Cross-sectional Scanning Electron Microscopy Research Articles

Thickness Variation of Conductive Polymer Coatings on Si Anodes for the Improved Cycling Stability in Full Pouch Cells.

Si-dominant anodes for Li-ion batteries provide very high gravimetric and volumetric capacity but suffer from low cycling stability due to an unstable solid electrolyte interphase (SEI). In this work, we improved the cycling performance of Si/NCM pouch cells by coating the Si anodes with the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) prior to cell assembly via an electropolymerization process. The thicknesses of the PEDOT coatings could be adjusted by a facile process parameter variation. Glow-discharge optical emission spectroscopy was used to determine the coating thicknesses on the electrodes prior to the cell assembly. During electrochemical testing, improvements were observed closely linked to the PEDOT coating thickness. Specifically, thinner PEDOT coatings exhibited a higher capacity retention and lower internal resistance in the corresponding pouch cells. For the thinnest coatings, the cell lifetime was 18% higher compared to that of uncoated Si anodes. Postmortem analyses via X-ray photoelectron spectroscopy and cross-sectional scanning electron microscopy revealed a better-maintained microstructure and a chemically different SEI for the PEDOT-coated anodes.

Exploring microstructural evolution, nitrogen depth profile, and dry wear performance in 31CrMoV9 steel through combined severe shot peening and plasma nitriding

The present study investigates the influence of severe shot peening (SSP) on the plasma nitriding behavior and sliding wear performance of 31CrMoV9 steel. Initially, the steel was austenitized at 880 °C, followed by oil quenching, and tempering at 520 °C for one hour. These samples were shot peened using high-carbon steel shots, resulting in an enhancement in surface hardness up to 447 HV, gradually converging to the initial martensitic hardness after 140 µm depth. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) scrutinized the initial and surface treated martensitic samples. Afterward, the plasma nitriding treatments were carried out at temperatures of 400 °C, 450 °C, and 500 °C for 8 hours in a 30% N2 + 70% H2 atmosphere and 300 Pa pressure. Microhardness testing, SEM, XRD, and glow-discharge optical emission spectroscopy (GDOES) evaluated both plasma nitrided (PN) and severe shot peened/plasma nitrided (SSP-PN) samples. Cross-sectional SEM observations revealed compound layer thicknesses of approximately 2.8 µm, 5.0 µm, and 6.3 µm for PN samples at 400 °C, 450 °C, and 500 °C, respectively. SSP-PN samples exhibited a substantial increase — roughly 71%, 44%, and 33% increase, respectively, compared to PN samples. GDOES analysis supported this trend and indicated enhanced nitrogen diffusion depth, particularly evident in SSP-PN samples at consistent temperatures. The XRD results showed the stability of Fe4N, Fe2–3N, and CrN phases at all three nitriding temperatures. Furthermore, the intensity of these phases increases with temperature and is augmented by the application of the SSP. Microhardness measurements indicated hardness escalation: from 775 HV to 980 HV at 400 °C, 932 HV to 1096 HV at 450 °C, and 1011 HV to 1205 HV at 500 °C due to SSP. Finally, the wear performance was investigated between the non-nitrided, SSP, PN, SSP-PN, samples. Initially, SSP led to decreased wear performance up to 500 m, followed by improved behavior up to 1500 m. At 400 °C, the SSP-PN sample exhibited a 12% lower wear rate than PN. At 450 °C and 1500 m, the SSP-PN sample displayed a 24% reduction, while at 500 °C, it showed a 27% reduction compared to PN. SEM observations indicated abrasion as the primary wear mechanism across all samples. The overall results indicated a significant similarity in the nitrogen depth profile, hardness depth, and wear performance between the SSP-PN sample at 450 °C and the PN sample at 500 °C. The fact suggested a potential reduction of approximately 50 °C in the typical plasma nitriding temperature for 31CrMoV9 steel as a result of the SSP process.

