Photoelectron Spectroscopy Studies Research Articles

Functional organic adlayers for controlling the adhesion strength of electrolessly deposited copper on super-engineering plastics

Effective metallization of super-engineering plastics such as liquid crystal polymers (LCP) and polyphenylene sulfides (PPS) via electroless deposition of copper thin films is an important step in the manufacturing of a wide range of devices. Copper deposition typically requires a pre-treatment step involving chemical and/or mechanical roughening to ensure high adhesion at the polymer/Cu interface; however such treatments are detrimental to patterns and topographic features of the polymer that possess µm resolution and/or high aspect ratio. Herein, we demonstrate that it is possible to regulate and improve adhesion of electrolessly deposited copper thin films at LCP and PPS materials via multilayer functionalization with aryldiazonium cations of a p-aminobenzoic acid precursor. We first demonstrate that aryldiazonium grafting conditions can be optimized to overcome the chemical inertness of LCP/PPS without resorting to harsh oxidative or mechanical treatments. We then show that the density of Ar-COOH groups can be regulated by modifying the number of functionalization cycles. X-ray photoelectron spectroscopy studies shows that this has a clear impact on the composition of the catalytic nanoparticle layer required for copper deposition. Adhesion strength studies demonstrate that such changes translate into improved adhesion strengths without any adverse effects on surface roughness. Control experiments with alternative chemical moieties suggest that specific chemical interactions between catalytic seeds and grafted carboxylate groups play an important role in the observed improved adhesion.

Dispersion leading potential energy surface of N2·NbN12-: Anion photoelectron spectroscopy and theoretical studies.

In order to understand the dispersion interactions between molecules and to provide information about the potential energy surface of geometry evolutions, NbN12- and N2·NbN12- complexes were investigated by using photoelectron spectroscopy and abinitio calculations. The experimental adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of NbN12- were both measured to be 2.129 ± 0.030eV. The experimental ADE and VDE of N2·NbN12- were measured to be 2.17 ± 0.05 and 2.23 ± 0.05eV, respectively, which are slightly higher than those of NbN12-. The structures of NbN12-/0 were confirmed to be hexacoordinated octahedrons. The investigation of N2·NbN12- structures shows that it is stable for N2 to bind to the face or vertex site of octahedron NbN12-; the face-side-on structure has the lowest energy. The calculations based on symmetry-adapted perturbation theory suggest that the dispersion term is predominant and leads to the stability of N2·NbN12- complexes.

Single Source Precursor Path to 2D Materials: A Case Study of Solution‐Processed Molybdenum‐Rich MoSe2‐x Ultrathin Nanosheets

AbstractTwo‐dimensional Molybdenum diselenide is a versatile and promising material used for a wide range of applications and its synthesis in high quality and yield is currently the subject of intense research. Low temperature solution phase synthesis of nanomaterials using designed molecular precursors enjoys tremendous advantages over traditional high‐temperature solid‐state synthesis. However, molecular precursor chemistry of molybdenum selenide nanomaterials is almost non‐existent. We report here synthesis and structural characterization of new molybdenum molecular precursors with selenoether and selenourea ligands, which due to their easy synthesis, desired Mo/Se composition and moderate processing properties, are highly promising as single source precursors for the scale‐up production of 2D molybdenum diselenide materials. This is demonstrated by the solution‐phase decomposition of the Mo‐selenourea precursor which produced Mo‐rich MoSe2‐x ultrathin nanosheets (NSs) in good yield. These NSs were characterized by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP‐OES), Powder X‐ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT‐IR), Thermogravimetric analysis (TGA), Transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS) studies.

Covalent Carbide Interconnects Enable Robust Interfaces and Thin SEI for Graphite Anode Stability under Extreme Fast Charging.

