Durable Catalysts Research Articles

Interfacial Reactivity-Triggered Oscillatory Lattice Strains of Nanoalloys.

Understanding the structure evolution of nanoalloys under reaction conditions is vital to the design of active and durable catalysts. Herein, we report an operando measurement of the dynamic lattice strains of dual-noble-metal alloyed with an earth-abundant metal as a model electrocatalyst in a working proton-exchange membrane fuel cell using synchrotron high-energy X-ray diffraction coupled with pair distribution function analysis. The results reveal an interfacial reaction-triggered oscillatory lattice strain in the alloy nanoparticles upon surface dealloying. Analysis of the lattice strains with an apparent oscillatory irregularity in terms of frequency and amplitude using time-frequency domain transformation and theoretical calculation reveals its origin from a metal atom vacancy diffusion pathway to facilitate realloying upon dealloying. This process, coupled with surface metal partial oxidation, constitutes a key factor for the nanoalloy's durability under the electrocatalytic oxygen reduction reaction condition, which serves as a new guiding principle for engineering durable or self-healable electrocatalysts for sustainable fuel cell energy conversion.

Developing Heterogeneous Catalysts for Reverse Water–Gas Shift Reaction in CO2 Valorization

Abstract Carbon dioxide capture and utilization (CCU) in chemical processes is vital for achieving sustainable and economically viable solutions in the context of climate change mitigation. This review focuses on the reverse water–gas shift (RWGS) reaction as a promising pathway for converting CO₂ into carbon monoxide (CO), which can subsequently be used as a precursor for the synthesis of various hydrocarbon compounds. The discussion centers on catalyst design strategies aimed at enhancing the low-temperature activity of the RWGS reaction, emphasizing the roles of catalyst supports and active sites. Key approaches include increasing surface area, introducing defect sites, and improving the redox properties of the catalysts. Methods for controlling the adsorption strength of gas reactants and products to enhance CO selectivity are explored, with particular attention to the use of ligands, promoters, doping, and advanced structures such as single-atom or core–shell configurations. Considerations regarding catalyst durability in reducing environments and the development of economically feasible catalysts are also addressed. Well-designed catalysts for the RWGS reaction offer significant advantages in CO₂ valorization, as the conversion of CO₂ to hydrocarbons is more readily achieved starting from CO.

Constructing Highly Porous Low Iridium Anode Catalysts Via Dealloying for Proton Exchange Membrane Water Electrolyzers.

Iridium (Ir) is the most active and durable anode catalyst for the oxygen evolution reaction (OER) for proton exchange membrane water electrolyzers (PEMWEs). However, their large-scale applications are hindered by high costs and scarcity of Ir. Lowering Ir loadings below 1.0 mgcm-2 causes significantly reduced PEMWE performance and durability. Therefore, developing efficient low Ir-based catalysts is critical to widely commercializing PEMWEs. Herein, an approach is presented for designing porous Ir metal aerogel (MA) catalysts via chemically dealloying IrCu alloys. The unique hierarchical pore structures and multiple channels of the Ir MA catalyst significantly increase electrochemical surface area (ECSA) and enhance OER activity compared to conventional Ir black catalysts, providing an effective solution to design low-Ir catalysts with improved Ir utilization and enhanced stability. An optimized membrane electrode assembly (MEA) with an Ir loading of 0.5 mgIr cm-2 generated 2.0 A cm-2 at 1.79V, higher than the Ir black at a loading of 2.0 mgIr cm-2 (1.63 A cm-2). The low-Ir MEA demonstrated an acceptable decay rate of ≈40 µV h-1 during durability tests at 0.5 (>1200 h) and 2.0 A cm-2 (400 h), outperforming the commercial Ir-based MEA (175 µV h-1 at 2.0 mgIr cm-2).

Cooperative Atomically Dispersed Fe-N4 and Sn-Nx Moieties for Durable and More Active Oxygen Electroreduction in Fuel Cells.

