Mesoporous Decoration of Freestanding Palladium Nanotube Arrays Boosts the Electrocatalysis Capabilities toward Formic Acid and Formate Oxidation

Fabricating high‐performance electrocatalysts is the most critical step in commercializing direct formic acid or formate fuel cells. In this work, a dual‐template electrodeposition method is used to create freestanding mesoporosity decorated palladium nanotube arrays (P‐PdNTA) as a bifunctional electrocatalyst toward formic acid and formate oxidation (FAO/FOR). The phytantriol‐based soft template modifies the superficial chemistry of aluminum anodic oxide inner surfaces, thereby facilitating the regulated electrodeposition of highly stable palladium nanotubes. The sacrifice of the soft template generates substantial mesoporosity on the nanotubes, resulting in a 189% increase in the electrochemically active surface area with respect to the mesopore‐free PdNTA baseline. In addition, the soft template significantly increases the density of catalytically active sites per unit area via perturbation on routine nanotube growth, as evidenced by the doubled areal catalytic activity of P‐PdNTA versus PdNTA. Remarkably, the P‐PdNTA delivered gravimetric catalytic currents of 3.65 and 3.87 A mg^?1 for FAO and FOR, which are 8.5 and 6.5 times higher, respectively, than those of commercial Pt/C. These values are among the most favorable reported and benefit from the unique synergy of fast substance transport, large electrochemical active surface area and high areal population of catalytically active sites.     

Enhanced Electrocatalysis for Energy‐Efficient Hydrogen Production over CoP Catalyst with Nonelectroactive Zn as a Promoter

As a non‐toxic species, Zn fulfills a multitude of biological roles, but its promoting effect on electrocatalysis has been rarely explored. Herein, the theoretic predications and experimental investigations that nonelectroactive Zn behaves as an effective promoter for CoP‐catalyzed hydrogen evolution reaction (HER) in both acidic and alkaline media is reported. Density function theory calculations reveal that Zn doing leads to more thermal‐neutral hydrogen adsorption free energy and thus enhanced HER activity for CoP catalyst. Electrochemical tests show that a Zn_0.08Co_0.92P nanowall array on titanium mesh (Zn_0.08Co_0.92P/TM) needs overpotentials of only 39 and 67 mV to drive a geometrical catalytic current of 10 mA cm^‐2 in 0.5 m H₂SO₄ and 1.0 m KOH, respectively. This Zn_0.08Co_0.92P/TM is also superior in activity over CoP/TM for urea oxidation reaction (UOR), driving 115 mA cm^‐2 at 0.6 V in 1.0 m KOH with 0.5 m urea. The high HER and UOR activity of this bifunctional electrode enables a Zn_0.08Co_0.92P/TM‐based two‐electrode electrolyzer for energy‐saving hydrogen production, offering 10 mA cm^‐2 at a low voltage of 1.38 V with strong long‐term electrochemical stability.     

Electrocatalysis with a Glucose-Oxidase-immobilized Graphite Electrode

Glucose oxidase was immobilized on the surface of a graphite electrode by irreversible adsorption. An electrocatalytic steady-state current for the oxidation of D-glucose was observed using this electrode in the presence of p-benzoquinone as an electron transfer mediator. The electrocatalytic current at 0.5 V vs. SCE was analyzed as a function of the concentrations of D-glucose and p-benzoquinone, and the maximum current, I_s^max, and the Michaelis constants (K₁ and K₂ for D-glucose and p-benzoquinone, respectively) of the electrocatalysis were determined. The dependence of the current on the electrode potential, pH, and temperature was also investigated. The results indicate that the kinetics of the immobilized enzyme are essentially the same as those of the enzyme in the solubilized state. The effect of various electron transfer mediators on the electrocatalytic current was also examined and evaluated in terms of I_s^max, K₁, and K₂ values.     