Carbonaceous and carbon-coated electrodes are ubiquitous in electrochemical energy storage and conversion technologies due to their electrochemical stability, lightweight nature, and relatively low cost. However, traditional reliance on conductive additives and binders leads to impermanent electrical pathways. Here, a general approach is presented to fabricate robust electrodes with a progressive failure mechanism by introducing carbide-based interconnects grown via carbothermal conversion of (5 wt%) titanium hydride nanoparticles. This method concurrently enhances both electrical and mechanical properties within the electrode architecture. The resulting chemical bonding between active materials establishes a novel mechanism to maintain stable electrical pathways during cycling. Employed as Li-ion battery anodes, these electrodes exhibit improved cyclability, achieving 80% capacity retention after 800 fast-charge cycles at moderate loading (1 mAh cm- 2). High loading cells with areal capacity of 3 mAh cm-2 show significantly improved cycle lifeover the same number of cycles. This performance improvement is attributed to the absence of significant impedance growth and a thinner solid electrolyte interphase (SEI) layer formed at high current densities (4C) as demonstrated by X-ray photoelectron spectroscopy and transmission electron microscopy studies. The enhanced conductivity facilitates SEI formation, lowering ionic impedance and mitigating lithium plating, ultimately leading to the reported extended cycle life.

Impacting the Surface Chemistry of NiAu by Immobilizing on MgO/N-Rich Nanoporous Carbon Heterostructures for Boosting Catalytic Activities.

Tuning the physical and chemical interaction between metal-metal' (M-M') and metal-support is an ideal way to realize enhanced catalytic activity of metal nanoparticles (NPs). As a proof of concept, herein we report the fabrication of nickel-gold (Ni-Au) alloy nanoparticles attached to N-doped nanoporous carbon (NPC) intervened with MgO (Ni73Au27@MgO-NPC), achieved through the impregnation of metal precursors into Schiff-base network polymer (SNP) framework along with Mg(OH)2 and pyrolysis at 800 °C in N2 atmosphere. With high stability and heterogeneity, the nickel rich Ni73Au27@MgO-NPC exhibited higher catalytic activities with turnover frequencies of 29,272 h-1 (hydrogenation of p-nitrophenol), 93,843 h-1 (degradation of methyl orange), and 2,218 h-1 (epoxidation of stilbene), compared to commercial 10 wt % Pd/C. Enhanced catalytic activity is correlated to the synchronized electron density enhancement in Au, by Ni and MgO/N-rich nanoporous carbon heterostructures, as evident from detailed X-ray photoelectron spectroscopic studies.

Atomically precise Cu32 nanoclusters with selenide doping: Synthesis, bonding, and catalysis

AbstractCopper nanoclusters with stable compositions and precise structures have long been sought after, as they possess properties that are absent in gold and silver counterparts. However, the creation of copper nanoclusters with novel compositions, structures, and functionalities remains largely unexplored in the literature. In this study, we demonstrate that selenide doping is an effective method for fabricating stable copper nanostructures through controlled synthesis and structure determination of a copper–selenide nanocluster. The nanocluster of [Cu32Se7(BnSe)18(PPh3)6]+ (denoted as Cu32Se7, Bn is benzyl) has been prepared by reducing copper salts in the presence of organic diselenides. The atomic structure of the Cu32Se7 cluster, accurately determined through single‐crystal X‐ray diffraction, reveals a core–shell arrangement of Cu20Se7@Cu12(BnSe)18(PPh3)6, where Se2− anions are well dispersed in the Cu20 framework. Notably, this cluster represents a rare example of copper–selenide semiconductor nanoclusters. Experimental and theoretical analysis shows strong interactions between Se ligands and metal atoms, resulting in high stability of the Cu32Se7 cluster. Furthermore, the cluster exhibits excellent catalytic performance in the hydroboration reaction of alkynes, producing a range of vinylboron compounds with adjustable structures and functions. Importantly, the cluster undergoes no structural or nuclearity changes during the reaction, as confirmed by extended X‐ray absorption fine structure and X‐ray photoelectron spectroscopy studies. This study not only presents a molecular cluster model highlighting the effectiveness of selenide dopants in fabricating new copper nanostructures but also paves the way for utilizing stable copper nanoclusters in diverse and exciting areas beyond catalysis.

Photoelectron Spectroscopy and Theoretical Studies on the Structures and Properties of Ge4C- and Ge4CH- Clusters.

