Alloy Catalysts Research Articles

Self-Powered Hydrogen Production via Laser-Coordinated NiCoPt Alloy Catalysts in an Integrated Zn-Hydrazine Battery with Hydrazine Splitting.

This study proposes a novel approach for the rapid transformation of bimetallic NiCo-oxides into trimetallic NiCoPt alloys using a pulsed laser technique in an ethanol medium in the presence of Pt salts. The electrochemical results demonstrate the exceptional dual-functional activity of the optimized NiCoPt-10 alloy, effectively catalyzing both hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). Specifically, the NiCoPt-10 alloy presents a low overpotential of 90 mV at 10 mA·cm-2 for HER and a small working potential of 0.068 V versus the reversible hydrogen electrode (RHE) at 10 mA·cm-2 for HzOR. In situ Raman spectroscopy and theoretical calculations delivered insights into the dual-functional activity of the NiCoPt alloy. Consequently, the overall hydrazine splitting (OHzS) electrolyzer, employing a NiCoPt-10||NiCoPt-10 configuration, required only 0.295 V to deliver 10 mA·cm-2. Notably, using this dual-functional NiCoPt-10 catalyst as the cathode combined with Zn foil as the anode in a Zn-hydrazine (Zn-Hz) battery, achieved efficient hydrogen (H2) production with an energy efficiency of 97%. Furthermore, self-powered H2 production is realized by integrating the Zn-Hz battery with the OHzS electrolyzer, demonstrating its excellent potential for practical applications. Thus, this rapid synthetic strategy can aid in designing effective electrocatalysts for addressing challenges in H2 energy production.

Supported Alloy Catalysts for Diversification of Biomass Resources

Supported Alloy Catalysts for Diversification of Biomass Resources

Observation of the surface morphology of carbon alloy catalysts in aqueous solution by atomic force microscopy

Observation of the surface morphology of carbon alloy catalysts in aqueous solution by atomic force microscopy

Role of “post-coordination interaction” boosted performance of rare-earth based MOFs derived catalyst for hydrogenation-alkylation cascade reaction

Post-coordination interactions (abbreviated as PCI) play an essential role in the synthesis and optimization of catalysts by influencing their coordination environment, stabilizing reaction intermediates, tuning activity, and allowing for dynamic behavior. In this work, a LaOCl incorporated into carbon-nitrogen supported metallic Co and CoFe alloy catalyst (termed as CF/L-CN-PCI) via PCI strategy has been synthesized. This catalyst was then utilized in a cascade reaction involving nitroarenes and benzyl alcohol. The developed CF/L-CN-PCI catalyst exhibits higher catalytic selectivity compared to CF/L-CN-IWI catalyst prepared by IWI method in cascade reactions. Additionally, this catalyst offers ease of separation and demonstrates good catalytic cycle stability. Various characterization techniques and control experiments were employed to validate the reasons for the enhanced catalytic performance and to investigate the key issues such as the rate-determining step during the reaction process. We hope that this catalyst preparation method can serve as a reference for the development of other superior catalysts and their application in different reactions.

One−Step Synthesis Strategy for a Platinum−Based Alloy Catalyst Designed via Crystal−Structure Prediction

One−Step Synthesis Strategy for a Platinum−Based Alloy Catalyst Designed via Crystal−Structure Prediction

Machine-learning-accelerated density functional theory screening of Cu-based high-entropy alloys for carbon dioxide reduction to ethylene

