Electrocatalytic Applications Research Articles

Synthesis of Solvent-Mediated Morphology-Controlled PdSn Alloy Nanocatalysts and their Application in Electrocatalysis of Ethylene Glycol and Ethanol.

2D nanodendrites (NDs) and nanosheets (NSs) have been regarded as efficient nanocatalysts for enhancing the electrocatalytic performance due to their low coordinated sites and abundant electrocatalytic centers. Nevertheless, it remains challenging to construct advanced NDs and NSs in a single reaction system. Herein, by tuning the volume ratios of mixed solvents, the reduction and diffusion rate of Sn2+ on Pd NSs template was rationally controlled to prepare PdSn NDs and PdSn NSs. Ascribed to the open 2D nanostructure, high specific surface area, and robust synergistic effect, the as-prepared PdSn NDs and PdSn NSs exhibited distinguished electrocatalytic activities for ethylene glycol oxidation reaction (EGOR) and ethanol oxidation reaction (EOR), as well as commendable electrocatalytic durability, which were far superior to the Pd NSs and commercial Pd/C. In addition, the PdSn NDs exhibited enhanced reaction kinetics because the characteristic branch structure exposed a high density of active sites. This work may provide significant guidance for preparing excellent nanocatalysts with various morphological features by simply optimizing the content of the coexisting solvents.

Palladium‐Boride Nanoflowers with Controllable Boron Content for Formic Acid Electrooxidation

AbstractThe rational design of the electronic structure and elemental compositions of anode electrocatalysts for formic acid electrooxidation reaction (FAOR) is paramount for realizing high‐performance direct formic acid fuel cells. Herein, palladium‐boride nanoflowers (Pd‐B NFs) with controllable boron content are rationally designed via a simple wet chemical reduction method, utilizing PdII‐dimethylglyoxime as precursor and NaBH4 as both reductant and boron source. The boron content of Pd‐B NFs can be regulated through manipulation of reaction time, accompanying with the crystal phase transition from face‐centered cubic to hexagonal close‐packed within the parent Pd lattice. The obtained Pd‐B NFs exhibit increased FAOR mass and specific activity with increasing boron content, showcasing remarkable inherent stability and anti‐poisoning capability compare to commercial Pd and platinum (Pt) nanocrystals. Notably, the sample reacted for 12 h reveals high FAOR specific activity (31.5 A m−2), which is approximately two times higher than the commercial Pd nanocrystals. Density functional theory calculations disclose that the d‐sp orbital hybridization between Pd and B modifies surface d‐band properties of Pd, thereby optimizing the adsorption of key intermediates and facilitating FAOR kinetics on the Pd surface. This study paves the way toward the utilization of metal boride‐based materials with simple synthesis methods for various electrocatalysis applications.

Electrocatalytic Applications of Carbon Dots and Their Composites

AbstractCarbon dots (CDs) have attracted much attention in the field of electrocatalysis due to their many advantages. These reactions are of great significance for energy conversion and storage, as well as environmental remediation. In this review, we summarize the latest achievements in the electrochemical applications of CDs and their composites, with a focus on environmentally relevant electrocatalysis. We present some representative examples of CDs‐based electrocatalysts for different reactions and analyze the catalytic mechanisms and the factors that affect the electrocatalytic performance. Furthermore, we conclude with some challenging issues and future perspectives of this emerging material. This review aims to help readers better understand the application of CDs in the field of electrocatalysis, reveal the reasons that affect electrocatalytic performance, and guide further constructing more efficient, stable, and green electrocatalysts.