Tuning Multimetallic Ordered Intermetallic Nanocrystals for Efficient Energy Electrocatalysis

Ordered intermetallic alloys have attracted extensive attention as advanced electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) reactions with much improved activity and stability. Here, latest progress in tuning intermetallic Pt‐ and Pd‐based nanocrystals with tunable morphology and structure for catalyzing both the cathodic reduction of oxygen and anodic oxidation of fuels (e.g., methanol, ethanol and formic acid) in PEMFCs is highlighted. Making/tuning interesting intermetallic PtM (M = Fe, Co, Pb, Cu, etc.)‐based nanocrystals for boosting oxygen reduction reaction with high activity and stability by using/controlling high‐temperature annealing treatment is discussed. In all the reported Pt‐based intermetallic nanocrystals, controlling the degree of ordering under the proper high temperature treatment is the key for achieving the optimized electrocatalysis. In order to search for cheaper catalysts, the progress on making Pd‐based intermetallic nanocrystals is also discussed. Furthermore, future research directions are proposed and discussed to further enhance the efficiency of such unique intermetallic multimetallic nanocatalysts. This report aims to demonstrate the potential of ordered intermetallic strategy for boosting electrocatalysis and stimulating more research efforts in this field.     

Confined Synthesis of 2D Nanostructured Materials toward Electrocatalysis

2D nanostructured materials have shown great application prospects in energy conversion, owing to their unique structural features and fascinating physicochemical properties. Developing efficient approaches for the synthesis of well‐defined 2D nanostructured materials with controllable composition and morphology is critical. The emerging concept, confined synthesis, has been regarded as a promising strategy to design and synthesize novel 2D nanostructured materials. This review mainly summarizes the recent advances in confined synthesis of 2D nanostructured materials by using layered materials as host matrices (also denoted as “nanoreactors”). By virtue of the space‐ and surface‐confinement effects of these layered hosts, various well‐organized 2D nanostructured materials, including 2D metals, 2D metal compounds, 2D carbon materials, 2D polymers, 2D metal‐organic frameworks (MOFs) and covalent‐organic frameworks (COFs), as well as 2D carbon nitrides are successfully synthesized. The wide employment of these 2D materials in electrocatalytic applications (e.g., electrochemical oxygen/hydrogen evolution reactions, small molecule oxidation, and oxygen reduction reaction) is presented and discussed. In the final section, challenges and prospects in 2D confined synthesis from the viewpoint of designing new materials and exploring practical applications are commented, which would push this fast‐evolving field a step further toward greater success in both fundamental studies and ultimate industrialization.     

Enhanced Electrocatalysis for Hydrogen Evolution Reactions from WS2 Nanoribbons

A facile route is developed to boost the electrocatalytic activity of WS₂ by chemically unzipping WS₂ nanotubes to form WS₂ nanoribbons (NRs) with increased edge content. Analysis indicates that the hydrogen evolution reaction activity is strongly associated with the number of exposed active edge sites. The formation of WS₂ NRs is an effective route for controlling the electrochemical properties of the 2D dichalcogenides, enabling their application in electrocatalysis.     

Electronic Structure Engineering of LiCoO2 toward Enhanced Oxygen Electrocatalysis

Developing low‐cost and efficient electrocatalysts for the oxygen evolution reaction and oxygen reduction reaction is of critical significance to the practical application of some emerging energy storage and conversion devices (e.g., metal–air batteries, water electrolyzers, and fuel cells). Lithium cobalt oxide is a promising nonprecious metal‐based electrocatalyst for oxygen electrocatalysis; its activity, however, is still far from the requirements of practical applications. Here, a new LiCoO₂‐based electrocatalyst with nanosheet morphology is developed by a combination of Mg doping and shear force‐assisted exfoliation strategies toward enhanced oxygen reduction and evolution reaction kinetics. It is demonstrated that the coupling effect of Mg doping and the exfoliation can effectively modulate the electronic structure of LiCoO₂, in which Co³⁺ can be partially oxidized to Co⁴⁺ and the Co–O covalency can be enhanced, which is closely associated with the improvement of intrinsic activity. Meanwhile, the unique nanosheet morphology also helps to expose more active Co species. This work offers new insights into deploying the electronic structure engineering strategy for the development of efficient and durable catalysts for energy applications.     

Superior Oxygen Electrocatalysis on RuSex Nanoparticles for Rechargeable Air Cathodes

A one‐step, facile supercritical‐ethanol‐fluid synthesis of Se‐modified Ru nanoparticles nucleated on carbon defects is reported, and it is demonstrated that these nanoparticles provide, with >70% efficiency at 1 A g^?1, a highly active and reversible oxygen‐reduction/oxygen‐evolution reaction on an air cathode in a nonaqueous electrolyte. The Se modification not only prevents Ru oxidation during charge/discharge cycling, but also improves the catalytic activity by promoting Li₂O₂ versus Li₂O deposited on the Ru particles during discharge. A computational calculation with density functional theory supports the role of a larger electron transfer to the oxygen of Li₂O₂ adsorbed on a surface layer of RuSe_2?δ than on a surface layer of RuO₂, thereby shifting the more stable adsorbent from Li₂O to Li₂O₂.     

