Noble Metal-based Catalysts Research Articles

Hydrothermal synthesis of CeSe anchored on graphitic carbon nitride nanoclusters as an electrocatalyst for enhanced oxygen evolution reaction

The oxygen evolution reaction (OER) is a critical half-reaction in the process of water splitting, yet its practical application is hindered by slow kinetics and the high cost of conventional electrocatalysts. This study explores the potential of a novel CeSe/g-C3N4 nanocomposite as an efficient catalyst for OER in an alkaline environment. The CeSe/g-C3N4 nanocomposite exhibits exceptional electrocatalytic performance, demonstrated by a low overpotential of 196 mV at a current density of 10 mA cm−2 and a reduced onset potential of 1.29 V versus the reversible hydrogen electrode (RHE). Additionally, nanocomposite's Tafel slope of 58.14 mV/dec is significantly lower compared to pure CeSe (76.89 mV/dec) and multi-layered g-C3N4 (89.76 mV/dec), indicating superior kinetic behavior. Remarkably, the CeSe/g-C3N4 composite also demonstrates excellent electrochemical stability, maintaining its performance over a 40-hour period. These findings suggest that the CeSe/g-C3N4 nanocomposite not only enhances the electrocatalytic properties necessary for OER but also holds the potential to outperform traditional noble metal-based catalysts, paving the way for more cost-effective and efficient water-splitting technologies.

C3N4/Se-CNTs as Advanced Metal-Free Catalysts for the Photoassisted Electrocatalytic Oxygen Evolution Reaction.

Photoassisted electrocatalysis is a frontier direction of electrocatalysis for promoting energy conversion. In this work, a metal-free C3N4/Se-CNTs is reported as a novel catalyst for photoassisted electrocatalytic oxygen evolution reaction (OER). C3N4 has an appropriate bandgap, high specific surface area, and long-term stability. CNTs can modulate the electronic environment of C3N4 by strong π-π interaction and greatly enhance the separation efficiency of photogenerated carriers. The distributed Se nanoparticles in CNTs can further increase the charge transfer ability. As a metal-free catalyst, the C3N4/Se-CNTs exhibits an overpotential of 231 mV at a current density of 10 mA cm-2 and a small Tafel slope of 52 mV dec-1 under illumination, which ranks among the best catalysts for photoassisted OER performance, surpassing most noble and transition metal-based catalysts. The result demonstrates the great potential of C3N4-based catalysts in the photoassisted OER process and provides a new perspective to explore the excellent metal-free OER catalysts.

Improving Glycerol Electrooxidation Performance on Nanocubic PtCo Catalysts.

As glycerol (GLY) has emerged as a highly functional and cheap platform molecule and as an abundant biodiesel production byproduct, possible conversion methods have been investigated. One of the promising approaches is the glycerol electrooxidation (GEOR) on noble metal-based catalysts. Although noble metals, especially Pt, are generally very stable at different pH and highly selective toward three-carbon (C3) products, their electrocatalytic performance can be further improved by morphology tuning and alloying with non-noble metals like Co. In the present study, cubic PtxCo100-x (x = 100, 80, and 60) nanoparticles were investigated in an alkaline medium at 20 and 40 °C. The effect of the composition and reaction conditions on the selectivity of the GEOR toward C3 products like lactate and glycerate was studied, and the reaction mechanism was discussed. The highest mass activity was found for Pt80Co20, although when the specific activity, glycerol conversion, and GEOR selectivity were compared, Pt60Co40 was the superior catalyst overall. In general, all catalysts, even those that are Co-rich, exhibited a high C3 product selectivity up to 95% at 0.67 V vs RHE. The low applied potential of 0.67 V vs RHE at 40 °C facilitated lactate formation with selectivity up to 72%. At the same time, the glycerate formation with a selectivity of up to 40%, as well as C-C bond cleavage, was more favored at 0.87 V vs RHE.

Unlocking the Electrocatalytic Behavior of Cu2MnS2 Nanoflake-Anchored rGO for the Oxygen Evolution Reaction in an Alkaline Medium.