Bagasse derived N-doped graphitic carbon encapsulated cobalt nanoparticles as an efficient bifunctional catalyst for water splitting reactions

The utilization of non-precious metal-based electrodes to unlock cost-effective and scalable processes for the production of clean energy is highly desirable. Herein, we reported a straightforward hydrothermal carbonization method for the synthesize of nitrogen-doped graphitic carbons integrated with cobalt (Co@NGC-600, Co@NGC-700, and Co@NGC-800) from sugarcane bagasse and their electrocatalytic applications in oxygen and hydrogen evolution reactions. The graphitic nature of the Co integrated N-doped carbon materials was confirmed by Raman and XPS analysis. FESEM and HRTEM analysis confirms the dispersion of Co on N-doped carbon nanosheets. The Co@NGC-800 catalyst shows low overpotential and Tafel slope, requiring only 304mV (84.1mV dec-1) for oxygen electrode and 234mV (118mV dec-1) for HER at a current density of 10mAcm-2. Moreover, Co@NGC-800 materials showed better activity than Co@NGC-700, Co Co@NGC-600, and Co@NC. The active Co@NGC-800 bifunctional electrocatalysts pair contributes to the fabrication of a water electrolyser with a 10mA/cm2 current density at 1.68V. The Co@NGC-800 // Co@NGC-800 electrocatalyst exhibits good stability over a period of 24h. with negligible potential aberration during the process of water splitting. The electrocatalytic performance of the prepared catalyst in a 1.0M KOH solution exhibits admirable bifunctional activity and remarkable stability. In fact, it outperforms cobalt-based and carbon-supported electrocatalysts, including highly valued commercial catalysts like IrO2 and Pt@C. The solar cell configuration, utilizing the energetic bifunctional Co@NGC-800 electrocatalyst, can continuously generate hydrogen and oxygen. The overall water-splitting process of Co@NGC-800 catalyst delivered at a cell voltage of 1.68V, enabling sustained and efficient oxygen and hydrogen evolution at a large scale.

Defect-rich PdCo bimetallene constructed by a self-reduction strategy for enhanced ethanol oxidation reaction

Direct ethanol fuel cells have garnered considerable attention owing to their minimal pollution, high energy density and diverse fuel sources. However, the slow anodic ethanol oxidation reaction has limited its large-scale application. In this work, the green self-reduction method of Co2(CO)8 as precursor and reducing agent is used to design PdCo bimetallene for ethanol oxidation reaction. The ultra-thin porous nanosheet structure of PdCo bimetallene leads to its abundant defects, facilitating increased active sites and enhanced electrical conductivity. The findings demonstrate substantial enhancements in both the activity and stability of the catalyst. The mass activity of PdCo bimetallene reached 1.58 A mg−1, marking a 2.8-fold increase compared to Pd black. Moreover, the catalyst maintained no less than 98% of the initial current over five consecutive 4000 s chronoamperometric tests, highlighting its remarkable stability. This work provides a green self-reduction synthesis strategy for the preparation of defect-rich bimetallene for ethanol electrocatalytic applications.

Silica-Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review.

Silica-derived nanostructured catalysts (SDNCs) are a class of materials synthesized using nanocasting and templating techniques, which involve the sacrificial removal of a silica template to generate highly porous nanostructured materials. The surface of these nanostructures is functionalized with a variety of electrocatalytically active metal and non-metal atoms. SDNCs have attracted considerable attention due to their unique physicochemical properties, tunable electronic configuration, and microstructure. These properties make them highly efficient catalysts and promising electrode materials for next generation electrocatalysis, energy conversion, and energy storage technologies. The continued development of SDNCs is likely to lead to new and improved electrocatalysts and electrode materials. This review article provides a comprehensive overview of the recent advances in the development of SDNCs for electrocatalysis and energy storage applications. It analyzes 337,061 research articles published in the Web of Science (WoS) database up to December 2022 using the keywords "silica", "electrocatalysts", "ORR", "OER", "HER", "HOR", "CO2RR", "batteries", and "supercapacitors". The review discusses the application of SDNCs for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO2RR), supercapacitors, lithium-ion batteries, and thermal energy storage applications. It concludes by discussing the advantages and limitations of SDNCs for energy applications.