3D Carbon Materials for Efficient Oxygen and Hydrogen Electrocatalysis

Sustainable energy production at an acceptable cost is key for its widespread application. At present, noble metals and metal oxides are the most widely used for electrocatalysis, but they suffer from low selectivity, poor durability, and scarcity. Because of this, metal‐free carbons have become the subject of great interest as promising alternative electrocatalysts for energy conversion and storage devices, and remarkable progress has been accomplished in the advance of metal‐free carbons as electrocatalysts for renewable energy technologies. Particularly interesting are 3D porous carbon architectures, which exhibit outstanding features for electrocatalysis applications, including broad range of active sites, interconnected porosity, high conductivity, and mechanical stability. This review summarizes the latest advances in 3D porous carbon structures for oxygen and hydrogen electrocatalysis. The structure–performance relationship of these materials is consequently rationalized and perspectives on creating more efficient 3D carbon electrocatalysts are suggested.     

Gadolinium‐Induced Valence Structure Engineering for Enhanced Oxygen Electrocatalysis

Rare earth doped materials with unique electronic ground state configurations are considered emerging alternatives to conventional Pt/C for the oxygen reduction reaction (ORR). Herein, gadolinium (Gd)‐induced valence structure engineering is, for the first, time investigated for enhanced oxygen electrocatalysis. The Gd₂O₃–Co heterostructure loaded on N‐doped graphene (Gd₂O₃–Co/NG) is constructed as the target catalyst via a facile sol–gel assisted strategy. This synthetic strategy allows Gd₂O₃–Co nanoparticles to distribute uniformly on an N‐graphene surface and form intimate Gd₂O₃/Co interface sites. Upon the introduction of Gd₂O₃, the ORR activity of Gd₂O₃–Co/NG is significantly increased compared with Co/NG, where the half‐wave potential (E_1/2) of Gd₂O₃–Co/NG is 100 mV more positive than that of Co/NG and even close to commercial Pt/C. The density functional theory calculation and spectroscopic analysis demonstrate that, owing to intrinsic charge redistribution at the engineered interface of Gd₂O₃/Co, the coupled Gd₂O₃–Co can break the OOH*–OH* scaling relation and result in a good balance of OOH* and OH* binding on Gd₂O₃–Co surface. For practical application, a rechargeable Zn–air battery employing Gd₂O₃–Co/NG as an air–cathode achieves a large power density and excellent charge–discharge cycle stability.     

Engineering Catalytic Active Sites on Cobalt Oxide Surface for Enhanced Oxygen Electrocatalysis

Tuning the catalytic active sites plays a crucial role in developing low cost and highly durable oxygen electrode catalysts with precious metal‐competitive activity. In an attempt to engineer the active sites in Co₃O₄ spinel for oxygen electrocatalysis in alkaline electrolyte, herein, controllable synthesis of surface‐tailored Co₃O₄ nanocrystals including nanocube (NC), nanotruncated octahedron (NTO), and nanopolyhedron (NP) anchored on nitrogen‐doped reduced graphene oxide (N‐rGO), through a facile and template‐free hydrothermal strategy, is provided. The as‐synthesized Co₃O₄ NC, NTO, and NP nanostructures are predominantly enclosed by {001}, {001} + {111}, and {112} crystal planes, which expose different surface atomic configurations of Co²⁺ and Co³⁺ active sites. Electrochemical results indicate that the unusual {112} plane enclosed Co₃O₄ NP on rGO with abundant Co³⁺ sites exhibit superior bifunctional activity for oxygen reduction and evolution reactions, as well as enhanced metal–air battery performance in comparison with other counterparts. Experimental and theoretical simulation studies demonstrate that the surface atomic arrangement of Co²⁺/Co³⁺ active sites, especially the existence of octahedrally coordinated Co³⁺ sites, optimizes the adsorption, activation, and desorption features of oxygen species. This work paves the way to obtain highly active, durable, and cost‐effective electrocatalysts for practical clean energy devices through regulating the surface atomic configuration and catalytic active sites.     

