The growing demand for safe, cost-effective, and environmentally sustainable energy-storage technologies has accelerated research into aqueous zinc-based systems as alternatives to lithium-ion batteries. Among these, zinc-ion hybrid capacitors (ZIHCs) have emerged as promising candidates by combining the high energy density of batteries with high power density and long cycle life of supercapacitors. In this context, MXenes—a rapidly expanding family of two-dimensional transition-metal carbides and nitrides—have attracted significant attention as advanced cathode materials due to their metallic conductivity, tunable surface chemistry, and layered structures that enable fast ion transport. This review comprehensively examines the role of MXene-based materials as cathodes in ZIHCs, with emphasis on synthesis strategies, electronic properties, surface terminations, and charge-storage mechanisms. The interplay between surface adsorption-dominated pseudocapacitance and Zn2+ intercalation-controlled storage is critically analyzed, alongside the influence of electrolyte chemistry, alternative ion charge carriers, and interfacial engineering. Recent advances in three-dimensional and 3D-printed MXene architectures for high-mass-loading and micro-ZIHCs are highlighted, demonstrating substantial improvements in areal capacitance, energy density, and cycling stability. Finally, key challenges related to surface termination control, long-term stability, and scalability are discussed, and future research directions are outlined to facilitate the translation of MXene-based ZIHCs from laboratory studies to practical energy-storage applications.
This study integrates batch adsorption experiments, post-adsorption XPS, and density functional theory (DFT) modeling to elucidate the uptake mechanisms of 17β-estradiol (E2), atorvastatin (ATV), diclofenac (DCF), and metformin (MET) on commercial, partially reduced graphene oxide (GO). The material exhibited low oxygen functionality (C/O ≈ 13) and pHₚzc ≈ 4.4. A nanometric GO sheet (~33.7 Å diameter; ~1827 Å2 accessible area) containing edge carboxyls and basal epoxides was constructed with an overall −1 charge, consistent with experimental characterization. Adsorption was rapid and followed pseudo-second-order kinetics. E2 and DCF were better described by the Langmuir model, with qmax values of 157 and 68.16 mg g−1, respectively. ATV and MET followed Freundlich behavior, with KF values of 30.73 and 3.96 and R2 values of 0.991 and 0.985, respectively. The Sips model provided the best fit for DCF (R2 = 0.994; qmax = 61.25 mg g−1), whereas the D–R model adequately described MET (R2 = 0.977), yielding a mean adsorption energy of 12.32 kJ mol−1. XPS and DFT linked selectivity (ATV ≈ E2 > DCF > MET) to π–π, hydrogen-bonding, polar, and electrostatic interactions. These results identify the C/O ratio and functional-group distribution as key parameters for tailoring GO-based adsorbents.
Nanostructure design and electrode architecture engineering play a crucial role in enhancing the electrochemical performance of energy-storage systems by promoting efficient electron/ion transport and maximizing the utilization of electroactive materials. In this study, a highly conductive binder-free current collector was fabricated by integrating reduced graphene hydrogel (RGH) with nickel foam (NF), followed by the direct growth of hierarchical Zn–Co–S and Fe–Co–Score–shell nanoarrays through a metal–organic framework (MOF)-assisted synthesis strategy. Owing to the synergistic effects of the conductive three-dimensional RGH framework and the hierarchical nanoarchitecture, the Zn–Co–S/RGH–NF and Fe–Co–S/RGH–NF electrodes delivered high specific capacitances of 3124 and 2418 F g−1, respectively, as calculated from cyclic voltammetry (CV) curves recorded at 5 mV s−1 in a three-electrode configuration. To further evaluate their practical applicability, asymmetric supercapacitor devices were assembled using RGH–NF as the negative electrode. The RGH–NF//Zn–Co–S/RGH–NF and RGH–NF//Fe–Co–S/RGH–NF devices delivered energy densities of 52 Wh kg−1 at a power density of 0.628 kW kg−1 and 41.88 Wh kg−1 at a power density of 0.625 kW kg−1, respectively, while retaining more than 80% of their initial capacitance after 10,000 galvanostatic charge–discharge cycles. These results demonstrate that the combination of MOF-derived hierarchical nanoarchitectures and RGH-supported three-dimensional conductive networks effectively accelerates charge-transfer kinetics and enhances electrochemical performance, providing a promising strategy for the development of next-generation high-performance supercapacitor electrodes and devices.