Optical response and temperature shielding coatings using tri-layer structure composed of titania/silica/titania

The fabrication of metamaterials with inspiration from nature paved the door for the creation of revolutionary passive and active devices. Butterfly wings are one of them, and their multilayered structure motivated nanotechnologists, physicists, and other optoelectronic and photonic engineers to develop photonic crystals, dielectric reflectors, and Bragg reflectors for use in visible light communication, solar cells, and other photonic and optoelectronic applications. We report the sol–gel spin coating of a dielectric reflector on the glass substrate, an optical passive component consisting of titania and silica thin films for infrared radiation reflection. Individual thin films of titania and silica on glass substrates were studied using an x-ray diffractometer, which indicated anatase of titania and the amorphous nature of silica at a Bragg angle of 25° with a sharp and wide peak, respectively. The multilayer structure of titania/silica/titania was further investigated using Fourier transform infrared spectroscopy, which revealed the presence of Ti–O–Ti and Si–O–Si vibrational bonds at wavenumbers 546 and 973 cm−1, respectively, as well as the presence of Ti–O–Si vibrational bond at 1100 cm−1. The thickness of the multilayer titania/silica/titania was measured using a cross-sectional field emission scanning electron microscope (FESEM) and found to be 160/240/160 nm, respectively. Finally, reflection investigation on the multilayer structure using ultraviolet–visible–near-infrared spectroscopy validated the reflection of the infrared spectrum area by around 70% and showed to be beneficial for temperature shielding applications on glass furnishings.

Improved uniformity of atomic-layer-deposited HfO2 film along the length of glass monocapillary with high length-diameter ratio

It has been a difficult to deposit a uniform film on the inner surface of monocapillary due to the high length-diameter ratio. Atomic layer deposition (ALD) shows great potential to coat conformal film on complex substrates. However, it is still a challenge to coat uniform film along the length of the capillary for regular deposition parameters. In this work, HfO2 film was deposited inside monocapillary via ALD. The film uniformity along the monocapillary was investigated by cross-section scanning electron microscope (SEM) images and the bond states of one of the HfO2 films were studied via X-ray photoelectron spectroscopy (XPS). Using the routine deposition parameters, the gas flowing through the monocapillary is controlled to be small, large and medium qualitatively by covering some of the inlets or outlets, changing the connection between monocapillary and outlets simply. SEM results demonstrate that smooth HfO2 film with uniform thickness can be acquired on the inner surface of monocapillary with length-diameter ratio 200 (length 10 cm and inner diameter 0.5 mm). XPS results show that Hf hydroxide is generated when the gas flowing through the monocapillary is large.

Bipolar pulse anodizing of aluminum: Understanding the fundamental electrochemical mechanisms

Anodic aluminum oxides (AAO) with attractive morphological properties might be obtained by pulse anodizing via controlled hydrogen release during the cathodic step. In order to enhance such processes currently relying on empirical studies, the present paper aims to investigate basically the AAO formation on pure aluminum in sulfuric acid during a bipolar pulse anodizing process, by combining in situ electrochemical measurements and cross-section scanning electron microscopy. Results show that the hydrogen evolution at the metal/oxide interface during the cathodic step can be easily managed by current control. Actually, under cathodic galvanostatic conditions, successive mechanisms occur, depending on both the duration and the current density: a first stage corresponds to the reorganization of the electric charges and the migration of H+ through the AAO barrier layer and is followed by hydrogen evolution at the metal/oxide interface, which induces the formation of local or more extended defects at the metal/oxide interface until the detachment of the AAO layer.