A catalyst of the oxygen evolution reaction (OER) that is viable, affordable, and active for effective water-splitting applications is critical. A variety of electrocatalysts have been discovered to replace noble metal-based catalysts. Of these, transition metal-based sulfides are essential for incorporating carbonaceous materials to improve electrical conductivity, resulting in better electrocatalytic performance. Our study illustrates the synthesis of Cu2MnS2 (CMS) nanoflakes and their different rGO composites (10 to 40 wt %) via a hydrothermal technique for an effective water oxidation reaction. The X-ray diffraction pattern reveals that the prepared Cu2MnS2 nanoflakes exhibit a cubic crystal structure. The high-resolution scanning electron microscopy and the high resolution transmission electron microscopy images corroborate the formation of the nanoflake-like morphology of Cu2MnS2 with the strong interaction of rGO. The selected area electron diffraction analysis pattern reveals a polycrystalline nature. The Fourier transform infrared spectrum shows the existence of a metal sulfur vibrational band at 590 cm-1, and Raman analysis infers the presence of rGO. The X-ray photoelectron spectroscopy spectra reveal the oxidation states of the elements present in the samples. Using Brunauer-Emmett-Teller analysis, the surface area of CMS-20 is found to be 117.04 m2/g. The measured OER overpotentials using linear sweep volammetry and the values are 380, 370, 340, 376, and 400 mV at 10 mA/cm2 for CMS, CMS-10, CMS-20, CMS-30, and CMS-40, respectively, and the corresponding Tafel slope values are 179, 158, 149, 206, and 240 mV/decade, respectively. The electrochemical active surface area is estimated using cyclic voltammetry for all of the catalysts, where CMS-20 showed a larger surface area. Also, the same catalyst exhibits good stability for ∼24 h at a constant potential, which is confirmed via chronoamperometry. Thus, combining transition metal-based sulfides with carbonaceous materials indicates improved catalytic behavior for the preparation of high-performance OER electrocatalysts. Overall, the prepared CMS-20 performed as an efficient OER electrocatalyst and can be utilized for practical applications in energy conversion.

Noble metal-free tandem catalysis enables efficient upcycling plastic waste into liquid fuel components

The lack of effective approaches for upcycling waste plastic has led to severe environmental pollution and squandering of carbon resources. While hydrocracking macromolecular polyolefins over typical metal-zeolite catalyst produces high quality liquid fuel components, the limited activity of base metal and restricted accessibility of acid sites within microporous zeolite renders this process still not in practical scale. A tandem catalyst comprising Ni-WO3/Al2O3 and Beta zeolite was developed for consecutive hydrocracking polyolefins, achieving a yield of 86.2 % of primarily gasoline-jet ranged hydrocarbons (mainly C5-C16 and minor C16+) at 280 °C. The incorporation of tungsten species onto Ni/Al2O3 largely enhances the surface acidity and accelerates the primary cracking process that converts polyethylene (PE) into medium-sized intermediates, which would readily diffuse into the pore networks of Beta and undergo further cracking to yield desired liquid hydrocarbons. In addition, this tandem catalyst also promotes facile hydrocracking of consumer-grade plastic waste and maintains excellent stability over 5 recycling tests. The noble-metal-free catalyst achieves an impressive liquid formation rate of 5.74 g·gcat.−1·h−1, rivaling the noble metal-based catalyst and demonstrating high application prospects.

Nanoarchitectonics of vanadium nanoparticles decorated mesoporous carbon nitride in photocatalytic systems: A study on ethylbenzene oxidation reaction

In this work, we have described the synthesis of vanadium (V) nanoparticles (NPs) anchored on mesoporous graphitic carbon nitride (V@mpg-C3N4) and their uses in photocatalytic ethylbenzene oxidation to the respective acetophenones. The mpg-C3N4 serves as the support for the decoration of V NPs, through a simple impregnation method. Various advanced techniques, such as XRD, UV–vis spectrometry, HRTEM, HAADF-STEM, AC-STEM, elemental mapping, and BET surface area analysis, were employed for the characterization of V@mpg-C3N4. The detailed characterization studies reveal that the V@mpg-C3N4 catalyst has a medium band gap (2.78 eV), a high surface area (76.7 m2g−1), and a mesoporous nature. The V@mpg-C3N4 photocatalysts demonstrated excellent performance in the light-assisted oxidation of ethylbenzene, achieving over 99 % conversion and selectivity for acetophenone in an environmentally friendly solvent (water) using a domestic light source (50 W white light). This developed synthesis strategy will be useful for synthesizing various noble and non-noble metal-based catalysts and their applications in organic transformation and environmental remediation.

