Highly Stable and Active Flexible Electrocatalysts Derived from Lotus Fibers

The stability and activity of electrocatalysts are fundamental in energy-related applications (e.g., hydrogen generation and energy storage). Electrocatalysts degrade over time when the active centers are not strongly anchored to the support. However, if the active centers are too strongly anchored, the activity of the electrocatalysts decreases due to reduced accessibility to reactants. Herein, a strategy is presented to balance the stability and activity of different active materials using a natural and flexible support material that can be woven and carbonized. Lotus fibers, which have surface hydroxyl and phenolic groups, high mechanical strength, and a mesoscale porosity post-pyrolysis, are used to load diverse functional metal-containing materials such as metal–organic frameworks, 2D materials, metal sulfide nanoparticles, metal ions, and high-entropy alloys. After pyrolysis, the electrocatalysts display flexibility, high catalytic performance, and long-term stability, outperforming commercial benchmarks (e.g., Pt/C) in specific scenarios for water splitting, liquid batteries, and flexible electronics.     

Photo-Driven Hydrogen Production from Methanol and Water using Plasmonic Cu Nanoparticles Derived from Layered Double Hydroxides

Methanol steam reforming (MSR) is viewed as an important technology in the growth of a future hydrogen economy, with methanol serving as an easily transportable and storable liquid hydrogen carrier. However, the thermocatalytic MSR reaction is energy intensive as it requires high temperatures. Herein, a novel L-Cu catalyst is successfully fabricated for photo-driven MSR through reduction of CuAl layered double hydroxide (CuAl-LDH) nanosheets. L-Cu offers outstanding activity for the photothermal conversion of methanol and water to hydrogen (160.5 µmol g_cat⁻¹ s⁻¹) under ultraviolet-visible irradiation, with this rate being much higher than that achieved for L-Cu at the same temperature in the dark. Characterization studies using X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and high-resolution transmission electron microscopy determine that L-Cu catalyst comprise Cu nanoparticles on an amorphous alumina support. Computational calculations reveale that Cu localized surface plasmon resonance effects promote the activation of H₂O, thereby underpinning the remarkable hydrogen production rates achieved during photo-driven MSR. This study introduces a novel photothermal strategy for hydrogen generation from methanol, demonstrating the enormous potential of photothermal catalysis in the chemical and energy sectors.     

Co3O4 Nanoparticles as Robust Water Oxidation Catalysts Towards Remarkably Enhanced Photostability of a Ta3N5 Photoanode

Despite the fact that Ta₃N₅ absorbs a major fraction of the visible spectrum, the rapid decrease of photocurrent encountered in water photoelectrolysis over time remains a serious hurdle for the practical application of Ta₃N₅ photoelectrodes. Here, by employing a Co₃O₄ nanoparticle water oxidation catalyst (WOC) as well as an alkaline electrolyte, the photostability of Ta₃N₅ electrode is significantly improved. Co₃O₄/Ta₃N₅ photoanode exhibits the best durability against photocorrosion to date, when compared with Co(OH)_x/Ta₃N₅ and IrO₂/Ta₃N₅ photoanodes. Specifically, about 75% of the initial stable photocurrent remains after 2 h irradiation at 1.2 V vs. RHE (reversible hydrogen electrode). Meanwhile, a photocurrent density of 3.1 mA cm^?2 has been achieved on Co₃O₄/Ta₃N₅ photoanode at 1.2 V vs. RHE with backside illumination under 1 sun AM 1.5 G simulated sunlight. The reason for the relatively high stability is discussed on the basis of electron microscopic observations and photoelectrochemical measurements, and the surface nitrogen content is monitored by X‐ray photoelectron spectroscopic analysis.     

Vesicle‐Assisted Assembly of Mesoporous Ce‐Doped Pd Nanospheres with a Hollow Chamber and Enhanced Catalytic Efficiency

Mesoporous Ce‐doped Pd nanospheres with a hollow chamber are synthesized by chemical reduction of PdCl₂ with KBH₄ in an aqueous solution containing Ce(NO₃)₃ and Bu₄PBr. The later acts as a template for the hollow chamber via forming organic vesicles. During the liquid‐phase phenol hydrogenation to cyclohexanone, the as‐prepared catalyst exhibits a much‐higher activity than the corresponding solid nanoparticle catalyst prepared in the absence of Bu₄PBr. Meanwhile, the Ce dopants greatly enhance the activity and selectivity to cyclohexanone. The hollow chamber is quite stable against heating in solution and the catalyst could be used repetitively many times. Such a catalyst shows a good potential in industrial applications.     

Lipid Oxidation Potential of Beef, Chicken, and Pork

Beef and pork longissimus dorsi and semimembranosus muscles and chicken breast and thigh muscles were excised 24 hr postmortem from carcasses of marketweight grain-finished feedlot beef cattle, marke-tweight hogs on a typical finishing diet, and broilers on a commercial grain diet. Muscle samples were immediately ground and formed into patties and stored raw or after cooking, at 4°C (cooked) or ?20°C (raw and cooked). TBA values (on sample weight basis) of frozen raw samples were higher for beef and pork than for chicken, as was heme iron content. However, TBA values of cooked samples were highest for chicken thigh muscles, which contained the most polyunsaturated fatty acids, at all storage temperatures.     