Multi-layer shearing induced high orientation of graphene oxide sheets towards high-performance macrostructures

The orientation of graphene nanosheets in microstructures is directly related to the mechanical properties and thermal conductivity of graphene-based macrostructures. However, efficient and scalable modulation of the orientation of 2D graphene nanosheets remains challenging. Herein, a simple and effective approach was proposed by introducing a multi-layer shearing field in thick graphene oxide (GO) gel coatings to improve the total orientation of GO films. Hydrodynamic simulations were performed via the lattice-Boltzmann method to reveal the microscale mechanism of the flow profile in improving the orientation of GO nanosheets. The result was experimentally verified by fast Fourier transform (FFT) of the cross-section scanning electron microscope (SEM) images of freeze-dried GO films and wide-angle X-ray scattering (WAXS) patterns of 16 various samples under different shearing line distances, velocities, and GO concentrations. The obtained GO films exhibit high orientation (Herman's orientation factor ƒ = 0.922), high strength (419.2 MPa), and high modulus (26.2 GPa), respectively, which are 1.06, 5.57, and 3.49 times higher compared to GO films prepared through the frequently used doctor blade method. The good orientation of GO is remained and further improved to the ultra-high orientation (ƒ = 0.968) after being graphitized at 3150 °C and roll pressing, and the oriented thick graphene films achieved the highest thermal conductivity (1629 W m−1 K−1 for 86 μm and 1593 W m−1 K−1 for 110 μm) compared to other graphene films mentioned in the literature as having a similar thickness. The multi-layered shearing strategy represents a facile technology for assembling two-dimensional (2D) nanoscale building blocks into a macroscopic structure with good orientation and high performance.

Pressure Indicator Composite Films via Compressive Deformation of a Translucent Matrix Containing a Contrasting Filler.

A neglected mechanism for pressure-responsive color change is demonstrated using cellulose acetate composites prepared by direct (solvent) immersion annealing (DIA), with different loadings of activated charcoal filler. Namely, compressive plastic deformation of the translucent cellulose acetate leads to a decrease in the optical path length and a concomitant increase in the visibility of the opaque contrasting filler. Composites bearing 1-7 wt% activated charcoal exhibited a linear relationship between applied pressure and resulting pressure mark brightness in the range of 12-56 MPa. Comparison of pressure mark patterns with cross-sectional scanning electron microscopy (SEM) supports the importance of the porous morphology arising from DIA for the tuning of the pressure indicator sensitivity. A simple ball drop test is used to illustrate the robustness and utility of these indicators in optical impact assessment.

One-step sputtering of MoSSe metastable phase as thin film and predicted thermodynamic stability by computational methods

We present the fabrication of a MoS2−xSex thin film from a co-sputtering process using MoS2 and MoSe2 commercial targets with 99.9% purity. The sputtering of the MoS2 and MoSe2 was carried out using a straight and low-cost magnetron radio frequency sputtering recipe to achieve a MoS2−xSex phase with x = 1 and sharp interface formation as confirmed by Raman spectroscopy, time-of-flight secondary ion mass spectroscopy, and cross-sectional scanning electron microscopy. The sulfur and selenium atoms prefer to distribute randomly at the octahedral geometry of molybdenum inside the MoS2−xSex thin film, indicated by a blue shift in the A1g and E1g vibrational modes at 355 cm−1 and 255 cm−1, respectively. This work is complemented by computing the thermodynamic stability of a MoS2−xSex phase whereby density functional theory up to a maximum selenium concentration of 33.33 at.% in both a Janus-like and random distribution. Although the Janus-like and the random structures are in the same metastable state, the Janus-like structure is hindered by an energy barrier below selenium concentrations of 8 at.%. This research highlights the potential of transition metal dichalcogenides in mixed phases and the need for further exploration employing low-energy, large-scale methods to improve the materials’ fabrication and target latent applications of such structures.

Formation and evolution of secondary phases and surface altered layers during borosilicate glass corrosion in pore water

The emergent secondary phases and surface altered layer (SAL) during the aqueous corrosion of borosilicate glass have a great impact on its chemical durability. However, the formation and evolution of these structures are still unclear. Here, by studying the borosilicate glass altered at 90 °C in pore water, the water in pore space between glass powders, the formation of secondary phases could follow two ways: 1. the consumption of aqueous ions forms analcime, zeolite, calcium silicate and barite at the surface of glass; 2. the reorganization of silica aggregates leads to smectite within the SAL. Small-angle X-ray scattering and cross-sectional scanning electron microscopy results show that the release of soluble elements and the formation of smectite within the SAL significantly increase the porosity of SAL. Furthermore, the layer containing smectite reorganizes inwardly and the crystallinity of smectite is gradually increased over time. The observations of transmission electron microscopy reveal that the dissolution of glass potentially goes through an interface-coupled dissolution-reprecipitation process.

