Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “catalytic electrode”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Investigating the Adsorption–Desorption Kinetics of a Molecular Water Oxidation Catalyst at an Electrode Interface

Probing the dynamics of molecular catalysts at electrode–electrolyte interfaces is essential for understanding catalytic mechanisms. Structure-specific spectroscopic methods are particularly powerful for examining electrocatalytic interfaces but are mostly used under steady-state conditions. Herein, we combined surface-enhanced infrared absorption spectroscopy (SEIRAS) with phase-sensitive detection (PSD) to investigate the dynamics of a molecular Ir-based water oxidation catalyst at the Au–electrolyte interface. We found that the amplitude of the absorbance of the catalyst is anticorrelated to that of interfacial water. This anticorrelation can be understood by the adsorption of the electrooxidized catalyst on the electrode and concurrent displacement of interfacial water. The infrared signals from the interface exhibit an increasing phase lag with respect to the electrode potential with an increasing scan rate of the potential. Kinetic modeling suggests that the potential-dependent adsorption–desorption kinetics of the molecular catalyst on the electrode gives rise to this phase lag. Furthermore, this study shows that PSD-SEIRAS is a powerful tool for investigating the interfacial dynamics of electrocatalytic systems.

Catalysts↗
NASA NTRS2006

Membrane electrode assembly for a fuel cell

A catalyst ink for a fuel cell including a catalytic material and poly(vinylidene fluoride). The ink may be applied to a substrate to form an electrode, or bonded with other electrode layers to form a membrane electrode assembly (MEA).

Prakash, Surya↗
DOE OSTI2025

Enhancing surface activity and durability in triple conducting electrode for protonic ceramic electrochemical cells

With the material system operating at lower temperatures, protonic ceramic electrochemical cells (PCECs) can offer high energy efficiency and reliable performance for both power generation and hydrogen production, making them a promising technology for reversible energy cycling. However, PCEC faces technical challenges, particularly regarding electrode activity and durability under high current density operations. To address these challenges, we introduce a nano-architecture oxygen electrode characterized by high porosity and triple conductivity, designed to enhance catalytic activity and interfacial stability through a self-assembly approach, while maintaining scalability. Electrochemical cells incorporating this advanced electrode demonstrate robust performance, achieving a peak power density of 1.50 W cm −2 at 600 °C in fuel cell mode and a current density of 5.04 A cm −2 at 1.60 V in electrolysis mode, with enhanced stability on transient operations and thermal cycles. The underlying mechanisms are closely related to the improved surface activity and mass transfer due to the dual features of the electrode structure. Additionally, the enhanced interfacial bonding between the oxygen electrode and electrolyte contributes to increased durability and thermomechanical integrity. This study underscores the critical importance of optimizing electrode microstructure to achieve a balance between surface activity and durability.

Protonic Ceramic Electrochemical Cells↗
DOE OSTI2026

Combining ToF‐SIMS and Multivariate Analysis to Resolve Active Sites on Ni‐Based HER Catalysts

Unambiguous identification of active sites in heterogeneous catalysis remains a major challenge, particularly for materials with ultrathin, chemically mixed surface layers. Here, we demonstrate a generalizable approach that combines time-of-flight secondary ion mass spectrometry (ToF-SIMS) with multivariate statistical analysis (principal component analysis [PCA] and multivariate curve resolution [MCR]) to resolve catalytically relevant motifs at the nanoscale. Using Ni electrodes as a model system, PCA distinguished hydroxide-enriched domains from oxide- and metal-rich regions, while MCR decomposed depth profiles and 3D images into hydroxide, oxide, and metallic layers with nanometer resolution. A unique secondary-ion fragment, NiO 3 H 3 − (m/z 108.94), emerged as a marker of hydroxide-rich environments and correlated with hydrogen evolution reaction (HER) activity across a series of Ni electrodes. Complementary density functional theory (DFT) calculations revealed that Ni(OH) 2 clusters adjacent to metallic Ni offer the most favorable water dissociation energetics, establishing the structural origin of the marker. While illustrated here for Ni-based HER, this workflow provides a broadly applicable framework to isolate and rank near-surface patterns that govern catalytic activity, thereby extending ToF-SIMS from a qualitative probe to a predictive tool for active site identification.

