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The commonly used "catalyst on carbon" architecture as a sulfur host is difficult to jointly achieve high gravimetric and volumetric energy densities for lithium–sulfur (Li–S) batteries due to the contradiction between low tap density/poor catalytic activity of carbon and the easy agglomeration of metal‐based compounds without carbon. Here, a non‐carbon‐dominated catalytic architecture using macroporous nickel/cobalt phosphide (NiCoP) is reported as the sulfur host for Li–S batteries. The macroporous framework, which accommodates a large amount of sulfur, can accelerate the electrochemical reaction kinetics by accelerated e− transport, Li+ diffusion, and superior adsorption and catalytic activity of inherent Ni2P/CoP heterostructures. The high tap density (0.45 g cm−3) and mechanically hard features contribute to the excellent structural and physicochemical stability of the NiCoP@S electrode after the pressing and rolling process. These features enable the Li–S coin cell to exhibit excellent electrochemical performance under conditions of high sulfur loading (10.2 mg cm−2) and lean electrolyte (electrolyte/sulfur of 2 µL mg−1). Inspiringly, the assembled pouch cell can simultaneously deliver a gravimetric energy density of 345.2 Wh kg−1 and an impressive volumetric energy density of 952.7 Wh L−1 based on the entire device configuration. [ABSTRACT FROM AUTHOR]

Oil–water separation membranes easily fail to oil foulants with low surface energy and high viscosity, which severely limits these membranes' applications in treating oily wastewater. Herein, an oil–water separation membrane by bioinspired bubble‐mediated antifouling strategy is fabricated via growing hierarchical cobalt phosphide arrays on stainless steel mesh. The as‐prepared membrane is superhydrophilic/superaerophobic and electrocatalytic for hydrogen evolution under water, which helps to rapidly generate and release abundant microbubbles surrounding the oil‐fouled region on the membrane. These microbubbles can spontaneously coalesce with the oil foulants to increase their buoyancy and warp their interface tension by morphing the oil shape. And this spontaneous coalescence also increases the kinetic energy of oil foulants resulting from the decreased bubbles' interface energy and potential energy. The synergy of the warped interface tension, increased buoyancy, and kinetic energy drives the efficiently dynamic antifouling of this membrane. This dynamic antifouling even can remove some solid sediment such as oily sand particles that causes more serious fouling of the membrane. Thus, this membrane maintains high flux (>11920 L m−2 h−1 bar−1) in the long‐term separation of oil–water and oil–sand–water emulsions by dynamically recovering the decayed flux on demand, which exhibits great potential in treating industrial oily wastewater. [ABSTRACT FROM AUTHOR]

The high intermediate (H*, OH*) energy barriers and slow mass/charge transfer increase the overpotential of alkaline water electrolysis at large‐current‐density. Engineering the electronic structure with the morphology of the catalyst to reduce energy barriers and improve mass/charge transportation is effective but remains challenging. Herein, a Ce‐doped CoP nanosheet is hybrid with Ni3P@NF (Ni foam) support to enhance mass/charge transfer, tune energy barriers, and improve water‐splitting kinetics through a synergistic activation. The engineered Ce0.2‐CoP/Ni3P@NF cathode exhibits an ultralow overpotential (η500, η1000) of −185, and −225 mV at −500 and −1000 mA cm−2 in 1.0 m KOH, along with an excellent pH‐universality. Impressively, an electrolyzer using the Ce0.2‐CoP/Ni3P@NF cathode can afford 500 mA cm−2 at a cell voltage of only 1.775 V and maintain stable electrolysis for 200 h in 25 wt% KOH (50 °C). Characterization and density functional theory calculation further reveal the Ce‐doping and CoP/Ni3P hybrid interaction synergistically downshift d‐band centers (εd = −2.0 eV) of Ce0.2‐CoP/Ni3P to the Fermi level, thereby activate local electronic structure for accelerating H2O dissociation and optimizing Gibbs free energy of hydrogen adsorption (∆GH*). [ABSTRACT FROM AUTHOR]