Photocatalytic Acetylene Hydrochlorination by Pairing Proton Reduction and Chlorine Oxidation over g-C3N4/BiOCl Catalysts.

Acetylene hydrochlorination is a vital industrial process for the manufacture of vinyl chloride monomer (VCM). Current thermocatalytic acetylene hydrochlorination requires toxic mercury-based or costly noble metal-based catalysts, high temperatures (≥180 °C) and excessive gaseous HCl. Here, we report a room-temperature photocatalytic acetylene hydrochlorination strategy involving concurrent coupling of electron-driven proton reduction (*H) and hole-driven chloride oxidation (*Cl) on photocatalyst surfaces. Under simulated solar light illumination, the developed noble-metal-free g-C3N4/BiOCl photocatalysts show a considerably high VCM production rate of 1198.6 μmol g-1 h-1 and a high VCM selectivity of 95% in a 0.1 M HCl aqueous solution. Even in chloride-rich natural seawater and acidified natural seawater, the VCM production rates of g-C3N4/BiOCl photocatalysts are up to 170.3 μmol g-1 h-1 with a VCM selectivity of 80.4% and 1247.7 μmol g-1 h-1 with a VCM selectivity of 94.7%, respectively. Moreover, with sunlight irradiation and acidified natural seawater, the g-C3N4/BiOCl photocatalysts in a large-scale photosystem retain outstanding acetylene hydrochlorination performance over 10 days of operation. The radical scavenging, in situ photochemical Fourier transform infrared spectroscopy, theoretical simulations, and control experiments reveal that active *Cl and *H play key roles in photocatalytic acetylene hydrochlorination via a possible reaction pathway of C2H2 → *C2H2 → *C2H2Cl → *C2H3Cl → C2H3Cl. With respect to sustainability and low cost, this photocatalytic acetylene hydrochlorination offers excellent advantages over conventional thermocatalytic hydrochlorination technologies.

Manipulation in local coordination of platinum single atom enables ultrahigh mass activity toward hydrogen evolution reaction

Atomic-engineering of noble metal into single-atom electrocatalysts with well-defined active sites has been considered as an effective approach to enhance the mass-activity towards hydrogen evolution reaction (HER), crucial for the practical implementation of this sustainable technology. Herein, we devise a metallic-coordination strategy via a facile one-step pyrolysis method, for the atomic isolation of a small amount of platinum (Pt, 0.45 wt%) atoms in the surface of nickel (Ni) nanoparticles (Pt1@Ni) encapsulated into nitrogen-doped carbon nanotubes (Pt1@Ni/NCNT). Such a Pt1@Ni/NCNT single-atom alloy catalyst exhibits a record-high and all-round superior HER performance including mass-activity (up to 350.7 A mgPt−1@η150), stability (>50 h at 100 mA cm−2), pH-tolerance by comparison with Pt1@NC. Our density functional theory calculations combined with in situ Raman spectroscopic studies reveal a synergistic dual-active-site catalytic mechanism, involving the fast hydrogen spillover effect on coordinated Ni supports and accelerated water dissociation in acidic and alkaline medium, respectively. A strong electronic hybridization of 5d orbital of alloyed Pt and 3d orbital of Ni atoms modulates the d band center of Pt, which not only boosts HER activity but also stabilizes Pt single atoms. Due to the double protecting strategy from strong anchoring effect in Ni support and chemically stable NCNT shell, a robust stability is achieved for Pt1@Ni/NCNT hierarchal catalyst. Our findings open up a new avenue to substantially tailor the activity of surface Pt atoms for the design of highly efficient and durable noble metal-based catalysts.