One grand challenge for deploying porous carbons with embedded metal-nitrogen-carbon (M-N-C) moieties as platinum group metal (PGM)-free electrocatalysts in proton-exchange membrane fuel cells is their fast degradation and inferior activity. Here, we report the modulation of the local environment at Fe-N4 sites via the application of atomic Sn-Nx sites for simultaneously improved durability and activity. We discovered that Sn-Nx sites not only promote the formation of the more stable D2 FeN4C10 sites but also invoke a unique D3 SnNx-FeIIN4 site that is characterized by having atomically dispersed bridged Sn-Nx and Fe-N4. This new D3 site exhibits significantly improved stability against demetalation and several times higher turnover frequency for the oxygen reduction reaction (ORR) due to the shift of the reaction pathway from a single-site associative mechanism to a dual-site dissociative mechanism with the adjacent Sn site facilitating a lower overpotential cleavage of the O-O bond. This mechanism bypasses the formation of the otherwise inevitable intermediate that is responsible for demetalation, where two hydroxyl intermediates bind to one Fe site. As a result, a mesoporous Fe/Sn-PNC catalyst exhibits a positively shifted ORR half-wave potential and more than 50% lower peroxide formation. This, in combination with the stable D3 site and enriched D2 Fe sites, significantly enhanced the catalyst's durability as demonstrated in membrane electrode assemblies using complementary accelerated durability testing protocols.

Boosting the Durability of High-Pt-Content Fuel Cell Cathode Catalysts Through TaOx Decorating.

Enhancing the durability of carbon-supported platinum catalysts (Pt/C) for the oxygen reduction reaction remains a significant challenge in the field of proton exchange membrane fuel cells (PEMFCs), especially for catalysts with high-Pt contents. Herein, a TaOx decorating strategy that is capable of effectively boosting the durability of Pt/C catalysts even with a high-Pt content of 50 wt.% is introduced. This strategy involves introducing reducible Ta2O5 nanoparticles into carbon supports, depositing Pt nanoparticles, and finally conducting high-temperature H2 annealing to convert reducible Ta2O5 nanoparticles into amorphous TaOx decorating the Pt nanoparticles. The annealing temperature found in the Ta2O5 incorporation step is critical for the formation of reducible Ta2O5 nanoparticles, which, in turn, determines the continuity of the TaOx subsequently formed around the Pt nanoparticles. By controlling annealing temperature, the formation of a relatively continuous TaOx distribution on the Pt nanoparticle surface is achieved, thereby maximizing the interaction between Pt and TaOx and enhancing the electrochemical stability of Pt nanoparticles. Following the accelerated durability test, the resulting high-Pt-content catalyst demonstrates an array of exceptional durability metrics, including an electrochemical surface area loss of 30%, a mass activity loss of 35%, and a voltage loss of 22mV at 0.8 A cm‒2.

Impact of hafnium dioxide morphology on catalytic transfer hydrogenation of methyl levulinate to γ-valerolactone: A comparative study

BackgroundThe catalytic transfer hydrogenation (CTH) of methyl levulinate (ML) to γ-valerolactone (GVL) is a promising method for producing renewable fuels and chemicals. The efficiency of this process depends heavily on the choice of catalysts, with morphology playing a critical role in their performance. MethodsThis study synthesized and characterized rice-like (r-HfO₂) and ball-like (b-HfO₂) hafnium oxide nanostructures. r-HfO₂ was prepared using a microwave system, while b-HfO₂ was synthesized via a solvothermal method. The catalysts were characterized using SEM, TEM, XRD, TPD-NH₃ analysis, and nitrogen sorption isotherms to determine their morphological, structural, and acidic properties. The catalytic performance of these nanostructures was tested under optimal conditions of 160 °C and 2 h in a batch-type solvothermal reactor. Significant FindingsThe results showed that b-HfO₂ exhibited a conversion efficiency of 90 % and a GVL yield of 90 %, outperforming r-HfO₂, which achieved 94.8 % conversion and 75.2 % yield. Recyclability tests confirmed the durability of both catalysts, with b-HfO₂ maintaining better activity. Detailed analyses revealed that b-HfO₂ exhibits superior catalytic activity and energy efficiency, achieving higher GVL yield and better energy efficiency. The conversion rates reached up to 100 % for both catalysts at 200 °C, with b-HfO₂ achieving a higher GVL yield and better energy efficiency. These findings demonstrate the potential of HfO₂-based catalysts, especially b-HfO₂, in efficiently converting biomass-derived feedstocks to valuable chemicals.