Engineering Multimetallic Aerogels for pH‐Universal HER and ORR Electrocatalysis

The advent of noble metal aerogels (NMAs), that feature the high catalytic activity of noble metals and unique structural attributes of aerogels, has stimulated research on a new class of outstanding electrocatalysts. However, limited by the available compositions, the explored electrocatalytic reactions on NMAs are highly restricted and certain important electrochemical processes have not been investigated. Here, an effective gelation approach is demonstrated by using a strong salting‐out agent (i.e., NH₄F), thereby expanding the composition of NMAs to various multimetallic systems and providing a platform to investigate composition‐dependent electrocatalytic performance of NMAs. Combining structural features of aerogels and optimized chemical compositions, the Au–Pt and Au–Rh aerogel catalysts manifest remarkable pH‐universal (pH = 0–14) performance surpassing commercial Pt/C and many other nanoparticle (NP)‐based catalysts in the electrocatalytic oxygen reduction reaction, hydrogen evolution reaction, and water splitting, displaying enormous potential for the electrochemical hydrogen production, fuel cells, etc.     

Engineering Self‐Supported Noble Metal Foams Toward Electrocatalysis and Beyond

Noble metals, despite their expensiveness, display irreplaceable roles in widespread fields. To acquire novel physicochemical properties and boost the performance‐to‐price ratio for practical applications, one core direction is to engineer noble metals into nanostructured porous networks. Noble metal foams (NMFs), featuring self‐supported, 3D interconnected networks structured from noble‐metal‐based building blocks, have drawn tremendous attention in the last two decades. Inheriting structural traits of foams and physicochemical properties of noble metals, NMFs showcase a variety of interesting properties and impressive prospect in diverse fields, including electrocatalysis, heterogeneous catalysis, surface‐enhanced Raman scattering, sensing and actuation, etc. A number of NMFs have been created and versatile synthetic approaches have been developed. However, because of the innate limitation of specific methods and the insufficient understanding of formation mechanisms, flexible manipulation of compositions, structures, and corresponding properties of NMFs are still challenging. Thus, the correlations between composition/structure and properties are seldom established, retarding material design/optimization for specific applications. This review is devoted to a comprehensive introduction of NMFs ranging from synthesis to applications, with an emphasis on electrocatalysis. Challenges and opportunities are also included to guide possible research directions in this field and promote the interest of interdisciplinary scientists.     

水稻土中CH4氧化的研究

在实验室条件下研究了水稻土中CH4氧化的特性 .结果表明 ,在早稻种植前采集的水稻土不能氧化大气中的CH4,但当所供给的CH4浓度 >1 0 μl·L- 1 时 ,能迅速氧化CH4,所供给的CH4浓度越高 ,氧化CH4的速度越大 .经高浓度 ( >1 0 0 0 μl·L- 1 )的CH4预培养 1 0d ,可使本来不具有氧化大气CH4能力的土壤氧化大气CH4.大田CH4排放通量高的水稻土 ,氧化CH4的能力较大 .     

Characterization and phylogeny of a novel methanotroph, Methyloglobulus morosus gen. nov., spec. nov

A novel methanotrophic gammaproteobacterium, strain KoM1, was isolated from the profundal sediment of Lake Constance after initial enrichment in opposing gradients of methane and oxygen. Strain KoM1 grows on methane or methanol as its sole source of carbon and energy. It is a Gram-negative methanotroph, often expressing red pigmentation. Cells are short rods and occur sometimes in pairs or short chains. Strain KoM1 grows preferably at reduced oxygen concentrations (pO₂ = 0.05–0.1 bar). It can fix nitrogen, and grows at neutral pH and at temperatures between 4 and 30 °C. Phylogenetically, the closest relatives are Methylovulum miyakonense and Methylosoma difficile showing 91% 16S rRNA gene sequence identity. The only respiratory quinone is ubiquinone Q8; the main polar lipids are phosphatidyl ethanolamine and phosphatidyl glycerol. The major cellular fatty acids are summed feature 3 (presumably C16:1ω7c) and C16:1ω5c, and the G + C content of the DNA is 47.7 mol%. Strain KoM1 is described as the type strain of a novel species within a new genus, Methyloglobulus morosus gen. nov., sp. nov.