Flower-like NiCo2O4 spinel microspheres for efficient chlorine evolution under neutral conditions

Dimensional stability anodes (DSA), constructed using noble metal oxides like RuO2 and IrO2, is widely used in industrial chlorine production. The DSA electrode demonstrates exceptional chlorine evolution capabilities in acidic solutions and high-chloride concentrations. However, under neutral conditions, its chlorine evolution efficiency diminishes significantly. In this paper, a low-cost, high-efficiency 3D flower-like NiCo2O4 catalyst was fabricated that exhibits high catalytic activity in neutral sodium chloride solutions. The 3D flower-like NiCo2O4 catalyst exhibits good chlorine evolution efficiency, achieving 90 % at 30 mA/cm2 in NaCl solutions. Furthermore, it's chlorine evolution efficiency of the electrocatalyst surpasses that of commercial DSA electrode at various current densities, making it a highly promising candidate for electrocatalytic applications.

Recent Developments in Two-Dimensional Carbon-Based Nanomaterials for Electrochemical Water Oxidation: A Mini Review

Water splitting is considered a renewable and eco−friendly technique for future clean energy requirements to realize green hydrogen production, which is, to a large extent, hindered by the oxygen evolution reaction (OER) process. In recent years, two−dimensional (2D) carbon−based electrocatalysts have drawn sustained attention owing to their good electrical conductivity, unique physicochemical properties, and excellent electrocatalytic performance. Particularly, it is easy for 2D carbon−based materials to form nanocomposites, which further provides an effective strategy for electrocatalytic applications. In this review, we discuss recent advances in synthetic methods, structure−property relationships, and a basic understanding of electrocatalytic mechanisms of 2D carbon−based electrocatalysts for water oxidation. In detail, precious, non−precious metal−doped, and non−metallic 2D carbon−based electrocatalysts, as well as 2D carbon−based confined electrocatalysts, are introduced to conduct OER. Finally, current challenges, opportunities, and perspectives for further research directions of 2D carbon−based nanomaterials are outlined. This review can provide significant comprehension of high−performance 2D carbon−based electrocatalysts for water-splitting applications.

Synthesis and Unique Behaviors of High-Purity HEA Nanoparticles Using Femtosecond Laser Ablation.

High-entropy alloys (HEAs) are a class of metal alloys consisting of four or more molar equal or near-equal elements. HEA nanomaterials have garnered significant interest due to their wide range of applications, such as electrocatalysis, welding, and brazing. Their unique multi-principle high-entropy effect allows for the tailoring of the alloy composition to facilitate specific electrochemical reactions. This study focuses on the synthesis of high-purity HEA nanoparticles using the method of femtosecond laser ablation synthesis in liquid. The use of ultrashort energy pulses in femtosecond lasers enables uniform ablation of materials at significantly lower power levels compared to longer pulse or continuous pulse lasers. We investigate how various femtosecond laser parameters affect the morphology, phase, and other characteristics of the synthesized nanoparticles. An innovative aspect of our solution is its ability to rapidly generate multi-component nanoparticles with a high fidelity as the input multi-component target material at a significant yielding rate. Our research thus focuses on a novel synthesis of high-entropy alloying CuCoMn1.75NiFe0.25 nanoparticles. We explore the characterization and unique properties of the nanoparticles and consider their electrocatalytic applications, including high power density aluminum air batteries, as well as their efficacy in the oxygen reduction reaction (ORR). Additionally, we report a unique nanowire fabrication phenomenon achieved through nanojoining. The findings from this study shed light on the potential of femtosecond laser ablation synthesis in liquid (FLASiL) as a promising technique for producing high-purity HEA nanoparticles.

Titanium Dioxide and N-Doped Carbon Hybrid Nanofiber Modulated Ru Nanoclusters for High-Efficient Hydrogen Evolution Reaction Electrocatalyst.

