Ligand-Exchange-Induced Amorphization of Pd Nanomaterials for Highly Efficient Electrocatalytic Hydrogen Evolution Reaction

Ultrafine IrMnOx Nanocluster Decorated Amorphous PdS Nanowires as Efficient Electrocatalysts for High C1 Selectivity in the Alkaline Ethanol Oxidation Reaction

As a novel electrochemical energy conversion device, direct ethanol fuel cells are currently encountering two significant challenges: CO poisoning and the difficulty of C-C bond cleavage in ethanol. In this work, an amorphous PdS nanowires/ultrafine IrMnOx bimetallic oxides (denoted as a-PdS/IrMnOx NWs) catalyst with abundant oxide/metal (crystalline/amorphous) inverse heterogeneous interfaces was synthesized via a hydrothermal process succeeded by a nonthermal air-plasma treatment. This unique interfacial electronic structure along with the incorporation of oxyphilic metal has resulted in a significant enhancement in the electrocatalytic performance of a-PdS/IrMnOx NWs toward the ethanol oxidation reaction, achieving current densities of 12.45 mA·cm-2 and 3.68 A·mgPd-1. Moreover, the C1 pathway selectivity for ethanol oxidation has been elevated to 47%, exceeding that of other as-prepared Pd-based counterparts and commercial Pd/C catalysts. Density functional theory calculations have validated the findings that the decoration of IrMn species onto the amorphous PdS surface has induced a charge redistribution in the interface region. The redistribution of surface charges on the a-PdS/IrMnOx NWs catalyst results in a significant decrease in the activation energy required for C-C bond cleavage and a notable weakening of the CO binding strength at the Pd active sites. Consequently, it enhanced both the EOR C1 pathway selectivity and CO poisoning resistance to the a-PdS/IrMnOx NWs catalyst.

Lattice-Disordered High-Entropy Alloy Engineered by Thermal Dezincification for Improved Catalytic Hydrogen Evolution Reaction

A disordered crystal structure is an asymmetrical atomic lattice resulting from the missing atoms (vacancies) or the lattice misarrangement in a solid-state material. It has been widely proven to improve the electrocatalytic hydrogen evolution reaction (HER) process. In the present work, due to the special physical properties (the low evaporation temperature of below 900 °C), Zn is utilized as a sacrificial component to create senary PtIrNiCoFeZn high-entropy alloy (HEA) with highly disordered lattices. The structure of the lattice-disordered PtIrNiCoFeZn HEA is characterized by the thermal diffusion scattering (TDS) in transmission electron microscope. Density functional theory calculations reveal that lattice disorder not only accelerates both the Volmer step and Tafel step during the HER process but also optimizes the intensity and distribution of projected density of states near the Fermi energy after the H2O and H adsorption. Anomalously high alkaline HER activity and stability are proven by experimental measurements. This work introduces a novel approach to preparing irregular lattices offering highly efficient HEA and a TDS characterization method to reveal the disordered lattice in materials. It provides a new route toward exploring and developing the catalytic activities of materials with asymmetrically disordered lattices.

Combating Atherosclerosis with Chirality/Phase Dual-Engineered Nanozyme Featuring Microenvironment-Programmed Senolytic and Senomorphic Actions

Senescence plays a critical role in the development and progression of various diseases. This study introduces an amorphous, high-entropy alloy (HEA)-based nanozyme designed to combat senescence. By adjusting the nanozyme's composition and surface properties, this work analyzes its catalytic performance under both normal and aging conditions, confirming that peroxide and superoxide dismutase (SOD) activity are crucial for its anti-aging therapeutic function. Subsequently, the chiral-dependent therapeutic effect is validated and the senolytic performance of D-handed PtPd2CuFe across several aging models is confirmed. Through multi-Omics analyses, this work explores the mechanism underlying the senolytic action exerted by nanozyme in depth. It is confirm that exposure to senescent conditions leads to the enrichment of copper and iron atoms in their lower oxidation states, disrupting the iron-thiol cluster in mitochondria and lipoic acid transferase, as well as oxidizing unsaturated fatty acids, triggering a cascade of cuproptosis and ferroptosis. Additionally, the concentration-dependent anti-aging effects of nanozyme is validated. Even an ultralow dose, the therapeutic can still act as a senomorphic, reducing the effects of senescence. Given its broad-spectrum action and concentration-adjustable anti-aging potential, this work confirms the remarkable therapeutic capability of D-handed PtPd2CuFe in managing atherosclerosis, a disease involving various types of senescent cells.

Recent Progress of Transition Metal Selenides for Electrochemical Oxygen Reduction to Hydrogen Peroxide: From Catalyst Design to Electrolyzers Application

Hydrogen peroxide (H2O2) is a highly value-added and environmental-friendly chemical with various applications. The production of H2O2 by electrocatalytic 2e- oxygen reduction reaction (ORR) has emerged as a promising alternative to the energy-intensive anthraquinone process. High selectivity Catalysts combining with superior activity are critical for the efficient electrosynthesis of H2O2. Earth-abundant transition metal selenides (TMSs) being discovered as a classic of stable, low-cost, highly active and selective catalysts for electrochemical 2e- ORR. These features come from the relatively large atomic radius of selenium element, the metal-like properties and the abundant reserves. Moreover, compared with the advanced noble metal or single-atom catalysts, the kinetic current density of TMSs for H2O2 generation is higher in acidic solution, which enable them to become suitable catalyst candidates. Herein, the recent progress of TMSs for ORR to H2O2 is systematically reviewed. The effects of TMSs electrocatalysts on the activity, selectivity and stability of ORR to H2O2 are summarized. It is intended to provide an insight from catalyst design and corresponding reaction mechanisms to the device setup, and to discuss the relationship between structure and activity.

Strain Engineering of Unconventional Crystal-Phase Noble Metal Nanocatalysts

The crystal phase, alongside the composition, morphology, architecture, facet, size, and dimensionality, has been recognized as a critical factor influencing the properties of noble metal nanomaterials in various applications. In particular, unconventional crystal phases can potentially enable fascinating properties in noble metal nanomaterials. Recent years have witnessed notable advances in the phase engineering of nanomaterials (PEN). Within the accessible strategies for phase engineering, the effect of strain cannot be ignored because strain can act not only as the driving force of phase transition but also as the origin of the diverse physicochemical properties of the unconventional crystal phase. In this review, we highlight the development of unconventional crystal-phase noble metal nanomaterials within strain engineering. We begin with a short introduction of the unconventional crystal phase and strain effect in noble metal nanomaterials. Next, the correlations of the structure and performance of strain-engineered unconventional crystal-phase noble metal nanomaterials in electrocatalysis are highlighted, as well as the phase transitions of noble metal nanomaterials induced by the strain effect. Lastly, the challenges and opportunities within this rapidly developing field (i.e., the strain engineering of unconventional crystal-phase noble metal nanocatalysts) are discussed.