Nickel-based hydroxide composite as electrocatalyst for hydrogen evolution reaction

The development of earth-abundant transition-metal-based electrocatalysts for hydrogen evolution reaction (HER) is commercial. In this work, Fe (Co) and Ni hydroxide nanocomposites on Ni foam were synthesized as HER catalyst, FeNi-LDH/NF has the overpotentials of 291 mV at 50 mA cm−2 and 369 mV at 100 mA cm−2. It is found that FeNi-LDH/NF and CoNi-LDH/NF have large Cdl and ECSA, low Rct. Therefore, this simple method to prepare FeNi-LDH/NF and CoNi-LDH/NF can enhance the properties of electrocatalysts, which make FeNi-LDH/NF and CoNi-LDH/NF a promising material to replace noble metal-based catalysts.

Boron-doped diamond composites for durable oxygen evolution

The urgent need to develop efficient, durable, and cost-effective oxygen evolution reaction (OER) catalysts for energy conversion and storage has prompted extensive research. Currently available commercial noble metal-based OER catalysts are expensive and exhibit limited long-term stability. In this study, boron-doped diamond composites (BDDCs) consisting of CoFe and CoFe2C nanoparticles supported by boron-doped diamond (BDD) particles have been prepared. The BDDC catalyst, prepared through a straightforward annealing process, exhibits exceptional durability (up to 72 h at 10 mA cm−2), a low overpotential (306 mV at 10 mA cm−2), and modest Tafel slope (58 mV dec-1). The coherent interfaces between CoFe/CoFe2C nanoparticles and the BDD substrate are essential for enhancing the OER performance. The fabrication method and composite structures presented in this study may facilitate the design and production of promising catalysts.

Hydrogenation of inert aromatic compounds under mild conditions catalyzed by confined trimetal sites in porous metal silicate materials

Complete hydrogenation of aromatic compounds is an important subject in various industry fields. However, due to the high stabilization energy of aromatic compounds resulting from their high aromaticity and non-polarity, the hydrogenation reaction is usually performed under harsh reaction conditions in the presence of noble metal-based catalysts. We report herein a porous metal silicate (PMS) material PMS-58, which consists of Cu, Ce and Co trimetal active sites, demonstrating high catalytic activity and selectivity in hydrogenating of a series of aromatic compounds under mild conditions (60 °C and 0.5 MPa H2). PMS-58 is superior to the previously reported non-noble metal-based catalysts and could be favorably compared to noble metal-based catalysts. The unique catalytic properties of PMS-58 are derived from the synergistic work of trimetal sites with Ce species serving as strong Lewis acid sites for dissociation of dihydrogen, Co species stabilizing Cu(I) species, and Cu(I) species playing a crucial role in activating aromatic rings. Therefore, this work provides a new approach in developing highly efficient non-noble metal catalysts for complete hydrogenation of arenes under mild conditions, which could be applied in removal of aromatic compounds in petroleum products.

Converting inert MOF into ultrafine CoOx particles embedded on N-doped hierarchical carbon as robust catalyst for nitrophenol wastewater management under ambient conditions

Developing metal oxide catalysts with comparable activity to precious metals has become a hot but challenging area of research for wastewater purification. Herein, CoOx particles and nitrogen co-doped carbon with a hierarchical structure were designed and synthesized via a temperature-controlled pyrolysis strategy using inert Co-based metal–organic frameworks (Co-MOFs) as precursors. Unlike traditional methods, the exquisite pyrolysis of the Co-MOF at 400 °C enabling the CoOx particles with an average diameter of 6.8 nm to uniformly disperse, thus facilitating the formation of the optimized CoOx/CN-400 composite. Benefiting from the unique morphology and composition, CoOx/CN-400 exhibited improved redox property and exceptional activity for the reduction of nitrophenol to form the corresponding aminophenol compounds. The complete conversion of 4-nitrophenol over CoOx/CN-400 requires only 35 min with a rate constant of 0.12 min−1, which is significantly higher than that of most non-noble metal catalysts and approaching some of the noble metal-based catalysts. Furthermore, leveraging the embedded CoOx particles, CoOx/CN-400 maintains its high catalytic efficiency even after six successive cycles, demonstrates an outstanding long-term catalytic capability and reusability. Finally, the mechanisms of 4-NP reduction have been hypothesized based on the combination of characterization and DTF calculations.