HER active sites↗
DOE OSTI2023

Amino Acid Residues Controlling Domain Interaction and Interdomain Electron Transfer in Cellobiose Dehydrogenase

The function of cellobiose dehydrogenase (CDH) in biosensors, biofuel cells, and as a physiological redox partner of lytic polysaccharide monooxygenase (LPMO) is based on its role as an electron donor. Before donating electrons to LPMO or electrodes, an interdomain electron transfer from the catalytic FAD-containing dehydrogenase domain to the electron shuttling cytochrome domain of CDH is required. This study investigates the role of two crucial amino acids located at the dehydrogenase domain on domain interaction and interdomain electron transfer by structure-based engineering. The electron transfer kinetics of wild-type Myriococcum thermophilum CDH and its variants M309A, R698S, and M309A/R698S were analyzed by stopped-flow spectrophotometry and structural effects were studied by small-angle X-ray scattering. The data show that R698 is essential to pull the cytochrome domain close to the dehydrogenase domain and orient the heme propionate group towards the FAD, while M309 is an integral part of the electron transfer pathway – its mutation reducing the interdomain electron transfer 10-fold. Structural models and molecular dynamics simulations pinpoint the action of these two residues on the domain interaction and interdomain electron transfer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Exsolution of NiCo alloys over Ruddlesden-Popper perovskite for mild electrochemical synthesis of ammonia on protonic ceramic electrochemical cells

Ammonia synthesis from renewable energies on protonic ceramic electrochemical cells (PCECs) shows great potential. The primary challenges in ammonia synthesis on PCECs include sluggish catalytic activity, competition from the hydrogen evolution reaction, and unsatisfactory durability of the cathode, which is the active site of ammonia generation. Here, in this study, we report an elaborate design of the cathode with an intended formula of Pr 4 Ni 1.79 Co 1.2R u 0.01 O 10-δ , where NiCo alloy nanoparticles are exsolved from Ruddlesden-Popper perovskite substrates after the reduction in 5 % H 2 /Ar at 400 °C for 1 h, for electrocatalysis of the nitrogen reduction reaction to ammonia. The host material Pr 4 Ni 1.8 Co 1.2 O 10-δ with embeddable layered structure and stability was deliberately chosen to fix the Ru cation and maximize the catalytic activity of NiCo. Also, density functional theory calculations suggest that Ru doping provides an optimal balance between structural stability and redox activity, facilitating the controlled exsolution of NiCo nanoparticles and enhancing catalytic performance. As a result, the composite electrode with exsolved NiCo alloy and abundant oxygen vacancies on fuel-electrode-supported PCECs achieves a superior electrochemical activity towards ammonia synthesis: a peak ammonia formation rate of 27.84 μg h −1 cm −2 and excellent Faradaic efficiencies of 62.6 % at 350 °C.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1989

Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications

In most instances separate electrocatalysts are needed to promote the reduction of O2 in the fuel cell mode and to generate O2 in the energy storage-water electrolysis mode in aqueous electrochemical systems operating at low and moderate temperatures (T greater than or equal to 200 C). Interesting exceptions are the lead and bismuth ruthenate pyrochlores in alkaline electrolytes. These catalysts on high area carbon supports have high catalytic activity for both O2 reduction and generation. Rotating ring-disk electrode measurements provide evidence that the O2 reduction proceeds by a parallel four-electron pathway. The ruthenates can also be used as self-supported catalysts to avoid the problems associated with carbon oxidation, but the electrode performance so far achieved in the research at Case Western Reserve University (CWRU) is considerably less. At the potentials involved in the anodic mode the ruthenate pyrochlores have substantial equilibrium solubility in concentrated alkaline electrolyte. This results in the loss of catalyst into the bulk solution and a decline in catalytic activity. Furthermore, the hydrogen generation counter electrode may become contaminated with reduction products from the pyrochlores (lead, ruthenium).