The designing and fabricating highly active hydrogen evolution reaction (HER) electrocatalysts that can superior to Pt/C is extremely desirable but challenging. Herein, the fabrication of Ru/TiO2/N-doped carbon (Ru/TiO2/NC) nanofiber is reported as a novel and highly active HER electrocatalyst through electrospinning and subsequent pyrolysis treatment, in which Ru nanoclusters are dispersed into TiO2/NC hybrid nanofiber. As a novel support, experimental and theoretical calculation results reveal that TiO2/NC can more effectively accelerate water dissociation as well as optimize the adsorption strength of *H than TiO2 and NC, thus leading to a significantly enhanced HER activity, which merely requires an overpotential of 18mV to reach 10mAcm-2, outperforming Pt/C in an alkaline solution. The electrolytic cell composed of Ru/TiO2/NC nanofiber and NiFe LDH/NF can generate 500 and 1000mAcm-2 at voltages of 1.631 and 1.753V, respectively. Furthermore, the electrolytic cell also exhibits remarkable durability for at least 100h at 200mAcm-2 with negligible degradation in activity. The present work affords a deep insight into the influence of support on the activity of electrocatalyst and the strategy proposed in this research can also be extended to fabricate various other types of electrocatalysts for diverse electrocatalytic applications.

Two-Dimensional Layered Heterojunctions for Photoelectrocatalysis.

Two-dimensional (2D) layered nanomaterial heterostructures, arising from the combination of 2D materials with other low-dimensional species, feature a large surface area to volume ratio, which provides a high density of active sites for catalytic applications and for (photo)electrocatalysis (PEC). Meanwhile, their electronic band structure and high electrical conductivity enable efficient charge transfer (CT) between the active material and the substrate, which is essential for catalytic activity. In recent years, researchers have demonstrated the potential of a range of 2D material interfaces, such as graphene, graphitic carbon nitride (g-C3N4), metal chalcogenides (MCs), and MXenes, for (photo)electrocatalytic applications. For instance, MCs such as MoS2 and WS2 have shown excellent catalytic activity for hydrogen evolution, while graphene and MXenes have been used for the reduction of carbon dioxide to higher value chemicals. However, despite their great potential, there are still major challenges that need to be addressed to fully realize the potential of 2D materials for PEC. For example, their stability under harsh reaction conditions, as well as their scalability for large-scale production are important factors to be considered. Generating heterojunctions (HJs) by combining 2D layered structures with other nanomaterials is a promising method to improve the photoelectrocatalytic properties of the former. In this review, we inspect thoroughly the recent literature, to demonstrate the significant potential that arises from utilizing 2D layered heterostructures in PEC processes across a broad spectrum of applications, from energy conversion and storage to environmental remediation. With the ongoing research and development, it is likely that the potential of these materials will be fully expressed in the near future.

Atomically precise Pdm(SR)n nanoclusters for efficient hydrogen evolution reaction

Thiolate (SR) protected noble metal nanoclusters have grasped immense attention because of their promising applications in electrocatalysis, electrochemical sensors, photoluminescencse, supercapacitor and energy production. Among the noble metals, numerous reports have highlighted interesting results for Au25(SR)18, Au22(SR)18 and Ag44(SR)30 clusters but Pd and Pt nanoclusters are less addressed. Room temperature ionic liquids (RTIL) show enhanced electrocatalytic activity and stability as a binding matrix as compared to commercial binders like Nafion, Polyvinylidene fluoride (PVDF) and so on. Here, we have synthesised water-soluble thiolate 3-mercaptopropyl sulfonate (MPS) capped Palladium nanoclusters (Pd-MPS NCs). Further, Poly Acrylamide Gel Electrophoresis (PAGE), a separation technique was used to isolate size-dependent NCs and their electrocatalytic activity for the hydrogen evolution reaction (HER) with room temperature ionic liquid as a binding matrix was demonstrated. The electron microscope images of isolated Pd-MPS NCs from these three bands (obtained from PAGE separation) resulted with size ranges of 0.8-1.8 nm, 2-4 nm and 4.2-8 nm respectively. Among the three bands obtained from PAGE gel from the crude Pd NCs, the ultrasmall Pdm(SR)n NCs was isolated from the lower band resulted in high HER activity with less overpotential of 197 mV and a Tafel slope of 125.2 mV dec-1 as compared to Pd-MPS NCs obtained from the other two distinctive bands.