We investigate the structures and properties of Ge4C-/0 and Ge4CH-/0 clusters using anion photoelectron spectroscopy and theoretical calculations. Our calculations show that the first two low-lying isomers coexist in the experiments of Ge4C- and Ge4CH-. The first two low-lying isomers of Ge4C- have trigonal bipyramidal structures with the C atom on the equatorial plane and the top vertex, respectively. It is found that the first two low-lying isomers of Ge4CH- can be obtained by adding an H atom to the top and equatorial C atoms of Ge4C-, respectively. The AdNDP analyses reveal that the C atom in Ge4C forms one 4c-2e σ bond, two 4c-2e π bonds, and one 5c-2e σ bond with Ge atoms. The C atom in Ge4C interacts with an H- forming a C-H σ bond in Ge4CH-. AIMD simulation results indicate high dynamic stabilities of Ge4C and Ge4CH- at 300 and 500 K. Our results show that the structures and chemical bonding of Ge4B- and Ge4N+ are similar to those of Ge4C, while those of Ge4BH2- and Ge4NH resemble those of Ge4CH-.

Porous fluorine-cerium nanosheets anchored with FeOOH quantum dots for synergistic enhanced visible-light-driven photo-Fenton degradation of phenol

The utilization of two-dimensional (2D) materials to construct heterogeneous catalysts provides opportunities for environmental remediation, while the incorporation of porous structures can further enhance catalytic performance. In this work, a porous 2D FeOOH/fluorine-cerium (F-Ce) nanosheet composite was designed and synthesized by a simple impregnation-precipitation method. The unique 2D porous structure of F-Ce promoted the high dispersion of FeOOH quantum dots (QDs) (∼1.4 nm) and their tight integration to form S-scheme heterojunctions. This structure offered a greater number of active sites, and significantly improved the capacity of light absorption and the separation and migration efficiency of photogenerated carriers, thus improving catalytic activity. This catalyst achieved a phenol removal rate of 98.1 % within 20 min during the photo-Fenton reaction, which significantly surpasses pure FeOOH (32.9 %) and F-Ce (21.7 %) alone. In particular, the optimized 14FeOOH/F-Ce catalyst achieved more than 95.0 % degradation efficiency within a remarkably short period of 5 min. Mott Schottky and in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) studies demonstrated that the S-scheme charge transfer mechanism of this heterojunction synergistically enhanced the catalytic activity of the Fenton-like reaction. This study provides valuable insights for designing efficient 2D porous heterojunction catalysts for visible-light-driven Fenton applications.

Selective Photocatalytic Oxidation of 5‐Hydroxymethylfurfural using Ce doped TiO2: A Crucial Role of Defective Sites

AbstractTransforming platform compounds with conventional catalysts, such as homogeneous and heterogeneous, into valuable chemicals encounters challenges associated with entailing high temperature/pressure and reusability during the reaction. To address these challenges, photocatalysis is one of the promising approaches, especially with visible‐light‐driven photocatalysts for selective transformation. A series of cerium‐doped TiO2 (CexTiO2; x=0.5, 1, 3 and 5 wt %) are prepared via a simple coprecipitation method for the cocatalyst‐free selective oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfuran (DFF) under visible light illumination. Introducing Ce into the network to TiO2 generates impurity energy levels, reduces the band gap, and extends the spectral response range. This also causes slight distortion to the surface structure, thereby originating defective sites and various surface oxygen species, confirmed by X‐ray photoelectron spectroscopy and electron paramagnetic resonance studies. The HMF adsorption studies infer that HMF forms a surface complex with CeTiO2, facilitating the formation of ligand‐to‐metal charge transfer complex (LMCT) under visible light (~420 nm), which efficiently catalyzes the conversion of HMF (54.4 %) to DFF with a selectivity of >99 %. In‐situ DRIFTS and surface passivation studies provide insight into the interaction between HMF and surface acidic/basic sites along with hydroxyl groups of CeTiO2, which subsequently convert selectively to DFF.

