Abstract Scanning electrochemical cell microscopy (SECCM) is a spatially resolved electrochemical technique capable of providing information on structure–activity relationships with nanoscale resolution. The spatial resolution of SECCM is governed by both the pipette aperture size and the extent of the wetted area. Even when nanoscale apertures are employed, droplet spreading can enlarge the effective interrogation region several-fold, limiting the ability to resolve sharp heterointerfaces. Here, we report nanoscale mapping of hydrogen evolution reaction (HER) activity in CVD-grown MoSe2–MoS2 lateral heterostructures using SECCM. MoSe2 and MoS2 exhibit distinct wettability behaviors, and controlled meniscus wetting was achieved through the addition of polyvinylpyrrolidone (PVP) to a 100 mM HClO4 electrolyte, enabling spatially resolved measurements with a lateral resolution of approximately 250 nm. The resulting activity maps reveal pronounced spatial heterogeneity between MoS2 and MoSe2 domains, as well as localized variations at their lateral interfaces. Complementary Kelvin probe force microscopy (KPFM) measurements identify surface potential gradients on the order of 100–300 mV and an interfacial potential modulation of approximately 200 mV, consistent with interfacial band alignment effects and charge redistribution across the heterojunction. This work highlights the capability of SECCM to resolve electrochemical heterogeneity in lateral heterostructures composed of materials with distinct wettability characteristics and provides a nanoscale framework for investigating structure–activity relationships in two-dimensional catalytic systems.

Reproducibility remains a major challenge in materials synthesis, particularly for nanomaterials whose properties are highly sensitive to experimental conditions. Here, we present a systematic review and meta-analysis evaluating the reproducibility of two widely used synthesis routes: the Turkevich method for gold nanoparticles (AuNPs) and the chemical vapor deposition (CVD) growth of MoS2. An adapted PRISMA-based protocol combined with a modified SPIDER framework was applied to assess methodological transparency, parameter reporting, and experimental consistency across the literature. More than 1,300 articles for each case study were retrieved from Scopus and Web of Science and systematically screened using structured checklists and a Python-based text classification algorithm validated against independent human reviewers. Despite the extensive literature and the widespread perception of these methods as reproducible, only a small fraction of studies rigorously addressed synthesis reproducibility. Critical experimental parameters were frequently underreported, and statistical analyses were rarely included, limiting inter-laboratory comparability and reproducibility. These findings demonstrate the value of systematic reviews and meta-analyses as tools for identifying reproducibility gaps and guiding the development of more transparent and reliable synthesis protocols in materials science.

Graphene oxide (GO) production via electrochemical exfoliation has attracted a lot of attention because it is a green, safe, and efficient technique with good quality and greater scalability compared to the conventional synthesis routes. In this study, we present the development of a low-cost (ca. US$50), automated electrochemical reactor for the GO synthesis via electrochemical exfoliation of graphite. The system is based on an Arduino-controlled reactor capable of modulating key synthesis parameters, including voltage levels, duration, and the number of cycles, enabling precise process control. A 24-1 factorial design was employed to investigate the influence of process variables-particularly the electrolyte concentration, voltage magnitude, electrolysis time, and number of voltage cycles-on the structural, morphological, and colloidal properties of GO. The results demonstrate that optimizing the electrolyte concentration and the reaction time flakes with uniform size distribution (11.38 +/- 0.48 mu m) were obtained. Increasing the number of cycles enhances exfoliation efficiency, yielding larger (ca. 35 mu m) and thinner (3-6 nm) flakes with higher oxidation degrees and improved colloidal stability, as evidenced by zeta potential measurements reaching-49 mV. Temperature monitoring revealed that the cycling strategy helps lower the reaction temperature by 5 degrees C, which promotes more controlled oxidation and exfoliation of graphite. This work highlights a versatile and scalable approach to GO production with tunable properties, offering an environmentally friendly and reproducible alternative to conventional chemical oxidation methods.