Unravelling the potential of prussian blue analogues in oxygen electrocatalysis: A perspective on surface reconstruction

Prussian blue analogues (PBAs) hold promises as catalysts for electrochemical energy conversion, especially in the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Their high surface area and porosity combined with a tunable electronic structure featuring abundant metallic centers, make them attractive alternatives to traditional noble metal-based catalysts. Amongst these fascinating properties, the capacity for surface reconstruction to form active layers is one of the most sought-after characteristics of PBAs for enhanced activity. Recent advancements in operando and in situ techniques have further highlighted PBAs' capability for surface reconstruction during the electrocatalysis, particularly in alkaline solutions. State-of-the-art strategies for enhancing activity and stability of PBA-based catalysts, such as metal doping, tuning metal centers, introducing coordination sphere vacancies (VFeCN), and utilizing carbon supports, are closely linked to their ability towards surface reconstruction. However, key aspects warrant further exploration to achieve high electrocatalytic activity, including identifying initiators and pathways for surface reconstruction, establishing structure-property-activity correlations, and strategically manipulating in-situ catalyst surface reconstruction. This perspective focuses on understanding the transformation of PBA-based pre-catalysts to surface active layers on catalysts via surface reconstruction. A recent progress in PBA-catalysts towards advancing the electrochemical energy systems is highlighted. This perspective will guide the new entrants in the field to understand the process of surface transformation for establishing structure-property-activity relationships and thus to develop highly efficient PBA-based electrocatalysts.

Al-Ni-Co decagonal quasicrystal application as an energy-effective catalyst for phenylacetylene hydrogenation

Intermetallic catalysts, including quasicrystals, are considered a sustainable alternative to noble metal-based catalysts in hydrogenation reactions. This study discusses the manufacturing and catalytic potential of an Al-Ni-Co quasicrystalline alloy. Energy-effective and simple catalyst production was provided by a melt-spinning process. The obtained ribbons, characterized in terms of microstructure, phase and chemical composition using X-ray diffraction, scanning and transmission microscopy methods, were composed of a decagonal quasicrystalline phase with traces of crystalline phases. The form of the melt-spun ribbons ensured easy application in the phenylacetylene hydrogenation reaction. The catalyst provided a substrate conversion of approximately 80% and a styrene selectivity of 54% after 1 h of reaction carried out under mild conditions. The repeatability of the reaction course was verified, with a maximum deviation of 10%. Moreover, the catalyst recovered after the reaction was evaluated in terms of its phase composition and surface changes. X-ray diffractograms confirmed the phase stability, however, the surface degradation and oxidation occurred. The catalytic activity after three months of catalyst storage is also discussed.

Study of photocatalytic degradation of dyeing wastewater with CdS nanoparticles anchored on cotton short staple-based carbon aerogels

The photocatalytic technology is widely recognized as an effective solution for both the energy crisis and environmental issues. Developing cost-effective alternatives to noble metal-based photocatalytic catalysts is crucial for the degradation of organic pollutants in dye wastewater; however, it remains a challenging task. In this study, a novel approach was presented, wherein a cotton-based carbon aerogel was synthesized using short staple cotton cellulose as the raw material. CdS nanoparticles were then anchored onto the three-dimensional porous structure of the carbon aerogel. The resulting materials were thoroughly characterized and analyzed using various techniques, including XRD, SEM, Mapping, XPS, BET, and UV-Vis spectroscopy, and their performance was extensively assessed. Experimental results indicated that the degradation efficiency of 20 ml (15 mg/L) methylene blue solution reached 95.7 % within 90 min, achieving near-complete degradation within 120 min using 10 mg catalyst material. Furthermore, photocatalytic degradation experiments were conducted on commonly used reactive red dye (K-type) and reactive yellow dye (M-type) that are typically employed in textile dyeing and finishing processes. For 20 ml of waste liquid, after 90 min, the degradation rates of the reactive red and yellow dyes reached 91.4 % and 94.4 %, respectively, with complete degradation achieved within 120 min. Free radical quenching experiments demonstrated that hydroxyl radicals (•OH) and superoxide radicals (•O2-) played a central role in mediating the photocatalytic degradation of organic pollutants using the CdS/carbon aerogel (CdS/CA) composite material. Overall, the research findings suggest that the CdS/CA composite material exhibited highly desirable attributes, effectively adsorbing and photodegrading methylene blue as well as organic dyes in dye wastewater. These results provide valuable insights for the development of cost-effective photocatalytic materials and the efficient degradation of dyes.