In situ self-reconstructed hierarchical bimetallic oxyhydroxide nanosheets of metallic sulfides for high-efficiency electrochemical water splitting

The advancement of economically efficient electrocatalysts for alkaline water oxidation based on transition metals is essential for hydrogen production through water electrolysis. In this investigation, a straightforward one-step solvent method was utilized to spontaneously cultivate bimetallic sulfide S-FeCo1 : 1/NIF on the surface of a nickel-iron foam (NIF). Capitalizing on the synergistic impact between the bimetallic constituents and the highly active species formed through electrochemical restructuring, S-FeCo1 : 1/NIF exhibited remarkable oxygen evolution reaction (OER) performance, requiring only a 310 mV overpotential based on 500 mA cm-2 current density. Furthermore, it exhibited stable operation at 200 mA cm-2 for 275 h. Simultaneously, the catalyst demonstrated excellent hydrogen evolution reaction (HER) and overall water-splitting capabilities. It only requires an overpotential of 191 mV and a potential of 1.81 V to drive current densities of 100 and 50 mA cm-2. Density functional theory (DFT) calculations were also employed to validate the impact of the bimetallic synergistic effect on the catalytic activity of sulfides. The results indicate that the coupling between bimetallic components effectively reduces the energy barrier required for the rate-determining step in water oxidation, enhancing the stability and activity of bimetallic sulfides. The exploration of bimetallic coupling to improve the OER performance holds theoretical significance in the rational design of advanced electrocatalysts.

Decorating Pd-Au Nanodots Around Porous In2 O3 Nanocubes for Tolerant H2 Sensing Against Switching Response and H2 S Poisoning

With the recently-booming hydrogen (H2 ) economy by green H2 as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H2 as a biomarker, H2 sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H2 sensing has been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/In2 O3 NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/In2 O3 NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/In2 O3 NCBs show 300 ppb-low detection limit, 5 s-fast response to 500 ppm H2 , 75%RH-high humidity tolerance, and 56 days-long stability at 280 °C. Further, Pd-Au NDs/In2 O3 NCBs show excellent stability against switching sensing response, and are tolerant to H2 S poisoning even being exposed to 10 ppm H2 S at 280 °C. Such excellent H2 sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H2 and H2 S. Practically, Pd-Au NDs/In2 O3 NCBs are integrated into the H2 sensing device, which can reliably communicate with a smartphone.

DNA Framework-Templated Fabrication of Ultrathin Electroactive Gold Nanosheets

Generally, two-dimensional gold nanomaterials have unique properties and functions that offer exciting application prospects. However, the crystal phases of these materials tend to be limited to the thermodynamically stable crystal structure. Herein, we report a DNA framework-templated approach for the ambient aqueous synthesis of freestanding and microscale amorphous gold nanosheets with ultrathin sub-nanometer thickness. We observe that extended single-stranded DNA on DNA nanosheets can induce site-specific metallization and enable precise modification of the metalized nanostructures at predefined positions. More importantly, the as-prepared gold nanosheets can serve as an electrocatalyst for glucose oxidase-catalyzed aerobic oxidation, exhibiting enhanced electrocatalytic activity (~3-fold) relative to discrete gold nanoclusters owing to a larger electrochemical active area and wider band gap. The proposed DNA framework-templated metallization strategy is expected to be applicable in a broad range of fields, from catalysis to new energy materials.

Amorphous RuPd bimetallene for hydrogen evolution reaction in acidic and alkaline conditions: a first-principles study

Metallene materials can provide a large number of active catalytic sites for the efficient use of noble metals as catalysts for hydrogen evolution reaction (HER), whereas the intrinsic activity on the surface is insufficient in crystal phase. The amorphous phase with an inherent long-range disorder can offer a rich coordinate environment and charge polarization on the surface is proposed for promoting the intrinsic catalytic activity on the surface of noble metals. Herein, we designed an amorphous RuPd (am-RuPd) structure by the first principles molecular dynamics method. The performance of the acidic HER on am-RuPd can have a huge enhancement due to the free energy change of hydrogen adsorption close to zero. In alkaline conditions, the H2O dissociation energy barrier on am-RuPd is just 0.49 eV, and it is predicted that the alkaline HER performance of am-RuPd will largely exceed that of Pt nanocrystalline sheets. This work provides a strategy for enhancing the intrinsic catalytic activity on the surface and a way to design an efficient HER catalyst based on metallene materials used in both acidic and alkaline conditions.

Amorphization Activated Multimetallic Pd Alloys for Boosting Oxygen Reduction Catalysis

Amorphous nanomaterials have drawn extensive attention owing to their unique features, while amorphization on noble metal nanomaterials still remains formidably challenging. Herein, we demonstrate a universal strategy to synthesize amorphous Pd-based nanomaterials from unary to quinary metals through the introduction of phosphorus (P). The amorphous Pd-based nanoparticles (NPs) exhibit generally promoted oxygen reduction reaction (ORR) activity and durability compared with their crystalline counterparts. Significantly, the quinary P-PdCuNiInSn NPs, benefiting from the amorphous structure and multimetallic component effect, exhibit mass activities as high as 1.04 A mgPd-1 and negligible activity decays of 1.8% among the stability tests, which are much better than values for original Pd NPs (0.134 A mgPd-1 and 28.4%). Experimental and theoretical analyses collectively reveal that the synergy of P-induced amorphization and the expansion of metallic components can considerably lower the free energy changes in the rate-determined step, thereby explaining the positive correlation with the catalytic activity.

Synthesis of 2H/fcc-Heterophase AuCu Nanostructures for Highly Efficient Electrochemical CO2 Reduction at Industrial Current Densities

Structural engineering of nanomaterials offers a promising way for developing high-performance catalysts toward catalysis. However, the delicate modulation of thermodynamically unfavorable nanostructures with unconventional phases still remains a challenge. Here, the synthesis of hierarchical AuCu nanostructures is reported with hexagonal close-packed (2H-type)/face-centered cubic (fcc) heterophase, high-index facets, planar defects (e.g., stacking faults, twin boundaries, and grain boundaries), and tunable Cu content. The obtained 2H/fcc Au99 Cu1 hierarchical nanosheets exhibit excellent performance for the electrocatalytic CO2 reduction to produce CO, outperforming the 2H/fcc Au91 Cu9 and fcc Au99 Cu1 . The experimental results, especially those obtained by in-situ differential electrochemical mass spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy, suggest that the enhanced catalytic performance of 2H/fcc Au99 Cu1 arises from the unconventional 2H/fcc heterophase, high-index facets, planar defects, and appropriate alloying of Cu. Impressively, the 2H/fcc Au99 Cu1 shows CO Faradaic efficiencies of 96.6% and 92.6% at industrial current densities of 300 and 500 mA cm-2 , respectively, as well as good durability, placing it among the best CO2 reduction electrocatalysts for CO production. The atomically structural regulation based on phase engineering of nanomaterials (PEN) provides an avenue for the rational design and preparation of high-performance electrocatalysts for various catalytic applications.