Exploring a general method for synthesizing 2D compounds with high accessible surface area and nano‐thickness as advanced electrocatalysts is essential yet challenging. Herein, a self‐assembly induced reverse micelle templating method followed by topochemical transformation is developed to synthesize a series of cobalt‐based compounds with varied anions and similar ultrathin 2D structures. Electrocatalytic behaviors for the hydrogen evolution reaction (HER) are systematically investigated, which demonstrate enhanced performances of ultrathin 2D compounds than their agglomerated counterparts. Among them, 2D CoP is particularly prominent. The overpotential of 144 mV at 10 mA cm−2, together with superb stability, place it among the best single‐phase phosphide HER catalysts reported thus far. Theoretical calculation and experimental results demonstrate the favorable valence electronic structure with moderate hydrogen adsorbability and good intracrystalline conductivity, as well as the homogeneous ultrathin 2D configuration with sufficiently exposed active sites and shortened intracrystalline electron transport route, are the dominant reasons that 2D CoP exhibits optimal electrocatalytic activity for HER. This study presents a novel and extendable strategy for synthesizing various 2D metal‐based compounds with valuable insights into the modulation essence of advanced electrocatalysts. [ABSTRACT FROM AUTHOR]

Seawater electrolysis under alkaline conditions presents an attractive alternative to traditional freshwater electrolysis for mass sustainable high‐purity hydrogen production. However, the lack of active and robust electrocatalysts severely impedes the industrial application of this technology. Herein, carbon‐doped nanoporous cobalt phosphide (C‐Co2P) prepared by electrochemical dealloying is reported as an electrocatalyst for hydrogen evolution reaction (HER). The C‐Co2P achieves an overpotential of 30 mV at a current density of 10 mA cm−2 in 1 m KOH, along with impressive catalytic activity and stability at large current densities in artificial alkaline seawater electrolyte containing mixed chlorides of NaCl, MgCl2, and CaCl2. Experimental analysis and density functional theory calculations reveal that the C atom with strong electronegativity and small atomic radius can tailor the electronic structure of Co2P, leading to weakened Co–H bonding toward promoted HER kinetics. Moreover, the C doping introduces a two‐stepped H delivery pathway by forming C–Had intermediate, thus reducing the energy barrier of water dissociation. This study offers a new vision toward the development of seawater electrolysis for large‐scale hydrogen production. [ABSTRACT FROM AUTHOR]

Electrocatalysis is a potential method for sustainable hydrogen production, and the development of non‐noble metal‐based effective electrocatalysts for electrochemical water splitting is the core of exploiting and utilizing renewable energy. Herein, a stupendous electrocatalyst with multiheterostructure interfaces and 3D porous structure is synthesized, and the mechanisms of enhanced electrocatalytic activity combining multicharacterizations and density functional calculations are clarified. Especially, the fabricated Co2P/N@Ti3C2Tx@NF (denoted as CPN@TC) exhibits an ultralow overpotential of 15 mV to arrive at a current density of 10 mA cm−2 with the long‐term durability and a small Tafel slope of 30 mV dec−1 in 1 m KOH, which even compares with noble metal catalysts favorably. The outstanding HER activity is ascribed to multiheterointerfaces for adsorbing H2O and H*, fine conductivity for the electronic transmission, and well‐designed structure for rapid transport of ions and gases. It is reasonable to think that the synthetic strategy of CPN@TC can be extended to the preparation of transition‐metal‐based phosphides for enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Catalysts based on earth‐abundant non‐noble metals are interesting candidates for alkaline water electrolysis in sustainable hydrogen economies. However, such catalysts often suffer from high overpotential and sluggish kinetics in both the hydrogen and oxygen evolution reactions (HER and OER). In this study, a hybrid catalyst made of iron‐doped cobalt phosphide (Fe‐CoP) nanowire arrays and Ni(OH)2 nanosheets is introduced that displays strong electronic interactions at the interface, which significantly improves the interfacial reactivity of reactants and/or intermediates with the hybrid catalyst surface. The combined experimental and theoretical study further confirms that the hybrid catalyst promotes the sluggish rate‐limiting steps in both the HER and OER. Full water electrolysis is thus enabled to take place at such a low cell voltage as 1.52 V to reach the current density of 10 mA cm−2 along with superior durability and high conversion efficiency. [ABSTRACT FROM AUTHOR]

Halide perovskite like methylammonium lead iodide perovskite (MAPbI3) with its prominent optoelectronic properties has triggered substantial concerns in photocatalytic H2 evolution. In this work, to attain preferable photocatalytic performance, a MAPbI3/cobalt phosphide (CoP) hybrid heterojunction is constructed by a facile in situ photosynthesis approach. Systematic investigations reveal that the CoP nanoparticle can work as co‐catalyst to not only extract photogenerated electrons effectively from MAPbI3 to improve the photoinduced charge separation, but also facilitate the interfacial catalytic reaction. As a result, the as‐achieved MAPbI3/CoP hybrid displays a superior H2 evolution rate of 785.9 µmol h−1 g−1 in hydroiodic acid solution within 3 h, which is ≈8.0 times higher than that of pristine MAPbI3. Furthermore, the H2 evolution rate of MAPbI3/CoP hybrid can reach 2087.5 µmol h−1 g−1 when the photocatalytic reaction time reaches 27 h. This study employs a facile in situ photosynthesis strategy to deposit the metal phosphide co‐catalyst on halide perovskite nanocrystals to conduct photocatalytic H2 evolution reaction, which may stimulate the intensive investigation of perovskite/co‐catalyst hybrid systems for future photocatalytic applications. [ABSTRACT FROM AUTHOR]

