Layer Of Pt Research Articles

High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer

Using a transfer printing technique, we imprint a layer of a designated near-infrared fluorescent dye BTP-eC9 onto a thin layer of Pt(II) complex, both of which are capable of self-assembly. Before integration, the Pt(II) complex layer gives intense deep-red phosphorescence maximized at ~740 nm, while the BTP-eC9 layer shows fluorescence at > 900 nm. Organic light emitting diodes fabricated under the imprinted bilayer architecture harvest most of Pt(II) complex phosphorescence, which undergoes triplet-to-singlet energy transfer to the BTP-eC9 dye, resulting in high-intensity hyperfluorescence at > 900 nm. As a result, devices achieve 925 nm emission with external quantum efficiencies of 2.24% (1.94 ± 0.18%) and maximum radiance of 39.97 W sr−1 m−2. Comprehensive morphology, spectroscopy and device analyses support the mechanism of interfacial energy transfer, which also is proved successful for BTPV-eC9 dye (1022 nm), making bright and far-reaching the prospective of hyperfluorescent OLEDs in the near-infrared region.

Photoexcited Hot Electron Catalysis in Plasmon-Resonant Grating Structures with Platinum, Nickel, and Ruthenium Coatings.

We report the electrochemical potential dependence of photocatalysis produced by hot electrons in plasmon-resonant grating structures. Here, corrugated metal surfaces with a period of 520 nm are illuminated with 785 nm wavelength laser light swept as a function of incident angle. At incident angles corresponding to plasmon-resonant excitation, we observe sharp peaks in the electrochemical photocurrent and dips in the photoreflectance consistent with the conditions under which there is wavevector matching between the incident light and the spacing between the lines in the grating. In addition to the bare plasmonic metal surface (i.e., Au), which is catalytically inert, we have measured grating structures with a thin layer of Pt, Ru, and Ni catalyst coatings. For the bare Au grating, we observe that the plasmon-resonant photocurrent remains relatively featureless over the applied potential range from -0.8 to +1.2 V vs NHE. For the Pt-coated grating, we observe a sharp peak around -0.3 V vs NHE, three times larger than the bare Au grating, and near complete suppression of the oxidation half-reaction, reflecting the reducing nature of Pt as a good hydrogen evolution reaction catalyst. The photocurrent associated with the Pt-coated grating is less noisy and produces higher photocurrents than the bare Au grating due to the faster kinetics (i.e., charge transfer) associated with the Pt-coated surface. The plasmon-resonant grating structures enable us to compare plasmon-resonant excitation with that of bulk metal interband absorption simply by rotating the polarization of the light while leaving all other parameters of the experiment fixed (i.e., wavelength, potential, electrochemical solution, sample surface, etc.). A 64X plasmon-resonant enhancement (i.e., p-to-s polarized photocurrent ratio) is observed for the Pt-coated grating compared to 28X for the bare grating. The nickel-coated grating shows an increase in the hot-electron photocurrent enhancement in both oxidation and reduction half-reactions. Similarly, Ru-coated gratings show an increase in hot-electron photocurrents in the oxidation half-reaction compared to the bare Au grating. Plasmon-resonant enhancement factors of 36X and 15X are observed in the p-to-s polarized photocurrent ratio for the Ni and Ru gratings, respectively.

Pt-modification on the thermal cycling behavior of NiCoCrAlYTa coating: A case study

A NiCoCrAlYTa coating possessing homogenous microstructure was fabricated by high velocity oxygen fuel (HVOF) technique, in which some of the coating samples were electroplated with a thin layer of Pt. After vacuum annealing, thermal cycling tests of the NiCoCrAlYTa coatings with and without Pt modification were carried out at 1050 °C till 1000 cycles. The results revealed that Pt modification has assisted to improve the stability of the coating and to develop a highly purified alumina scale, where lower oxidation rate and residual stress were achieved in the Pt-modified NiCoCrAlYTa coating.

Phase textures of metal-oxide nanocomposites self-orchestrated by atomic diffusions through precursor alloys.