Computational screening of high-entropy alloy (HEA) catalysts as alternatives to the typical Cu electrocatalyst for CO2 reduction reaction (CO2RR) has been extensively focused on C1 products, but C2+ products have received significantly less attention. This work optimized CuZnPdAgAu HEA catalyst composition for CO2RR to ethylene via density functional theory and supervised machine learning regression techniques. Candidates were identified from 106,045 HEA data for enthalpy of adsorption of *CO2, *H, *HOCCOH, and *C2H4 species, and the Gibbs free energy of *H. The electrocatalytic properties during the reaction were examined on the surface of the optimized HEA candidate – Cu0.36Zn0.18Pd0.10Ag0.18Au0.18 benchmarked to Cu (111). The Pd site of such a candidate functions as the active site for the CO2 activation step. In terms of catalytic activity, it showed lower Gibbs free energy for the potential determining step – the *OCCOH formation step compared to that on the Cu (111). Insight into electronic properties demonstrated that the candidate reduces the uphill reaction energy for *HOCCOH production pathway due to increased electron density in the C–C bond, donated from two Cu sites. It is shown that the HEA catalyst candidate has the potential for CO2RR targeting ethylene, an alternative to a common Cu catalyst.

Manipulating C-C coupling pathway in electrochemical CO2 reduction for selective ethylene and ethanol production over single-atom alloy catalyst.

Manipulation C-C coupling pathway is of great importance for selective CO2 electroreduction but remain challenging. Herein, two model Cu-based catalysts, by modifying Cu nanowires with Ag nanoparticles (AgCu NW) and Ag single atoms (Ag1Cu NW), respectively, are rationally designed for exploring the C-C coupling mechanisms in electrochemical CO2 reduction reaction (CO2RR). Compared to AgCu NW, the Ag1Cu NW exhibits a more than 10-fold increase of C2 selectivity in CO2 reduction to ethanol, with ethanol-to-ethylene ratio increased from 0.41 over AgCu NW to 4.26 over Ag1Cu NW. Via a variety of operando/in-situ techniques and theoretical calculation, the enhanced ethanol selectivity over Ag1Cu NW is attributed to the promoted H2O dissociation over the atomically dispersed Ag sites, which effectively accelerated *CO hydrogenation to form *CHO intermediate and facilitated asymmetric *CO-*CHO coupling over paired Cu atoms adjacent to single Ag atoms. Results of this work provide deep insight into the C-C coupling pathways towards target C2+ product and shed light on the rational design of efficient CO2RR catalysts with paired active sites.

FeCo Alloy-Decorated Proton-Conducting Perovskite Oxide as an Efficient and Low-Cost Ammonia Decomposition Catalyst

Ammonia is known as an alternative hydrogen supplier because of its high hydrogen content and convenient storage and transport. Hydrogen production from ammonia decomposition also provides a source of hydrogen for fuel cells. While catalysts composed of ruthenium metal atop various support materials have proven to be effective for ammonia decomposition, non-precious-metal-based catalysts are attracting more attention due to desires to reduce costs. We prepared a series of Fe, Co, Ni, Mn, and Cu monometallic catalysts and their alloys as catalysts over proton-conducting ceramics via the impregnation method as precious-metal-free ammonia decomposition catalysts. While Co and Ni showed superior performance compared to Fe, Mn, and Cu on a BaZr0.1Ce0.7Y0.1Yb0.1O3−б (BZCYYb) support as an ammonia decomposition catalyst, the cost of Fe is much lower than that of other metals. Alloying Fe with Co can significantly increase the conversion and stability and lower the overall cost of materials. The measured ammonia decomposition rate of FeCo/BZCYYb reached 100% at 600 °C, and the ammonia decomposition rate was almost unchanged during the long-term test of 200 h, which reveals its good catalytic activity for ammonia decomposition and thermal stability. When the metallic catalyst remained unchanged, BZCYYb also exhibited better performance compared to other commonly used oxide supports. Finally, when ammonia cracked using our alloy catalyst was fed to solid oxide fuel cells (SOFCs), the peak power densities were very close to that achieved with a simulated fully cracked gas stream, i.e., 75% H2 + 25% N2, thus proving the effectiveness of this new type of ammonia decomposition catalyst.

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.

Generative Pretrained Transformer for Heterogeneous Catalysts.