Abstract: Development of electrocatalysts for hydrogen evolution reaction (HER) with low overpotential and robust stability remains as one of the most serious challenges for energy conversion. Herein, a serviceable and highly active HER electrocatalyst with multilevel porous structure (Co‐Co2P nanoparticles@N, P doped carbon/reduced graphene oxides (Co‐Co2P@NPC/rGO)) is synthesized by Saccharomycete cells as template to adsorb metal ions and graphene nanosheets as separating agent to prevent aggregation, which is composed of Co‐Co2P nanoparticles with size of ≈104.7 nm embedded into carbonized Saccharomycete cells. The Saccharomycete cells provide not only carbon source to produce carbon shells, but also phosphorus source to prepare metal phosphides. In order to realize the practicability and permanent stability, the binderless and 3D electrodes composed of obtained Co‐Co2P@NPC/rGO powder are constructed, which possess a low overpotential of 61.5 mV (achieve 10 mA cm−2) and the high current density with extraordinary catalytic stability (1000 mA cm−2 for 20 h) in 0.5 m H2SO4. The preparation process is appropriate for synthesizing various metal or metal phosphide@carbon electrocatalysts. This work may provide a biological template method for rational design and fabrication of various metals or metal compounds@carbon 3D electrodes with promising applications in energy conversion and storage. [ABSTRACT FROM AUTHOR]

Abstract: Replacement of precious metals with earth‐abundant electrocatalysts for oxygen evolution reaction (OER) holds great promise for realizing practically viable water‐splitting systems. It still remains a great challenge to develop low‐cost, highly efficient, and durable OER catalysts. Here, the composition and morphology of Ni–Co bimetal phosphide nanocages are engineered for a highly efficient and durable OER electrocatalyst. The nanocage structure enlarges the effective specific area and facilitates the contact between catalyst and electrolyte. The as‐prepared Ni–Co bimetal phosphide nanocages show superior OER performance compared with Ni2P and CoP nanocages. By controlling the molar ratio of Ni/Co atoms in Ni–Co bimetal hydroxides, the Ni0.6Co1.4P nanocages derived from Ni0.6Co1.4(OH)2 nanocages exhibit remarkable OER catalytic activity (η = 300 mV at 10 mA cm−2) and long‐term stability (10 h for continuous test). The density‐functional‐theory calculations suggest that the appropriate Co doping concentration increases density of states at the Fermi level and makes the d‐states more close to Fermi level, giving rise to high charge carrier density and low intermedia adsorption energy than those of Ni2P and CoP. This work also provides a general approach to optimize the catalysis performance of bimetal compounds. [ABSTRACT FROM AUTHOR]

Hydrogen generation from water splitting driven by electric/solar energy is highly desirable, which requires efficient and robust bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions. 2D porous hybrids with attractive chemical and structural properties are the first-class candidates for water splitting, while control over efficient and modulable synthesis remains a huge challenge. This work demonstrates a zeolitic imidazolate framework-67 (ZIF-67) nanoplate self-template approach to fabricate 2D porous oxygen-incorporated cobalt phosphide (CoPO) ultrathin nanosheets. The synthesis starts with the oriented growth of ZIF-67 nanoplates along [211] crystal plane, followed by oxidation/phosphorization processes for pore generation and O/P coincorporation in the hybrid. The resultant 2D porous CoPO nanosheets afford very small voltages of 1.52 and 1.98 V for overall water splitting at 10 and 200 mA cm-2, respectively. This excellent bifunctionality further provides the basis for photovoltage-driven water splitting at a Faradaic efficiency of 97.6%. These findings offer a general strategy for rational design and modulation of 2D porous catalysts for various electrocatalytic and other applications. [ABSTRACT FROM AUTHOR]