Accurate assessment of glioblastoma multiforme (GBM) tissue heterogeneity remains challenging because tumor core, infiltrative, margin, necrotic, and adjacent tissue regions can differ substantially in biochemical and electrochemical composition. Here, we evaluate monolayer graphene as a tissue-interfaced Raman transducer for detecting tissue-induced modulation of graphene phonons. Surgically resected glioma specimens were placed in direct contact with chemical vapor deposition (CVD)-grown monolayer graphene, and Raman mapping was used to quantify shifts in the graphene 2D band. Histopathology, performed blinded to Raman analysis, was used to assign tissue regions after Raman acquisition. For GBM specimens, tissue-contacting graphene showed measurable 2D-band shifts of approximately 2.3–5.9 cm−1, corresponding to estimated n-type carrier densities of approximately −4.4 to −13.5 × 1012 cm−2. Histologically confirmed margin tissue and one oligodendroglioma specimen displayed larger 2D-band shifts than the GBM cohort average, indicating that the graphene Raman response is sensitive to tissue-dependent interfacial chemistry. These findings support the use of tissue-interfaced graphene as a label-free platform for probing local electrochemical heterogeneity in glioma specimens. Larger cohorts, rigorous strain/doping deconvolution, and blinded diagnostic validation will be required before diagnostic or intraoperative use can be established.
For monitoring renal/metabolic diseases it is very important to quantify simultaneously uric acid (UA) and ascorbic acid (AA); however, when using traditional electrochemical sensors, both overlapping oxidation potentials and electrode fouling can introduce signal interference. This work reports on the successful development of a borophene-modified carbon screen-printed electrode (CSPE/Borophene) that allows the selective dual analyte detection of UA and AA. Borophene was synthesized by liquid phase exfoliation, resulting in the formation of a highly crystalline material with various electrocatalytically active defect sites. Using DPV, electrochemical measurements made in a neutral environment (pH 7.0) revealed well-resolved oxidation peaks for AA (0.20 V) and UA (0.32 V) are well resolved from each other providing an approximate 120 mV separation, thus eliminating any potential cross-talk during simultaneous detection. The CSPE/Borophene sensor demonstrated very wide linear dynamic ranges for UA (0.5–500 μM) and AA (5.0–5000 μM). The limits of detection are extremely low for both UA (0.54 μM) and AA (5.17 μM) along with high analytical sensitivity (UA: 182.78 μA/(μM·cm2); AA: 21.32 μA/(μM·cm2)). The sensor was able to distinguish UA and AA through selectivity against many biologically relevant interferents; showing superior reproducibility (RSD < 1.2%); and provided long-term stability (more than 95% signal retention for more than 30 days). The sensor's quantitative performance in human blood serum and simulated sweat matrices demonstrates the real-world application of the borophene-based sensor for rapid, point-of-care clinical diagnostics.