Catalytic activity of Zr/CeO2-Al2O3 catalyst for diesel soot oxidation: synthesis, characterization, and performance evaluation.

Diesel soot is a significant contributor to air pollution. Soot particles present in diesel engine exhaust have a negative impact on the environment and human health. Diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs) currently use noble metal-based catalysts for soot oxidation. Due to the use of noble metals in the catalyst, the cost of diesel after-treatment systems is steadily rising. As a result, diesel vehicles have become commercially less viable than gasoline vehicles and electronic vehicles. The study focuses on an alternative diesel oxidation catalyst with efficiency similar to that of a noble metal catalyst but with a much lower cost. CeO2-Al2O3 catalysts are known for their oxygen storage capacity and high redox activity, making them suitable for soot oxidation. Adding Zr to these catalysts has been shown to influence their structural and chemical properties, significantly affecting their catalytic behavior. Therefore, the current study is focused on using Zr/CeO2-Al2O3 as a substitute for noble metal-based catalysts to enhance its performance for diesel soot oxidation in automotive exhaust. Evaporation-induced self-assembly (EISA) was used to prepare 1, 3, and 5 weight (wt) % Zr supported mesoporous CeO2-Al2O3 catalysts. Morphological, structural, and physicochemical properties of the synthesized catalysts were examined using Brunauer-Emmett-Teller (BET) absolute isotherm, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Temperature programmed reduction (TPR), and Temperature-programmed desorption of ammonia (NH3-TPD). XRD, BET, and SEM data confirmed that the catalysts were mesoporous and low-crystalline with a high surface area. The soot oxidation activity of the catalysts was evaluated using a thermogravimetric analysis (TGA) technique. The loose contacts soot oxidation activity test suggested that 50% oxidation of soot occurred at 390°C in the absence of a catalyst. T50 of CeO2-Al2O3 catalyzed soot oxidation was 296°C. Adding Zr to the catalyst significantly improved catalytic activity for diesel soot oxidation. We observed a further drastic change in T50 of soot over 1, 3, and 5% Zr/CeO2-Al2O3, which were 220°C, 210°C, and 193°C, respectively. According to these results, incorporating Zr into the CeO2-Al2O3 catalyst significantly improved the oxidation process of soot.

In Situ Growth of Mn-Co3O4 on Mesoporous ZSM-5 Zeolite for Boosting Lean Methane Catalytic Oxidation

The low-temperature oxidation of methane gas in coal mine exhaust gas is important for reducing the greenhouse effect and protecting the environment. Unfortunately, the carbon–hydrogen bonds in methane molecules are highly stable, requiring higher reaction temperatures to achieve effective catalytic oxidation. However, metal oxide-based catalysts face the problem of easy sintering and the deactivation of active components at high temperatures, which is an important challenge that catalysts need to overcome in practical applications. In this work, a series of Mn-Co3O4 active components were grown in situ on ZSM-5 zeolite with mesoporous pore structures treated with an alkaline solution via a hydrothermal synthesis method. Due to the presence of polyethylene glycol as a structure-directing agent, manganese can be uniformly doped into the Co3O4 lattice. The large specific surface area of ZSM-5 zeolite allows the active component Mn-Co3O4 to be uniformly dispersed, effectively preventing the sintering and growth of active component particles during the catalytic reaction process. It is worth mentioning that the Mn-Co3O4/meso-ZSM-5-6.67 catalyst has a methane conversion rate of up to 90% at a space velocity of 36,000 mL·g−1·h−1 and a reaction temperature of 363 °C. This is mainly due to the mesoporous ZSM-5 carrier with a high specific surface area, which is conducive to the adsorption and mass transfer of reaction molecules. The active component has an abundance of oxygen vacancies, which is conducive to the activation of reaction molecules and enhances its catalytic activity, which is even higher than that of noble metal-based catalysts. The new ideas for the preparation of metal oxide-based low-temperature methane oxidation catalysts proposed in this work are expected to provide new solutions for low-temperature methane oxidation reactions and promote technological progress in related fields.

Sub-2 nm Microstrained High-Entropy-Alloy Nanoparticles Boost Hydrogen Electrocatalysis.

