A high-surface-area Ce doped mullite YMn2 O5 was developed via a facile hydrothermal approach, which exhibited higher catalytic activity with a long thermal stability towards propane oxidation in regards to pristine mullite YMn2 O5 . T90 (the temperature at 90% conversion of reactant) of propane over the mixed oxides is 40°C lower than that over pristine YMn2 O5 mullite (147 m2 /g). The complete oxidation temperature occurs at as low as 225°C (1000 ppm C3 H8 and 10% O2 balanced with N2 , WHSV=30,000 mL/gh). Notably, the mixed oxides maintain superior catalytic stability at 250°C for 120 h without noticeable loss in the activity. Fundamentally, the remarkable performance stems from the abundant oxygen defects caused by the lattice mismatch between CeO2 and YMn2 O5 , which is conducive to the gas phase oxygen adsorption and activation, thereby enhancing the low temperature catalytic activity of the material. In addition, the CeO2 on the catalyst's surface acts as an oxygen reservoir and provides additional adsorption sites for propane to promote the oxidation reaction. In situ DRIFTS results indicates that the dissociation of acrylate could be the key step for propane oxidation since acrylate is more difficult to decompose and desorb than formate and acetate. These findings revealed the roles of ceria on mullite oxides for propane oxidation activity. © 2022 Wiley-VCH GmbH.

Low temperature hydrazine fuel cells have been advocated as potential energy carriers by virtue of their exceptional power densities and carbon free containing byproducts. However, the large-scale application of these renewable energy systems has been extremely inhibited by the insufficient performance and high cost of the state-of-art platinum (Pt) catalysts. To pursue better activity, electrocatalysts must demonstrate low operating overpotentials and high tolerances to poisoning species, which are critical factors for increasing the energy conversion efficiency. Despite the tremendous progress of Pt-based catalysts, controlling sluggish kinetics on microscopic surfaces is still a serious issue because the accumulation of reaction product slugs onto surface may impede the liquid fuel transport to catalytic sites, resulting in a low activity. Thus, the development of earth abundant electrocatalysts with an improved activity is unambiguously a principal requirement. In this review, recent trends in the rational design and synthesis of Ni-based electrocatalysts with various compositions for hydrazine oxidation reaction (HzOR) are summarized. In particular, development of multicomponent compounds and employment of Ni-based materials for HzOR are demonstrated to be effective approaches from tuning the electrochemical performance of Ni-based catalyst materials. Moreover, some potential challenges and prospects are deliberated to further advance the improvement of Ni-based materials for effective HzOR.

Sustainable and high performance energy devices such as solar cells, fuel cells, metal-air batteries, as well as alternative energy conversion and storage systems have been considered as promising technologies to meet the ever-growing demands for clean energy. Hydrogen evolution reaction (HER) is a crucial process for cost-effective hydrogen production; however, functional electrocatalysts are potentially desirable to expedite reaction kinetics and supply high energy density. Thus, the development of inexpensive and catalytically active electrocatalysts is one of the most significant and challenging issues in the field of electrochemical energy storage and conversion. Realizing that advanced nanomaterials could engender many advantageous chemical and physical properties over a wide scale, tremendous efforts have been devoted to the preparation of earth-abundant transition metals as electrocatalysts for HER in both acidic and alkaline environments because of their low processing costs, reasonable catalytic activities, and chemical stability. Among all transition metal-based catalysts, nickel compounds are the most widely investigated, and have exhibited pioneering performances in various electrochemical reactions. Heterostructured nickel phosphide (NixPy) based compounds were introduced as promising candidates of a new category, which often display chemical and electronic characteristics that are distinct from those of non-precious metals counterparts, hence providing an opportunity to construct new catalysts with an improved activity and stability. As a result, the library of NixPy catalysts has been enriched very rapidly, with the possibility of fine-tuning their surface adsorption properties through synergistic coupling with nearby elements or dopants as the basis of future practical implementation. The current review distils recent advancements in NixPy compounds/hybrids and their application for HER, with a robust emphasis on breakthroughs in composition refinement. Future perspectives for modulating the HER activity of NixPy compounds/hybrids, and the challenges that need to be overcome before their practical use in sustainable hydrogen production are also discussed.