Unveiling Potential of Gallium Ferrite (GaFeO3) as an Anode Material for Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) serve as the backbone of modern technologies with ongoing efforts to enhance their performance and sustainability driving the exploration of new electrode materials. This study introduces a new type of alloy-conversion-based gallium ferrite (GFO: GaFeO3) as a potential anode material for Li-ion battery applications. The GFO was synthesized by a one-step mechanochemistry-assisted solid-state method. The powder X-ray diffraction analysis confirms the presence of an orthorhombic phase with the Pc21 n space group. The photoelectron spectroscopy studies reveal the presence of Ga3+ and Fe3+ oxidation states of gallium and iron atoms in the GFO structure. The GFO was evaluated as an anode material for Li-ion battery applications, displaying a high discharge capacity of ∼887 mA h g-1 and retaining a stable capacity of ∼200 mA h g-1 over 450 cycles, with a Coulombic efficiency of 99.6 % at a current density of 100 mA g-1. Cyclic voltammetry studies confirm an alloy-conversion-based reaction mechanism in the GFO anode. Furthermore, density functional theory studies reveal the reaction mechanism during cycling and Li-ion diffusion pathways in the GFO anode. These results strongly suggest that the GFO could be an alternative anode material in LIBs.

C–H bond activation over chitosan based Fe(III) and Ni(II) catalysts

Chitosan (Cs) supported heterogeneous catalysts of Fe(III) and Ni(II) is developed by the equimolar reaction of two schiff base ligands, L1 [Cs-HACP] and L2 [ANI-HACP] and Metal salts {where Metal = Fe(III) and Ni(II)}with chitosan. The L1 ligand is prepared by the reaction of chitosan (Cs) and ortho hydroxyl (HACP) acetophenone in methanol and L2 ligand is prepared by the condensation of aniline (ANI) and ortho hydroxyl acetophenone (HACP) in solvent free condition. The prepared catalysts {M-[Cs-L1-L2]Cl2} are characterized by different analytical techniques viz. scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman, UV-VIS-NIR, X-ray photoelectron spectroscopy (XPS) and computational studies. The catalytic behavior of newly synthesized catalysts are tested for the C–H activation using 70 % tert-butyl hydroperoxide (TBHP). The best results are obtained for tetralin oxidation. The order of catalytic reactivity of {M-[Cs-L1-L2]Cl2}catalyst is in decreasing order: {Fe(III)-[Cs-L1-L2]Cl2} > {Ni(II)-[Cs-L1-L2]Cl2}. The {Fe(III)-[Cs-L1-L2]Cl2} gives maximum conversion 81.99 % of tetralin with 84.50 % selectivity of tetralone (T-lone) and 6.47 % selectivity of tetralol (T-lol) after 5 h of reaction at 80 °C temperature. The chitosan based heterogeneous catalyst is easy to separate and recover. It can be recycled seven times.

Bimetallic Rh–Pd aerogels as efficient materials for ethanol electrooxidation

This study introduces a series of Rh–Pd bimetallic aerogels Rh75Pd25, Rh50Pd50, and Rh25Pd75 as efficient electrocatalysts for ethanol electrooxidation, crucial for direct ethanol fuel cell technology. The bimetallic Rh–Pd and monometallic Rh and Pd aerogels were synthesized from RhCl3 and PdCl2 as starting materials and sodium borohydride as the reducing agent. A combination of X-ray photoelectron spectroscopy, elemental mapping, and electron microscopy studies of the bimetallic aerogels enable compositional analysis of the materials and provide insight into the porous 3D nanoarchitecture. Importantly, the material performs efficiently as an electrocatalyst on glassy carbon electrodes for the oxidation of ethanol under basic conditions (1.0 M KOH) at onset potentials ranging from −0.59 to −0.64 V (vs. Hg/HgO). Importantly, these materials exhibit high peak current densities of 216 mA/cm2 for the Rh-rich Rh75Pd25 to 536 mA/cm2 for Rh25Pd75, which are significantly higher than reported peak current densities for other Pd-containing electrocatalysts. The 1H and 13C NMR techniques were used to evaluate products for ethanol electrooxidation, with the results indicating selectivity for acetic acid. This demonstrates an enhanced catalytic activity, selectivity to acetic acid vs. CO2, representing a significant step in advancing DEFCs and their broader application in sustainable energy technologies.

Photoelectron spectroscopy of deprotonated benzonitrile.