Wastewater treatment is a fundamental necessity for a polluted environment, and photocatalysis and adsorption are popular methods for addressing this issue. This research is based on the one-pot hydrothermal synthesis of reduced graphene oxide-based nickel nanocomposites to investigate the efficiency for anthropogenic, carcinogenic, and organic pollutants (ACOP) removal. Different characterization techniques were carried out to determine the functional group (by using FTIR), crystal structure (by XRD), morphology (by SEM), emission-excitation intensity (by PL), absorbance-related band gap (by UV), surface charge, and stability of the nanocomposites (by Zeta potential) related to photocatalysis and adsorption. XRD analysis elaborates that the GNC (cubic structure), GNF (cubic structure), and GNM (orthorhombic and monoclinic structure) show 3.72, 24.08, and 10.92 nm sizes, respectively. SEM analysis gives the size range of 0.14–0.22, 0.4–1.6, and 0.12–0.24 μm for GNC, GNF, and GNM. Process-based applications, like photocatalysis and adsorption, were carried out against ACOP. Photocatalysis was carried out in both Sunlight and UV radiation to determine the effect of radiation on catalysis in rGONCs, and the analysis shows that sunlight shows superior results by degradation of Congo red, Methylene blue, and Methyl orange at upto 99, 86, and 96% over UV radiation degradation 66, 91, 99.5%, respectively. To determine stability and mechanism, reusability and scavenging were also evaluated. Excellent catalytic effectiveness was demonstrated by quantitative degradation capacities of up to 132.73 mg/g of GNF. Every rGONC in the kinetics study follows pseudo-second-order kinetics, according to the analysis of adsorption kinetics and models for various rGONCs against various dyes: GNC shows 95% (Congo red), 91% (Methylene blue), and 86% (Methyl orange); GNF shows 90.7% (Congo red), 90.3% (Methylene blue), and 70% (Methyl orange); and GNM shows 88% (Congo red), 79% (Methylene blue), and 63% (Methyl orange). Because of its advantageous bandgap and surface charge properties, GNF performed the best overall among the produced materials, indicating its promise as an effective multifunctional material for wastewater remediation applications.
With the rapid progress in industrial sectors, energy scarcity and environmental pollution have become the two problematic issues of the current century. A photocatalytic fuel cell (PFC) represents an emerging approach for wastewater remediation, simultaneously enabling pollutant degradation and energy recovery. In this context, the crucial point is to rationally construct high- efficiency photoanodes, which remains a major challenge for the commercial development of photocatalytic fuel cells. g-C3N4 is a low-cost and visible-light responsive semiconductor that indicates an excellent performance as a photoelectrode. This work summarizes the g-C3N4-based PFC systems with the aim of simultaneous photocatalytic degradation of emerging pollutants and electricity generation. In this regard, we will discuss the basic principles and technical facets of the recently-developed g-C3N4–supported PFCs to facilitate the development and improvement of sustainable photoelectrodes. Furthermore, the fundamental working aspects of these systems will be discussed, considering the advantages and disadvantages, as well as the practical restrictions of the constructions. Concluding remarks and several recommendations are presented at the end to provide helpful insights for future research on PFCs.
We investigate Andreev reflection and valley-dependent transport in a graphene/line-defect/superconductor junction. Using a tight-binding model combined with the Bogoliubov–de Gennes formalism and a scattering matrix approach, we show that the line defect acts as a universal valley filter for both electrons and holes, independent of their band index. This universal behavior originates from the invariance of the pseudospin structure governing transmission across conduction and valence bands. Based on this property, we identify two distinct transport mechanisms associated with different Andreev reflection regimes. In the retro-Andreev reflection regime, where electrons and holes reside in the same band, the defect induces a double-filtering mechanism that enhances valley selectivity and produces strongly asymmetric angular distributions. In contrast, in the specular regime, the interband nature of Andreev reflection leads to a complementary filtering mechanism, which suppresses transport at large incident angles and restores angular symmetry. These features are quantitatively captured by an analytical equation for coherent multiple scattering, which accurately reproduces the zero-bias differential conductance. Our results establish a direct connection between microscopic valley filtering and macroscopic transport observables, demonstrating that differential conductance measurements provide a clear signature of both the Andreev reflection regime and the efficiency of valley filtering.
Hydrogen-bonded organic frameworks (HOFs) represent a burgeoning class of porous materials distinguished by their remarkable attributes, such as substantial structural flexibility, facile synthetic conditions, excellent solution processability, inherent regenerative capabilities, and notable recyclability. These advantages position HOFs as promising candidates for diverse applications, especially in the realms of energy storage and conversion. However, the intrinsic fragility and reversibility of the hydrogen bonds constituting their frameworks frequently lead to instability, thereby undermining their ability to preserve permanent porosity and restricting their widespread application. This review provides a comprehensive overview of the various synthetic strategies employed to fabricate HOFs, categorizes the approaches designed to enhance their structural stability, and delves into the latest progressions in their utilization, particularly in alkali metal ion batteries (AMIBs). The paper critically addresses the challenges and opportunities associated with the current limitations of HOFs, proposing strategies to ameliorate these constraints and bolster their performance in energy storage applications. Furthermore, it outlines prospective avenues for advancing the development of HOFs, emphasizing the need for innovative solutions to improve their stability and porosity for sustained use in energy-related technologies.