Lithium-sulfur batteries (Li-S batteries) are promising candidates for the next generation high-energy rechargeable Li batteries due to their high theoretical specific capacity (1672 mAh g(-1)) and energy density (2500Wh kg(-1)). The commercialization of Li-S batteries is impeded by several key challenges at cathode side, e.g. the insulating nature of sulfur and discharged products (Li2S2 and Li2S2), the solubility of long-chain polysulfides and volume variation of sulfur cathode upon cycling. Recently, the carbonbased derivatives from metal-organic frameworks (MOFs) has emerged talent in their utilization as cathode hosts for Li-S batteries. They are not only highly conductive and porous to enable the acceleration of Li+/e(-) transfer and accommodation of volumetric expansion of sulfur cathode during cycling, but also enriched by controllable chemical active sites to enable the adsorption of polysulfides and promotion of their conversion reaction kinetics. In this review, based on the types of MOFs (e.g. ZIF-8, ZIF-67, Prussian blue, Al-MOF, MOF-5, Cu-MOF, Ni-MOF), the synthetic methods, formation process and morphology, structural superiority of MOFs-derived carbon frameworks along with their electrochemical performance as cathode host in Li-S batteries are summarized and discussed. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Oxygen redox catalysis, including the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), is crucial in determining the electrochemical performance of energy conversion and storage devices such as fuel cells, metal-air batteries,and electrolyzers. The rational design of electrochemical catalysts replaces the traditional trial-and-error methods and thus promotes the R&D process. Identifying descriptors that link structure and activity as well as selectivity of catalysts is the key for rational design. In the past few decades, two types of descriptors including bulk- and surface-based have been developed to probe the structure-property relationships. Correlating the current descriptors to one another will promote the understanding of the underlying physics and chemistry, triggering further development of more universal descriptors for the future design of electrocatalysts. Herein, the current benchmark activity descriptors for oxygen electrocatalysis as well as their applications are reviewed. Particular attention is paid to circumventing the scaling relationship of oxygen-containing intermediates. For hybrid materials, multiple descriptors will show stronger predictive power by considering more factors such as interface reconstruction, confinement effect, multisite adsorption, etc. Machine learning and high-throughput simulations can thus be crucial in assisting the discovery of new multiple descriptors and reaction mechanisms.

Li-metal batteries are re-arising as the promising next-generation battery system due to its potential high energy density, as long as the issue of Li dendrite growth can be effectively addressed. Solid state battery architecture is a potential solution to dendrite free anode. However its high performance is still hampered by the low Li-ion conductivity of solid electrolyte and transport limitation at interface. In this review, we summary the recent progresses on Li dendrite inhibition at the anode side and conductivity enhancement at the solid electrolyte side from the viewpoints of halogen-based strategies. The methods based on electrolyte additive and artificial coating layer on anode are especially effective to construct F-rich solid electrolyte interface. Large-sized halogen as ligand modifier enables desired mineral phases of high Li-ion conductivity.

Non-lithium energy storage devices, especially sodium ion batteries, are drawing attention due to insufficient and uneven distribution of lithium resources. Prussian blue and its analogs ( Prussian blue analogs [PBAs]), or hexacyanoferrates, are well-known since the 18th century and have been used for hydrogen storage, cancer therapy, biosensing, seawater desalination, and sewage treatment. Owing to their unique features, PBAs are receiving increasing interest in the field of energy storage, such as their high theoretical specific capacity, ease of synthesis, as well as low cost. In this review, a general summary and evaluation of the applications of PBAs for rechargeable batteries are given. After a brief review of the history of PBAs, their crystal structure, nomenclature, synthesis, and working principle in rechargeable batteries are discussed. Then, previous works classified based on the combination of insertion cations and transition metals are analyzed comprehensively. The review includes an outlook toward the further development of PBAs in electrochemical energy storage.

Exploring electrochemically driven conversion reactions for the development of novel energy storage materials is an important topic as they can deliver higher energy densities than current Li-ion battery electrodes. Conversion-type fluorides promise particularly high energy densities by involving the light and small fluoride anion, and bond breaking can occur at relatively low Li-activity (i.e., high cell voltage). Cells based on such electrodes may become competitors to other envisaged alternatives such as Li-sulfur or Li-air systems with their many unsolved thermodynamic and kinetic problems. Relevant conversion reactions are typically multiphase redox reactions characterized by nucleation and growth processes along with pronounced interfacial and mass transport phenomena. Hence significant overpotentials and nonequilibrium reaction pathways are involved. In this review, we summarize recent findings in terms of phase evolution phenomena and mechanistic features of (oxy) fluorides at different redox stages during the conversion process, enabled by advanced characterization technologies and simulation methods. It can be concluded that well-designed nanostructured architectures are helpful in mitigating kinetic problems such as the usually pronounced voltage hysteresis. In this context, doping and open-framework strategies are useful. By these tools, simple materials that are unable to allow for substantial Li nonstoichiometry (e.g., by Li-insertable channels) may be turned into electroactive materials.

Non-lithium energy storage devices, especially sodium ion batteries, are drawing attention due to insufficient and uneven distribution of lithium resources. Prussian blue and its analogs ( Prussian blue analogs [PBAs]), or hexacyanoferrates, are well-known since the 18th century and have been used for hydrogen storage, cancer therapy, biosensing, seawater desalination, and sewage treatment. Owing to their unique features, PBAs are receiving increasing interest in the field of energy storage, such as their high theoretical specific capacity, ease of synthesis, as well as low cost. In this review, a general summary and evaluation of the applications of PBAs for rechargeable batteries are given. After a brief review of the history of PBAs, their crystal structure, nomenclature, synthesis, and working principle in rechargeable batteries are discussed. Then, previous works classified based on the combination of insertion cations and transition metals are analyzed comprehensively. The review includes an outlook toward the further development of PBAs in electrochemical energy storage.