Ultrathin 2D Pd/Cu Single-Atom MOF Nanozyme to Synergistically Overcome Chemoresistance for Multienzyme Catalytic Cancer Therapy

Single-atom nanozymes (SAzymes) have obtained increasing interest to mimic natural enzymes for efficient cancer therapy, while challenged by chemoresistance from cellular redox homeostasis and the interface of reductive species in tumor microenvironment (TME). Herein, a dual single-atomic ultrathin 2D metal organic framework (MOF) nanosheet of multienzyme (Pd/Cu SAzyme@Dzy) is prepared to synergistically overcome chemoresistance for multienzyme enhanced cancer catalytic therapy. The Pd SAzyme exhibits peroxidase (POD)-like catalytic activity for overcoming chemoresistance via disturbing cellular redox balance. This is further enhanced by cascade generation of more ∙OH via Cu+ -catalyzed POD-like reactions, initiated by in situ-reduction of Cu2+ into Cu+ upon GSH depletion. This process can also avoid the consumption of ∙OH by endogenous reductive GSH in TME, ensuring the adequate amount of ∙OH for highly efficient therapy. Besides, the DNAzyme is also delivered for gene therapy of silencing cancer-cell-targeting VEGFR2 protein to further enhance the therapy. Based on both experiments and theoretical calculations, the synergetic multienzyme-based cancer therapy is examined and the enhancement by the cascade tumor antichemoresistance is revealed.

Organic molecule-assisted intermediate adsorption for conversion of CO2 to CO by electrocatalysis

Currently, Zn-based catalysts for electrochemical CO2 reduction reactions are limited by their moderate carbophilicity, resulting in low catalytic activity and CO selectivity. To this end, we selected 5-mercapto-1-methylimidazole, a small molecule that possesses the ability to both coordinate to Zn and interact with the intermediates, to modify electrochemically deposited Zn nanosheets. The interaction between them effectively enhances intermediate adsorption by lowering the Gibbs free energy, which leads to an increase of the Faraday efficiency to 1.9 times and the CO partial current density to 3.0 times that of the pristine sample (-1.0 V vs. RHE).

Recent Progress on Phase Engineering of Nanomaterials

As a key structural parameter, phase depicts the arrangement of atoms in materials. Normally, a nanomaterial exists in its thermodynamically stable crystal phase. With the development of nanotechnology, nanomaterials with unconventional crystal phases, which rarely exist in their bulk counterparts, or amorphous phase have been prepared using carefully controlled reaction conditions. Together these methods are beginning to enable phase engineering of nanomaterials (PEN), i.e., the synthesis of nanomaterials with unconventional phases and the transformation between different phases, to obtain desired properties and functions. This Review summarizes the research progress in the field of PEN. First, we present representative strategies for the direct synthesis of unconventional phases and modulation of phase transformation in diverse kinds of nanomaterials. We cover the synthesis of nanomaterials ranging from metal nanostructures such as Au, Ag, Cu, Pd, and Ru, and their alloys; metal oxides, borides, and carbides; to transition metal dichalcogenides (TMDs) and 2D layered materials. We review synthesis and growth methods ranging from wet-chemical reduction and seed-mediated epitaxial growth to chemical vapor deposition (CVD), high pressure phase transformation, and electron and ion-beam irradiation. After that, we summarize the significant influence of phase on the various properties of unconventional-phase nanomaterials. We also discuss the potential applications of the developed unconventional-phase nanomaterials in different areas including catalysis, electrochemical energy storage (batteries and supercapacitors), solar cells, optoelectronics, and sensing. Finally, we discuss existing challenges and future research directions in PEN.

WO3 -Assisted Synergetic Effect Catalyzes Efficient and CO-Tolerant Hydrogen Oxidation for PEMFCs

Developing anode catalysts with substantially enhanced activity for hydrogen oxidation reaction (HOR) and CO tolerance performance is of great importance for the commercial applications of proton exchange membrane fuel cells (PEMFCs). Herein, an excellent CO-tolerant catalyst (Pd-WO3 /C) has been fabricated by loading Pd nanoparticles on WO3 via an immersion-reduction route. A remarkably high power density of 1.33 W cm-2 at 80 °C is obtained by using the optimized 3Pd-WO3 /C as the anode catalyst of PEMFCs, and the moderately reduced power density (73% remained) in CO/H2 mixed gas can quickly recover after removal of CO-contamination from hydrogen fuel, which is not possible by using Pt/C or Pd/C as anode catalyst. The prominent HOR activity of 3Pd-WO3 /C is attributed to the optimized interfacial electron interaction, in which the activated H* adsorbed on Pd species can be effectively transferred to WO3 species through hydrogen spillover effect and then oxidized through the H species insert/output effect during the formation of Hx WO3 in acid electrolyte. More importantly, a novel synergetic catalytic mechanism about excellent CO tolerance is proposed, in which Pd and WO3 respectively absorbs/activates CO and H2 O, thus achieving the CO electrooxidation and re-exposure of Pd active sites for CO-tolerant HOR.

Applications of Transmission Electron Microscopy in Phase Engineering of Nanomaterials

Phase engineering of nanomaterials (PEN) is an emerging field that aims to tailor the physicochemical properties of nanomaterials by precisely manipulating their crystal phases. To advance PEN effectively, it is vital to possess the capability of characterizing the structures and compositions of nanomaterials with precision. Transmission electron microscopy (TEM) is a versatile tool that combines reciprocal-space diffraction, real-space imaging, and spectroscopic techniques, allowing for comprehensive characterization with exceptional resolution in the domains of time, space, momentum, and, increasingly, even energy. In this Review, we first introduce the fundamental mechanisms behind various TEM-related techniques, along with their respective application scopes and limitations. Subsequently, we review notable applications of TEM in PEN research, including applications in fields such as metallic nanostructures, carbon allotropes, low-dimensional materials, and nanoporous materials. Specifically, we underscore its efficacy in phase identification, composition and chemical state analysis, in situ observations of phase evolution, as well as the challenges encountered when dealing with beam-sensitive materials. Furthermore, we discuss the potential generation of artifacts during TEM imaging, particularly in scanning modes, and propose methods to minimize their occurrence. Finally, we offer our insights into the present state and future trends of this field, discussing emerging technologies including four-dimensional scanning TEM, three-dimensional atomic-resolution imaging, and electron microscopy automation while highlighting the significance and feasibility of these advancements.