Facile growth of a heteroepitaxial layer on perovskite oxide surfaces for active and durable fuel cell cathodes

Polycrystalline perovskite oxide particles are promising candidates for cathode materials in solid oxide fuel cells. However, their limited activity and stability pose significant challenges for practical applications. In this study, we demonstrate a novel approach to achieve both high activity and durability in a PrBaCo2O5+δ catalyst through a simple epitaxial layer growth strategy. We found that an amorphous precursor of the highly durable catalyst SmBa0.5Ca0.5CoCuO5+δ can spontaneously adhere to the surface of PrBaCo2O5+δ particles. Upon heat treatment, it grows along the perovskite lattice, forming a heteroepitaxial layer with just a few atomic layers thickness. This heterostructure enhances the operational stability of PrBaCo2O5+δ transforming a 78% decrease over 100 h into a 7% increase. After 100 h, the power output density of the cell with the modified sample is more than 500% higher than that of unmodified PrBaCo2O5+δ. This work presents a new strategy for fabricating heteroepitaxial layers on polycrystalline ceramic catalysts and introduces a pioneering approach for developing high-performance oxygen reduction catalysts and related materials.

Exploring the potential of perovskite LaBO3 (B = Co, Fe, Cu, Al) as an efficient and durable hydrogen production catalyst for methanol steam reforming: Experimental and DFT studies

In this study, LaBO3 (B = Co, Fe, Cu, Al) perovskite catalysts were introduced for Methanol Steam Reforming (MSR). Results showed that LaCoO3 displayed a 100 % methanol conversion efficiency and a notable hydrogen production rate of 7.86 mol/min/gcat, maintaining stability for more than 40 h at 600 °C. Theoretical computations indicate that the CH3O dehydrogenation to CH2O (a rate-determining process) occurs without methanol breaking down into methane and coke, thus ensuring its long-lasting stability. The fusion of experimental findings with theoretical forecasts underscores the prowess of LaCoO3 as a remarkable perovskite catalyst and its extensive possibilities in the realm of methanol hydrogen generation.

Application of Corn Oil Derived Carbon Nano-onions Using Flame Pyrolysis as Durable Catalyst Support for Polymer Electrolyte Membrane Fuel Cells

Application of Corn Oil Derived Carbon Nano-onions Using Flame Pyrolysis as Durable Catalyst Support for Polymer Electrolyte Membrane Fuel Cells

Strategic Design for High-Efficiency Oxygen Evolution Reaction (OER) Catalysts by Triggering Lattice Oxygen Oxidation in Cobalt Spinel Oxides.

High-efficiency catalysts with refined electronic structures are highly desirable for promoting the kinetics of the oxygen evolution reaction (OER) and enhancing catalyst durability. This study comprehensively explores strategies involving metal doping and oxygen vacancies for enhancing the acidic OER catalytic activity of Co3O4. Through extensive screening of 3d and 4d transition metals using density functional theory (DFT) simulations, we demonstrate that the incorporation of metal dopants and oxygen vacancies into Co3O4 potentially triggers a transition from the adsorbate evolution mechanism (AEM) to the lattice oxygen oxidation mechanism (LOM) in the oxygen evolution reaction (OER). While the formation of the O-O bond in the intermediate *OOH poses challenges, a significantly reduced overpotential facilitates efficient conversion of O to O2 through the LOM in *OH and lattice oxygen. Additionally, we find that Mn doping can significantly improve the stability of the catalyst. Building upon the rationale above, we employed a dual doping strategy in subsequent experiments to enhance both the activity and stability. Our final design involved the codoping of Mn and Ru in Co3O4, along with an appropriate amount of oxygen vacancies. This catalyst demonstrates a low overpotential (η10 = 230 mV) compared to pure Co3O4 and maintains stable operation for over 120 h, representing a 12-fold increase. By exploring and harnessing the LOM, more efficient, stable, and cost-effective OER catalysts can be designed, providing crucial support for technologies such as water electrolysis in clean energy.