Cone array formation on Si surfaces by low-energy He plasma irradiation with magnetron sputtering pre-deposited Ta

Low-energy ion beam irradiation, combined with the introduction of impurities, presents a promising approach for nanopatterning silicon (Si) surfaces. In this research, we investigate the surface evolution of Si (100) surfaces irradiated by 75 eV helium (He) plasma, in the presence of tantalum (Ta), traditionally regarded as an impurity incapable of initiating pattern formation, as evidenced in prior studies. The Ta impurities are pre-deposited onto the Si surfaces using the magnetron sputtering method, which offers a more controlled and quantifiable approach compared with the conventional co-deposition route. After irradiation at 800 K, dense cone arrays are produced on the Si surface. The growth of the cones is explored for fluence spanning (1–10) × 1025 m−2. The cross-sectional scanning electron microscope images indicate that the cone lengths and base width are well characterized by t1/2 dependence. The kinetics of the cone growth follow Fick’s law, characterized by an effective diffusive mechanism with the coefficients of diffusion: D = 6.49 ± 0.83 × 10−16 m−2 s−1. Transmission electron microscope observations reveal that the cone has distinct inner and outer parts with different microstructures and a clear interface. The growth mechanism of these cones is elucidated as a composite process involving preferential sputtering, the destabilizing influence of He bubbles, and the migration of adatoms.

Wurster Technology-Assisted Step-by-Step Engineering of Multi-layered Pellets (Sprinkles): Microscopy, Micro-CT, and e-Tongue-Based Analysis.

The advancement in the formulation and characterization techniques have paved the path for development of new as well as modification of existing dosage forms. The present work explores the role of micro-computed tomography (micro-CT) as advanced characterization technique for multi-layered-coated pellets to ascertain the quality of coated pellets. The work further explored in-house e-tongue technique for understanding palatability of formulation in early stages of development thus by reducing clinical taste evaluation time. The developed multi-layered-coated pellets were characterized using microscopy (optical and electron microscopy). The obtained results demonstrated formation of spherical-shaped pellets with uniform coating. The uniform coating was further confirmed by results obtained from scanning electron microscopy (SEM) and cross-sectional SEM analysis, which showed visible difference in pellet surface before and after multi-layered coating. The micro-CT results confirmed the visible demarcation of layers (drug and polymer, i.e., hydroxypropyl methylcellulose (HPMC) and eudragit (EPO)) along with uniform thickness of various layering. The dissolution study of developed pellets suggested the role of layering EPO on drug release from pellets. The e-tongue analysis proved to be an excellent tool for early prediction of taste masking of drug via multi-layered pellets and can serve as potential platform for taste masking with high specificity. The overall results suggest the suitability of developed multi-layered platform as efficient dosage form (sprinkle) in pediatric/geriatric product development.

Modeling the Thermal-Compression Flip-Chip Process by Finite Element Analysis

Abstract For the first time, finite element analysis (FEA) is applied to the thermal-compression flip-chip process in micro-electronics. By adding the bump height nonuniformity and the morphology variance, a common basal line is established. Although the experiment confirms the rate dependence of indium, an approximation is made to derive the material properties in FEA. The relative standard deviation (RSD) of deformation between the FEA model and the reality is around 1% when predicting the misaligned flip-chip specimen. Besides, the modeled bump characteristic with misalignment coincides with the cross-sectional scanning electron microscope (SEM) picture. The model could be served as a powerful tool to guide the manufacturing process.