Molybdenum carbides have emerged as promising catalysts for the hydrogen evolution reaction (HER). While numerous studies have investigated synthesis methods, structural properties, and their application, the understanding of their local electrochemical behavior and the correlation between particle size and activity remains elusive. This study addresses this gap by carrying out a comprehensive investigation of the HER activity of well-defined morphologies and sizes of alpha-Mo2C nanoplates, grown via chemical vapor deposition. Scanning electrochemical cell microscopy (SECCM) is employed for high-resolution HER mapping on flakes with dimensions ranging from 1 mu m to 40 mu m in lateral size, using SECCM capillaries with approximate to 130 nm tip diameter. Our findings reveal a significant variability in the HER activity at the subparticle level, suggesting that the heterogeneous activity observed in pristine flakes larger than 10 mu m is due to an addition of effects caused by the long-term growth, such as step-edge formation, Mo2C oxidation, and the presence of residual graphene. This study underscores the importance of local characterization of individual Mo2C nanoplates, shedding light on the impact of size-dependence on the HER activity.

The development of graphene oxide (GO)-based nanofluids presents a promising strategy for enhanced oil recovery (EOR), given GO's potential to alter rock wettability and interact with oil and reservoir surfaces. This study explores the synthesis, functionalization, and application of GO nanofluids for EOR. GO nanosheets were prepared with varying oxidation levels using the Hummers method and functionalized with anionic or cationic surfactants and hyperbranched polyglycerol (HPG) to improve dispersion stability. Stability in water and brine with controlled salinity was assessed via zeta potential measurements. Contact angle analyses evaluated wettability changes on aged calcite and glass surfaces. Raman spectroscopy and atomic force microscopy provided insights into the nanofluid-rock interaction mechanisms. Oil displacement tests were performed in porous media packed with limestone and sandstone. Results showed that GO nanofluids significantly enhanced oil recovery over conventional methods, particularly when modified with HPG and dispersed in sulfate-rich, controlled-salinity water. The best system recovered 19% of the residual oil from limestone, highlighting the importance of nanofluid composition and stability for optimizing EOR performance. These findings suggest that tailored GO-based nanofluids hold substantial potential for improving oil recovery in challenging reservoir conditions.

Redox-exfoliated layered transition metal dichalcogenides (LTMDs) find many applications in nonlinear optics, displays, and electronics. The investigated redox LTMD suspensions in this work were characterized optically and found to be highly stable due to surface anionic polyoxometalates (POMs), which maintained the separation between sheets by Coulombic repulsion. However, exposure of the uniform suspensions of LTMDs to an electric field led to agglomeration of the TMDs into clumps of the material in a nearly transparent solvent. This was attributed to the electrochemical reduction of the surface anionic POMs. The electrochemical stability of the redox-exfoliated ACN-MoS2 samples was also investigated by cyclic voltammetric measurements, which confirmed the POM reduction process. This study highlights that the stability of the LTMD/POM system can be compromised by the application of a low-intensity electric field and has bearings on its reliability in optoelectronic devices.

Photonic biosensors based on optical waveguides are at the forefront of biosensing technology, offering exceptional sensitivity and robustness. This study presents a proof-of-concept for detecting Brucella abortus antibodies in bovine serum using He-Ne laser-excited integrated optical waveguides. The antigen-antibody interactions in positive samples resulted in agglutination, forming scattering spots on the light-coupled waveguide, while no such spots were observed in negative samples. These spots were imaged over time using a microscope-coupled camera, generating 718 images that were processed to create a dataset for an artificial neural network (ANN). The ANN accurately distinguished between positive and negative samples, achieving 98.6 % accuracy, 98.7 % precision, and 98.7 % recall, with only a 1.4 % loss. This method detected bacterial antibodies in real animal samples within 20 min, using just 100 mu L of reagents without requiring prior waveguide surface modification for antigen immobilization. Combining light scattering-based sensing protocols in photonic waveguides with machine learning tools offers a promising pathway for revolutionizing infectious disease diagnostics.