In this work, we report one-pot synthesis of Cu2Te/rGO nanohybrid and investigation of its intrinsic peroxidase-like nanozyme activity and photocatalytic degradation of organic dyes. The synthesized nanohybrid, analysed by P-XRD, XPS, SEM, TEM, and EDS, confirms the homogeneous anchoring of Cu2Te nanoparticles onto a reduced graphene oxide sheet, ensuring high dispersion and strong interfacial interaction. Cu2Te/rGO nanohybrid showed significantly enhanced peroxidase-like activities towards two chromogenic substrates, 3,3′,5,5′-tetramethylbenzidine and o-phenylenediamine, in the presence of H2O2, when it was compared with bare Cu2Te, and natural enzyme HRP. Michaelis-Menten kinetics of Cu2Te/rGO showed lower Km values (8.3 mM for TMB and 0.26 mM for H2O2) and higher Vmax values (1.32 × 10−6 M.s−1 for TMB, and 1.38 × 10−7 M.s−1 for H2O2) as compared to bare Cu2Te, indicating the improved substrate binding affinity and catalytic efficiency due to the synergistic effect of Cu2Te and rGO. A mechanistic study using terephthalic acid as a fluorescent probe and radical scavenger assay confirmed the generation of hydroxyl radical as the dominant reactive oxygen species for the catalytic activity of Cu2Te/rGO. The excellent detection of H2O2 with a low detection limit (0.34 μM), and a wide linear range (1–70 μM), demonstrates the strong potential of the Cu2Te/rGO nanohybrid as a sensitive and reliable colorimetric nanozyme for H₂O₂ detection. Furthermore, the Cu2Te/rGO nanohybrid showed superior photocatalytic performance under controlled UV lamp irradiation source and achieved significantly high efficiency degradation of Rhodamine B and Methylene blue with pseudo-first-order kinetics, with significant enhanced rate constant of Cu2Te/rGO as compared to the bare Cu2Te. Overall, Cu2Te/rGO nanohybrid showed a multifunctional catalyst with promising peroxidase-like activities and a sustainable approach towards the degradation of environmental pollutants.
With the rapid development of modern electronic technologies, electromagnetic pollution has become an increasingly serious concern, creating an urgent demand for highly efficient electromagnetic interference (EMI) shielding materials. Herein, Ag/nitrogen-doped graphene (Ag/N-rGO) composites were fabricated through a two-step strategy involving urea-assisted nitrogen doping by thermal reduction and subsequent controlled electroless plating of Ag. The N-rGO framework contains abundant nitrogen configurations, including pyridinic N, pyrrolic N, and graphitic N. These configurations enhance the intrinsic conductive response and defect-induced polarization of graphene. Moreover, N-doping can provide active adsorption sites for Ag⁺, which contributes to the uniform anchoring of Ag nanoparticles on the N-rGO surface. Thus, by loading Ag nanoparticles, continuous conductive networks and abundant Ag/N-rGO heterointerfaces can be constructed. By optimizing the Ag loading, the ANG2 composite (N-rGO and AgNO₃ mass ratio of 1:2) exhibits the best EMI shielding performance, with an average total shielding effectiveness (SET) of 93.56 dB and an electrical conductivity of 157.81 S cm⁻¹. This outstanding performance is attributed to the synergistic contributions of conduction loss, polarization loss, and multiple reflection and scattering. This study provides insights into the rational design and fabrication of high-performance and tunable graphene-based EMI shielding materials.