Characterization and In Vitro Behavior of PEO Coated Mg Modified with Antibacterial Ag(I) and Cu(II) Complexes.

The use of Mg-based biomaterials with a number of their advantageous properties are overshadowed by uncontrollable metal corrosion. Moreover, the use of implants goes alongside with the threat of pathogens-associated complications. In this study, PEO coated Mg biomaterial loaded with antibacterial Ag(I) and Cu(II) complexes is produced and tested to meet both appropriate protective characteristics as well as sufficient level of antibacterial activity. To achieve a suitable level of anticorrosion protection phosphate and fluoride-phosphate electrolytes are used in the PEO process. Investigation of the surface thickness and morphology done by means of cross-section analysis and scanning electron microscopy (SEM), as well as electrochemical impedance spectroscopy (EIS) assay show precedence of the fluoride containing PEO coating and make it the material of choice for further modification with Ag(I) and Cu(II) complexes. The presence of the complexes on the PEO surface is confirmed by energy dispersive X-ray spectroscopy (EDX). X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and glow discharge optical emission spectroscopy (GDOES) are used to estimate the complexes' chemical state and depth of penetration in the coating surface. Based on the results of antibacterial assay, the modified coatings are found to be active against both Gram-positive and Gram-negative bacteria.

Lithium plating induced volume expansion overshoot of lithium-ion batteries: Experimental analysis and modeling

Under extreme charging conditions such as fast-charging and low-temperature charging, lithium-ion batteries suffer from volume expansion overshoot, i.e. battery volume expansion rapidly exceeds the maximal value during normal charging and falls to a steady value. Battery volume expansion overshoot can result in severe stress within module/pack and threaten battery safety. Though lithium plating has been reported as a possible cause of battery expansion overshoot, the quantitative relationship between the expansion overshoot and lithium plating remains elusive. In this paper, the correlation between the volume expansion overshoot and the lithium plating is firstly demonstrated through a series of non-destructive and post-mortem analyses. Differential analyses of the battery voltage and expansion ratio profiles demonstrate the concurrence of the expansion overshoot and the lithium plating, which is further validated through cross-section scanning electron microscopy. Furthermore, a battery volume expansion model is established to reproduce the expansion overshoot during charging process, for the first time. The simulation results further confirm that lithium plating is the root cause of the expansion overshoot. Based on the model, a linear relationship between the volume expansion overshoot and the amount of plated lithium is derived, which can be applied for quantitative detection of lithium plating in practical application.

Boosted hydrophobic properties of leather surfaces by atmospheric pressure plasma brush reactor

In this article, we demonstrate the application of an atmospheric pressure plasma brush (APPB) reactor for improving the hydrophobic properties of leather surfaces treated with organo-silane precursors for the first time. A comprehensive investigation was conducted to analyze the influence of various process parameters, including plasma access current, treatment duration, nozzle height, and gas flow rate, on the observed outcomes effects. The dispersion of active particles in the APPB was scrutinized using an Optical Emission Spectrometer (OES), while the underlying reaction mechanism was elucidated through the integration of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), cross-sectional Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) analysis. The findings unveiled that the resultant polysiloxane polymers bestowed a remarkable degree of hydrophobicity upon the leather, persisting steadfastly even following a 90-day aging period (WCA >140°). This APPB treatment combined with organosilane strategy may open a new design avenue for the development of surface treatments for intricate and temperature-sensitive substrates materials.

Sol-gel Spin Coated Hydrophilic Composite Titania-Silica Coatings on the Glass Substrates for Automotive Applications