Lattice-Strain Engineering for Heterogenous Electrocatalytic Oxygen Evolution Reaction

The energy efficiency of metal-air batteries and water-splitting techniques is severely constrained by multiple electronic transfers in the heterogenous oxygen evolution reaction (OER), and the high overpotential induced by the sluggish kinetics has become an uppermost scientific challenge. Numerous attempts are devoted to enabling high activity, selectivity, and stability via tailoring the surface physicochemical properties of nanocatalysts. Lattice-strain engineering as a cutting-edge method for tuning the electronic and geometric configuration of metal sites plays a pivotal role in regulating the interaction of catalytic surfaces with adsorbate molecules. By defining the d-band center as a descriptor of the structure-activity relationship, the individual contribution of strain effects within state-of-the-art electrocatalysts can be systematically elucidated in the OER optimization mechanism. In this review, the fundamentals of the OER and the advancements of strain-catalysts are showcased and the innovative trigger strategies are enumerated, with particular emphasis on the feedback mechanism between the precise regulation of lattice-strain and optimal activity. Subsequently, the modulation of electrocatalysts with various attributes is categorized and the impediments encountered in the practicalization of strained effect are discussed, ending with an outlook on future research directions for this burgeoning field.

Strain and Surface Engineering of Multicomponent Metallic Nanomaterials with Unconventional Phases

Multicomponent metallic nanomaterials with unconventional phases show great prospects in electrochemical energy storage and conversion, owing to unique crystal structures and abundant structural effects. In this review, we emphasize the progress in the strain and surface engineering of these novel nanomaterials. We start with a brief introduction of the structural configurations of these materials, based on the interaction types between the components. Next, the fundamentals of strain, strain effect in relevant metallic nanomaterials with unconventional phases, and their formation mechanisms are discussed. Then the progress in surface engineering of these multicomponent metallic nanomaterials is demonstrated from the aspects of morphology control, crystallinity control, surface modification, and surface reconstruction. Moreover, the applications of the strain- and surface-engineered unconventional nanomaterials mainly in electrocatalysis are also introduced, where in addition to the catalytic performance, the structure-performance correlations are highlighted. Finally, the challenges and opportunities in this promising field are prospected.

Design and Synthesis of Noble Metal-Based Alloy Electrocatalysts and Their Application in Hydrogen Evolution Reaction

Hydrogen energy is regarded as the ultimate energy source for future human society, and the preparation of hydrogen from water electrolysis is recognized as the most ideal way. One of the key factors to achieve large-scale hydrogen production by water splitting is the availability of highly active and stable electrocatalysts. Although non-precious metal electrocatalysts have made great strides in recent years, the best hydrogen evolution reaction (HER) electrocatalysts are still based on noble metals. Therefore, it is particularly important to improve the overall activity of the electrocatalysts while reducing the noble metals load. Alloying strategies can shoulder the burden of optimizing electrocatalysts cost and improving electrocatalysts performance. With this in mind, recent work on the application of noble metal-based alloy electrocatalysts in the field of hydrogen production from water electrolysis is summarized. In this review, first, the mechanism of HER is described; then, the current development of synthesis methods for alloy electrocatalysts is presented; finally, an example analysis of practical application studies on alloy electrocatalysts in hydrogen production is presented. In addition, at the end of this review, the prospects, opportunities, and challenges facing noble metal-based alloy electrocatalysts are tried to discuss.

A tube-like Pd@coordination polymer with enhanced solar light harvesting for boosting photocatalytic H2 production in a wide pH range and seawater

Coordination polymers (CPs) have emerged as promising candidates for photocatalytic H₂ production owing to their structural tailorability and functional diversity. However, the development of CPs with high energy transfer efficiency for highly efficient photocatalytic H₂ production in a wide pH range still faces many challenges. Here we constructed a novel tube-like Pd(ii) coordination polymer with well-distributed Pd nanoparticles (denoted as Pd/Pd(ii)CPs) based on the coordination assembly of rhodamine 6G and Pd(ii) ions and further photo-reduction under visible light irradiation. Both the Br^- ion and double solvent play a key role in forming the hollow superstructures. The resulting tube-like Pd/Pd(ii)CPs exhibit high stability in aqueous solution with the pH range from 3 to 14 due to the high Gibbs free energies of protonation and deprotonation, which provides the feasibility of photocatalytic hydrogen generation in a wide pH range. Electromagnetic field calculations showed that the tube-like Pd/Pd(ii)CPs have a good confinement effect on light. Therefore, the H₂ evolution rate could reach 112.3 mmol h^-1 g^-1 at pH 13 under visible light irradiation, which is far superior to those of reported coordination polymer-based photocatalysts. Moreover, such Pd/Pd(ii)CPs could also reach a H₂ production rate of 37.8 mmol h^-1 g^-1 in seawater under visible light with low optical density (40 mW cm^-2) close to morning or cloudy sunlight. The above unique characteristics make the Pd/Pd(ii)CPs possess great potential for practical applications.

Amorphous Copper-Based Nanoparticles with Clusterization-Triggered Phosphorescence for Ultrasensing 2,4,6-Trinitrotoluene

Amorphous metal-based nanostructures have attracted great attention recently due to their facilitative electron transfer and abundant reactive sites, whereas it remains enigmatic as to whether amorphous copper-based nanoparticles (CuNPs) can be achieved. Here, for synthesizing amorphous CuNPs, glutathione is adopted as a ligand to inhibit the nucleation and crystallization process via its electrostatic repulsion. By subtly tailoring the solvent polarity, not only can amorphous glutathione-functionalized CuNPs (GSH-CuNPs) with phosphorescent performance be achieved after transferring the non-conjugation of GSH ligand to through-space conjugation, namely clusterization-triggered emission, but also the phosphorescence-off of GSH-CuNPs toward 2,4,6-trinitrotoluene (TNT) can be realized by the photoinduced electron-transfer process through the hydrogen bond channel, which is established between carboxyl and amino groups of GSH-CuNPs with the nitryl group of TNT. Benefitting from the intrinsic superiorities of the amorphous CuNPs, desired phosphorescence and detection performances of GSH-CuNPs toward airborne TNT microparticulates are undoubtedly realized, including high quantum yield (13.22%), excellent specificity in 33 potential interferents, instantaneous response, and ultralow detection limit (1.56 pg). The present GSH-CuNPs are expected to stretch amorphous metal-based nanostructures and deepen the insights into amorphous materials for optical detection.