Finding strategies to enhance catalysts' electrochemical activity is based on controlling the material design. Bidimensional materials (2DM) such as MoS2 are explored as catalysts for the hydrogen evolution reaction (HER). A comprehensive study of the effects of doping 2D materials with transition metals based on theoretical predictions in tandem with experimental investigation correlates the doping type to the changes in the electronic and electrochemical activity. Localized electrochemical maps obtained by scanning electrochemical cell microscopy (SECCM) reveal that Ti-doping induces a heterogeneous increase in 2H-MoS2 basal plane electrochemical activity, while Ni-doping induces a homogeneous decrease. Additionally, Kelvin probe microscopy provides insight into Ti-doping, showcasing a decline in the 2H-MoS2 work function, therefore confirming the predictions from density functional theory simulations. In essence, the findings underscore the potential of transition metal coordination on the 2H-MoS2 surface as an attractive method for locally doping 2D materials with minimal damage to the crystalline lattice, consequently enhancing the electrochemical activity on the material's basal plane. Theoretical studies indicate the designing of functionalized MoS2 as electrocatalysts for energy conversion. The doping method tailors the electrochemical activity for the hydrogen evolution reaction visualized by scanning electrochemical cell microscopy. Moreover, localized measurement of the potential of zero charges and Kelvin probe microscopy support the findings on the impact of different transition metal-functionalization on work function and electrochemical activity of MoS2. image

Enhanced oil recovery (EOR) techniques are crucial for maximizing the extraction of residual oil from mature reservoirs. This review explores the latest advancements in surfactant carriers for EOR, focusing on their mechanisms, challenges, and opportunities. We delve into the role of inorganic nanoparticles, carbon materials, polymers and polymeric surfactants, and supramolecular systems, highlighting their interactions with reservoir rocks and their potential to improve oil recovery rates. The discussion includes the formulation and behavior of nanofluids, the impact of surfactant adsorption on different rock types, and innovative approaches using environmentally friendly materials. Notably, the use of metal oxide nanoparticles, carbon nanotubes, graphene derivatives, and polymeric surfacants and the development of supramolecular complexes for managing surfacant delivery are examined. We address the need for further research to optimize these technologies and overcome current limitations, emphasizing the importance of sustainable and economically viable EOR methods. This review aims to provide a comprehensive understanding of the emerging trends and future directions in surfactant carriers for EOR.

Understanding electrode-analyte interactions at the atomic level is vital for improving analytical techniques, yet the complexity of these interactions poses a significant challenge for refinement. In this study, we investigate the detection of transition metals using Bi film electrodes, combining Density Functional Theory (DFT) simulations with experimental Anodic Stripping Voltammetry (ASV). Our experiments focus on the electrodeposition and detection of Zn2+, Cd2+, and Pb2+ using Bi-modified carbon electrodes. The ASV experiments reveal a notably higher sensitivity for Pb2+ detection compared to Zn2+ and Cd2+, whether evaluated individually or simultaneously. DFT calculations demonstrate that the higher adsorption energy of Pb on the Bi surface promotes a uniform distribution of Pb atoms, resulting in a homogeneous phase. Conversely, Cd and Zn tend to present lower adsorption energies and form metallic clusters, leading to phase segregation. The correlation between theoretical and experimental data suggests that a more uniform deposition of Pb on the electrode surface facilitates a regular sweep in the redissolution step, achieving a detection limit as low as 0.062 nM for Pb. This synergistic approach not only enhances our understanding of electrode-analyte interactions but also provides valuable insights for optimizing electrode materials and detection methodologies in analytical chemistry.

