Transition Metal-based Nanomaterials Research Articles

Identifying the dynamic behaviors in complete reconstruction of Co-based complex precatalysts during electrocatalytic oxygen evolution

Transition metal-based nanomaterials have emerged as promising electrocatalysts for oxygen evolution reaction (OER). Considerable research efforts have shown that self-reconstruction occurs on these nanomaterials under operating conditions of OER process. However, most of them undergo incomplete reconstruction with limited thickness of reconstruction layer, leading to low component utilization and arduous exploration of real catalytic mechanism. Herein, we identify the dynamic behaviors in complete reconstruction of Co-based complexes during OER. The hollow phytic acid (PA) cross-linked CoFe-based complex nanoboxes with porous nanowalls are designed because of their good electrolyte penetration and mass transport ability, in favor of the fast and complete reconstruction. A series of experiment characterizations demonstrate that the reconstruction process includes the fast substitution of PA by OH− to form Co(Fe)(OH)x and subsequent potential-driven oxidation to Co(Fe)OOH. The obtained CoFeOOH delivers a low overpotential of 290 mV at a current density of 10 mA cm−2 and a long-term stability. The experiment results together with theory calculations reveal that the Fe incorporation can result in the electron rearrangement of reconstructed CoFeOOH and optimization of their electronic structure, accounting for the enhanced OER activity. The work provides new insights into complete reconstruction of metal-based complexes during OER and offers guidelines for rational design of high-performance electrocatalysts.

Modulating active sites: A-site doped ACu-CeO2 catalyst for efficient CO-SCR of NO

Transition metal-based nanomaterials have gained significant attention as highly active and cost-effective catalysts for the selective catalytic reduction (SCR) of NO with CO. Using a simple wet impregnation method, the catalyst composition and active sites can be modulated. In this paper, we present a novel cerium-based co-solvent catalyst, A-site doped ACu-CeO2 (A = Co, Fe, Mn), for CO-SCR of NO. The doping of A-site elements induces structural changes and enhances catalytic performance. Among the doped catalysts, CoCu-CeO2 exhibits a wide temperature window for operation and high selectivity towards nitrogen, achieving 100% NO conversion at 200 °C. Furthermore, A-site modulation not only promotes electron/ion transfer within the catalyst but also enables uniform and dispersed distribution of the active metal species, particularly copper, in the CoCu-CeO2 catalyst. This provides reaction centers for the selective reduction of NO by CO and enhances the adsorption capacity of the catalyst for NO. The ACu-CeO2 catalyst demonstrates excellent CO-SCR catalytic performance and resistance to vapor. Characterization techniques such as XPS, Raman spectroscopy, and in situ DRIFTS elucidate the reaction mechanism of the ACu-CeO2 cerium-based co-solvate in the CO-SCR reaction. This study furthers our understanding and improvement of catalyst design, while also providing an efficient and straightforward denitrification catalyst for controlling air pollutants.

Novel B-doped FeNi/C alloy nanofibers electrocatalyst for efficient oxygen evolution reaction from water splitting

Industrial-scale water splitting processes will require economical and efficient electrocatalyst materials. Many oxygen evolution electrocatalysts prepared with non-precious metals have been reported. However, transition metal-based nanomaterials experience unavoidable aggregation and low stability in corrosion environments, which substantially reduces their catalytic performance. Herein, we successfully used a simple electrospinning technique followed by carbonation to synthesize a porous B-doped carbon fiber electrocatalyst with embedded B-doped FeNi alloy nanoparticles. To prepare the optimal catalyst sample, 1.05 g PAN, 5.0 mmol H3BO3, 2.5 mmol Fe(NO3)3, and 2.5 mmol Ni(NO3)2 were used as precursors. The electrospun pristine fibers were annealed for 1 h at 800 °C in argon. Its overpotential for oxygen evolution at a current density of 10 mA cm−2 was only 231 mV, and a 60.99 mV·dec−1 Tafel slope was achieved. At this current density, this catalyst exhibits good performance for over 24 h or for more than 1000 CV cycles. This is due to the doping of non-metallic B atoms into the alloy nanoparticles, as well as the support and protection on them by carbon nanofibers. Insight This research provides a more thorough understanding of the preparation and practical application of low-cost and high-efficiency transitional metal alloy based water splitting catalysts.