Disordered Au Nanoclusters for Efficient Ammonia Electrosynthesis

The electrochemical nitrogen (N₂ ) reduction reaction (N₂ RR) under mild conditions is a promising and environmentally friendly alternative to the traditional Haber-Bosch process with high energy consumption and greenhouse emission for the synthesis of ammonia (NH₃ ), but high-yielding production is rendered challenging by the strong nonpolar N≡N bond in N₂ molecules, which hinders their dissociation or activation. In this study, disordered Au nanoclusters anchored on two-dimensional ultrathin Ti₃ C₂ T_x MXene nanosheets are explored as highly active and selective electrocatalysts for efficient N₂ -to-NH₃ conversion, exhibiting exceptional activity with an NH₃ yield rate of 88.3±1.7 μg h^-1  mg_cat. ^-1 and a faradaic efficiency of 9.3±0.4 %. A combination of in situ near-ambient pressure X-ray photoelectron spectroscopy and operando X-ray absorption fine structure spectroscopy is employed to unveil the uniqueness of this catalyst for N₂ RR. The disordered structure is found to serve as the active site for N₂ chemisorption and activation during the N₂ RR process.

Noble-Metal-Metalloid Alloy Architectures: Mesoporous Amorphous Iridium-Tellurium Alloy for Electrochemical N2 Reduction

Amorphous noble metals with high surface areas have attracted significant interest as heterogeneous catalysts due to the numerous dangling bonds and abundant unsaturated surface atoms created by the amorphous phase. However, synthesizing amorphous noble metals with high surface areas remains a significant challenge due to strong isotropic metallic bonds. This paper describes the first example of a mesoporous amorphous noble metal alloy [iridium-tellurium (IrTe)] obtained using a micelle-directed synthesis method. The resulting mesoporous amorphous IrTe electrocatalyst exhibits excellent performance in the electrochemical N₂ reduction reaction. The ammonia yield rate is 34.6 μg mg^-1 h^-1 with a Faradaic efficiency of 11.2% at -0.15 V versus reversible hydrogen electrode in 0.1 M HCl solution, outperforming comparable crystalline and Ir metal counterparts. The interconnected porous scaffold and amorphous nature of the alloy create a complementary effect that simultaneously enhances N₂ absorption and suppresses the hydrogen evolution reaction. According to theoretical simulations, incorporating Te in the IrTe alloy effectively strengthens the adsorption of N₂ and lowers the Gibbs free energy for the rate-limiting step of the electrocatalytic N₂ reduction reaction. Mesoporous chemistry enables a new route to achieve high-performance amorphous metalloid alloys with properties that facilitate the selective electrocatalytic reduction of N₂.

Sulfur-Induced Low Crystallization of Ultrathin Pd Nanosheet Arrays for Sulfur Ion Degradation-Assisted Energy-Efficient H2 Production

The utilization of thermodynamically favorable sulfur oxidation reaction (SOR) as an alternative to sluggish oxygen evolution reaction is a promising technology for low-energy H₂ production while degrading the sulfur source from wastewater. Herein, amorphous/crystalline S-doped Pd nanosheet arrays on nickel foam (a/c S-Pd NSA/NF) is prepared by S-doping crystalline Pd NSA/NF.  Owing to the ultrathin amorphous nanosheet structure and the incorporation of S atoms, the a/c S-Pd NSA/NF provides a large number of active sitesand the optimized electronic structure, while exhibiting outstanding electrocatalytic activity in hydrogen evolution reaction (HER) and SOR. Therefore, the coupling system consisting of SOR-assisted HER can reach a current density of 100 mA cm^-2 at 0.642 V lower than conventional electrolytic water by 1.257 V, greatly reducing energy consumption. In addition, a/c S-Pd NSA/NF can generate H₂ over a long period of time while degrading S^2- in water to the value-added sulfur powder, thus further reducing the cost of H₂ production. This work proposes an attractive strategy for the construction of an advanced electrocatalyst for H₂ production and utilization of toxic sulfide wastewater by combining S-doping induced partial amorphization and ultrathin metal nanosheet arrays.

Micron-Scale Fabrication of Ultrathin Amorphous Copper Nanosheets Templated by DNA Scaffolds

Two-dimensional (2D) amorphous materials could outperform their crystalline counterparts toward various applications because they have more defects and reactive sites and thus could exhibit a unique surface chemical state and provide an advanced electron/ion transport path. Nevertheless, it is challenging to fabricate ultrathin and large-sized 2D amorphous metallic nanomaterials in a mild and controllable manner due to the strong metallic bonds between metal atoms. Here, we reported a simple yet fast (10 min) DNA nanosheet (DNS)-templated method to synthesize micron-scale amorphous copper nanosheets (CuNSs) with a thickness of 1.9 ± 0.4 nm in aqueous solution at room temperature. We demonstrated the amorphous feature of the DNS/CuNSs by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Interestingly, we found that they could transform to crystalline forms under continuous electron beam irradiation. Of note, the amorphous DNS/CuNSs exhibited much stronger photoemission (∼62-fold) and photostability than dsDNA-templated discrete Cu nanoclusters due to the elevation of both the conduction band (CB) and valence band (VB). Such ultrathin amorphous DNS/CuNSs hold great potential for practical applications in biosensing, nanodevices, and photodevices.

Pd-PdO Nanodomains on Amorphous Ru Metallene Oxide for High-Performance Multifunctional Electrocatalysis

Developing highly efficient multifunctional electrocatalysts is crucial for future sustainable energy  pursuits, but remains a great challenge. Herein, a facile synthetic strategy is used to confine atomically thin Pd-PdO nanodomains to amorphous Ru metallene oxide (RuO₂ ). The as-synthesized electrocatalyst (Pd₂ RuOx-0.5 h) exhibits excellent catalytic activity toward the pH-universal hydrogen evolution reaction (η₁₀  = 14 mV in 1 m KOH, η₁₀  = 12 mV in 0.5 m H₂ SO₄ , and η₁₀  = 22 mV in 1 m PBS), alkaline oxygen evolution reaction (η₁₀  = 225 mV), and overall water splitting (E₁₀  = 1.49 V) with high mass activity and operational stability. Further reduction endows the material (Pd₂ RuOx-2 h) with a promising alkaline oxygen reduction activity, evidenced by high halfway potential, four-electron selectivity, and excellent poison tolerance. The enhanced catalytic activity is attributed to the rational integration of favorable nanostructures, including 1) the atomically thin nanosheet morphology, 2) the coexisting amorphous and defective crystalline phases, and 3) the multi-component heterostructural features. These structural factors effectively regulate the material's electronic configuration and the adsorption of intermediates at the active sites for favorable reaction energetics.