This study investigates the scope of application of a recently designed inversion methodology that is capable of obtaining structural information about disordered systems through the analysis of their conductivity response signals. Here we demonstrate that inversion tools of this type are capable of sensing the presence of disorderly distributed defects and impurities even in the case where the scattering properties of the device are only weakly affected. This is done by inverting the DC conductivity response of monolayered MoS2 films containing a minute amount of AuCl3 coordinated complexes. Remarkably, we have successfully extracted detailed information about the concentration of AuCl3 by decoding its signatures on the transport features of simulated devices. In addition to the case of theoretically generated Hamiltonians, we have also carried out a full inversion procedure from experimentally measured signals of similar structures. Based on experimental input signals of MoS2 with naturally occurring vacancies, we were able to quantify the vacancy concentration contained in the samples, which indicates that the inversion methodology has experimental applicability as long as the input signal is able to resolve the characteristic contributions of the type of disorder in question. Being able to handle more complex, realistic scenarios unlocks the method's applicability for designing and engineering even more elaborate materials.

This study investigates the scope of application of a recently designed inversion methodology that is capable of obtaining structural information about disordered systems through the analysis of their conductivity response signals. Here we demonstrate that inversion tools of this type are capable of sensing the presence of disorderly distributed defects and impurities even in the case where the scattering properties of the device are only weakly affected. This is done by inverting the DC conductivity response of monolayered MoS2films containing a minute amount of AuCl3coordinated complexes. Remarkably, we have successfully extracted detailed information about the concentration of AuCl3by decoding its signatures on the transport features of simulated devices. In addition to the case of theoretically generated Hamiltonians, we have also carried out a full inversion procedure from experimentally measured signals of similar structures. Based on experimental input signals of MoS2with naturally occurring vacancies, we were able to quantify the vacancy concentration contained in the samples, which indicates that the inversion methodology has experimental applicability as long as the input signal is able to resolve the characteristic contributions of the type of disorder in question. Being able to handle more complex, realistic scenarios unlocks the method's applicability for designing and engineering even more elaborate materials.

Biopolymers, serving as Enhanced Oil Recovery (EOR) agents, are posing challenges and opportunities within the oil industry, particularly in demanding operational conditions. The assessment of trimethyl chitosan (TMC) and its hydrophobized derivative with myristoyl chloride (TMC-C14) becomes crucial in these rigorous scenarios, presenting a significant challenge for polymer flooding. The study subjected TMC and TMC-C14 to comprehensive evaluations as EOR agents, employing contact angle measurements, interfacial tension tests using the Drop Shape Analyzer (DSA), and core flood tests under conditions of 60 degrees C, 1000 psi, and elevated salinity. Relative permeabilities were deduced from the results, while spontaneous imbibition tests provided insights into rock wettability. Amott cell tests underscored that both TMC and TMC-C14 induced accelerated spontaneous oil production within a span of 30 days. Notably, TMC-C14 exhibited superior interfacial activity compared to TMC, attributed to its hydrophobic segments. The impact on rock wettability was distinct: TMC shifted it towards water-wet, while TMC-C14 induced a neutral-wet condition. This transformation was corroborated by contact angle measurements, imbibition tests, and relative permeability curves. Capillary forces, computed from DSA data and spontaneous imbibition tests, further validated the wettability-altering tendencies of the chitosan derivatives on the rock. In core flooding tests and relative permeability curves, TMC demonstrated a notable improvement in the recovery factor (RF) compared to seawater. Specifically, RFTMC achieved 69%, surpassing RFbrine at 49%, affirming that the primary mechanism of action for chitosan derivatives lies in their ability to modify rock wettability. This study shows the potential of TMC and TMC-C14 as effective EOR agents, shedding light on their interfacial activities, impact on rock wettability, and enhanced recovery factors in challenging operational conditions.

Bovine brucellosis is an infectious illness caused mainly by Brucella abortus that may affect domestic and wild animals. Accurate and fast diagnosis is critical for disease control and eradication. Thus, we have identified Brucella abortus antibodies in bovine serum by exploring the agglutination process that is carried out when positive samples are mixed with the antigen. In this case, when placed above the on-chip integrated waveguide, the reaction led to scattering spots that indicated the positive serum. The monitoring was performed through optical images over time and analyzed by artificial neural network. Classification models were able to differentiate the positive from the negative samples with 81.25% accuracy. This work may represent a breakthrough for the diagnosis of other infectious diseases.