Edge-controlled ultrathin PdAg/PdPtAg ternary nanosheets for efficient ethanol oxidation reaction

Ultrathin metal alloy nanosheets offer promising applications in electrocatalysis due to their superior performance. In this study, we present a rational synthesis of ternary alloy ultrathin PdAg/PtPdAg nanosheets possessing highly porous edges (PdAg/PtPdAg P-NSs). By adopting mild reduction conditions and eliminating the need for strong surface-binding stabilizers, we effectively suppressed 3D growth and stabilized the unstable edges, resulting in ultrathin nanosheets with highly porous features. Importantly, these PdAg/PtPdAg P-NSs demonstrate remarkable electrocatalytic performances for the ethanol oxidation reaction, outperforming both their ternary counterparts and commercial Pd/C catalysts. This innovative synthetic approach offers a pathway to the design of high-performance 2D electrocatalysts for a broad spectrum of applications.

Facile Synthesis of Imidazole based Ionic Liquid Supported CdWO4/TiO2 for Superior Photo and Electrocatalytic Applications

Facile Synthesis of Imidazole based Ionic Liquid Supported CdWO4/TiO2 for Superior Photo and Electrocatalytic Applications

Rational Design of Organic Electrocatalysts for Hydrogen and Oxygen Electrocatalytic Applications.

Efficient electrocatalysts are pivotal for advancing green energy conversion technologies. Organic electrocatalysts, as cost-effective alternatives to noble-metal benchmarks, have garnered attention. However, the understanding of the relationships between their properties and electrocatalytic activities remains ambiguous. Plenty of research articles regarding low-cost organic electrocatalysts started to gain momentum in 2010 and have been flourishing recently though, a review article for both entry-level and experienced researchers in this field is still lacking. This review underscores the urgent need to elucidate the structure-activity relationship and design suitable electrode structures, leveraging the unique features of organic electrocatalysts like controllability and compatibility for real-world applications. Organic electrocatalysts are classified into four groups: small molecules, oligomers, polymers, and frameworks, with specific structural and physicochemical properties serving as activity indicators. To unlock the full potential of organic electrocatalysts, five strategies are discussed: integrated structures, surface property modulation, membrane technologies, electrolyte affinity regulation, and addition of anticorrosion species, all aimed at enhancing charge efficiency, mass transfer, and long-term stability during electrocatalytic reactions. The review offers a comprehensive overview of the current state of organic electrocatalysts and their practical applications, bridging the understanding gap and paving the way for future developments of more efficient green energy conversion technologies.

2D Ferromagnetic M3 GeTe2 (M = Ni/Fe) for Boosting Intermediates Adsorption toward Faster Water Oxidation.

In this work, 2D ferromagnetic M3 GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv ) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3 GeTe2v exhibits superior OER activity with only 370mV overpotential to reach the current density of 100mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200mV in alkaline media. Furthermore, a 2D-Ni3 GeTe2v -based anion-exchange membrane (AEM) water electrolysis cell (1 cm2 ) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3V feeding with 0.1 and 1m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3 GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.

Rational design of bimetallic metal-organic framework derived three-dimensional flower-like and porous NiCoFe LDH/NF electrocatalyst for electrochemical overall water splitting

Porous structured metal–organic frameworks (MOFs) and their derivatives are desired in catalysis and energy storage. Herein, three-dimensional (3D) flower-like NiCoFe LDH/NF are first synthesized though a convenient cathodic electrodeposition strategy subsequent an ion-exchange process. And the morphology and catalytic performance of the CoFe-MOF/NF can be finely by tailoring the electrodeposition voltage, deposition time and the ratio of Co: Fe. The 3D flower-like and porous NiCoFe/NF not only retains structural integrity to promote durability but also greatly alleviates the aggregation of active sites. In addition, the 3D flower-like and porous NiCoFe/NF display remarkable results with low overpotentials of 233 mV at a current density of 50 mA cm−2 for OER and 84 mV at a current density of 10 mA cm−2 for HER in 1 M KOH, respectively. When acting as electrocatalytic electrodes for overall water splitting, NiCoFe/NF displays a low overpotential of 1.52 V to achieve a current density of 10 mA cm−2. The study provides a promising approach to design MOF electrocatalysts for electrocatalytic applications.