Metallene-related materials for electrocatalysis and energy conversion

As a member of graphene analogs, metallenes are a class of two-dimensional materials with atomic thickness and well-controlled surface atomic arrangement made of metals or alloys. When utilized as catalysts, metallenes exhibit distinctive physicochemical properties endowed from the under-coordinated metal atoms on the surface, making them highly competitive candidates for energy-related electrocatalysis and energy conversion systems. Significantly, their catalytic activity can be precisely tuned through the chemical modification of their surface and subsurface atoms for efficient catalyst engineering. This minireview summarizes the recent progress in the synthesis and characterization of metallenes, together with their use as electrocatalysts toward reactions for energy conversion. In the Synthesis section, we pay particular attention to the strategies designed to tune their exposed facets, composition, and surface strain, as well as the porosity/cavity, defects, and crystallinity on the surface. We then discuss the electrocatalytic properties of metallenes in terms of oxygen reduction, hydrogen evolution, alcohol and acid oxidation, carbon dioxide reduction, and nitrogen reduction reaction, with a small extension regarding photocatalysis. At the end, we offer perspectives on the challenges and opportunities with respect to the synthesis, characterization, modeling, and application of metallenes.

Low-Coordinated Pd Site within Amorphous Palladium Selenide for Active, Selective, and Stable H2 O2 Electrosynthesis

The development of high-performance catalysts with high activity, selectivity, and stability are essential for the practical applications of H₂ O₂ electrosynthesis technology, but it is still formidably challenging. It is reported that the low-coordinated structure of Pd sites in amorphous PdSe₂ nanoparticles (a-PdSe₂ NPs) can significantly boost the electrocatalytic synthesis of H₂ O₂ . Detailed investigations and theoretical calculations reveal that the disordered arrangement of Pd atoms in a-PdSe₂ NPs can promote the activity, while the Pd sites with low-coordinated environment can optimize the adsorption toward oxygenated intermediate and suppress the cleavage of O-O bond, leading to a significant enhancement in both the H₂ O₂ selectivity and productivity. Impressively, a-PdSe₂ NPs/C exhibits high H₂ O₂ selectivity over 90% in different pH electrolytes. H₂ O₂ productivities with ≈3245.7, 1725.5, and 2242.1 mmol g_Pd ^-1  h^-1 in 0.1 m KOH, 0.1 m HClO₄ , and 0.1 m Na₂ SO₄ can be achieved, respectively, in an H-cell electrolyzer, being a pH-universal catalyst for H₂ O₂ electrochemical synthesis. Furthermore, the produced H₂ O₂ can reach 1081.8 ppm in a three-phase flow cell reactor after 2 h enrichment in 0.1 m Na₂ SO₄ , showing the great potential of a-PdSe₂ NPs/C for practical H₂ O₂ electrosynthesis.

Amorphous Mo-doped NiS0.5 Se0.5 Nanosheets@Crystalline NiS0.5 Se0.5 Nanorods for High Current-density Electrocatalytic Water Splitting in Neutral Media

It is vitally important to develop highly active, robust and low-cost transition metal-based electrocatalysts for overall water splitting in neutral solution especially at large current density. In this work, amorphous Mo-doped NiS_0.5 Se_0.5 nanosheets@crystalline NiS_0.5 Se_0.5 nanorods (Am-Mo-NiS_0.5 Se_0.5 ) was synthesized using a facil one-step strategy. In phosphate buffer saline solution, the Am-Mo-NiS_0.5 Se_0.5 shows tiny overpotentials of 48 and 209 mV for hydrogen evolution reaction (HER), 238 and 514 mV for oxygen evolution reaction (OER) at 10 and 1000 mA cm^-2 , respectively. Moreover, Am-Mo-NiS_0.5 Se_0.5 delivers excellent stability for at least 300 h without obvious degradation. Theoretical calculations revealed that the Ni sites in the defect-rich amorphous structure of Am-Mo-NiS_0.5 Se_0.5 owns higher electron state density and strengthened the binding energy of H₂ O, which will optimize H adsorption/desorption energy barriers and reduce the adsorption energy of OER determining step.

Harvesting PdH Employing Pd Nano Icosahedrons via High Pressure

Palladium hydrides (PdH_x ) have important applications in hydrogen storage, catalysis, and superconductivity. Because of the unique electron subshell structure of Pd, quenching PdH_x materials with more than 0.706 hydrogen stoichiometry remains challenging. Here, the 1:1 stoichiometric PdH ( F m 3 ¯ m ) $Fm\bar{3}m)$ is successfully synthesized using Pd nano icosahedrons as a starting material via high-pressure cold-forging at 0.2 GPa. The synthetic initial pressure is reduced by at least one order of magnitude relative to the bulk Pd precursors. Furthermore, PdH is quenched at ambient conditions after being laser heated ≈2000 K under ≈30 GPa. Corresponding ab initio calculations demonstrate that the high potential barrier of the facets (111) restricts hydrogen atoms' diffusion, preventing hydrogen atoms from combining to generate H₂ . This study paves the way for the high-pressure synthesis of metal hydrides with promising potential applications.

Universal Synthesized Strategy for Amorphous Pd-Based Nanosheets Boosting Ambient Ammonia Electrosynthesis

The electrocatalytic nitrogen reduction reaction (NRR) is emerging as a great promise for ambient and sustainable NH₃ production while it still suffers from the high adsorption energy of N₂ , the difficulty of *NN protonation, and inevitable hydrogen evolution, leading to a great challenge for efficient NRR. Herein, we synthesized a series of amorphous trimetal Pd-based (PdCoM (M = Cu, Ag, Fe, Mo)) nanosheets (NSs) with an ultrathin 2D structure, which shows high efficiency and robust electrocatalytic nitrogen fixation. Among them, amorphous PdCoCu NSs exhibit excellent NRR activity at low overpotentials with an NH₃ yield of 60.68 µg h^-1 mg_cat ^-1 and a corresponding Faraday efficiency of 42.93% at -0.05 V versus reversible hydrogen electrode as well as outstanding stability with only 5% decrease after a long test period of 40 h at room temperature. The superior NRR activity and robust stability should be attributed to the large specific surface area, abundant active sites as well as structural engineering and electronic effect that boosts up the Pd 4d band center, which further efficiently restrains the hydrogen evolution. This work offers an opportunity for more energy conversion devices through the novel strategy for designing active and stable catalysts.