Prakash, Jai↗
DOE OSTI2024

Critical Assessment of Electronic Structure Descriptors for Predicting Perovskite Catalytic Properties

The discovery and design of materials which can efficiently catalyze the oxygen reduction and evolution reactions at reduced temperatures is important for facilitating the widespread adoption of fuel cell and electrolyzer technologies. Numerous studies have produced correlations between catalytic properties, such as oxygen surface exchange or electrode area specific resistance (ASR), and properties of the catalyst material. However, correlations have historically been limited in scope (e.g., using only a few materials or at a single temperature) and it has been difficult to provide detailed assessments of their robustness. Here, in this study, we assess the ability of the O p-band center electronic structure descriptor, obtained from density functional theory (DFT) calculations, to correlate with oxygen surface exchange rates, diffusivities, and area specific resistances for a large database of perovskite oxide catalytic properties. By data mining the literature, we obtain 747 catalytic property value data points spanning 299 unique perovskite compositions from 313 studies. We assess linear correlations of each property with the O p-band center and find generally modest correlations that are qualitatively useful (prediction mean absolute errors of about 0.5 log units are typical), where the correlations are improved at higher temperatures (e.g., 800 °C vs. 500 °C) and significantly improve when considering fits to the subset of materials which have multiple independent measurements. These findings suggest that the spread of property data is significantly influenced by experimental uncertainty, and subsequent measurements of additional materials will likely improve the O p-band center correlations.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Few-Atom Copper Catalyst for the Electrochemical Reduction of CO to Acetate: Synergetic Catalysis between Neighboring Cu Atoms

Single-atom catalysts (SACs) are gaining increasing recognition because of their superior catalytic properties for various reactions. However, the performance of SACs is often limited by the lack of neighboring metal centers to cooperate in catalysis. Herein, a synergetic interaction between neighboring Cu atoms of a few-atom catalyst (FAC) on graphdiyne is found to greatly enhance the production of acetate in CO electroreduction reaction relative to Cu SACs. In a 1.0 M KOH electrolyte, this Cu FAC exhibits an acetate Faradaic efficiency of 53.8±1.5 % and an ultrahigh relative purity of up to 97 wt% for liquid products, and excellent stability of over 23 h continuous electrolysis at -0.8 V versus reversible hydrogen electrode (RHE). Theoretical studies suggest that the intersite catalytic communication between two neighboring metal atoms confined in each pore of GDY facilitates the formation of acetic acid through either stepwise hydrogenation of CH 2 CO* or the direct reaction of H 2 O with CH 2 CO*. Our study demonstrates the unprecedented synergetic catalysis of Cu FAC in promoting the selective CO electroreduction toward acetate production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Cu[Ni(2,3-pyrazinedithiolate) 2 ] Metal–Organic Framework for Electrocatalytic Hydrogen Evolution

The application of metal–organic frameworks (MOFs) as electrocatalysts for small molecule activation has been an emerging topic of research. Previous studies have suggested that two-dimensional (2D) dithiolene-based MOFs are among the most active for the hydrogen evolution reaction (HER). Here, a three-dimensional (3D) dithiolene-based MOF, Cu[Ni(2,3-pyrazinedithiolate) 2 ] (1), is evaluated as an electrocatalyst for the HER. In pH 1.3 aqueous electrolyte solution, 1 exhibits a catalytic onset at –0.43 V vs the reversible hydrogen electrode (RHE), an overpotential (η 10 mA/cm 2 ) of 0.53 V to reach a current density of 10 mA/cm 2 , and a Tafel slope of 69.0 mV/dec. Interestingly, under controlled potential electrolysis, 1 undergoes an activation process that results in a more active catalyst with a 200 mV reduction in the catalytic onset and η 10 mA/cm 2 . It is proposed that the activation process is a result of the cleavage of Cu–N bonds in the presence of protons and electrons. Furthermore, this hypothesis is supported by various experimental studies and density functional theory calculations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1989

Electrocatalysts for oxygen electrodes in fuel cells and water electrolyzers for space applications