A dual-phase PtNiCuMnMo high-entropy alloy as high-performance electrocatalyst for oxygen evolution reaction

Development of high-performance, durable and cost-effective Pt-based catalysts is essential for improving oxygen evolution reaction (OER) under alkaline conditions. In this study, we introduce a dual-phase PtNiCuMnMo high-entropy alloy (HEA) catalyst with an OER overpotential of 250 mV and a Tafel slope of 124 mV/dec at a current density of 10 mA/cm2. Remarkably, the PtNiCuMnMo HEA catalyst maintains 77 % of its activity after 64 h at a current density of 200 mA/cm2. Theoretical calculations further validate the remarkable OER performance of the PtNiCuMnMo HEA catalyst, highlighting its favourable adsorption and charge transfer characteristics. The exceptional OER activity of the PtNiCuMnMo HEA catalyst considerably surpass those of commercial RuO2 catalysts, highlighting the potential of this catalyst to revolutionise water-splitting technology.

A Chalcogenide-Derived NiFe2O4 as Highly Efficient and Stable Anode for Anion Exchange Membrane Water Electrolysis.

Developing low-cost, highly active, and durable oxygen evolution reaction (OER) electrodes is one of the critical scientific issues for anion exchange membrane water electrolyzer (AEM-WE). Herein, we report a vacancy-rich and alkali-stable NiFe2O4-type electrode (named as NiFeOx-350-Ov), derived from the chemical-vapor deposited precursor NiFeSexSy-350, as an efficient and robust anode material. The obtained electrode affords current densities of 100 and 500 mA cm-2 at overpotentials of 245 and 270 mV, respectively, and displays excellent long-term durability sustaining 1.0 A cm-2 at least for 1000 h. When coupled with Ni4Mo/MoO2/NF as a hydrogen evolution reaction (HER) catalyst, the resulting platinum-group metal (PGM)-free single-cell AEM-WE exhibits a cell voltage of 1.71 V at the current density of 1000 mA cm-2 at 80 °C and long-term durability during a current-cycling test between 0.5 A cm-2 and 1.0 A cm-2 over 150 h at 60 °C. This work highlights a unique reconstruction strategy for preparing highly active and durable OER catalysts used in PGM-free AEM-WE.

Designing Ultra‐Stable and Surface‐Exposed Ni Nanoparticles with Dually Confined Microenvironment for High‐Temperature Methane Dry Reforming

AbstractConversion of CO2 and CH4 into syngas offers a promising route to reduce emissions of greenhouse gases, which facilitates large‐scale carbon fixation and boosts carbon‐neutral goal. The main obstacle for CO2/CH4 reforming is the lack of durable catalysts showing both high metal‐exposure and high‐temperature structure stability, since the reported Ni‐based catalysts have difficulty in avoiding deactivation by sintering metal at high temperature. Herein, ultra‐small Ni nanoparticles, which display multiple characteristics of high surface‐exposure and stabilized structure, are constructed from the evolution of atomically dispersed low‐valent nickel under a dually confined microenvironment. Consequently, the developed strategy can not only break the stable‐exposure trade‐off in heterogeneous catalysis but also provide new opportunity for the engineering of high‐performance and sintering‐resistant reforming catalysts as well as other durable heterogeneous catalysts.

Mg and Cr doped ZnO nanoparticles for oxygen evaluation reaction

This study introduces an innovative approach to developing low-cost materials for renewable energy technologies by synthesizing a novel series of zinc oxide (ZnO)-based nanoparticles, including chromium-doped zinc oxide (ZnOCr) and magnesium-chromium co-doped zinc oxide (ZnOCr-Mg), via the solution combustion method. The novelty of this work lies in the strategic co-doping of ZnO with both Cr and Mg, a combination not extensively explored in the field of electrocatalysis for Oxygen Evolution Reactions (OER). By leveraging this co-doping strategy, the structural, morphological, and electrocatalytic properties of the nanoparticles were systematically analyzed using techniques such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). Among the tested variants, ZnOCr-Mg:5 exhibited a significantly lower overpotential and superior stability, maintaining its catalytic performance over 18,000 s, thus outperforming traditional ZnO catalysts. These findings highlight the synergistic effects of Cr and Mg doping, showcasing ZnOCr-Mg:5 as a highly efficient and durable catalyst for OER, offering a novel and scalable solution for advancing sustainable energy technologies.