Recent advances in Fenton and Fenton-like reaction mediated nanoparticle in cancer therapy

Fenton and Fenton like reaction have been well clarified as efficient reactive oxygen species (ROS) sources in tumor, and have been widely developed into a cancer treatment method. Meanwhile, transition metal-based nanomaterials with Fenton or Fenton like reaction characteristics also have been well explored as therapeutic agents for the cancer therapy, mainly in chemo-dynamic and ferroptosis induced cancer therapy. Herein,to summarize recent advances in Fenton and Fenton like reaction mediated nanoparticles for cancer therapy, in this minireview, we first introduced the mechanisms of Fenton and Fenton like reaction and two therapeutic methods based on Fenton and Fenton like reaction, and then we introduced the well-designed nanoparticles with Fenton reaction or Fenton-like reaction characteristics for the cancer therapies. Finally its challenges and perspectives are discussed.

Compositionally modulated FeMn bimetallic skeletons for highly efficient overall water splitting

A brand-new porous and hierarchical nano/micro sheet-to-sheet morphology of FeMnZn/Mn-FeS (FMZS2) electrocatalyst endows optimal intrinsic activity, high specific surface area and favorable conductivity, which delivers great HER/OER performance.

(Digital Presentation) Bismuth and Transition Metal-Doped Bismuth Nanoparticles As Electrochemical Biosensors

Current non-enzymatic electrochemical biosensors rely heavily on transition metal-based nanomaterials, such as Pt, Ni, Co, and Cu, for molecule adsorption and charge transfer. Although high performance (sensitivity and selectivity) was usually demonstrated, these elements are generally toxic, making them less applicable for wearable/in vivo sensors.Two general strategies are approached to address such drawbacks: minimizing their usage without sacrificing the activity and searching for other elements with lower toxicity. In this study, we demonstrated that the overlooked bismuth nanoparticles (NPs) could be used for non-enzymatic electrochemical glucose sensing with comparable performance [1]. Using a laser ablation approach (see Figure 1A), stabilizer-free Bi NPs (~10 nm diameter) were prepared, showing amperometric sensitivity of 127 µA mM−1 cm−2. The synthesis approach also enabled the one-step surface doping of the Bi NPs, producing Ni and Co-doped Bi NPs with an atomic doping ratio of ~10%, and led to further sensitivity boost to 677 and 2326 µA mM−1 cm−2 (see Figure 1B). Kinetic analysis revealed that the oxidation of Bi(III) to Bi(V) species was the key to enabling glucose electrooxidation on Bi NPs. Such results demonstrate the vast potential of the overlooked bismuth in electrochemical biosensing. Figure 1 (A) Top: illustration of the laser ablation approach of preparing Bi and metal-doped Bi NPs; Bottom: TEM images of as-prepared Bi NPs and Co-Bi NPs; (B) Amperometric correlation between glucose concentration and the current density using Bi NPs and Co-Bi NPs as sensors. Reference: Zheng, W.; Li, Y.; Lee, L. Y. S., Bismuth and metal-doped bismuth nanoparticles produced by laser ablation for electrochemical glucose sensing, Sens. Actuators, B 2022, 357, 131334. Figure 1

Metal-Organic Framework-Based Nanomaterials for Electrocatalytic Oxygen Evolution.

Oxygen evolution reaction (OER) is an energy-determined half-reaction for water splitting and many other energy conversion processes, such as rechargeable metal-air batteries and CO2 reduction, due to its four-electron sluggish process. To reduce the energy consumption and cost of these advanced technologies, various transition metal-based nanomaterials, like metal oxides/hydroxides, nitride, and phosphide are synthesized. Among these, metal-organic framework (MOF)-based materials are considered as the ideal candidate for the fabrication of efficient OER electrocatalysts owing to their unique physicochemical properties. In this review, the fundamental catalytic mechanisms and key evaluation parameters of OER in acidic and alkaline media are presented first. Then, design strategies for MOF-based OER catalysts and research progress in the study of the structure-performance relationship are summarized. Subsequently, the recent research advances of MOF-based OER electrocatalysts in alkaline, acidic, and neutral electrolytes are overviewed. Finally, current challenges and future opportunities are provided under the frame of materials design, theoretical understanding, advanced characterization techniques, and industrial applications.

Prospective applications of transition metal-based nanomaterials

Prospective applications of transition metal-based nanomaterials

Recent developments in transition metal-based nanomaterials for supercapacitor applications

Recent developments in transition metal-based nanomaterials for supercapacitor applications

Recent Advances in Transition-Metal Based Nanomaterials for Noninvasive Oncology Thermal Ablation and Imaging Diagnosis.