Discovery of novel and promising materials is a critical challenge in the field of chemistry and material science, traditionally approached through methodologies ranging from trial-and-error to machine-learning-driven inverse design. Recent studies suggest that transformer-based language models can be utilized as material generative models to expand the chemical space and explore materials with desired properties. In this work, we introduce the catalyst generative pretrained transformer (CatGPT), trained to generate string representations of inorganic catalyst structures from a vast chemical space. CatGPT not only demonstrates high performance in generating valid and accurate catalyst structures but also serves as a foundation model for generating the desired types of catalysts by text-conditioning and fine-tuning. As an example, we fine-tuned the pretrained CatGPT using a binary alloy catalyst data set designed for screening two-electron oxygen reduction reaction (2e-ORR) catalyst and generated catalyst structures specialized for 2e-ORR. Our work demonstrates the potential of generative language models as generative tools for catalyst discovery.

MoZn-based high entropy alloy catalysts enabled dual activation and stabilization in alkaline oxygen evolution.

It remains a grand challenge to develop electrocatalysts with simultaneously high activity, long durability, and low cost for the oxygen evolution reaction (OER), originating from two competing reaction pathways and often trade-off performances. The adsorbed evolution mechanism (AEM) suffers from sluggish kinetics due to a linear scaling relationship, while the lattice oxygen mechanism (LOM) causes unstable structures due to lattice oxygen escape. We propose a MoZnFeCoNi high-entropy alloy (HEA) incorporating AEM-promoter Mo and LOM-active Zn to achieve dual activation and stabilization for efficient and durable OER. Density functional theory and chemical probe experiments confirmed dual-mechanism activation, with representative Co-Co†-Mo sites facilitating AEM and Zn-O†-Ni sites enhancing LOM, resulting in an ultralow OER overpotential (η10 = 221 mV). The multielement interaction, high-entropy structure, and carbon network notably enhance structural stability for durable catalysis (>1500 hours at 100 mA cm-2). Our work offers a viable approach to concurrently enhance OER activity and stability by designing HEA catalysts to enable dual-mechanism synergy.

CO2-Mediated Hydrogen Energy Release-Storage Enabled by High-Dispersion Gold-Palladium Alloy Nanodots.

Developing and fabricating a heterogeneous catalyst for efficient formic acid (FA) dehydrogenation coupled with CO2 hydrogenation back to FA is a promising approach to constructing a complete CO2-mediated hydrogen release-storage system, which remains challenging. Herein, a facile two-step strategy involving high-temperature pyrolysis and wet chemical reduction processes can synthesize efficient pyridinic-nitrogen-modified carbon-loaded gold-palladium alloy nanodots (AuPd alloy NDs). These NDs exhibit a prominent electron synergistic effect between Au and Pd components and tunable alloy-support interactions. The pyridinic-N dosage in carbon substrate improves the surface electron density of the alloy catalyst, thus regulating the chemical adsorption of FA molecules. Specifically, the engineered Au3Pd7/CN0.25 demonstrates an outstanding room-temperature FA dehydrogenation efficiency, achieving ≈100% conversion and an initial turnover frequency (TOF) of up to 9049h-1. The versatile AuPd alloy NDs also show the ability to convert CO2, one of the products of FA dehydrogenation, into FA (formate) with a 90.8% yield under mild conditions. Moreover, in-depth insights into the unique alloyed microstructure, structure-activity relationship, key intermediates, and the alloy-driven five-step reaction mechanism involving the rate-determining step of C─H bond cleavage from critical *HCOO species via D-labeled isotope, in situ infrared spectroscopy, and theoretical calculations are investigated.

CO2-Assisted Controllable Synthesis of PdNi Nanoalloys for Highly Selective Hydrogenation of Biomass-Derived 5-Hydroxymethylfurfural.

