Ge₂Se₂P₄ monolayer has superior HER activity compared to that of most 2D materials, and it also outperforms the reference catalysts IrO₂(110) and Pt(111) in terms of low overpotential values for ORR and OER mechanisms. Such superior catalytic performance in the 2D Ge₂Se₂P₄ monolayer can be attributed to its electron states, charge transfer process, and suitable band alignments referring to normal hydrogen electrodes. Overall, the study suggests that the Ge₂Se₂P₄ monolayer could be an excellent bifunctional catalyst for advancing photo-/electrochemical energy systems.

The present study highlights the efficiency of Ag₃PO₄ photocatalyst with a band gap of 2.25 eV, synthesized by a green and one-pot simple mechanochemical method, towards photodegradation of orange G under visible irradiation. The phase structure, morphology, and optical properties of mechano-synthesized Ag₃PO₄ were investigated using X-ray diffraction, Scanning Electron Microscopy, Thermogravimetric Analysis, Fourier Transform Infrared, the Brunauer-Emmet-Teller surface area, and UV–vis diffuse reflectance spectroscopy. DFT calculations were also conducted for band gap energy prediction. The photocatalytic activity of the sample was evaluated using a central composite design for surface response methodology (CCD-RSM) to determine the optimal conditions for Orange G (OG) removal. The photocatalytic activity of Ag₃PO₄ was approximately 93 % within 20 min of reaction under irradiation for 24.6 mg/L and 11 mg/L of Ag₃PO₄ and Orange G, respectively. Trapping experiments confirmed that peroxides and hydroxyl radicals are the dominant active species in the photodegradation process.

A primary concern towards achieving a robust and sustainable water-splitting strategy consists in the development and designing of non-precious hydrogen evolution electrocatalysts capable of operating at relatively high current densities. In the present density functional theory (DFT) based study, we explored and identified α-NbB₂-based catalysts consisting of Borophene as graphene-like noble metal-free networks in Niobium-metal based networks, as promising catalysts for the hydrogen-evolution reaction (HER). Our results unveiled that Fe/Co covalent doping in α-NbB₂ {001} surface provides high-efficiency HER activity sites, namely, T_Nb-sites in Nb-terminated Fe/Co-NbB₂ {001} surface with the lowest ΔG_H^∗ Gibbs free energy value of about 0.264/0.278 eV, which further drops to a very optimal value in the range of ΔG_H^∗ ≤ ± 0.10 eV upon the implementation of an external electric field. Furthermore, it was also revealed that in contrast to the extensively used Pt-based surface catalysts, both α-NbB₂ and Fe/Co-NbB₂ catalysts can sustain consistently high catalytic activity for HER over a very large hydrogen coverage and thus ensure a large density of effective catalytic free sites.

Through a density functional theory-driven survey, a comprehensive investigation of two-dimensional (2D) Janus aluminum-based monochalcogenides (Al₂XY with X/Y = S, Se, and Te) has been performed within this study. To begin with, it is established that the examined phase, in which the Al-atoms are located at the two inner planes while the (S, Se, and Te)-atoms occupy the two outer planes in the unit cell, are energetically, mechanically, dynamically, and thermally stable. To address the electronic and optical properties, the hybrid function HSE06 has been employed. It is at first revealed that all three monolayers display a semiconducting nature with an indirect band gap ranging from 1.82 to 2.79 eV with a refractive index greater than 1.5, which implies that they would be transparent materials. Furthermore, the monolayers feature strong absorption spectra of around 10⁵ cm⁻¹ within the visible and ultraviolet regions, suggesting their potential use in optoelectronic devices. Concerning the photocatalytic performance, the conduction band-edge positions straddle the hydrogen evolution reaction redox level. Also, it is observed that the computed Gibbs free energy is around 1.15 eV, which is lower and comparable to some recently reported 2D-based Janus monolayers. Additionally, the thermoelectric properties are further investigated and found to offer a large thermal power as well as a high figure of merit (ZT) around 1.03. The aforementioned results strongly suggest that the 2D Janus Al-based monochalcogenide exhibits suitable characteristics as a potential material for high-performance optoelectronic and thermoelectric applications.

All-solid electrolytes could lead to a technological breakthrough in the performance of all-solid-state batteries when combined with a lithium-metal anode. However, the use of a lithium-metal anode presents several challenges, such as dendrite growth, interface electrochemical stability, formation and propagation of cracks, and delamination of the electrode/electrolyte interfaces. This work aims to explore the effectiveness of using newly synthesized 2D graphyne-based membranes (namely graphyne, graphdiyne, and graphtriyne) for electrode protection in a solid polymer electrolyte battery through first-principle calculations, nudged elastic band method, and classical molecular dynamics simulation. Specifically, we aim to investigate the effectiveness of these membranes in mitigating the aforementioned challenges. A high external electric field of up to 0.5 V/Å, 0.75 V/Å, and 1 V/Å was applied to accelerate the ions diffusion process. The adsorption energies, charge transfer, and in-plane/out-plane diffusion of single lithium on graphyne-based surfaces were investigated. Afterward, we calculated and compared the Li⁺ permeability, the electrolyte molecules’ rejection efficiency, and the intrinsic properties of graphyne-based nanoporous membranes. Our findings show that both graphyne and graphdiyne surfaces effectively permit Li⁺ intercalation while preventing other electrolyte molecules from reaching the electrodes.

An attractive approach to mitigate hydrogen embrittlement (HE) is to use nano-sized particles to immobilize hydrogen. However, the atomic scale relationship between different particle-matrix characteristics in aluminum alloys and the susceptibility to HE is unknown. In this study, the effects of interactions between various interfaces and hydrogen in aluminum alloys are investigated using a comprehensive multiscale experimental and simulation-based approach that includes atomic-scale observations, simulation and advanced hydrogen mapping techniques. Depending on the nature of interfaces, e.g., coherency, size, and crystal structure, some are useful for mitigating HE, others provide hydrogen to sensitive sites, and some act as crack initiation sites.