The pollutants from the environment can also degrade the surface of the glass, which result in loss of transmittance of the glass surface. This necessitates the formation of a dedicated crew for the correct maintenance of glass furniture, notably in the Middle East. In this paper, we describe sol-gel spin coating of titania thin films on glass substrates, which may function as a hydrophilic coating by spreading water molecules across the substrate and removing pollutants and other dust particles, hence eliminating the need for maintenance and wipers. The fabricated coating was tested with X-ray diffractogram (XRD) and evidenced anatase nature of titania and amorphous nature of silica at Bragg angle 25° in the coating. Fourier transform infrared spectroscopy (FTIR) investigations endorsed Ti-O-Ti and Si-O-Si functional linkages at wavenumbers 551, and 957 cm-1 demonstrating the presence of titania and silica in the as-developed coating. Cross sectional field emission scanning electron microscopy (FESEM) investigation evidenced the formation of composite titania-silica film on the glass substrate with a thickness about 36 nm. The coating transmittance was studied by ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopy and found 95% transmittance in the visible region. Moreover, wetting study utilizing the sessile drop technique yielded a 74° contact angle when the water droplets were interacted.

Enhanced photoelectrochemical performance of quantum dot-sensitized solar cell using Cu2+ co-doped CdS and CdSe nanoscrystals.

Today, nanoscrystals are researched and developed very quickly because of their advantages in many areas of life. One of the potential applications is quantum dot-sensitized solar cells. This is a green, clean, environmentally friendly cell, and has been studied by scientists since 2000. In this study, we fabricated photoanodes with Cu2+ ions co-doped into cadmium sulfide (CdS) and cadmium selenide (CdSe) nanoscrystals by successive ionic layer adsorption and reaction, and chemical bath deposition methods to improve absorption spectral intensity of films. The results showed that the absorption intensity increased by eight times compared with our previous results on Cu2+ ions doped with CdSe nanoscrystals. The CdS:Cu2+ film is optimized at 2% doping, the efficiency is 4.6819%, and the current density is 27.3501 mA.cm-2, which is higher when compared with the Cu2+ ion only doped into the CdSe quantum dot (19.915 mA.cm-2). In addition, the composition of the photoanode was determined by surface and cross-sectional field-emission scanning electron microscope images, and the structure of the film was determined by X-ray diffraction, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy. Finally, the film's optical properties were studied by ultraviolet-visible spectroscopy, photoluminescence spectroscopy and electrochemical properties by electrochemical impedance spectroscopy. The results obtained have been discussed and presented in great detail.

Fabrication and Characterization of LiNi1/3Mn1/3Co1/3O2/Li0.6La0.4TiO3/Li4Ti5O12 Full Cell All-Solid-State Thin Film Li-Ion Batteries for Energy Applications

Recent days, natural calamities caused by the global warming and climate changes are major concern for the entire globe and there is a pressing need to address such issues to save the mankind from further havoc and devastation. To reduce the carbon emission, countries are shifting dramatically towards renewable sources for their energy needs for their day-to-day life. Li ion batteries are in the forefront of the battle towards the sustainable growth and development due to their high energy density and renewable in nature. In the present case, we report on development of thin film based all-solid-state batteries (ASSB) for energy applications. LiNi1/3Mn1/3Co1/3O2 (NMC), Li0.6La0.4TiO3 (LLTO) and Li4Ti5O12 (LTO) materials are employed as a cathode, solid electrolyte and anode layers for fabricating a full cell all-solid-state thin film batteries. All the layers are fabricated employing RF sputtering technique. Before fabricating the full cell, individual layers are fabricated and their electrochemical and/or ionic conductivity properties are explored. Li0.6La0.4TiO3 solid electrolyte thin films are seen to exhibit room temperature in-plane ionic conductivity in the order of 10-3 S/cm. NMC thin film with the thickness of 100 nm exhibits specific capacity of 91 µAh/cm2 and the redox peaks at 3.8 V and 3.5 V. LTO anode thin films shows the specific capacity close to 100 mAh/cm2and the redox peaks around 1.5 V. XRD pattern of NMC/LLTO/LTO full cell shows the diffraction peaks corresponding to all the three layers. Cross-sectional scanning electron microscope (SEM) image indicates the uniform coating and presence of all the layers. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) along with the energy dispersive X-ray is employed to image the cross-sectional details and the elements present in each layer of the full cell all-solid-state thin film battery. Impedance spectroscopy was employed to calculate the total conductivity of the fabricated full cell. Obtained results indicates that the full cell NMC/LLTO/LTO thin film batteries can be fabricated employing a sputtering technique for the energy applications. Figure 1