With the developments of nanobiotechnology and nanomedicine, non-invasive thermal ablation with fewer side effects than traditional tumor treatment methods has received extensive attention in tumor treatment. Non-invasive thermal ablation has the advantages of non-invasiveness and fewer side effects compared with traditional treatment methods. However, the clinical efficiency and biological safety are low, which limits their clinical application. Transition-metal based nanomaterials as contrast agents have aroused increasing interest due to its unique optical properties, low toxicity, and high potentials in tumor diagnosis. Transition-metal based nanomaterials have high conversion efficiency of converting light energy into heat energy, good near-infrared absorption characteristics, which also can targetedly deliver those loaded drugs to tumor tissue, thereby improving the therapeutic effect and reducing the damage to the surrounding normal tissues and organs. This article mainly reviews the synthesis of transition-metal based nanomaterials in recent years, and discussed their applications in tumor thermal ablation and diagnosis, hopefully guiding the development of new transition metal-based nanomaterials in enhancing thermal ablation.

One-step solution combustion synthesis of nanostructured transition metal antiperovskite nitride and alloy

Multicomponent transition metal-based nanomaterials (MTMAs) are of interest to the materials science community because of their structure-tunable properties. However, it is challenging to support the phase stabilization and homogeneous distribution of the constituent elements within a single phase. Herein, we report the successful one-step combustion syntheses of a novel quaternary antiperovskite nitride, (Co0.33Cu0.33Ni0.33)4N, and a ternary CoCuNi alloy as examples of MTMAs. The synthesized nanomaterials have hollow spherical and sponge-like morphologies. We also share the results of a study of the parameters that influence the alloy and nitride phase formation and discuss possible mechanisms for the combustion synthesis of the MTMAs. It was established that the synthesis approach as well as adjusting the environment conditions created through the main synthesis parameters, including molar φ ratio, furnace temperature (Tfurn) and carrier gas flow rate, are the key characteristics responsible for the formation and stabilization of specific phase composition and morphology of the final product. The optimal parameters for the ternary CoCuNi alloy synthesis by sol–gel combustion were φ in the range of 1.25–1.5. The stoichiometric (Co0.33Cu0.33Ni0.33)4N phase stabilizes during a spray combustion synthesis with φ = 3, Tfurn = 900 °C and a flow rate of 4 L/min. The produced alloy possesses a high saturation magnetization of 74 emu/g, while the nitride retains only 11 emu/g. The study of the nitride phase’s hydrogenation reaction showed ∼96 % efficiency of NH3 evolution (3.797 mmol/g).

Inside Front Cover: Anisotropic transition metal–based nanomaterials for biomedical applications (View 4/2021)

Transition metal-based nanoparticles have attracted more and more attention in biomedicine, owing to their special characteristics that arise from finite-size and surface effects, like intense and broad light absorption, strong oxidation ability, catalytic activity, and robust mechanical properties. In article number 20200154, Nan Li, Jinping Wang and their co-workers summarize in detail the mechanism and advantages of three main shape categories of anisotropic transition metal-based nanomaterials in biomedical applications, including one-dimension (1D, e.g., nanowire), two-dimension (2D, e.g., nanosheet), and three-dimension (3D, e.g., nanorod, nanocube, and nanoflower) anisotropic shape. In addition, the critical challenges and prospects of this field will be also proposed and discussed.

Controlled Synthesis and Structure Engineering of Transition Metal-based Nanomaterials for Oxygen and Hydrogen Electrocatalysis in Zinc-Air Battery and Water-Splitting Devices.

Electrocatalytic energy conversion plays a crucial role in realizing energy storage and utilization. Clean energy technologies such as water electrolysis, fuel cells, and metal-air batteries heavily depend on a series of electrochemical redox reactions occurring on the catalysts surface. Therefore, developing efficient electrocatalysts is conducive to remarkably improved performance of these devices. Among numerous studies, transition metal-based nanomaterials (TMNs) have been considered as promising catalysts by virtue of their abundant reserves, low cost, and well-designed active sites. This Minireview is focused on the typical clean electrochemical reactions: hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction. Recent efforts to optimize the external morphology and the internal electronic structure of TMNs are described, and beginning with single-component TMNs, the active sites are clarified, and strategies for exposing more active sites are discussed. The summary about multi-component TMNs demonstrates the complementary advantages of integrating functional compositions. A general introduction of single-atom TMNs is provided to deepen the understanding of the catalytic process at an atomic scale. Finally, current challenges and development trends of TMNs in clean energy devices are summarized.