Metal-oxide nanocomposites (MONs) are of pivotal importance as electrode materials, yet lack a guiding principle to tune their phase texture. Here we report that the phase texture of MONs can be tuned at the nanoscale by controlling the nanophase separation of precursor alloys. In situ transmission electron microscopy (in situ TEM) has demonstrated that a MON material of platinum (Pt) and cerium oxide (CeO2) is obtained through promoted nanophase separation of a Pt5Ce precursor alloy in an atmosphere containing oxygen (O2) and carbon monoxide (CO). The Pt-CeO2 MON material comprised an alternating stack of nanometre-thick layers of Pt and CeO2 in different phase textures ranging from lamellae to mazes, depending on the O2 fraction in the atmosphere. Mathematical simulations have demonstrated that the phase texture of MONs originates from a balance in the atomic diffusions across the alloy precursor, which is controllable by the O2 fraction, temperature, and composition of the precursor alloys.

Performance and Durability of Carbon-Free Ionomer-Free PEFC Cathode Using Pt Nanosheet Catalyst

Polymer electrolyte fuel cells (PEFCs) have been attracting attention as highly efficient power sources and have been commercialized for use in residential power plants and automobiles. However, further widespread adoption requires the development of low-platinum catalysts. Additionally, for installation in heavy duty vehicles such as large trucks, high durability at high temperatures is necessary. Pt nanosheets (Pt(ns)), consisting of several atomic layers of Pt with a flat structure, possess high mass activity and durability due to the high specific surface area and low surface energy [1]. Conventional PEFC electrodes consisting of carbon-supported platinum (Pt/C) catalyst and ionomer suffer from degradation due to dissolution/redeposition, Ostwald ripening, and agglomeration of Pt, corrosion of the carbon support, and Pt poisoning by ionomer. Therefore, using unsupported Pt(ns) for an electrode that consists of neither carbon nor ionomer is expected to eliminate the degradation factors, resulting in a highly active and durable electrode. The purpose of this study is to develop highly active and durable electrodes by using Pt(ns) and eliminating degradation factors by making them carbon-free and ionomer-free.Polycrystalline Pt(ns) was synthesized by interlayer oxidation of graphene, as described elsewhere [2]. Catalyst ink was prepared, and cathode catalyst layers were created by dropping or spraying it onto carbon paper. A membrane-electrode assembly (MEA) was made by hot-pressing the cathode catalyst layer together with an anode made of Pt/C onto an electrolyte membrane. Power generation was conducted at 80˚C by supplying H2 to the anode and O2 or air to the cathode, each humidified under ambient pressure. Durability was evaluated by repeatedly applying cyclic potentials between 1.0 V and 1.5 V, supplying N2 to the anode and cathode, and examining changes in the cyclic voltammogram.The I-V curves of MEAs with ionomer-free carbon-free Pt(ns) cathodes fabricated using drop-coating and spray-coating methods and measured using air and oxygen as the cathode supply gases are shown in Fig. 1. As demonstrated in the figure, the activation overpotential at low current density was high, suggesting a low Pt utilization. The shape of the I-V curve of MEA using the spray method at high current density indicated that the concentration overpotential was suppressed under oxygen conditions but was high under air conditions. On the other hand, the concentration overpotential of the MEA using the drop method was high even under oxygen conditions. This may be attributed to the small spaces between the restacked nanosheets, which inhibited diffusion.A start-stop simulated potential cycle test was conducted for the MEA using ionomer-free carbon-free Pt(ns) cathode. The CV curves measured after a certain number of cycles are shown in Fig. 2. As shown in the figure, the change in the shape of the CV was small, and the ECSA remaining rate of the electrode was above 80% even after 8000 cycles, whereas that of the Pt/C cathode was less than 50% after 4000 cycles. This suggests that carbon-free ionomer-free Pt(ns) electrode has the potential as highly durable low Pt electrodes.AcknowledgementPart of this paper is based on results obtained from a project, JPNP20003, subsidized by the New Energy and Industrial Technology Development Organization (NEDO).