Magnetic properties of nano(iron oxide)-decorated graphene oxide

Graphene oxide (GO) decorated with magnetic iron oxide nanoparticles is of great interest due to its potential applications in nanomedicine, electromagnetic insulation, and electro-catalysis. Herein, we studied the effect of the preparation conditions by hydrothermal synthesis on the phase composition of graphene oxide decorated with iron oxide nanoparticles. GO samples using two different amounts of a 2Fe3+/Fe2+ solution were prepared under a pH = 11, whereas hydrazine treatment was done to half the batch. Electron microscopy images show that Fe-oxide nanoparticles with an average size of 5–10 nm appeared decorating graphene platelets. Graphene oxide decorated rolls form in hydrazine-treated samples. Infrared spectra suggest a mixture of iron oxide phases with increased goethite upon hydrazine treatment. X-ray diffraction and X-ray Absorption Near Edge Structure spectroscopy (XANES) in the Fe K-edge determined the relative amount of the resulting iron oxide phases. Mixtures of magnetite, maghemite, hematite, and goethite were observed depending on the sample preparation conditions. The effect of phase composition on the magnetic properties was also studied. The saturation magnetization varied from 3.5 to ca. 50 Am2/kg at 300 K; it is proportional to the magnetite/maghemite content and reduces as the amount of goethite increases. The coercive field in the samples increases up to 1.6–2.4 mT at 300 K. The saturation magnetization has a slower decay with temperature when compared to a reference sample of magnetite nanoparticles, which suggests a magnetoelectric coupling due to the nanoparticle distribution onto the conductive graphene sheet.

Fluidized Bed Chemical Vapor Deposition on Hard Carbon Powders to Produce Composite Energy Materials.

Herein, we report a general route for the uniform coating of hard carbon (HC) powders via fluidized bed chemical vapor deposition. Carbon-based fine powders are excellent substrate materials for many catalytic and electrochemical applications but intrinsically difficult to fluidize and prone to elutriation. The reactor was designed to achieve as much retention of powders as possible, supported by a computational fluid dynamics study to assess the hydrodynamic behavior for varying gaseous flow rates. Solutions of the tin seleno- and thio-ether complexes [SnCl4{nBuSe(CH2)3SenBu}] and [SnCl4{nBuS(CH2)3SnBu}] were used as single source precursors and injected at high temperature into a fluidized bed of HC powders under nitrogen flow. The method allowed for the synthesis of HC-SnSx-SnSe2 composites at the gram scale with potential applications in electrocatalysis and sodium-ion battery anodes.

High‐performance BCN‐C heterostructured electrocatalyst derived from covalent triazine frameworks for nitrogen reduction

AbstractDesigning and synthesizing heterostructure‐based catalysis combining two‐dimensional (2D) materials has attracted enormous attention in materials chemistry, especially for electrocatalysis, due to their tunable electronic properties and structure. In this work, a boron carbon nitride (BCN)‐coupled carbon (BCN‐C) heterostructure with improved electronic performance was synthesized starting from C‐ and N‐enriched 2D covalent triazine frameworks (CTFs) via a simple thermal transformation process using NaBH4 as the B source. The characterizations results showed that the B released from NaBH4 reacted with N and C in CTF, forming the BCN‐C heterostructure coupling the BCN and carbon with a strong interfacial effect. The electrocatalytic NRR experiments and density functional theory (DFT) calculation revealed that the interfacial electronic properties and large numbers of active sites of the BCN‐C heterostructure benefited the NRR. The BCN‐C‐1 catalyst showed a high Faradaic efficiency of 27.8% and an NH3 yield of 4.3 μg h−1 mgcat.−1 in 0.1 M HCl electrolyte, owing to its high specific surface area (288 m2/g) with a large number of exposed active sites and the Mott–Schottky effect from the BCN‐C heterostructure. This work highlights the design and synthesis of metal‐free catalysts with high activity and selectivity and makes them excellent candidates for electrocatalytic applications.