In most instances separate electrocatalysts are needed to promote the reduction of O2 in the fuel cell mode and to generate O2 in the energy storage-water electrolysis mode in aqueous electrochemical systems operating at low and moderate temperatures (T greater than or equal to 200 C). Interesting exceptions are the lead and bismuth ruthenate pyrochlores in alkaline electrolytes. These catalysts on high area carbon supports have high catalytic activity for both O2 reduction and generation (1,2). Rotating ring-disk electrode measurements provide evidence that the O2 reduction proceeds by a parallel four-electron pathway. The ruthenates can also be used as self-supported catalysts to avoid the problems associated with carbon oxidation, but the electrode performance so far achieved in the research at Case Western Reserve University (CWRU) is considerably less. At the potentials involved in the anodic mode the ruthenate pyrochlores have substantial equilibrium solubility in concentrated alkaline electrolyte. This results in the loss of catalyst into the bulk solution and a decline in catalytic activity. Furthermore, the hydrogen generation counter electrode may become contaminated with reduction products from the pyrochlores (lead, ruthenium). A possible approach to this problem is to immobilize the pyrochlore catalyst within an ionic-conducting solid polymer, which would replace the fluid electrolyte within the porous gas diffusion O2 electrode. For bulk alkaline electrolyte, an anion-exchange polymer is needed with a transference number close to unity for the Oh(-) ion. Preliminary short-term measurements with lead ruthenates using a commercially available partially-fluorinated anion-exchange membrane as an overlayer on the porous gas-fed electrode indicate lower anodic polarization and virtually unchanged cathodic polarization.

Prakash, Jai↗
DOE OSTI2025

Perovskite-driven solar C 2 hydrocarbon synthesis from CO 2

Photoelectrochemistry (PEC) presents a direct pathway to solar fuel synthesis by integrating light absorption and catalysis into compact electrodes. Yet, PEC hydrocarbon production remains elusive due to high catalytic overpotentials and insufficient semiconductor photovoltage. Here we demonstrate ethane and ethylene synthesis by interfacing lead halide perovskite photoabsorbers with suitable copper nanoflower electrocatalysts. The resulting perovskite photocathodes attain a 9.8% Faradaic yield towards C 2 hydrocarbon production at 0 V against the reversible hydrogen electrode. The catalyst and perovskite geometric surface areas strongly influence C 2 photocathode selectivity, which indicates a role of local current density in product distribution. The thermodynamic limitations of water oxidation are overcome by coupling the photocathodes to Si nanowire photoanodes for glycerol oxidation. These unassisted perovskite–silicon PEC devices attain partial C 2 hydrocarbon photocurrent densities of 155 µA cm -2 , 200-fold higher than conventional perovskite–BiVO 4 artificial leaves for water and CO 2 splitting. These insights establish perovskite semiconductors as a versatile platform towards PEC multicarbon synthesis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Intermediate Temperature Proton‐Conducting Solid Oxide Electrolysis Cells with Improved Performance and Durability

Technical understanding: A high-performance and stable intermediate temperature proton-conducting solid oxide electrolysis cell (PCEC) will add significantly to the hydrogen roadmap of EERE. However, the low electrocatalytic activity of the air electrode and the instability of the electrolyte are technical barriers. In this research, we utilized computational fluid dynamic modeling and materials/microstructure engineering to investigate the complex reaction chain and to improve the performance and reliability of the protonic ceramic electrochemical cells. An active and stable Pr 1.8 Ba 0.2 NiO 4+δ -BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) scaffold conformal coating electrode was rationally designed where the robust Pr 1.8 Ba 0.2 NiO 4+δ functions both as a catalytic active and a protective layer. The PCECs with porosity-optimized scaffold conformal coating electrodes demonstrate 1.46 Acm -2 under 1.3 V at 600°C, which is among the highest in recent years. The final optimization by computational fluid dynamic modeling and conformal coating technique was applied to evolve the PCEC air electrode from Pr 2 NiO 4+δ to Pr 1.8 Ba 0.2 NiO 4+δ -BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ scaffold conformal coating. The electrolysis current was boosted from 0.445A/cm 2 to 1.46A/cm 2 at 600°C and 1.3V. A superior low degradation rate of 1mV/kh was achieved in a 5000-hour of operation. Technical effectiveness and economic feasibility: The effectiveness of this TCO conformal coating on electrolyte backbone as air electrode has been proven by long-term demonstration. Based on the highly conductive BZCYYb electrolyte and the TCO steam electrode PNO, this project rationally took advantage of the existent materials to structure a PCEC device with high TRL and low risk. The solution infiltration method used to structure the conformal coating is a standard method used by the solid oxide cell community. Very minimal adoption is needed in the current SOC fabrication process. It is a cost-effective, scalable method for manufacturing, and brings up remarkable impact on the current technical status of PCEC. Benefit to the public: The findings in the research showed the industry that the severe challenge in PCEC can be overcome in a practical way. A various energy-hydrogen ecosystem is not beyond reach. The success of this technology provides sustainable and affordable H 2 to society. It will stimulate investment from the governmental and private sectors in response to the device manufacture and deployment, and the related infrastructure construction. It will generate high-pay domestic jobs and environmental benefits to the general public in the United States.