Carbon Dots Boost the Electrocatalytic Ammonia Oxidation Reaction on Pt2Pd Nanosheet

AbstractThe development of efficient catalysts for high‐performance ammonia oxidation reaction (AOR) is crucial for direct ammonia fuel cells. However, AOR is severely affected by slow kinetics and the toxicity of reaction intermediates, which reduce the durability of precious metal catalysts. Here, a two‐dimensional carbon dots modified Pt2Pd nanoporous alloy (Pt2Pd‐CDs) is synthesized through the borane morpholine reduction of a platinum palladium oxide nanosheet. The Pt2Pd_3 % CDs (the mass of CDs is 3 % of Pt2Pd) exhibits high AOR activity and stability in alkaline media, with an onset potential of 0.41 V vs. RHE, which is 170 mV lower than that of the commercial Pt/C (0.58 V vs. RHE). In addition, after 2000 cycles of accelerated durability testing, the peak mass activity (115.3 A gPGM−1) decreases by only 25.8 %. This enhancement is mainly attributed to the unique advantage of two‐dimensional nanoporous structure with a high electrochemical surface area, and the strong ammonia adsorption and the electron deliver capacity of CDs.

Electronic Modulation and Symmetry-Breaking Engineering of Single-Atom Catalysts Driving Long-Cycling Li-S Battery.

Developing efficient and durable single-atom catalysts is vitally important for the sulfur redox reaction (SROR) in Li-S battery, while it remains enormous challenging. Herein, undercoordinated Ni-N3 moieties anchored on N,S-codoped porous carbon (Ni-NSC) is obtained to enhance the SROR. The experiments and theoretical calculations indicate that the symmetry-breaking charge transfer in Ni single-atom catalyst originates from tuning effect of sulfur atoms mediated Ni-N3 moieties, which can both facilitate the chemical adsorption by formation of N-Ni⋅⋅⋅Sn 2-, and achieve a rapid redox conversion of polysulfides because of the enhanced electron transfer. As results, the Ni-NSC based Li-S battery delivers a very high initial reversible capacity (1025 mAh g-1 at 1 C), as well as outstanding cycling-stability for 2400 cycles at 2 C and 3 C, respectively. Noteworthy, the areal capacity can reach 7.8 mAh cm-2 at 0.05 C and a retention capacity of 4.7 mAh cm-2 after 100 cycles at 0.2 C for Ni-NSC based Li-S battery with sulfur loading of 5.88 mg cm-2. This work provides profound insight for rational optimizing microscopic electronic density of active site to promoting SROR in metal-sulfur batteries.

Regulating the Local Spin States in Spinel Oxides to Promote the Activity of Li-CO2 Batteries.

Due to the high energy barrier, slow reaction kinetics, and complex reaction environments of Li-CO2 batteries, the development of durable and efficient catalysts is essential. Transition metal oxides are promising for their availability, stability, and 3d electronic features, with spin states playing an important role in CO2 activation. In this study, the local spin states are regulated by incorporating Ni into Co3O4 and its impact on activity in Li-CO2 batteries is explored. The results show that Ni atoms with high spin states in Ni0.1Co2.9O4 facilitate electron transfer from the catalyst to the unoccupied orbitals of CO2, providing sufficient active sites for the nucleation and growth of small Li2CO3 crystals. These small crystals have a low decomposition barrier, leading to improved battery efficiency. Therefore, Ni0.1Co2.9O4 shows superior catalytic performance with an overpotential of 0.72V and an energy efficiency of ≈70% after 500h. This work provides insights into the relationship between spin states and CO2 reactions, highlighting a promising avenue for developing high-performance metal-CO2 batteries.