Ultra-low Pt loading catalyst on (Nb–Ti)2AlC support as advanced material for low-temperature fuel cell application

ABSTRACT The oxygen reduction reaction was investigated at 10 monolayers (MLs) of Pt electrodeposited on (Nb–Ti)2AlC substrate. Following the discussion of detailed kinetics and electrodeposition optimisation in the authors’ previous paper, the focus of this research was on stability testing. Previously performed optimisation results showed the best activity shown by 10 monolayers of Pt. Catalyst characterisation was performed by scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. SEM, EDS and XPS analysis showed that the surface was covered with a homogeneous layer of Pt. TEM analysis of a cross-section confirmed the presence of Pt layer of thickness ∼3.5 nm, corresponding to the 10 MLs of Pt. Although the mass activity for the ORR at 0.8 V vs. RHE of 37.4 A g−1 was comparable with the best one for the Pt/C benchmark, US Department of Energy Protocols revealed excellent catalyst stability – the loss of electrochemically active surface area (EASA) was found to be only 9.3%.

Hysteresis of magnetization statics and dynamics in [Pt/Co] multilayer

The magnetic multilayer of Co separated by thin spacer layer of Pt was deposited by DC-magnetron sputtering. From the longitudinal magneto-optical Kerr effect based magnetometry and microscopy as well as magnetic force microscopy, the hybrid magnetization structure was deduced: the large size, micrometer scale magnetic domains with in-plane “core magnetization” patterned by nanometer scale domains with out-of-plane components. The hysteresis as a function of in-plane applied magnetic field of both: (i) magnetization curve measured by Superconducting Quantum Interference Device and (ii) dynamic responses measured by broadband Vector Network Analyzer spectroscopy were observed. The experimental results are well described by micromagnetic simulations. These magnetic history dependent effects were explained by magnetization cores, with in plane component, switching.

Role of the middle-shell in the stability of three-shell nanoparticles: A molecular dynamics study

In this study, the role of different middle-shells including Ni, Cu, Pd, Ag, Pt, and Au on the stability of three-shell Pd@M@Ag and Ag@M@Pd nanoparticles has been studied using molecular dynamics simulation. The simulation results show that without the influence of the type of middle layer, Pd@M@Ag nanoparticles are more stable than Ag@M@Pd nanoparticles due to more release of compressive strain in the core. The results also show that the stability of three-shell nanoparticles is a result of the competition between cohesive energy and strain caused by lattice mismatch at the core/middle-shell and the middle-shell/outer-shell interface. In this competition, cohesive energy acts as the dominant factor. In such a way that the middle layer of Pt with the highest cohesive energy acts as the first and most effective middle layer in increasing the stability of three-shell nanoparticles. The middle layers of Ni and Cu have the largest lattice mismatch at the interface of the layers. Therefore, by releasing compressive strain in the middle layer, they can increase the stability of three-shell nanoparticles and are known as the second and third effective middle layers, respectively. The middle layer of Au, with low cohesive energy and also low lattice mismatch at the interface of the layers shows a negligible effect on increasing the stability of three-shell nanoparticles. The middle layers of Ag and Pd transform Pd@M@Ag and Ag@M@Pd three-shell nanoparticles into Pd@Ag and Ag@Pd core-shell nanoparticles, respectively. Therefore, these middle layers decrease the stability of nanoparticles by reducing the number of layers and the effects caused by strain at the interface of the layers. In general, the results of this study show that in addition to factors such as size, composition, morphology, and crystallographic structures, which have been investigated in many studies, it is possible to achieve nanoparticles with high stability by adjusting the middle-shell in three-shell nanoparticles, which will be a new perspective on the catalytic applications of nanoparticles.