Paper-based Analytical Devices (PADs) have changed the paradigm of chemical sensor development in point-of-need detection and diagnostics. Instead of the univariate method, the potentiality to extract a large quantity of information based on chemometrics techniques can enhance the well-known potential of the PADs to detect multiple analytes or discriminate and classify samples. The proposed article reviews recent progress on PADs using different analytical techniques to extract information (Colorimetric, Electrochemical, SERS, and Fluorescence) and their combination with chemometrics, demonstrating their combined advantages to generate powerful analytical platforms. The pioneering studies that significantly impacted the field of paper-based sensing are critically reviewed, along with future challenges to overcome.

Niobium disulfide is a layered transition metal dichalcogenide that is being exploited as a two-dimensional material. Although it is a superconductor at low temperatures and demonstrates great potential to be applied as a catalyst or co-catalyst in hydrogen evolution reactions, only a few reports have demonstrated the synthesis of a few-layer NbS2. However, before applications can be pursued, it is essential to understand the main characteristics of the obtained material and its stability under an atmospheric environment. In this work, we conducted a thorough characterization of redox-exfoliated NbS2 nanoflakes regarding their structure and stability in an oxygen-rich environment. Structural, morphological, and spectroscopic characterization demonstrated different fingerprints associated with distinct oxidation processes. This led us to identify oxide species and analyse the stability of the redox exfoliated NbS2 nanosheets in air, suggesting the most likely reaction pathways during the NbS2 interaction with oxygen, which agrees with our density-functional theory results. The mastery over the stability of layered materials is of paramount importance to target future applications, mainly because the electronic properties of these materials are strongly affected by an oxidizing environment.

Light is being vastly explored towards favoring the advancement of technology and the improvement of the life quality of the population. Photonic materials that can manipulate light in a nanometric scale have become very competitive for the construction of chemical and bio sensors, mainly because they can be more sensitive, specific, and of a lower cost. Considering the serious health crisis experienced worldwide due to COVID-19, the importance of research in this field has become even clearer and greater. In this article, sensing platforms based on the exciting and promising plasmonic materials is broadly addressed. The sections covered here seek not just to introduce the theoretical concepts and state-of-the-art techniques, but also highlight the achieved advances and inspire future research on this rich and promising area.

Global consumption of petroleum is increasing, and there is a significant prospect of a further surge in oil demand in the upcoming years. An alternative to meet this energy need is the increase of oil recovery in new or mature oils reservoirs. Research in the advanced oil recovery sector, specifically focusing on surfactant injection, has shown promising results and the potential to contribute to global oil production. However, the high costs associated with surfactant injection, attributed to losses through adsorption on the rock, is a major concern. Surfactants play a crucial role in reducing interfacial tension and modifying wettability, crucial parameters to increase the oil recovery factor. To mitigate the issues of surfactant injection, the utilization of surfactant carriers has proven effective. This comprehensive article reviews four major classes of surfactant-carrying materials, namely inorganic nanoparticles, carbon materials, polymers, and supramolecular systems, with the objective of minimizing surfactant loss in enhanced oil recovery. The review identifies challenges, proposes alternative approaches, and explores opportunities for applying different surfactant nanocarrires systems for EOR. Furthermore, it discusses the classification, mechanisms of action, and synergistic effects between carrier-surfactant systems, addressing the importance of systematically grouping these systems for the advancement of science and technology. The review also highlights the permeation capabilities of these carrier materials through porous media, their size-based rock adsorption, and the potential synergistic effects on interfacial properties in the reservoir. By examining these aspects, innovative techniques for EOR can be developed and a deeper understanding of the subject can be achieved.