Atomically Reconstructed Palladium Metallene by Intercalation-Induced Lattice Expansion and Amorphization for Highly Efficient Electrocatalysis

As an emerging class of materials with distinctive physicochemical properties, metallenes are deemed as efficient catalysts for energy-related electrocatalytic reactions. Engineering the lattice strain, electronic structure, crystallinity, and even surface porosity of metallene provides a great opportunity to further enhance its catalytic performance. Herein, we rationally developed a reconstruction strategy of Pd metallenes at atomic scale to generate a series of nonmetallic atom-intercalated Pd metallenes (M-Pdene, M = H, N, C) with lattice expansion and S-doped Pd metallene (S-Pdene) with an amorphous structure. Catalytic performance evaluation demonstrated that N-Pdene exhibited the highest mass activities of 7.96 A mg^-1, which was 10.6 and 8.5 time greater than those of commercial Pd/C and Pt/C, respectively, for methanol oxidation reaction (MOR). Density functional theory calculations suggested that the well-controlled lattice tensile strain as well as the strong p-d hybridization interaction between N and Pd resulted in enhanced OH adsorption and weakened CO adsorption for efficient MOR catalysis on N-Pdene. When tested as hydrogen evolution reaction (HER) catalysts, the amorphous S-Pdene delivered superior activity and durability relative to the crystalline counterparts because of the disordered Pd surface with a further elongated bond length and a downshifted d-band center. This work provides an effective strategy for atomic engineering of metallene nanomaterials with high performance as electrocatalysts.

Tailoring Amorphous PdCu Nanostructures for Efficient C-C Cleavage in Ethanol Electrooxidation

The large-scale application of direct ethanol fuel cells has long been obstructed by the sluggish ethanol oxidation reaction at the anode. Current wisdom for designing and fabricating EOR electrocatalysts has been focused on crystalline materials, which result in only limited improvement in catalytic efficiency. Here, we report the amorphous PdCu (a-PdCu) nanomaterials as superior EOR electrocatalysts. The amorphization of PdCu catalysts can significantly facilitate the C-C bond cleavage, which thereby affords a C1 path faradic efficiency as high as 69.6%. Further tailoring the size and shape of a-PdCu nanocatalysts through the delicate kinetic control can result in a maximized mass activity up to 15.25 A/mg_Pd, outperforming most reported catalysts. Notably, accelerated durability tests indicate that both the isotropic structure and one-dimensional shape can dramatically enhance the catalytic durability of the catalysts. This work provides valuable guidance for the rational design and fabrication of amorphous noble metal-based electrocatalysts for fuel cells.

Amorphous-crystalline PdRu bimetallene for efficient hydrogen evolution electrocatalysis

In this work, PdRu bimetallene is prepared by a wet-chemical method using CO as a structure-directing agent and reductant derived from the decomposition of W(CO)₆. The PdRu bimetallene exhibits excellent catalytic activity with a small overpotential of -32 mV compared to Pd metallene (-62 mV) at -10 mA cm^-2 in acidic conditions.

Supra Hydrolytic Catalysis of Ni3 Fe/rGO for Hydrogen Generation

Light metal hydrolysis for hydrogen supply is well suited for portable hydrogen fuel cells. The addition of catalysts can substantially aid Mg hydrolysis. However, there is a lack of clear catalytic mechanism to guide the design of efficient catalysts. In this work, the essential role of nanosized catalyst (Ni₃ Fe/rGO) in activating micro-sized Mg with ultra-rapid hydrolysis process is investigated for the first time. Here, an unprecedented content of 0.2 wt% Ni₃ Fe/rGO added Mg can release 812.4 mL g^-1 hydrogen in just 60 s at 30 °C. Notably, an impressive performance with a hydrogen yield of 826.4 mL g^-1 at 0 °C in only 30 s is achieved by the Mg-2 wt% Ni₃ Fe/rGO, extending the temperature range for practical applications of hydrolysis. Moreover, the four catalysts (Ni₃ Fe/rGO, Ni₃ Fe, Ni/rGO, Fe/rGO) are designed to reveal the influence of composition, particle size, and dispersion on catalytic behavior. Theoretical studies corroborate that the addition of Ni₃ Fe/rGO accelerates the electron transfer and coupling processes and further provides a lower energy barrier diffusion path for hydrogen. Thus, a mechanism concerning the catalyst as migration relay is proposed. This work offers guidelines designing high-performance catalysts especially for activating the hydrolysis of micro-sized light weight metals.

Pt- and Pd-modified transition metal nitride catalysts for the hydrogen evolution reaction

Hydrogen production via electrochemical splitting of water using renewable electricity represents a promising strategy. Currently, platinum group metals (PGMs) are the best performing hydrogen evolution reaction (HER) catalysts. Thus, the design of non-PGM catalysts or low-loading PGM catalysts is essential for the commercial development of hydrogen generation technologies via electrochemical splitting of water. Here, we employed density functional theory (DFT) calculations to explore Pt and Pd modified transition metal nitrides (TMNs) as low-cost HER catalysts. Our calculations show that Pt/Pd binds strongly with TMs on TMN(111) surfaces, leading to the formation of stable Pt and Pd-monolayer (ML)-TMN(111) structures. Furthermore, our calculated hydrogen binding energy (HBE) demonstrates that Pt/MnN, Pt/TiN, Pt/FeN, Pt/VN, Pt/HfN, Pd/FeN, Pd/TaN, Pd/NbN, Pd/TiN, Pd/HfN, Pd/MnN, Pd/ScN, Pd/VN, and Pd/ZrN are promising candidates for the HER with a low value of limiting potential (U_L) similar to that calculated on Pt(111).

Urchin-like PdOs nanostructure for hydrogen evolution electrocatalysis

The compositional and structural engineering of advanced nanomaterials for hydrogen evolution reaction (HER) is highly necessary for efficient hydrogen production. Herein, PdOs nanospine assemblies (PdOs NAs) with urchin-like structures are fabricated via one-step route using DM-970 and KBr as surfactant agent and capping agent, respectively. Benefiting from electronic effect and multi-branched structure, the PdOs NAs exhibit superior performance for HER in alkaline and neutral solutions, requiring overpotentials of 28 and 35 mV at -10 mA cm^-2, respectively, as well as superior long-term stability. This study offers a universal approach for the fabrication of active Pd-based catalysts with multi-branched morphology for efficient water electrolysis and beyond.

Shape-Controlled Photochemical Synthesis of Noble Metal Nanocrystals Based on Reduced Graphene Oxide

The fabrication of supported noble metal nanocrystals (NCs) with well-controlled morphologies have been attracted considerable interests due to their merits in a wide variety of applications. Photodeposition is a facile and effective method to load metals over semiconductors in a simple slurry reactor under irradiation. By optimizing the photodeposition process, the size, chemical states, and the geometrical distribution of metal NCs have been successfully tuned. However, metal NCs with well-controlled shapes through the photodeposition process have not been reported until now. Here, we report our important advances in the controlled photodeposition process to load regular noble metal NCs. Reduced graphene oxide (rGO) is introduced as a reservoir for the fast transfer of photoelectrons to avoid the fast accumulation of photogenerated electrons on the noble metals which makes the growth process uncontrollable. Meanwhile, rGO also provides stable surface for the controlled nucleation and oriented growth. Noble metal NCs with regular morphologies are then evenly deposited on rGO. This strategy has been demonstrated feasible for different precious metals (Pd, Au, and Pt) and semiconductors (TiO₂, ZnO, ZrO₂, CeO₂, and g-C₃N₄). In the prototype application of electrochemical hydrogen evolution reaction, regular Pd NCs with enclosed {111} facets showed much better performance compared with that of irregular Pd NCs.