Thin film epitaxial [111] Co_{50}Pt_{50}: structure, magnetisation, and spin polarisation

Ferromagnetic films with perpendicular magnetic anisotropy are of interest in spintronics and superconducting spintronics. Perpendicular magnetic anisotropy can be achieved in thin ferromagnetic multilayer structures, when the anisotropy is driven by carefully engineered interfaces. Devices with multiple interfaces are disadvantageous for our application in superconducting spintronics, where the current perpendicular to plane is affected by the interfaces. Robust intrinsic PMA can be achieved in certain Co_xPt_{100-x} alloys and compounds at any thickness, without increasing the number of interfaces. Here, we grow equiatomic Co_{50}Pt_{50} and report a comprehensive study on the structural, magnetic, and spin-polarisation properties in the L1_1 and L1_0 ordered compounds. Primarily, interest in Co_{50}Pt_{50} has been in the L1_0 crystal structure, where layers of Pt and Co are stacked alternately in the [100] direction. There has been less work on L1_1 crystal structure, where the stacking is in the [111] direction. For the latter L1_1 crystal structure, we find magnetic anisotropy perpendicular to the film plane. For the former L1_0 crystal structure, the magnetic anisotropy is perpendicular to the [100] plane, which is neither in-plane or out-of-plane in our samples. We obtain a value for the ballistic spin polarisation of the L1_1 and L1_0 Co_{50}Pt_{50} to be 47pm 3%.

Experimental study platform for electrocatalysis of atomic-level controlled high-entropy alloy surfaces

High-entropy alloys (HEAs) have attracted considerable attention to improve performance of various electrocatalyst materials. A comprehensive understanding of the relationship between surface atomic-level structures and catalytic properties is essential to boost the development of novel catalysts. In this study, we propose an experimental study platform that enables the vacuum synthesis of atomic-level-controlled single-crystal high-entropy alloy surfaces and evaluates their catalytic properties. The platform provides essential information that is crucial for the microstructural fundamentals of electrocatalysis, i.e., the detailed relationship between multi-component alloy surface microstructures and their catalytic properties. Nanometre-thick epitaxially stacking layers of Pt and equi-atomic-ratio Cr-Mn-Fe-Co-Ni, the so-called Cantor alloy, were synthesised on low-index single-crystal Pt substrates (Pt/Cr-Mn-Fe-Co-Ni/Pt(hkl)) as a Pt-based single-crystal alloy surface model for oxygen reduction reaction (ORR) electrocatalysis. The usefulness of the platform was demonstrated by showing the outperforming oxygen reduction reaction properties of high-entropy alloy surfaces when compared to Pt-Co binary surfaces.

Palladium-based membranes for potential application in bio-jet fuel production unit

ABSTRACT The hydrogen in the vent gas stream of the hydrocracker (used to produce bio-jet fuel) cannot be reused since it has many impurities. The metal membrane can be a potential candidate for recovering hydrogen from this vent gas. In this work, the authors report the development of a composite palladium membrane and its application, for the first time, in the recovery of hydrogen from a simulated vent gas environment. A dense thin film (thickness ∼3 µm) of Pd metal was coated on a ceramic support tube by the sputter deposition technique. The hydrogen permeance of the Pd membrane was found to be 18.75 × 10−6 mol·m−2·h−1·Pa−1, which was reduced to 3.25 × 10−6 mol·m−2·h−1·Pa−1, with an exposure of 100 h in the simulated bio-jet fuel environment. To avoid the loss of permeability, a thin layer of Pt can be coated over the Pd membrane. The present study used MATLAB software to simulate the Pt-coated Pd composite membrane performance in the bio-jet fuel production environment. Simulation studies confirmed that a membrane area of ∼95 cm2 (250 mm length and 12 mm OD) is sufficient for the complete recovery of hydrogen from the vent gas stream of hydrocracker at a feed velocity of 0.075 m/s.

Electric double layer of Pt(111): Known unknowns and unknown knowns

The electric double layer is one of the most fundamental concepts in electrochemistry. Nevertheless, its exact structure is still often unresolved. In this contribution, we discuss what we, at present, believe to know and what we believe not to know about the structure of the Pt(111) double layer close to the potential of zero charge. To this end, we discuss and compare several models put forward in the last few years in order to explain recent (and less recent) experimental observations. Through a discussion of several models, we conclude that water adsorption at the interface likely plays an important role in correctly interpreting capacitance features observed close to the potential of zero charge (pzc). The capacitance features at low electrolyte concentration, which show important deviations from Gouy-Chapman diffuse layer theory, are, to date, not yet resolved beyond doubt, but we critically analyze and compare the various models that have been put forward to model the interface. We thereby point out weaknesses in the models as well as similarities and differences between the models.