Hierarchically Structured Catalysts Toward Sustainable Hydrogen Economy: Electro- and Thermo-Chemical Pathways.

Hydrogen, as an important clean energy source, plays a more and more crucial role in decarbonizing the planet and meeting the global climate challenge due to its high energy density and zero-emission. The demand for sustainable hydrogen is increasing drastically worldwide as driven by the global shift towards low-carbon energy solutions. Thermochemical catalysis process dominates hydrogen production at scale given its relatively mature technology and commercialization status, as well as the established manufacturing infrastructure. While due to its environmentally friendly nature and growing abundant sources of renewable electricity, the electrochemical path for hydrogen production is rising as a major alternative to the thermochemical means. Nevertheless, hierarchically structured catalysts and devices have gradually taken the center stage toward replacing the traditional counterparts, especially with the rapid advancement of the design and manufacture of such ordered nanostructure assemblies toward high activity, efficient mass transport, and superb stability. In this review, the latest progress of the hierarchically structured catalysts for hydrogen production have been surveyed on electro- and thermo- chemical pathways comparatively. It covers the structure designs of atomic dispersion, nanoscale surfaces and interfaces for achieving highly active and durable catalysts, components, and devices. Both electrochemical and thermochemical approaches are reviewed in terms of the vast design details, engineered benefits, and understandings of various Pt-group metal (PGM) and non-PGM based transition metal catalysts for hydrogen production. As the growing trend, brief discussions are also presented toward the high-level assembly and manufacture of complexly structured components and devices at scale in the electrochemical and thermochemical energy systems.

Ultra-High Activity and Durability of Low-Platinum Fuel Cells Enabled by Encapsulation of L10-PtCo and L12-Pt3Co Intermetallic Compounds.

Developing high-performance, durable, and ultralow-loading platinum (Pt) catalysts for the oxygen reduction reaction (ORR) is crucial for advancing fuel cells. Here, a novel structured alloy catalyst is reported, characterized by Pt-Co intermetallic compounds with a Pt-skin, encapsulated by a covalent organic framework (COF) derived carbon support. This unique structure, combining alloy-induced strain effects and protective encapsulation, leads to exceptional catalytic activity and stability at an ultralow Pt loading of 0.02 mgPt cm-2. To be specific, this catalyst exhibits peak power densities of 1.77W cm-2 in fuel cell tests. It demonstrates a state-of-the-art mass activity of 2.15 A mgPt -1 (@0.9 V), which is 5.38 times that of commercial Pt/C (0.40 A mgPt -1). More importantly, the fuel cell assembled with this novel catalyst displays exceptional durability, with a voltage degradation of only 9.9mV after 100,000 cycles at 0.8 A cm-2 and a mass activity retention of 85% (1.83 A mgPt -1), far exceeding the 2025 initial mass activity (MA) target (0.44 A mgPt -1) of DOE by 4.2 times. Notably, the current density at 0.6 V under hydrogen-air conditions shows only a slight decline after more than 230 h.

Consolidating the Oxygen Reduction with Sub-Polarized Graphitic Fe-N4 Atomic Sites for an Efficient Flexible Zinc-Air Battery.

The effectuation of the Zn-air battery (ZAB) is appealing for active and durable catalysts to kinetically drive the sluggish cathodic oxygen reduction reaction (ORR). Atomic metal-Nx-C sites are widely witnessed with Pt-like activity, but their demetalations still severely restrict the durability in ORR. Here we have profiled an ordered hierarchical porous carbon supported Fe-N4 single-atom (FeNC) catalyst by a template derivation method for efficient ORR and flexible ZAB studies. The FeNC structure is observed with a sub-polarized graphitic Fe-N4 coordination with a shortened Fe-N bond for potentially consolidating the ORR, together with the hierarchical porous matrix for kinetical mass transfer. Resultantly, the optimized FeNC catalyst showcases Pt-beyond alkaline ORR activity (E1/2 = 0.95 V) with long-term durability for 100 h, delivering the flexible ZAB device with high power density (251 mW cm-2) and durable cycle life (80 h). This research underscores the criterion in rationalizing active and robust ORR catalysts through metal-nitrogen bond modulation.