The recent discovery of cyano-substituted aromatic and two-ring polycyclic aromatic hydrocarbon molecules in Taurus Molecular Cloud-1 has prompted questions on how the electronic structure and excited-state dynamics of these molecules are linked with their existence and abundance. Here, we report a photodetachment and frequency- and angle-resolved photoelectron spectroscopy study of jet-cooled para-deprotonated benzonitrile (p-[Bzn-H]-). The adiabatic detachment energy was determined as 1.70 ± 0.01eV, in good agreement with CCSD(T)/aug-cc-pVTZ calculations. The spectra across the first few electron-volts above threshold are dominated by prompt autodetachment processes associated with excitation of at least five short-lived (tens of femtoseconds) temporary anion shaped resonances since excitation cross sections are several orders of magnitude larger than direct photodetachment cross sections. The photoexcitation vibronic profile is dominated by a ≈640 cm-1 ring deformation mode. [Bzn-H]- lacks a valence-localized excited state situated below the detachment threshold and does not exhibit thermionic emission following excitation of the temporary anion resonances. Thus, [Bzn-H]- is unlikely to be stable in many interstellar environments.

Electromagnetic interference shielding properties of PMMA modified-Co0.5Zn0.5Fe2O4 − polyaniline composites

Present work reports solution combustion synthesis (SCS) of Co0.5Zn0.5Fe2O4 spinel ferrite, its chemical modification with polymethylmethacrylate (PMMA), synthesis of polyaniline (PANI), and electromagnetic interference (EMI) shielding properties of their composites. Both as-prepared and PMMA-modified Co0.5Zn0.5Fe2O4 adopt cubic spinel structure as shown by X-ray diffraction studies. Field emission scanning electron microscopy images show the agglomerated and microporous nature of the ferrites. High resolution transmission electron microscopy image of as-prepared Co0.5Zn0.5Fe2O4 shows lattice fringes related to (311) plane of the spinel structure. X-ray photoelectron spectroscopy studies reveal the presence of Co2+, Zn2+, and Fe3+ in tetrahedral and octahedral coordinations in the ferrite. EMI shielding properties are evaluated for PMMA-modified Co0.5Zn0.5Fe2O4 and PANI composites in different weight ratios. Composites containing PMMA-modified ferrite and PANI with 50:50 and 10:90 weight ratios show the best performance among all the composites in 2−20 GHz frequency range. Optimized PMMA-modified Co0.5Zn0.5Fe2O4 and PANI composite with the ratio of 10:90 shows shielding effectiveness (SE) values of −16.6 to −24.2 dB in 2−20 GHz frequency region.Graphical

Counterion Loss from Charged Surface-Bound Complexes Drives the Formation of Loosely Packed Monolayers.

The functionality of multicomponent self-assembled monolayers (SAMs) can be severely diminished by the segregation of like components into nanoscale domains, a process that maximizes favorable short-range intermolecular interactions. Here, we explore the use of a modular family of sulfur-functionalized metal bis(terpyridine) complexes ([M(tpy-R)2]2+(PF6-)2) to prepare mixed SAMs, considering that the comparable structure, dimensions, and ionic composition of these species should render them interchangeable within the adsorbed surface layer. While surface voltammetry experiments show that these SAMs do exhibit compositions representative of their assembly solutions, they also suggest, in line with previous reports, that adjacent complexes in the monolayer are separated by a gap of ∼ 1 nm. Remarkably, X-ray photoelectron spectroscopy studies reveal no F 1s peak features that would confirm the proliferation of PF6- counterions on the surface. We propose that the loosely packed structure of these SAMs results from the loss or exchange of PF6- counterions, which introduces significant repulsive Coulomb interactions between the adsorbed 2+ charged complexes. The hypothesis is supported by an electrostatic model which indicates that these complexes should form close-packed SAMs if mobile counterions are present. First-principles calculations demonstrate that complex-counterion binding interactions are weakened by charge transfer to the gold substrate, suggesting that this may play an important role in the formation of such low-coverage SAMs. Together, this study raises important questions regarding the assembly, organization, and composition of charged SAMs and highlights new opportunities in the design of multicomponent monolayer assemblies with free volume, for example, to facilitate surface-based reactions or support molecular switches.