Pressure-Induced Amorphization and Crystallization of Heterophase Pd Nanostructures

Control of structural ordering in noble metals is very important for the exploration of their properties and applications, and thus it is highly desired to have an in-depth understanding of their structural transitions. Herein, through high-pressure treatment, the mutual transformations between crystalline and amorphous phases are achieved in Pd nanosheets (NSs) and nanoparticles (NPs). The amorphous domains in the amorphous/crystalline Pd NSs exhibit pressure-induced crystallization (PIC) phenomenon, which is considered as the preferred structural response of amorphous Pd under high pressure. On the contrary, in the spherical crystalline@amorphous core-shell Pd NPs, pressure-induced amorphization (PIA) is observed in the crystalline core, in which the amorphous-crystalline phase boundary acts as the initiation site for the collapse of crystalline structure. The distinct PIC and PIA phenomena in two different heterophase Pd nanostructures might originate from the different characteristics of Pd NSs and NPs, including morphology, amorphous-crystalline interface, and lattice parameter. This work not only provides insights into the phase transition mechanisms of amorphous/crystalline heterophase noble metal nanostructures, but also offers an alternative route for engineering noble metals with different phases.

Surface Molecular Functionalization of Unusual Phase Metal Nanomaterials for Highly Efficient Electrochemical Carbon Dioxide Reduction under Industry-Relevant Current Density

The electrochemical carbon dioxide reduction reaction (CO₂ RR) provides a sustainable strategy to relieve global warming and achieve carbon neutrality. However, the practical application of CO₂ RR is still limited by the poor selectivity and low current density. Here, the surface molecular functionalization of unusual phase metal nanomaterials for high-performance CO₂ RR under industry-relevant current density is reported. It is observed that 5-mercapto-1-methyltetrazole (MMT)-modified 4H/face-centered cubic (fcc) gold (Au) nanorods demonstrate greatly enhanced CO₂ RR performance than original oleylamine (OAm)-capped 4H/fcc Au nanorods in both an H-type cell and flow cell. Significantly, MMT-modified 4H/fcc Au nanorods deliver an excellent carbon monoxide selectivity of 95.6% under the industry-relevant current density of 200 mA cm^-2 . Density functional theory calculations reveal distinct electronic modulations by surface ligands, in which MMT improves while OAm suppresses the surface electroactivity of 4H/fcc Au nanorods. Furthermore, this method can be extended to various MMT derivatives and conventional fcc Au nanostructures in boosting CO₂ RR performance.

Self-supporting Electrocatalyst Film based on Self-assembly of Heterogeneous Bottlebrush and Polyoxometalate for Efficient Hydrogen Evolution Reaction

Developing efficient electrocatalysts to promote the hydrogen evolution reaction (HER) is essential for green and sustainable future energy supply. For practical applications, it is a challenge to achieve self-assembly of electrocatalyst from microscopic to macroscopic scales. Herein, we propose a facile strategy to fabricate a self-supporting electrocatalyst film (CNT-g-PSSCo/PW₁₂ ) for HER by electrostatic interaction induced self-assembly of cobalt polystyrene sulfonate-grafted carbon nanotube heterogeneous bottlebrush (CNT-g-PSSCo) and polyoxometalates (PW₁₂ ). Co²⁺ ions of CNT-g-PSSCo can function as junctions for interconnecting neighbouring bottlebrushes to form the 3D nanonetwork structure and enable electrostatic capture of negatively-charged PW₁₂ nanodots. Moreover, CNT backbones can provide highly conductive pathways to CNT-g-PSSCo/PW₁₂ . Such a self-assembled CNT-g-PSSCo/PW₁₂ displays a low overpotential of 31 mV at a current density of 10 mA cm^-2 and a small Tafel slope of 25 mV dec^-1 , showing high efficiency toward HER. Furthermore, CNT-g-PSSCo/PW₁₂ with a stable self-supporting film morphology exhibits long-term electrocatalytic stability over 1000 CV cycles without noticeable overpotential change in acidic media. Our findings may provide a new avenue for constructing self-assembled functional nanonetwork materials with well-orchestrated structural hierarchy for many applications in energy, environment, catalysis, medicine, and others. This article is protected by copyright. All rights reserved.

Boosting Hydrogen Evolution through the Interface Effects of Amorphous NiMoO4-MoO2 and Crystalline Cu

The rational design and synthesis of a highly efficient and cost-effective electrocatalyst for hydrogen evolution reaction (HER) are of great importance for the efficient generation of sustainable energy. Herein, amorphous/crystalline heterophase Ni-Mo-O/Cu (denoted as a/c Ni-Mo-O/Cu) was synthesized by a one-pot electrodeposition method. Thanks to the introduction of metallic Cu and the formation of amorphous Ni-Mo-O, the prepared electrocatalyst exhibits favorable conductivity and abundant active sites, which are favorable to the HER progress. Moreover, the interfaces consisting of Cu and Ni-Mo-O show electron transfers between these components, which might modify the absorption/desorption energy of H atoms, thus accelerating HER activity. As expected, the prepared a/c Ni-Mo-O/Cu possesses excellent HER performance, which affords an ultralow overpotential of 34.8 mV at 10 mA cm^-2, comparable to that of 20 wt % Pt/C (35.0 mV), and remarkable stability under alkaline conditions.

Pd Doped Co3O4 Loaded on Carbon Nanofibers as Highly Efficient Free-Standing Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions

Self-supporting electrodes usually show excellent electrocatalytic performance which does not require coating steps, additional polymer binders, and conductive additives. Rapid in situ growth of highly active ingredient on self-supporting electric conductors is identified as a straight forward path to prepare binder-free and integrated electrodes. Here, Pd-doped Co₃O₄ loaded on carbon nanofiber materials through electrospinning and heat treatment was efficiently synthesized, and used as a free-standing electrode. Benefiting from its abundant active sites, high surface area and effective ionic conduction capability from three-dimensional (3D) nanofiber framework, Pd-Co₃O₄@CNF works as bifunctional oxygen electrode and exhibits superior activity and stability superior to commercial catalysts.

Simultaneous photocatalytic H2 generation and organic synthesis over crystalline-amorphous Pd nanocube decorated Cs3Bi2Br9

Cs3Bi2Br9 decorated with crystalline-amorphous Pd nanocubes as cocatalyst is reported to photocatalytically coproduce ca. 1400 μmol h−1 g−1 of H2 and benzaldehyde from the selective benzyl alcohol oxidation. This route...