2D materials with intrinsic magnetic ordering opened new grounds in spintronics and quantum information processing. Out of these CrSBr has been suggested to be an air stable 2D magnet. Herein, we ponder into the mechanisms behind structural stability and thermal oxidation of bulk CrSBr crystals in air. Our XAS and XPS studies show that long-time storage of this material in air produces Br vacancies as well as near-surface defective S and Cr atoms. Experimental AFM, XAS and XPS studies supported by DFT calculations show that heating CrSBr crystals produces vacancies first and then some surface-bound oxides/hydroxides, which increase the surface micro-roughness. In particular, fifteen minutes heating at 270 °C leads to Br and S vacancies as well as presence of sulfates at the surface but without any Cr oxides. However, 15 min heating at 330 °C induces oxidation of Cr atoms into Cr2O3 and/or Cr(OH)3. Furthermore, defective CrSBr undergoes a unique thermal oxidative etching with formation of sub-surface square etch pits. This leads to occasional bursts of the top-most layers once a maximum strain within the CrSBr membrane has been met. The DFT calculations support favorable oxygen incorporation underneath the top-most layers through the Br vacancies and passivation of the S vacancies in the top-most layer.
There are few established methods of robust and high-coverage surface functionalization for black phosphorus (BP), effectively limiting the control of its surface reactivity and chemistry. Photochemical grafting of terminal alkenes is known route for the formation of molecular layers on semiconductor surfaces, and here we demonstrate that this chemistry can be applied successfully to BP. We demonstrate that a model alkene 1H-1H-2H-perfluoro-1-decene (PFD) grafts to the surface of BP when illuminated with ultraviolet (UV) light. The reaction self terminates at one molecular monolayer with a surface coverage of approximately 3 molecules/nm2. Control experiments without illumination exhibit only small surface coverages, confirming that the reaction with PFD is light initiated. We find when BP is exposed to 1-decene and allylpentafluorobenzene (APFB) without illumination, the surface exhibits significant amounts of oxygen and oxidized carbon. This suggests carbon‑oxygen impurities likely have a high affinity for pristine BP surfaces even when reactions are conducted using high-purity reagents under stringent glovebox conditions.
Hybrid epoxy nanocomposites incorporating carbon-based nanofillers are promising materials for advanced multifunctional applications. This study provides a multiscale characterization of nanohybrids incorporating multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) at 0.1 and 0.5 wt%. By systematically varying MWCNT:GNP ratios, we investigate the synergistic effects of 1D and 2D nanofillers on local behavior. Dynamic mechanical responses were captured via frequency-dependent nanoindentation (10–200 Hz), precisely evaluating viscoelastic properties across a broad spectrum. Simultaneously, high-resolution Tunneling Atomic Force Microscopy (TUNA) was deployed to map nanoscale conductive pathways and surface nanotopography. These results establish a critical correlation between global roughness and nanomechanical features like contact depth and hardness. To transcend experimental limitations, a high-fidelity, experimentally validated multiphysics dual-domain 3D model was developed as a key innovation in the field. This computational framework demonstrates exceptional predictive power across both time and frequency domains, bridging the gap between nanoscale morphology and macro-scale dynamic integrity. By establishing a deterministic link between surface roughness and contact mechanics, the integration of dynamic nanoindentation, TUNA mapping, and numerical modeling offers valuable insights for the precision engineering of advanced hybrid materials under complex dynamic loading conditions.
Interfacial energy-level mismatch, inefficient charge extraction, and trap-assisted recombination remain major barriers to high-efficiency and stable perovskite solar cells (PSCs). Although TiO₂ modification, carbon-based interlayers, molecular dipoles, and single-atom engineering have been widely explored, most reported strategies mainly improve only one aspect of interfacial regulation, such as defect passivation, band alignment, or charge transport. Herein, we report a CuTi dual-atom-engineered TiO₂/N-doped graphene interface, denoted as Cu–O–Ti@TiO₂@N-G, as a multifunctional electron transport layer for simultaneous band alignment, defect modulation, and recombination suppression. The novelty of this design lies in cooperative Cu–O–Ti atomic coupling, where Cu provides redox-active electronic regulation and Ti ensures lattice-compatible anchoring with TiO₂. Unlike previously reported single-atom or conventional TiO₂-based interfaces, the CuTi dual sites generate stronger interfacial dipoles, stabilize oxygen vacancies, and create efficient electron-hopping pathways. Meanwhile, the N-doped graphene framework provides a conductive scaffold that accelerates charge extraction and suppresses interfacial carrier accumulation. Benefiting from this integrated dual-atom/vacancy/conductive-network design, the optimized PSCs achieve a power conversion efficiency of 22.1%, with V_OC = 1.15 V, J_SC = 24.5 mA cm−2, and FF = 79.8%. The device also exhibits rapid charge extraction, reflected by a carrier lifetime of 7.5 ns, and retains over 90% of its initial efficiency after 1000 h of ambient storage.