08 HYDROGEN↗
DOE OSTI2023

Intercalation-type catalyst for non-aqueous room temperature sodium-sulfur batteries

Abstract Ambient-temperature sodium-sulfur (Na-S) batteries are potential attractive alternatives to lithium-ion batteries owing to their high theoretical specific energy of 1,274 Wh kg −1 based on the mass of Na 2 S and abundant sulfur resources. However, their practical viability is impeded by sodium polysulfide shuttling. Here, we report an intercalation-conversion hybrid positive electrode material by coupling the intercalation-type catalyst, MoTe 2 , with the conversion-type active material, sulfur. In addition, MoTe 2 nanosheets vertically grown on graphene flakes offer abundant active catalytic sites, further boosting the catalytic activity for sulfur redox. When used as a composite positive electrode and assembled in a coin cell with excess Na, a discharge capacity of 1,081 mA h g s −1 based on the mass of S with a capacity fade rate of 0.05% per cycle over 350 cycles at 0.1 C rate in a voltage range of 0.8 to 2.8 V is realized under a high sulfur loading of 3.5 mg cm −2 and a lean electrolyte condition with an electrolyte-to-sulfur ratio of 7 μL mg −1 . A fundamental understanding of the electrocatalysis of MoTe 2 is further revealed by in-situ synchrotron-based operando X-ray diffraction and ex-situ time-of-flight secondary ion mass spectrometry.

25 ENERGY STORAGE↗
DOE OSTI2024

Catalytic, Spectroscopic, and Theoretical Studies of Fe 4 S 4 -Based Coordination Polymers as Heterogenous Coupled Proton–Electron Transfer Mediators for Electrocatalysis

Iron–sulfur clusters play essential roles in biological systems, and thus synthetic [Fe 4 S 4 ] clusters have been an area of active research. Recent studies have demonstrated that soluble [Fe 4 S 4 ] clusters can serve as net H atom transfer mediators, improving the activity and selectivity of a homogeneous Mn CO 2 reduction catalyst. Here, in this work, we demonstrate that incorporating these [Fe 4 S 4 ] clusters into a coordination polymer enables heterogeneous H atom transfer from an electrode surface to a Mn complex dissolved in solution. A previously reported solution-processable Fe 4 S 4 -based coordination polymer was successfully deposited on the surfaces of different electrodes. The coated electrodes serve as H atom transfer mediators to a soluble Mn CO 2 reduction catalyst displaying good product selectivity for formic acid. Furthermore, these electrodes are recyclable with a minimal decrease in activity after multiple catalytic cycles. The heterogenization of the mediator also enables the characterization of solution-phase and electrode surface species separately. Surface enhanced infrared absorption spectroscopy (SEIRAS) reveals spectroscopic signatures for an in situ generated active Mn–H species, providing a more complete mechanistic picture for this system. The active species, reaction mechanism, and the protonation sites on the [Fe 4 S 4 ] clusters were further confirmed by density functional theory calculations. The observed H atom transfer reactivity of these coordination polymer-coated electrodes motivates additional applications of this composite material in reductive H atom transfer electrocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Flexible and Extensive Platinum Ion Gel Condensers for Programmable Catalysis

Catalytic condensers composed of ion gels separating a metal electrode from a platinum-on-carbon active layer were fabricated and characterized to achieve more powerful, high surface area dynamic heterogeneous catalyst surfaces. Ion gels comprised of poly(vinylidene difluoride)/1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide were spin coated as a 3.8 μm film on a Au surface, after which carbon sputtering of a 1.8 nm carbon film and electron-beam evaporation of 2 nm Pt clusters created an active surface exposed to reactant gases. Electronic characterization indicated that most charge condensed within the Pt nanoclusters upon application of a potential bias, with the condenser device achieving a capacitance of ∼20 μF/cm 2 at applied frequencies of up to 120 Hz. The maximum charge of ∼10 14 |e – | cm –2 was condensed under stable device conditions at 200 °C on catalytic films with ∼10 15 sites cm –2 . Grazing incidence infrared spectroscopy measured carbon monoxide adsorption isobars, indicating a change in the CO* binding energy of ∼19 kJ mol –1 over an applied potential bias of only 1.25 V. Condensers were also fabricated on flexible, large area Kapton substrates allowing stacked or tubular form factors that facilitate high volumetric active site densities, ultimately enabling a fast and powerful catalytic condenser that can be fabricated for programmable catalysis applications.