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-bishydroxymethyltetrahydrofuran (BHMTHF), a vital fuel precursor and solvent, is crucial for biomass refining. Herein, we report highly selective and stable PdNi nanoalloy catalysts for this deep hydrogenation process. A CO2-assisted green method was developed for the controllable synthesis of various bimetallic and monometallic catalysts. The PdNi/SBA-15 catalysts with various Pd/Ni ratios exhibited a volcano-like trend between BHMTHF yield and Pd/Ni ratio. Among all catalysts tested, Pd2Ni1/SBA-15 achieved the best performance, converting 99.0 % of HMF to BHMTHF with 96.0 % selectivity, surpassing previously reported catalysts. Additionally, the Pd2Ni1/SBA-15 catalyst maintained excellent stability even after five recycling runs. Catalyst characterizations (e. g., HAADF-STEM) and density functional theory (DFT) calculations confirmed the successful formation of the alloy structure with electron transfer between Ni and Pd, which accounts for the remarkable performance and stability of the catalyst. This work paves the way for developing highly selective and stable alloy catalysts for biomass valorization.

CO2‐Assisted Controllable Synthesis of PdNi Nanoalloys for Highly Selective Hydrogenation of Biomass‐Derived 5‐Hydroxymethylfurfural

AbstractThe selective hydrogenation of 5‐hydroxymethylfurfural (HMF) to 2,5‐bishydroxymethyltetrahydrofuran (BHMTHF), a vital fuel precursor and solvent, is crucial for biomass refining. Herein, we report highly selective and stable PdNi nanoalloy catalysts for this deep hydrogenation process. A CO2‐assisted green method was developed for the controllable synthesis of various bimetallic and monometallic catalysts. The PdNi/SBA‐15 catalysts with various Pd/Ni ratios exhibited a volcano‐like trend between BHMTHF yield and Pd/Ni ratio. Among all catalysts tested, Pd2Ni1/SBA‐15 achieved the best performance, converting 99.0 % of HMF to BHMTHF with 96.0 % selectivity, surpassing previously reported catalysts. Additionally, the Pd2Ni1/SBA‐15 catalyst maintained excellent stability even after five recycling runs. Catalyst characterizations (e. g., HAADF‐STEM) and density functional theory (DFT) calculations confirmed the successful formation of the alloy structure with electron transfer between Ni and Pd, which accounts for the remarkable performance and stability of the catalyst. This work paves the way for developing highly selective and stable alloy catalysts for biomass valorization.

Toward economy hydrogenation: Highly efficient hydrodeoxygenation of guaiacol to cyclohexanol over a CoNi-NC catalyst

Lignin and other underutilized biomass resources have significant potential for producing specific chemicals through hydrogenation. However, current challenges in this field include not only the high cost of catalyst preparation but also the demanding reaction conditions required. In this study, a CoNi-NC alloy catalyst with high specific surface area and mesoporous structure was prepared by calcining Ni-doped ZIF-67 material. The Co3Ni1-NC catalyst achieved complete conversion of guaiacol with a cyclohexanol yield reaching 92.7 %, under conditions of 1.2 MPa H2 pressure and 180 °C reaction temperature. The study found that Co-Ni alloys possess superior hydrogen adsorption activation capability, which is a critical factor affecting the hydrogenation capacity of the catalyst. The prepared Co3Ni1-NC not only significantly reduces the H2 pressure and temperature for the guaiacol hydrodeoxygenation (HDO) reaction but also achieves high-efficiency conversion of guaiacol in water as the primary solvent. This undoubtedly saves costs and reduces environmental impact. The CoNi-NC catalyst also possesses magnetic properties, making it easy to fully recover. Related characterization and cycling experiments have demonstrated that the catalyst has excellent recyclability. These properties of the CoNi-NC catalyst will significantly enhance its economic viability. Furthermore, this catalyst exhibited excellent hydrogenation performance for lignin model compounds, providing a valuable reference for the application of alloy MOFs materials in the hydrogenation of lignin compounds.