Maximizing Upconversion Luminescence of Co-Doped CaF₂:Yb, Er Nanoparticles at Low Laser Power for Efficient Cellular Imaging.

Upconversion nanoparticles (UCNPs) are well-reported for bioimaging. However, their applications are limited by low luminescence intensity. To enhance the intensity, often the UCNPs are coated with macromolecules or excited with high laser power, which is detrimental to their long-term biological applications. Herein, we report a novel approach to prepare co-doped CaF2:Yb3+ (20%), Er3+ with varying concentrations of Er (2%, 2.5%, 3%, and 5%) at ambient temperature with minimal surfactant and high-pressure homogenization. Strong luminescence and effective red emission of the UCNPs were seen even at low power and without functionalization. X-ray diffraction (XRD) of UCNPs revealed the formation of highly crystalline, single-phase cubic fluorite-type nanostructures, and transmission electron microscopy (TEM) showed co-doped UCNPs are of ~12 nm. The successful doping of Yb and Er was evident from TEM-energy dispersive X-ray analysis (TEM-EDAX) and X-ray photoelectron spectroscopy (XPS) studies. Photoluminescence studies of UCNPs revealed the effect of phonon coupling between host lattice (CaF2), sensitizer (Yb3+), and activator (Er3+). They exhibited tunable upconversion luminescence (UCL) under irradiation of near-infrared (NIR) light (980 nm) at low laser powers (0.28-0.7 W). The UCL properties increased until 3% doping of Er3+ ions, after which quenching of UCL was observed with higher Er3+ ion concentration, probably due to non-radiative energy transfer and cross-relaxation between Yb3+-Er3+ and Er3+-Er3+ ions. The decay studies aligned with the above observation and showed the dependence of UCL on Er3+ concentration. Further, the UCNPs exhibited strong red emission under irradiation of 980 nm light and retained their red luminescence upon internalization into cancer cell lines, as evident from confocal microscopic imaging. The present study demonstrated an effective approach to designing UCNPs with tunable luminescence properties and their capability for cellular imaging under low laser power.

Impeding conduction by breaking the charge carrier hopping in charge-ordered perovskite BaBiO3 ([formula omitted]): Experimental and theoretical electronic structural correlations

BaBiO3 (BBO), a charge-ordered perovskite with mixed-valent states of Bi (Bi3+ and Bi5+), is known for its charge density wave (CDW) semiconducting and topological insulating properties. BBO has been extensively investigated for its superconducting, electrical, and photocatalytic properties. The present study aims to understand the alterations in the CDW and electronic properties of BaBi0.53+Bi0.55+O3 by valence-selective substitution of Bi3+ and Bi5+ with La3+ and Nb5+, respectively, in the solid solutions BaBi0.5−x3+LaxBi0.55+O3 and BaBi0.53+Bi0.5−y5+NbyO3 (x = y = 0.0, 0.1, 0.3, and 0.5). The samples synthesized via high-temperature solid-state reaction method were characterized by powder X-ray diffraction and various spectroscopic techniques (FT-IR, Laser Raman, EPR, XPS, and UPS). Impedance analysis revealed an upsurge in total impedance with the substitution of Bi3+/Bi5+ by La3+/Nb5+ indicating the blocking of electron/hole hopping by disruption of the charge ordering of redox pair Bi3+ and Bi5+. The valence-selective substitution of Bi3+/Bi5+ in BaBiO3 resulted in an alteration of the electronic structure and changes in the bandwidth of BaBi0.5−x3+LaxBi0.55+O3 and BaBi0.53+Bi0.5−y5+NbyO3 (x = y = 0.0, 0.1, 0.3, and 0.5) solid solutions, which were confirmed by both theoretical density of states (DOS) calculations and experimental ultraviolet photoelectron spectroscopic (UPS) studies.