Catalysis↗
DOE OSTI2023

A Bifunctional Ionic Liquid for Capture and Electrochemical Conversion of CO 2 to CO over Silver

Electrochemical conversion of CO 2 requires selective catalysts and high solubility of CO 2 in the electrolyte to reduce the energy requirement and increase the current efficiency. In this study, the CO 2 reduction reaction (CO 2 RR) over Ag electrodes in acetonitrile-based electrolytes containing 0.1 M [EMIM][2-CNpyr] (1-ethyl-3-methylimidazolium 2-cyanopyrolide), a reactive ionic liquid (IL), is shown to selectively (>94%) convert CO 2 to CO with a stable current density (6 mA·cm –2 ) for at least 12 h. The linear sweep voltammetry experiments show the onset potential of CO 2 reduction in acetonitrile shifts positively by 240 mV when [EMIM][2-CNpyr] is added. This is attributed to the pre-activation of CO 2 through the carboxylate formation via the carbene intermediate of the [EMIM] + cation and the carbamate formation via binding to the nucleophilic [2-CNpyr] – anion. The analysis of the electrode–electrolyte interface by surface-enhanced Raman spectroscopy (SERS) confirms the catalytic role of the functionalized IL where the accumulation of the IL-CO 2 adduct between –1.7 and –2.3 V vs Ag/Ag + and the simultaneous CO formation are captured. Furthermore, this study reveals the electrode surface species and the role of the functionalized ions in lowering the energy requirement of CO 2 RR for the design of multifunctional electrolytes for the integrated capture and conversion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Erratum to: Soft- and reactive landing of ions onto surfaces: concepts and applications

Soft- and reactive landing of mass-selected ions is gaining attention as a promising approach for the precisely-controlled preparation of materials on surfaces that are not amenable to deposition using conventional methods. A broad range of ionization sources and mass filters are available that make ion soft-landing a versatile tool for surface modification using beams of hyperthermal (<100?eV) ions. The ability to select the mass-to-charge ratio of the ion, its kinetic energy and charge state, along with precise control of the size, shape, and position of the ion beam on the deposition target distinguishes ion soft landing from other surface modification techniques. Soft- and reactive landing have been used to prepare interfaces for practical applications as well as precisely-defined model surfaces for fundamental investigations in chemistry, physics, and materials science. For instance, soft- and reactive landing have been applied to study the surface chemistry of ions isolated in the gas-phase, prepare arrays of proteins for high-throughput biological screening, produce novel carbon-based and polymer materials, enrich the secondary structure of peptides and the chirality of organic molecules, immobilize electrochemically-active proteins and organometallics on electrodes, create thin films of complex molecules, and immobilize catalytically active organometallics as well as ligated metal clusters. In addition, soft landing has enabled investigation of the size-dependent behavior of bare metal clusters in the critical subnanometer size regime where chemical and physical properties do not scale predictably with size. The morphology, aggregation, and immobilization of larger bare metal nanoparticles, which are directly relevant to the design of catalysts as well as improved memory and electronic devices, have also been studied using ion soft landing. This review article begins in section 1 with a brief introduction to the existing applications of ion soft- and reactive landing. Section 2 provides an overview of the ionization sources and mass filters that have been used to date for soft landing of mass-selected ions. A discussion of the competing processes that occur during ion deposition as well as the types of ions and surfaces that have been investigated follows in section 3. Section 4 discusses the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition. The influence of soft landing on the secondary structure and biological activity of complex ions is addressed in section 5. Lastly, an overview of the structure and mobility as well as the catalytic, optical, magnetic, and redox properties of bare ionic clusters and nanoparticles deposited onto surfaces is presented in section 6. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:439–479, 2016.

Johnson, Grant E.↗