Infrared-driven pyroelectric effect in magnetoelectric sensor for suspended on-chip magnetic nanoparticles quantification

Precise and real-time quantification of suspended magnetic nanoparticles (MNPs) is essential for augmenting the efficacy of the present MNP-based lab-on-a-chip systems. Existing MNP quantification techniques use bulky external electromagnets, which make such techniques expensive, energy-inefficient, and result in significant side effects on the surrounding healthy tissues. Here, we report on the development of an infrared-driven, Ni/lead magnesium niobate–lead titanate (PMN–PT) magnetoelectric (ME) heterostructure-based sensor that enables rapid assessment of the suspended MNPs in a fluidic environment without using an external magnetic field. The injected MNPs are captured by the generated magnetic field gradient of the Ni thin film. Subsequently, the optothermal-pyroelectric property of the underlying PMN–PT layer is utilized to quantitatively assess the MNPs' concentration. Under the incident infrared pulse at zero bias voltage, the device shows different transient photocurrent responses against varied MNP concentrations with a sensitivity of 0.29 nA mg−1 ml and a response time of less than 2 s. Such a ME device can improve the efficacy of current ME-based lab-on-a-chip systems, where a single device can capture, manipulate, as well as quantitatively assess the MNPs efficiently for critical biomedical applications such as drug delivery, drug regulation, and hyperthermia.

Electrocatalytic Hydrogen Evolution at Full Atomic Utilization over ITO-Supported Sub-nano-Ptn Clusters: High, Size-Dependent Activity Controlled by Fluxional Pt Hydride Species.

A combination of density functional theory (DFT) and experiments with atomically size-selected Ptn clusters deposited on indium-tin oxide (ITO) electrodes was used to examine the effects of applied potential and Ptn size on the electrocatalytic activity of Ptn (n = 1, 4, 7, and 8) for the hydrogen evolution reaction (HER). Activity is found to be negligible for isolated Pt atoms on ITO, increasing rapidly with Ptn size such that Pt7/ITO and Pt8/ITO have roughly double the activity per Pt atom compared to atoms in the surface layer of polycrystalline Pt. Both the DFT and experiment find that hydrogen under-potential deposition (Hupd) results in Ptn/ITO (n = 4, 7, and 8) adsorbing ∼2H atoms/Pt atom at the HER threshold potential, equal to ca. double the Hupd observed for Pt bulk or nanoparticles. The cluster catalysts under electrocatalytic conditions are hence best described as a Pt hydride compound, significantly departing from a metallic Pt cluster. The exception is Pt1/ITO, where H adsorption at the HER threshold potential is energetically unfavorable. The theory combines global optimization with grand canonical approaches for the influence of potential, uncovering the fact that several metastable structures contribute to the HER, changing with the applied potential. It is hence critical to include reactions of the ensemble of energetically accessible PtnHx/ITO structures to correctly predict the activity vs Ptn size and applied potential. For the small clusters, spillover of Hads from the clusters to the ITO support is significant, resulting in a competing channel for loss of Hads, particularly at slow potential scan rates.

Controlling interface anisotropy in CoFeB/MgO/HfO2 using dusting layers and magneto-ionic gating

In this work, we present the magneto-ionic response to ionic liquid gating in Ta/CoFeB/MgO/HfO2 stacks, where heavy metal dusting layers of Ta, W, and Pt are inserted at the Ta/CoFeB and CoFeB/MgO interfaces. Dusting layers of W inserted at the Ta/CoFeB interface increase perpendicular magnetic anisotropy (PMA) by more than 50%, while no significant changes are seen for Pt. In these samples, gating cannot break the PMA seeded at the CoFeB/MgO interface, only relatively small changes in the coercivity can be induced, about 20% for Ta and Pt and 6% for W. At the CoFeB/MgO interface, a significant quenching of the magnetization is seen when W and Ta dusting layers are inserted, which remains unchanged after gating, suggesting a critical deterioration of the CoFeB. In contrast, Pt dusting layers result in an in-plane anisotropy that can be reversibly converted to PMA through magneto-ionic gating while preserving the polycrystalline structure of the MgO layer. This shows that dusting layers can be effectively used not only to engineer magnetic properties in multilayers but also to strongly modify their magneto-ionic performance.