Indole-3-Carbinol Upconversion with Copper Oxide Nanoparticles Supported Graphitic Carbon Nitride: A Sustainable Approach

Electro-organic chemistry offers a sustainable and efficient approach to organic synthesis by utilizing electrochemical processes. This field has gained significant attention due to its potential for minimizing waste, reducing energy consumption, and enabling selective transformations. Herein, we report the development of a graphitic carbon nitride-coated carbon fiber electrode modified with electropolymerized amino-2-thiazole and electrodeposited Cu2O nanoparticles from copper nitrate trihydrate for the oxidation of Indole-3-carbinol (IC). Scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy studies were carried out to characterize the developed electrode. Cyclic voltammetry, electrochemical impedance spectroscopy, and bulk electrolysis techniques were employed for the electrochemical studies. The enhanced electrochemical activity of the Cu2O-pAT-GCN-TCFP electrode compared to the individual GCN and polymer electrode was studied using electrochemical characterization, which revealed a 3-fold increase in the current response for Cu2O-pAT-GCN-TCFP (0.0011 A) compared to the bare electrode. The reaction was carried out using an aqueous carbonate buffer solution as an electrolyte via bulk electrolysis at a set potential of 0.82 V. The product obtained was isolated by column chromatography to obtain a yield of 74% and characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy. Additionally, the Cu2O-pAT-GCN-TCFP electrode was studied for its stability, reproducibility, and selectivity.

Ultrafast joule-heating synthesis of FeCoMnCuAl high-entropy-alloy nanoparticles as efficient OER electrocatalysts

High entropy alloys (HEAs), known for their synergistic orbital interactions among multiple elements, have been recognized as promising electrocatalysts for enhancing the sluggish kinetics of oxygen evolution reaction (OER). Despite their potential, the facile and rapid preparation of HEA nanoparticles (NPs) with high electrocatalytic activity remains challenging. Here, we report an ultrafast synthesis of noble-metal-free FeCoMnCuAl HEA NPs loaded on conductive carbon fiber networks using a Joule heating strategy. The prepared HEA NPs exhibited a face-centered cubic (FCC) structure with an average size of approximately 25 ​nm. Synchrotron X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) studies were performed to investigate the atomic and electronic structures of the HEA NPs, revealing the co-presence of Fe, Co, Mn, Cu and Al elements as well as their different valences across surface and internal regions. The HEA NPs showed remarkable OER performance, exhibiting an overpotential of 280 ​mV at 10 ​mA ​cm−2 and a low Tafel slope of 76.13 ​mV dec−1 in a 1.0 ​M KOH solution with high electrochemical stability, superior to commercial RuO2 electrocatalysts. This work provides a new approach for synthesizing nanoscale noble-metal-free HEA electrocatalysts for clean energy conversion applications on a large-scale basis for practical commercialization.

Complementary Multisite Turnover Catalysis toward Superefficient Bifunctional Seawater Splitting at Ampere-Level Current Density.

The utilization of seawater for hydrogen production via water splitting is increasingly recognized as a promising avenue for the future. The key dilemma for seawater electrolysis is the incompatibility of superior hydrogen- and oxygen-evolving activities at ampere-scale current densities for both cathodic and anodic catalysts, thus leading to large electric power consumption of overall seawater splitting. Here, in situ construction of Fe4N/Co3N/MoO2 heterostructure arrays anchoring on metallic nickel nitride surface with multilevel collaborative catalytic interfaces and abundant multifunctional metal sites is reported, which serves as a robust bifunctional catalyst for alkaline freshwater/seawater splitting at ampere-level current density. Operando Raman and X-ray photoelectron spectroscopic studies combined with density functional theory calculations corroborate that Mo and Co/Fe sites situated on the Fe4N/Co3N/MoO2 multilevel interfaces optimize the reaction pathway and coordination environment to enhance water adsorption/dissociation, hydrogen adsorption, and oxygen-containing intermediate adsorption, thus cooperatively expediting hydrogen/oxygen evolution reactions in base. Inspiringly, this electrocatalyst can substantially ameliorate overall freshwater/seawater splitting at 1000mA cm-2 with low cell voltages of 1.65/1.69V, along with superb long-term stability at 500-1500mA cm-2 for over 200 h, outperforming nearly all the ever-reported non-noble electrocatalysts for freshwater/seawater electrolysis. This work offers a viable approach to design high-performance bifunctional catalysts for seawater splitting.