A MoNi4(312) surface preferred reconstruction enhancing hydrogen evolution

Nickel-molybdenum (Ni-Mo) alloys have garnered significant attention for superior electrocatalytic hydrogen evolution reaction (HER). Generally, catalysts undergo reconstruction during HER, leading to surface structure evolution, which is crucial for catalytic properties. However, the real electroactive sites and mechanisms underlying the structure evolution of Ni-Mo alloys through the electrochemical process remain unclear. Herein, we propose a Ni-Mo alloy with enriched MoNi4(312) plane exposure after electrochemical reconstruction due to its preferential growth during the HER. The atomic interaction within the MoNi4(312) plane facilitates the electron transfer from Ni to Mo and optimizes the electronic configuration, accelerating the release of gaseous hydrogen and smoothing the HER process. The reconstructed Ni-Mo alloy demonstrates exceptional HER performance, achieving an ultrasmall overpotential of 23 mV at 10 mA cm–2. Additionally, by scaling up the electrode by 8 times, the overpotentials required remain similar to a small electrode. This study provides insights into surface reconstruction and orientational crystal plane design of low-cost transition metal-based alloy catalysts for industrial hydrogen production.

High-Throughput UV-Induced Synthesis and Screening of Alloy Electrocatalysts.

The combination of different elements in alloy catalysts can lead to improved activity as it provides opportunities to tune the electronic structures of surface atoms. However, the synthesis and performance screening of alloy catalysts through a vast chemical space are cost- and labor-intensive. Herein, a UV-induced, high-throughput method is reported for the synthesis and screening of alloy electrocatalysts in a fast and low-cost manner. A platform that integrates 37 mini-reaction-cells enables simultaneous UV-induced photodeposition of alloy nanoparticles with up to 37 compositions. These mini-reaction-cells further allow a transfer-free, high-throughput electrochemical performance screening. Binary (PtPd, PtIr, PdIr), ternary (PtPdIr, PtRuIr) and quaternary (PtPdRuIr) alloys have been synthesized with the activity of the binary alloys (57 compositions) for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) being screened. The predicted high performance of identified alloy compositions are subsequently validated by standard measurements using a rotating disk electrode configuration. It is found that the as-synthesized alloy nanoparticles are rich in twin boundaries and thus possess lattice strain. Density functional theory calculation implies that the high ORR activity of the screened Pt0.75Pd0.25 alloy originates from the interplay between the differentiated adsorption sites because of alloying and the strain-induced modulation of the d-band center.

Catalytic Methane Decomposition on In Situ Reduced FeCo Alloy Catalysts Derived from Layered Double Hydroxides.

Catalytic methane decomposition (CMD) reaction is considered a promising process for converting greenhouse gas CH4 into hydrogen and high-value-added carbon materials. In this work, a series of Al2O3-supported FeCo alloy catalysts were successfully prepared in the CMD process. Compared to the pre-reduced catalysts, the in situ reduced FeCo alloy catalysts showed higher methane conversion rates, with the highest reaching 83% at 700 °C, due to the finer active nanoparticle size and greater exposure of active site. Furthermore, the time-on-stream tests demonstrated that the catalytic activity of in situ reduced FeCo alloy catalysts could remain above 92.3% of the highest catalytic activity after 10 h. In addition, TEM analyses of the carbon products from the CMD in situ reduced catalysts revealed the production of carbon nanofibers and nanotubes several microns in length after the reaction. This indicates that the in situ reduced FeCo alloy catalysts more effectively promoted the growth of carbon nanofibers. These results could provide a viable strategy for future methane decomposition development aimed at producing hydrogen and high-value carbon.

The performance of PdNi alloy catalysts supported on glassy carbon electrode toward formic acid electro-oxidation

In this research, PdNi alloy electrocatalysts with different compositions were prepared using the hydrothermal method and characterized using FE-SEM, EDX, and XRD analyses. The electro-oxidation of formic acid was investigated on the prepared samples using electrochemical techniques. It was observed that the electrocatalytic activity as well as the stability of samples were increased by increasing the Ni content. Among the studied samples, the PdNi4.09 sample exhibited superior electrocatalytic activity with a mass activity of 2982.46 mA/mgPd which was considerably higher than commercial Pd/C catalyst. Additionally, the PdNi4.09 sample was the most effective sample against CO intermediate poisoning. The role of Ni was attributed to the formation of Ni–O or Ni–OH entities near the Pd site that accelerated the oxidation of Pd–CO entities and therefore reduced the poisoning of Pd active sites for formic acid oxidation.

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.