Magnetic properties and thermal stability of ultrathin TbFeCo films encapsulated by heavy metals Pt and W

Amorphous rare earth (RE)-transition metal (TM) ferrimagnetic alloy films have been intensively studied recently in spintronics and ultrafast information storage due to the large perpendicular magnetic anisotropy (PMA), ultrafast magnetization switching, and the presence of magnetization compensation and angular momentum compensation. In this work, we fabricate <i>X</i>/Tb<sub><i>x</i></sub>(Fe<sub>0.75</sub>Co<sub>0.25</sub>)<sub>1–<i>x</i></sub>/<i>X</i> (0.13 ≤ <i>x</i> ≤ 0.32, <i>X</i> = SiO<sub>2</sub>, Pt and W) trilayers by magnetron sputtering, and systematically investigate the magnetic properties and thermal stabilities of the ultrathin TbFeCo films encapsulated by heavy metals Pt and W at room temperature. The 5–50-nm-thick TbFeCo films sandwiched by SiO<sub>2</sub> exhibit PMA with magnetic compensation occurring in Tb concentration <i>x</i> between 0.21 with 0.24. For 3-nm- and 5- nm-thick TbFeCo ultrathin films encapsulated by Pt, however, there is no magnetic compensation observed throughout the composition range 0.13 ≤ <i>x</i> ≤ 0.32 with the film magnetization dominated by the FeCo moment. Nevertheless, the weakened PMA for the Pt/ultrathin TbFeCo/Pt trilayers is completely destroyed after annealing at 250 ℃. When the buffer layer and capping layer of Pt are replaced by W, the ultrathin TbFeCo films show magnetic compensation at 0.21 < <i>x</i> < 0.24, so do the thick TbFeCo films. The effective PMA field (<i>H</i><sub>K</sub>) exceeds 11.5 T for the W/ultrathin TbFeCo/W films near the compensation composition, and remarkably, the <i>H</i><sub>K</sub> decreases slowly on annealing, with PMA maintained even after annealing at 350–400℃. We further prepare [Pt/TbFeCo]<sub>5</sub>/Pt and [W/TbFeCo]<sub>5</sub>/W multilayers to clarify the origin of the huge difference between Pt/ultrathin TbFeCo/Pt and the W counterpart. It is found that there are partial recrystallization and phase separation for TbFeCo layer around the Pt/TbFeCo interface, leading to the disappearance of magnetic compensation and the deterioration of the PMA in the Pt/ultrathin TbFeCo/Pt films. With large PMA, W/ultrathin TbFeCo/W films show the presence of magnetic compensation, and excellent thermal robustness. The present study provides a promising heavy metal/RE-TM heterostructure for spintronic applications.

Unraveling the spin current flow in Bi layers

Although heavy metal materials, due to their large spin-orbit interaction, would be expected to act as an efficient converter of spin current to charge current, Bismuth does not obey this rule. Heterostructures of yttrium iron garnet (YIG)/Bi are investigated by means of the spin pumping technique and the results show that Bi exhibits negligible spin-charge conversion. In addition to not converting spin to charge, Bi exhibits an exotic spin relaxation mechanism, which is driven by its large diamagnetic response. By considering a nonlinear stochastic model of diffusing spin particles, the results show that the Bi layer acts as a binary classifier device that categorizes the pumped spins into relaxed spins and those that flow upwards and eventually reach the top layer of Pt. This shows that the investigation reported here opens different perspectives involving fundamental aspects in the fields of machine learning and condensed matter physics.

