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Metal phosphides (MPs) with high theoretical capacity and fast kinetics are considered useful anode materials for lithium-ion batteries (LIBs). Phosphorus-rich MPs are more attractive than phosphorus-lean ones for the preparation of lithium battery anodes because the capacity of MPs is usually proportional to the content of the phosphorus component. In this work, we synthesized a nest-like molybdenum diphosphide-carbon nanotube (MoP2–CNT) nanocomposite for a high-capacity and long-term cycle-stable anode. Due to the nanoscale size and carbon nanotube cross-linking, the nest-like MoP2–CNT possessed a short diffusion path of lithium ions, a good conductive network, and a permeable buffer layer. As a result, after 500 cycles, the specific capacity reached 504.7 mA h g–1 at 1.0 A g–1 and 310.6 mA h g–1 at 4.0 A g–1. Superior electrochemical performances were also achieved at high-mass-loading MoP2–CNT electrodes. In addition, the full cell composed of the MoP2–CNT anode and LiCoO2 cathode also exhibited an energy density of 378.2 Wh kg–1 and excellent rate and cycling performances, indicating the potential application of the MoP2–CNT nanocomposite. The above superior electrochemical performances demonstrated that the phosphorus-rich composites were promising candidates for the preparation of a high-capacity LIB anode. [ABSTRACT FROM AUTHOR]

The polymorphism of phosphorus-based materials has garnered much research interest, and the variable chemical bonding structures give rise to a variety of micro and nanostructures. Among the different types of materials containing phosphorus, elemental phosphorus materials (EPMs) constitute the foundation for the synthesis of related compounds. EPMs are experiencing a renaissance in the post-graphene era, thanks to recent advancements in the scaling-down of black phosphorus, amorphous red phosphorus, violet phosphorus, and fibrous phosphorus and consequently, diverse classes of low-dimensional sheets, ribbons, and dots of EPMs with intriguing properties have been produced. The nanostructured EPMs featuring tunable bandgaps, moderate carrier mobility, and excellent optical absorption have shown great potential in energy conversion, energy storage, and environmental remediation. It is thus important to have a good understanding of the differences and interrelationships among diverse EPMs, their intrinsic physical and chemical properties, the synthesis of specific structures, and the selection of suitable nanostructures of EPMs for particular applications. In this comprehensive review, we aim to provide an in-depth analysis and discussion of the fundamental physicochemical properties, synthesis, and applications of EPMs in the areas of energy conversion, energy storage, and environmental remediation. Our evaluations are based on recent literature on well-established phosphorus allotropes and theoretical predictions of new EPMs. The objective of this review is to enhance our comprehension of the characteristics of EPMs, keep abreast of recent advances, and provide guidance for future research of EPMs in the fields of chemistry and materials science. [ABSTRACT FROM AUTHOR]

Energy-efficient production of hydrogen through urea electrolysis is still challenging due to the lack of satisfactory catalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) in urea containing solution. In this study, Ni–W x C/C (x = 1,2) composite with high activity for urea electrocatalysis was prepared by direct electro-reduction of affordable feedstock of NiO–CaWO 4 –C in molten CaCl 2 –NaCl at 873–973 K. The addition of graphite in precursor decreases the particle size of Ni. Introducing W x C into Ni particles can reduce the overpotential for UOR. As a result, the obtained Ni-W x C/graphite composite exhibits high current density for urea oxidation, which is about 11-folds and 52-folds higher than that of Ni/graphite and Ni (@1.53 V vs. RHE), respectively. After changing the carbon source from graphite to CNTs, the anodic current density was further increased by 43%, reaching 50.31 mA cm−2. Moreover, the cathodic catalyst W x C/CNTs obtained by the same preparation process exhibits high performance towards HER, with a low onset potential of 131.5 mV and a Tafel slope of 69.5 mV dec−1. Assembling an electrolyzer using Ni-W x C/CNTs as anode and W x C/CNTs as cathode can yield a current density of 10 mA cm−2 at merely 1.65 V in 1 M KOH/0.33 M urea aqueous solution, with excellent long-term electrochemical durability. The environmental-friendly production process uses affordable feedstocks for the synthesis of efficient catalysts toward urea electrolysis, promising an energy-saving hydrogen production as well as waste treatment. [Display omitted] • Ni-W x C/C were prepared by electroreduction of solid NiO-CaWO 4 -C in molten salt. • The electrolytic Ni-W x C/C shows enhanced catalysis activity for urea oxidation. • Ni-W x C/CNTs prepared from NiO-CaWO 4 -CNTs exhibit super catalysis activity. • W x C/CNTs prepared from CaWO 4 -CNTs is active to HER in urea containing solution. • An efficient electrolyzer consisting of HER/UOR was constructed. [ABSTRACT FROM AUTHOR]

The wettability of molten carbonate on carbon determines the electrochemical performances of high-temperature direct carbon fuel cells (DCFCs). However, a universal method to measure the high-temperature wettability of molten carbonate is absent and the wetting kinetics is not well understood. Herein, we develop a dispensed drop (DD) method to measure the wetting kinetics of molten carbonate (Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 , 43.5:31.5:25.0, molar ratio) on the carbon substrate at 450-750 °C under controlled atmospheres (100%Ar, 100%CO 2 , and 1%O 2 -99%N 2 ). The measured contact angles under different conditions reveal that increasing the O 2- concentration in the gas-liquid-solid (GLS) interface decreases the contact angle. In addition, elevating the temperature, introducing O 2 in the gas atmosphere, or pretreating the carbon substrate can enhance the wetting kinetics of molten carbonates. The molten carbonate completely wets the carbon substrate in 150 min in Ar gas atmosphere and in 30 min in 1%O 2 -99%N 2 gas atmosphere at 600 °C. Further, it takes only 30 min to completely wet the pretreated carbon substrate in Ar atmosphere at 600 °C. Overall, this paper offers the DD method to study the wettability of molten carbonate on the carbon substrate, which is helpful to understand the underlying wetting mechanism and engineer the electrode design for DCFCs.