DNA strand commutation, a recently proposed mechanism in which mismatched single-stranded DNA (ssDNA) strands interact through reversible low-affinity binding, offers an alternative to conventional complementary base-pairing for DNA-based information processing. Translating this solution-phase process onto solid-state platforms is essential for practical biosensor and biocomputing applications, yet the behavior of mismatched ssDNA at two-dimensional material interfaces remains largely unexplored. Here we use a graphene field-effect transistor (GFET) as a real-time, label-free transducer to study mismatched ssDNA binding via strand commutation directly on the device surface. A probe oligonucleotide (S) was covalently anchored to graphene via pyrenebutanoic acid succinimidyl ester chemistry. Mismatched ssDNA strands (Q) with two or three mismatches were introduced to bind S, followed by a higher-affinity mismatched strand (I) intended to displace Q. We find that π–π stacking of short ssDNA on the graphene lattice competes with, and substantially hinders, mismatched strand binding, even when fully complementary strands are used as displacing agents. Surface passivation with bovine serum albumin (BSA) partially restores displacement efficiency, and heating BSA-passivated chips to 70 °C was also found to reduce non-specific adsorption. Notably, the GFET can detect ssDNA binding events at concentrations as low as 10 fM. On unpassivated graphene, cognate and non-cognate strand pairs, whose solution-phase affinities differ by four orders of magnitude, produce indistinguishable displacement signals, indicating that non-specific adsorption dominates the GFET response. Surface passivation with BSA partially restores selectivity between cognate and non-cognate pairs. These results provide new insight into the interplay between molecular recognition and surface interactions at the graphene interface, with direct implications for the design of graphene-based biosensors and solid-state biocomputing platforms.
Organic solar cells (OSCs) have gained intensive research attention for their cost-effectiveness, flexibility, and light weight over traditional silicon devices. However, commercialization is partially hindered by using indium tin oxide (ITO) as the standard transparent conductive electrode (TCE) due to high fabrication costs, mechanical brittleness, and indium scarcity. Graphene TCEs offer a promising alternative with excellent conductivity, transparency, flexibility, chemical stability, and cost-effectiveness. Among synthesis methods, chemical vapor deposition (CVD) stands out for scalability, high-quality output, and thickness control, although challenges related to transfer processes, defect control, and large-area uniformity still limit practical implementation. This review evaluates graphene as an ITO-alternative, focusing on CVD synthesis. It highlights reported top efficiencies of OSCs with CVD-grown graphene-based TCEs and discusses key synthesis challenges. Plasma-enhanced CVD has emerged as a promising alternative to conventional thermal CVD for addressing some of these limitations, with recent advancements enabling the direct synthesis of graphene on transparent and flexible target substrates at lower temperatures compared to conventional CVD. Furthermore, practical strategies for improving scalability, uniformity, stability, and device integration of CVD-grown graphene TCEs for OSC applications are discussed.
Pyrogallol (PYL), a photographic developing agent, is a toxic pollutant released into water bodies through industrial effluents. In this study, a Y3Al5O12-N@MWCNT (YAO/N@MW) nanocomposite was synthesized via hydrothermal method and ultrasonication for electrochemical detection of PYL. The optimized sensor exhibited a wide linear range (2.4–321.3 μM), ultra-low detection limit (6.02 nM), and high sensitivity (0.4372 μA μM−1 cm−2). The oxidation followed a diffusion-controlled two-electron two-proton mechanism. The sensor showed excellent repeatability (1.319%), reproducibility (2.43%), and stability (91.5% retention after 28 days). Real sample analysis in pond, tap, and river water yielded excellent recoveries (99.41–100.68%) with low RSD (<0.55%). The superior performance is attributed to the synergistic combination of YAO, conductive N-doped MWCNT, and the strong interfacial interactions between the components. This work presents a reliable electrochemical platform for monitoring PYL as a pollutant in aquatic environments.