Photocatalytic Pt/Ag3VO4 micromotors with inherent sensing capabilities for corroding environments

Autonomous self-propelled micromachines based on semiconductors are at the forefront of environmental pollutants degradation research to palliate the effects of the contamination arising from the constant manufacturing of new products. Nonetheless, testing these micromotors with real-life products is almost an unexplored field, limiting the degradation of pollutants to single-component aqueous solutions or suspensions at the laboratory scale, which hinders the translation of these micromachines into useful systems. Herein, Ag3VO4 has been devised as a micromotor by an asymmetric deposition of a thin layer of Pt, giving rise to Pt/Ag3VO4 micromotors (Janus particle). Their motion capabilities have been demonstrated under UV light in fuel-free conditions. Their photocatalytic performance at laboratory scale has been confirmed for the degradation of Rhodamine B while, as a first approximation of a real-life application, the degradation of an energy drink has also been tested. During this latter exploration, the Pt/Ag3VO4 micromotors were corroded by the citric acid present in the pollutant, releasing Ag nanoparticles into the media. As a proof of concept, the position of the generated Ag nanoparticles’ surface plasmon resonance absorption maximum has been demonstrated to show a dependency on the concentration of citric acid.

Compressive Stress and Charge Redistribution during CO Adsorption Onto Pt

Electroorganic reactions, where energy is either stored or released from chemical bonds within carbon-based molecules, are essential to help achieve a circular carbon-based economy. Central to electrochemical conversion of organic molecules is carbon monoxide (CO), which serves as both an intermediate in electrochemical CO2 reduction to hydrocarbons and electrochemical oxidation in fuel cells that operate via oxygenated hydrocarbons (e.g., ethanol, methanol). For the latter, Pt has been the predominate catalyst of choice, and substantial effort has been spent to identify the mechanistic details for complete oxidation of alcohol-based fuels. With CO conversion serving as an important if not rate-limiting step of the oxidative process, it is critical to understand the state of a catalytic surface when CO is present.The change in surface stress associated with the adsorption and oxidative stripping of CO on (111)-textured Pt is examined using the wafer curvature method in 0.1 mol/L KHCO3 electrolyte.1 The curvature of the Pt cantilever electrode was monitored as a function of potential in both CO free and CO-saturated electrolyte. Although CO adsorbs as a neutral molecule, significant compressive stress, up to -1.3 N/m, is induced in the Pt. The magnitude of the stress change correlates directly with the CO coverage, and within the detection limits of the stress measurement, is elastically reversible. Density functional theory calculations of a CO bound Pt surface indicate that charge redistribution from the first atomic layer of Pt to subsurface layers account for the observed compressive stress induced by the charge neutral adsorption of CO. A better understanding of adsorbate-induced surface stress is critical for the development of materials platforms for sensing and catalysis. References D. Raciti, K.A. Schwarz, J. Vinson, and G.R. Stafford, The Journal of Physical Chemistry C , 126, 4446-4457 (2022).

Thermal catalytic device for toluene decomposition via direct heating

A thermal catalytic device that reduces the energy required for the catalytic oxidation of volatile organic compounds (VOCs) was developed. The catalytic oxidation of VOCs is typically performed under indirect heating conditions resulting in high energy consumption. The proposed device drastically decreases the energy consumed and increases the amount of toluene decomposed during catalytic oxidation because the catalysts are heated directly via a carbon nanotube (CNT) element. The proposed device consists of a glass-fiber textile coated in CNTs, α-MnO<sub>2</sub> nanostructures, and Pt nanostructures. The effect of different α-MnO<sub>2</sub> nanostructures (granular and urchin-like) on device performance was investigated. Moreover, the effect of each device component on the toluene decomposition efficiency and energy consumption of the device was explored by determining the toluene concentration of gaseous toluene after the catalytic oxidation process and the associated energy consumption. The device featuring urchin-like α-MnO<sub>2</sub> nanostructures coated in a thin layer of Pt achieves higher toluene decomposition efficiency than the device featuring granular α-MnO<sub>2</sub> nanostructures coated in Pt nanoparticles. Moreover, the device featuring urchin-like α-MnO<sub>2</sub> nanostructures coated in a thin Pt layer achieves higher toluene decomposition efficiency and lower energy consumption under direct heating conditions than under conventional indirect heating conditions.