Engineering transition metal-based nanomaterials for high-performance electrocatalysis

Transition metal (TM) based electrocatalysts attract increasing attention in energy conversion reactions, and current effects focus on material engineering strategies to tailor physicochemical properties of TM based electrocatalysts for improved performance. This review provides a summary about the recent advances of engineering TM based nanomaterials for electrocatalytic reactions, which include hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO 2 reduction reaction (CO 2 RR), and nitrate reduction reaction (NO 3 − RR). We highlight four engineering strategies, namely, size engineering, facet engineering, composition engineering, and crystal structure engineering for TM based electrocatalysts, and pay a special emphasis on exploring the relationship between their physicochemical properties and catalytic activities. We outline the opportunities in this research field, in particular, the strategy of rationally combining in-situ and operando techniques and theoretical predication to design efficient electrocatalysts. Finally, issues that deserve attention and consideration for practical applications are discussed.

Non-noble nanoalloy of Ni0, Cu0 and Fe0 used for hydride transfer reaction for CO2

Carbon dioxide (CO2) emissions from the combustion of fossil fuels cause the intensification of greenhouse effect. Consequently, a new non-noble nanoalloy of Ni0, Cu0 and Fe0 was prepared for the production of formate (HCO2−) from CO2 in flue gas by hydride transfer reaction under atmospheric pressure and mild temperature in this work. Under the optimal reaction conditions obtained by experimental optimization, which were that catalyst dosage was 1 g·L-1, KBH4 concentration was 0.15 mol·L-1, reaction temperature was 55 °C, solution pH was 9.5 and flow velocity of flue gas was 0.5 L min-1, the CO2 conversion efficiency (CCE) was achieved as 55.97 %. Due to the employment of nanoalloy of Ni0, Cu0 and Fe0, the CCE was improved by about 25 % compared with that in non-catalytic conditions, and meanwhile, the KBH4 dosage was reduced by around 45 %. Based on the catalyst properties before and after the reaction as well as the product detection, we put forward that the electrode potential differences among the ternary transition metals resulted in the improvement of catalyst surface activity to promote KBH4 activation and the hydride transfer reaction for CO2. The work presented herein is conducive to the development of novel transition metal-based nanomaterials for CO2 resource utilization in a low-energy way.

Sprout-shaped Mo-doped CoP with maximized hydrophilicity and gas bubble release for high-performance water splitting catalyst

The electrochemical water splitting reaction offers an attractive approach to generate hydrogen fuels as green and renewable energy, in helping ease the global warming and energy crisis, working as a clean energy carrier. In this study, we present the sprout-shaped Mo-doped CoP (denoted CP) as a catalyst for efficient water splitting electrode under alkaline environment. The electrode possesses a unique nanoarray type ‘pillar’ and microscale ‘tip’ structure, which promotes high hydrophilicity and effective gas bubble release, hence achieving a future goal of highly efficient water splitting device for practical use. For both hydrogen and oxygen evolution reaction (HER and OER), the electrode shows remarkable catalytic activity together with reliable stability in alkaline solution, which makes CP a promising electrocatalyst to date. By investigating the gas releasing efficiency regarding various nano/microstructured electrodes, as-prepared CP surpasses the compared samples, indicating maximized nano/microstructures specialized for gas evolution electrode. When the CP performedas an overall water splitting electrode, only 1.49 V of overpotential is needed to achieve the current density of 10 mA·cm−2 and maintained 10 and 200 mA·cm−2 for over 35 h with little degradation of catalytic activity. This work would give inspiration to many investigators who work on optimizing structures of transition metal-based nanomaterials, promoting their applications in other renewable energy options.

Anion Etching for Accessing Rapid and Deep Self-Reconstruction of Precatalysts for Water Oxidation

<h2>Summary</h2> Transition metal-based nanomaterials represent an emerging class of highly active and low-cost precatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, most OER precatalysts undergo slow or incomplete self-reconstructions to generate real active sites, which is a time-consuming process for achieving high OER performance. Thus, we report a new class of OER precatalysts that can achieve highly active OER species by a rapid and deep self-reconstruction (denoted by SELF-RECON). The precatalysts with a core-shell structure comprising NiMoO₄ (core) and NiFe/NiFeO_x nanoparticles in N-doped amorphous carbons (shell) (denoted by NiMoFeO@NC), can realize rapid MoO₄²⁻ dissolution and fast formation of NiOOH with Fe incorporation simultaneously. <i>In situ</i> Raman spectroscopy together with electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests indicate that the obtained NiFeOOH/NiFe-LDH after SELF-RECON behave as the real active species that outperform NiMoFeO@NC, with ultralow overpotentials and extraordinary long-term stability.