2D materials are ideal for constructing flexible electrochemical energy storage devices due to their great advantages of flexibility, thinness, and transparency. Here, a simple one-step hydrothermal process is proposed for the synthesis of nickel-cobalt phosphate 2D nanosheets, and the structural influence on the pseudocapacitive performance of the obtained nickel-cobalt phosphate is investigated via electrochemical measurement. It is found that the ultrathin nickel-cobalt phosphate 2D nanosheets with an Ni/Co ratio of 4:5 show the best electrochemical performance for energy storage, and the maximum specific capacitance up to 1132.5 F g−1. More importantly, an aqueous and solid-state flexible electrochemical energy storage device has been assembled. The aqueous device shows a high energy density of 32.5 Wh kg−1 at a power density of 0.6 kW kg−1, and the solid-state device shows a high energy density of 35.8 Wh kg−1 at a power density of 0.7 kW kg−1. These excellent performances confirm that the nickel-cobalt phosphate 2D nanosheets are promising materials for applications in electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Searching the high-efficient, stable, and earth-abundant electrocatalysts to replace the precious noble metals holds the promise for practical utilizations of hydrogen and oxygen evolution reactions (HER and OER). Here, a series of highly active and robust Co-doped nickel phosphides (Ni2− xCo xP) catalysts and their hybrids with reduced graphene oxide (rGO) are developed as bifunctional catalysts for both HER and OER. The Co-doping in Ni2P and their hybridization with rGO effectively regulate the catalytic activity of the surface active sites, accelerate the charge transfer, and boost their superior catalytic activity. Density functional theory calculations show that the Co-doped catalysts deliver the moderate trapping of atomic hydrogen and facile desorption of the generated H2 due to the H-poisoned surface active sites of Ni2− xCo xP under the real catalytic process. Electrochemical measurements reveal the high HER efficiency and durability of the NiCoP/rGO hybrids in electrolytes with pH 0-14. Coupled with the remarkable and robust OER activity of the NiCoP/rGO hybrids, the practical utilization of the NiCoP/rGO|NiCoP/rGO for overall water splitting yields a catalytic current density of 10 mA cm−2 at 1.59 V over 75 h without an obvious degradation and Faradic efficiency of ≈100% in a two-electrode configuration and 1.0 m KOH. [ABSTRACT FROM AUTHOR]

Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the innovative exploration regarding the design of efficient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well-defined mesoporosity and a high specific surface area (148 m2 g−1) can be directly employed as a bifunctional and flexible working electrode for both hydrogen and oxygen evolution reactions, showing superior activities as compared with noble metal benchmarks and state-of-the-art transition-metal-based catalysts. This is intimately related to the unique nanorod array electrode configuration, leading to excellent electric interconnection and improved mass transport. A further step is taken toward an alkaline electrolyzer that can achieve a current density of 10 mA cm−2 at a voltage around 1.62 V over a long-term operation, better than the combination of Pt and IrO2. This development is suggested to be readily extended to obtain other electrocatalysis systems for scale-up water-splitting technology. [ABSTRACT FROM AUTHOR]

The construction of a novel 3D self‐supported integrated NixCo2−xP@NC (0 < x < 2) nanowall array (NA) on Ni foam (NF) electrode constituting highly dispersed NixCo2−xP nanoparticles, nanorods, nanocapsules, and nanodendrites embedded in N‐doped carbon (NC) NA grown on NF is reported. Benefiting from the collective effects of special morphological and structural design and electronic structure engineering, the NixCo2−xP@NC NA/NF electrodes exhibit superior electrocatalytic performance for water splitting with an excellent stability in a wide pH range. The optimal NiCoP@NC NA/NF electrode exhibits the best hydrogen evolution reaction (HER) activity in acidic solution so far, attaining a current density of 10 mA cm−2 at an overpotential of 34 mV. Moreover, the electrode manifests remarkable performances toward both HER and oxygen evolution reaction in alkaline medium with only small overpotentials of 37 mV at 10 mA cm−2 and 305 mV at 50 mA cm−2, respectively. Most importantly, when coupling with the NiCoP@NC NA/NF electrode for overall water splitting, an alkali electrolyzer delivers a current density of 20 mA cm−2 at a very low cell voltage of ≈1.56 V. In addition, the NiCoP@NC NA/NF electrode has outstanding long‐term durability at j = 10 mA cm−2 with a negligible degradation in current density over 22 h in both acidic and alkaline media. [ABSTRACT FROM AUTHOR]

Z.‐Y. Yuan and coworkers present self‐supported CoP mesoporous nanorod arrays on page 7337 as a high‐efficiency bifunctional electrode towards both electrochemical hydrogen and oxygen evolution reactions. Benefiting from the 3D electrode configuration and well‐defined mesoporosity, the bulk elecrode provide unprecedented improvements in the electrochemical activity and reaction kinetics in full water splitting over long‐term operation. [ABSTRACT FROM AUTHOR]