High-entropy alloys (HEAs) confine multifarious elements into the same lattice, leading to intense lattice distortion effect. The lattice distortion tends to induce local microstrain at atomic level and thus affect surface adsorptions toward different adsorbates in various electrocatalytic reactions, yet remains unexplored. Herein, this work reports a class of sub-2nm IrRuRhMoW HEA nanoparticles (NPs) with distinct local microstrain induced by lattice distortion for boosting alkaline hydrogen oxidation (HOR) and evolution reactions (HER). This work demonstrates that the distortion-rich HEA catalysts with optimized electronic structure can downshift the d-band center and generate uncoordinated oxygen sites to enhance the surface oxophilicity. As a result, the IrRuRhMoW HEA NPs show a remarkable HOR kinetic current density of 8.09mA µg-1 PGM at 50mV versus RHE, 8.89, 22.47 times higher than those of IrRuRh NPs without internal strain and commercial Pt/C, respectively, which is the best value among all the reported non-Pt based catalysts. IrRuRhMoW HEA NPs also display great HER performances with a turnover frequency (TOF) value of 5.93 H2 s-1 at 70mV versus RHE, 4.6-fold higher than that of Pt/C catalyst, exceeding most noble metal-based catalysts. Experimental characterizations and theoretical studies collectively confirm that weakened hydrogen (Had) and enhanced hydroxyl (OHad) adsorption are achieved by simultaneously modulating the hydrogen adsorption binding energy and surface oxophilicity originated from intensified ligand effect and microstrain effect over IrRuRhMoW HEA NPs, which guarantees the remarkable performances toward HOR/HER.

Dilute RuCo Alloy Synergizing Single Ru and Co Atoms as Efficient and CO-Resistant Anode Catalyst for Anion Exchange Membrane Fuel Cells.

Ruthenium (Ru) is considered a promising candidate catalyst for alkaline hydroxide oxidation reaction (HOR) due to its hydrogen binding energy (HBE) like that of platinum (Pt) and its much higher oxygenophilicity than that of Pt. However, Ru still suffers from insufficient intrinsic activity and CO resistance, which hinders its widespread use in anion exchange membrane fuel cells (AEMFCs). Here, we report a hybrid catalyst (RuCo)NC+SAs/N-CNT consisting of dilute RuCo alloy nanoparticles and atomically single Ru and Co atoms on N-doped carbon nanotubes The catalyst exhibits a state-of-the-art activity with a high mass activity of 7.35 A mgRu -1. More importantly, when (RuCo)NC+SAs/N-CNT is used as an anode catalyst for AEMFCs, its peak power density reaches 1.98 W cm-2, which is one of the best AEMFCs properties of noble metal-based catalysts at present. Moreover, (RuCo)NC+SAs/N-CNT has superior long-time stability and CO resistance. The experimental and density functional theory (DFT) results demonstrate that the dilute alloying and monodecentralization of the exotic element Co greatly modulates the electronic structure of the host element Ru, thus optimizing the adsorption of H and OH and promoting the oxidation of CO on the catalyst surface, and then stimulates alkaline HOR activity and CO tolerance of the catalyst.

Magnetic cobalt metal organic framework for photocatalytic water splitting hydrogen evolution

Using water as a renewable and safe energy source for hydrogen generation has reduced the need to use toxic fossil fuels. Photocatalytic approaches provide a worthy solution to avoid the high expenditure on complicated electrochemical pathways to promote Hydrogen Evolution Reactions. However, several types of photocatalysts including noble metal-based catalysts have already been in use for this purpose, which are generally considered high-cost as well. The present study aims to use the benefits of metal–organic frameworks (MOFs) with semiconductor-like characteristics, highly porous structures and high design flexibility. These properties of MOFs allow more efficient and effective mass transport as well as exposure to light.in this paper, using MOF technology and benefiting from the characteristics of Fe3O4 nanoparticles as catalyst support for more efficient separation of catalyst, we have synthesized a novel composite. Our proposed photocatalyst demonstrates efficient harvest of light in all wavelengths from UV to visible to generate electron/hole pairs suitable for water splitting with a turnover frequency of 0.222 h−1 at ambient conditions without requiring any additives.Graphical abstract