Direct growth of holey Fe3O4-coupled Ni(OH)2 sheets on nickel foam for the oxygen evolution reaction

The oxygen evolution reaction (OER) is a half-reaction of water electrolysis, and the OER performance of an electrocatalyst is significantly related to its energy conversion efficiency. Due to their high OER activity, transition metal-based nanomaterials have become potential low-cost substitutes for Ir/Ru-based OER electrocatalysts in an alkaline environment. Herein, holey Fe3O4-coupled Ni(OH)2 sheets (Ni(OH)2-Fe H-STs) were easily achieved by a simple mixed-cyanogel hydrolysis strategy. The two-dimensional (2D) Ni(OH)2-Fe H-STs with ca. 1 nm thickness have a high specific surface area, abundant unsaturated coordination atoms, and numerous pores, which are highly favorable for electrocatalytic reactions. Meanwhile, the introduction of Fe improves the conductivity and regulates the electronic structure of Ni. Due to their special structural features and synergistic effect between the Fe and Ni atoms, Ni(OH)2-Fe H-STs with an optimal Ni/Fe ratio show excellent OER activity in a 1 M KOH solution, which significantly exceeds that of the commercial RuO2 nanoparticle electrocatalyst. Furthermore, Ni(OH)2-Fe H-STs can be grown on nickel foam (NF), and the resulting material exhibits enhanced OER activity, such as a small overpotential of 200 mV and a small Tafel slope of 56 mV dec−1, than that of Ni(OH)2-Fe H-STs without NF.

Synergistic coupling Co3Fe7 alloy and CoFe2O4 spinel for highly efficient removal of 2,4-dichlorophenol by activating peroxymonosulfate.

Efficient wastewater restoration depends on the robustness and capability of the catalyst to promote sophisticated decontamination technologies. In this study, Co3Fe7-CoFe2O4 nanoparticles (NPs) prepared by facile pyrolysis were completely characterized and used to decompose 2,4-dichlorophenol (2,4-DCP). Furthermore, the catalytic performance and relevant mechanisms involved in the activation of peroxymonosulfate (PMS) were also investigated. The optimal conditions were achieved at the catalyst loading of 0.05 g L-1, PMS dosage of 1.26 g L-1, and pH of 7.7 through the response surface methodology by using the Box-Behnken design model. Under optimal conditions, 97.1% efficiency of 2,4-DCP removal was obtained within 30 min. Moreover, the quenching experiments and electron paramagnetic resonance result indicated that sulfate (SO4•-) and hydroxyl (HO•) radicals were considered as the dominant reactive oxygen species, which resulted in the effective removal of 2,4-DCP in the Co3Fe7-CoFe2O4/PMS system. Moreover, Co3Fe7-CoFe2O4 showed efficient catalytic performance in continuous five runs and exhibited less metal leaching of 0.052 and 0.036 mg L-1 for Co and Fe species, respectively. Furthermore, no considerable change was observed in the structural characteristics of the fresh and used Co3Fe7-CoFe2O4 catalytic system. The above-mentioned results indicated that the synergistic effects between Co3Fe7 alloy and CoFe2O4 spinel not only significantly improved the activity and long-term durability of the catalyst, but also accelerated the Co3+/Co2+ and Fe3+/Fe2+ redox cycles. Overall, the Co3Fe7-CoFe2O4/PMS system provides a novel advanced oxidation approach to further develop multifunctional transition metal-based nanomaterials responsible for producing surface-bound radicals and enhancing the remediation of refractory pollutants in the environmental application.

A Ni-P@NiCo LDH core-shell nanorod-decorated nickel foam with enhanced areal specific capacitance for high-performance supercapacitors.

Recently, transition metal-based nanomaterials have played a key role in the applications of supercapacitors. In this study, nickel phosphide (Ni-P) was simply combined with NiCo LDH via facile phosphorization of Ni foam and subsequent electrodeposition to form core-shell nanorod arrays on the Ni foam; the Ni-P@NiCo LDH was then directly used for a pseudocapacitive electrode. Owing to the splendid synergistic effect between Ni-P and NiCo LDH nanosheets as well as the hierarchical structure of 1D nanorods, 2D nanosheets, and 3D Ni foam, the hybrid electrode exhibited significantly enhanced electrochemical performances. The Ni-P@NiCo LDH electrode showed a high specific capacitance of 12.9 F cm-2 at 5 mA cm-2 (3470.5 F g-1 at a current density of 1.3 A g-1) that remained as high as 6.4 F cm-2 at a high current density of 100 mA cm-2 (1700 F g-1 at 27 A g-1) and excellent cycling stability (96% capacity retention after 10 000 cycles at 40 mA cm-2). Furthermore, the asymmetric supercapacitors (ASCs) were assembled using Ni-P@NiCo LDH as a positive electrode and activated carbon (AC) as a negative electrode. The obtained ASCs delivered remarkable energy density and power density as well as good cycling performance. The enhanced electrochemical activities open a new avenue for the development of supercapacitors.