On the Catalytic Activity of Sn Monomers and Dimers at Graphene Edges and the Synchronized Edge Dependence of Diffusing Atoms in Sn Dimers

In this study, in situ transmission electron microscopy is performed to study the interaction between single (monomer) and paired (dimer) Sn atoms at graphene edges. The results reveal that a single Sn atom can catalyze both the growth and etching of graphene by the addition and removal of C atoms respectively. Additionally, the frequencies of the energetically favorable configurations of an Sn atom at a graphene edge, calculated using density functional theory calculations, are compared with experimental observations and are found to be in good agreement. The remarkable dynamic processes of binary atoms (dimers) are also investigated and is the first such study to the best of the knowledge. Dimer diffusion along the graphene edges depends on the graphene edge termination. Atom pairs (dimers) involving an armchair configuration tend to diffuse with a synchronized shuffling (step-wise shift) action, while dimer diffusion at zigzag edge terminations show a strong propensity to collapse the dimer with each atom diffusing in opposite directions (monomer formation). Moreover, the data reveals the role of C feedstock availability on the choice a single Sn atom makes in terms of graphene growth or etching. This study advances the understanding single atom catalytic activity at graphene edges.     

Silver Stars: Silver–Polymer Composite Stars: Synthesis and Applications (Adv. Funct. Mater. 9/2011)

Colloidal “silver stars” were synthesized upon poly(lactic‐co‐glycolic) acid nanosphere templates via a facile two‐step silver reduction method. Myriad dendrimer‐like Ag star morphologies were synthesized by varying the amount of poly(vinyl alcohol) and trisodium citrate used during silver reduction. Scanning electron microscopy studies revealed that star‐shaped silver–polymer composites possessing nanoscopic, fractal morphologies with diameters ranging from 500 nm to 7 μm were produced. These composites have broad applications from antibacterial agents to catalysis; two such applications were tested here. Surface‐enhanced Raman spectroscopy (SERS) studies showed multiple hot spots of SERS activity within a single star. Electrochemical catalysis experiments demonstrated the feasibility of using the silver stars instead of platinum for the oxygen reduction reaction in alkaline fuel cells.     

Creating Atomic Ordering in Electrocatalysis

Catalysis always proceeds in a chaotic fashion. Therefore, identifying the working principles of heterogeneous catalysts is a challenging task. Creating atomic order in heterogeneous catalysts simplifies this task and also offers new opportunities for rationally designing active sites to manipulate catalytic performance. The recent rapid advances in heterogeneous electrocatalysis have led to exciting progress in the construction of atomically ordered materials. Here, the latest progress in electrocatalysts with the periodic atomic arrangement, including intermetallic compounds with long-range order and metal atom-array catalysts with short-range order is summarized. The synthesis principles and the intriguing physical and chemical properties of these electrocatalysts are discussed. Furthermore, the compelling prospects of atomically ordered catalysts in the frontier of catalyst research are outlined.     

Re-Looking into the Active Moieties of Metal X-ides (X- = Phosph-, Sulf-, Nitr-, and Carb-) Toward Oxygen Evolution Reaction

Non-precious metal-based catalysts for oxygen evolution reaction (OER) have been extensively studied, among which the transition metal X-ides (including phosph-ides, sulf-ides, nitr-ides, and carb-ides) materials are emerging as promising candidates to replace the benchmark Ir/Ru-based materials in alkaline media. However, it is controversial whether the metal Xides host the real active sites since these metal Xides are thermodynamically unstable under a harsh OER environment—it has been reported that the initial metal Xides can be electrochemically oxidized and transformed into corresponding oxides and (oxy)hydroxides. Therefore, the metal Xides are argued as “pre-catalysts”; the electrochemically formed oxides and (oxy)hydroxides are believed as the real active moieties for OER. Herein, the recent advances in understanding the transformation behavior of metal Xides during OER are re-looked; importantly, hypotheses are provided to understand why the electrochemically formed oxides and (oxy)hydroxides catalysts derived from metal Xides are superior for OER to the as-prepared metal oxides and (oxy)hydroxides catalysts.     

Highly Dispersed NiO Clusters Induced Electron Delocalization of Ni?N?C Catalysts for Enhanced CO2 Electroreduction

Oxygen-regulated Ni-based single-atom catalysts (SACs) show great potential in accelerating the kinetics of electrocatalytic CO₂ reduction reaction (CO₂RR). However, it remains a challenge to precisely control the coordination environment of Ni O moieties and achieve high activity at high overpotentials. Herein, a facile carbonization coupled oxidation strategy is developed to mass produce NiO clusters-decorated Ni N C SACs that exhibit a high Faradaic efficiency of CO (maximum of 96.5%) over a wide potential range (−0.9 to −1.3 V versus reversible hydrogen electrode) and a high turnover frequency for CO production of 10 120 h⁻¹ even at the high overpotential of 1.19 V. Density functional theory calculations reveal that the highly dispersed NiO clusters induce electron delocalization of active sites and reduce the energy barriers for *COOH intermediates formation from CO₂, leading to an enhanced reaction kinetics for CO production. This study opens a new universal pathway for the construction of oxygen-regulated metal-based SACs for various catalytic applications.