Optical emission spectroscopy of vanadium cathodic arc plasma at different nitrogen pressure

Optical emission spectroscopy studies of vanadium plasma in a cathodic-arc discharge in a nitrogen atmosphere have been carried out. Spectral lines of neutral atoms and ions of the cathode material V, V1+, and V2+, and nitrogen N2 and N2+ were observed in the discharge plasma. Analysis and comparison of the intensity of vanadium and nitrogen spectral lines as a function of nitrogen pressure showed that in vacuum excited ions V2+ and V+ are registered, with increasing pressure, the lines V+*, N2*, and N2+* are observed, and at pressures above 0.5 Pa, the neutral vanadium lines are additionally registered. The electron temperature of Te decreases from 5.9 to 3–4 eV with increasing pressure. Studies of cross-sectional scanning electron microscopy images of VN coatings deposited at different nitrogen pressures have shown that a dense, homogeneous, fine-grained microstructure is formed in the coating when the number of neutral V in the plasma is low, while in the presence of a large number of neutrals, the coating structure changes to a dense structure with columnar growth.

Importance of Directed Water Removal: Intruding Microporous Layer Material into the Gas Diffusion Layer Substrate

Proton exchange membrane fuel cells (PEMFC) are an essential component of net zero emission scenarios by the International Energy Agency (IEA), most prominent in the heavy-duty transportation sector.[1-2] During operation, the PEMFC is subject to different operating conditions, particularly wet conditions where liquid water removal is crucial. It was observed that a microporous layer (MPL), commonly consisting of a carbon component (e.g. carbon black, carbon fibers) and a hydrophobic binder (e.g. PTFE), placed at the interface of the catalyst layer (CL) and the gas diffusion layer substrate (GDL-S), has a large impact on the water removal properties. Among other advantages, the addition of an MPL can guide the localization of water clusters in the GDL.[3] However, if interfaces exhibit large interfacial gaps, as was demonstrated for the CL/MPL interface,[4] liquid water can accumulate in the large openings, thereby creating a mass transport barrier. Seeking to understand the importance of interfaces, which can either guide water formation or create obstacles, this study further investigates the MPL/GDL-S interface.We created an intruding MPL by pressing the MPL slurry into the GDL-S using mechanical force (further on referred to as “intruded-GDL”) and compared it to a GDL, where the MPL sits quasi on top (further on referred to as “sheet-GDL”). Figure 1a shows a cross-sectional scanning electron microscopy (SEM image) of the sheet-GDL, while Figure 1b shows an intruded-GDL. The boundaries between the MPL material and the GDL-S are marked in red. The MPL/GDL-S interface of the sheet-GDL is relatively flat, following only the surface contour of the GDL-S, while the MPL/GDL-S interface of the intruded-GDL is pressed into the GDL-S and locally penetrates deeper into the GDL-S. It is also visible that the penetration into the GDL-S is inhomogeneous. We characterized the altered morphology using SEM (see Figure 1), mercury intrusion porosimetry (MIP), and x-ray tomographic microscopy (XTM). We found that the MPL of the intruded-MPL intrudes significantly into the GDL-S and preferably fills the larger pores of the GDL-S.Both types of GDLs were subject to single-cell fuel cell testing under various operating conditions. We found that the intruding MPL poses an additional oxygen transport resistance at dry conditions compared to the sheet-GDL. Under conditions where liquid water formation can be expected, the intruded-GDL starts to have an advantage compared to the sheet-GDL. From the data obtained in this study, a delicate interplay between the additional dry transport resistance, the missing macropores that were filled with MPL material, and the guided water removal properties can be deduced. We can derive an improved water removal mechanism for the intruded-GDL as a cause of the structural changes, which can serve as a guideline to improve GDL design parameters.