The exploitation of cheap and efficient electrocatalysts is the key to make energy‐related electrocatalytic techniques commercially viable. In recent years, transition metal phosphides (TMPs) ...electrocatalysts have gained a great deal of attention owing to their multifunctional active sites, tunable structure, and composition, as well as unique physicochemical properties. This review summarizes the up‐to‐date progress on TMPs in energy‐related electrocatalysis from diversified synthetic methods, ingenious‐modulated strategies, and novel applications. In order to set forth theory–structure–performance relationships upon TMPs, the corresponding reaction mechanisms, electrocatalytsts' structure/composition designs and desired electrochemical performance are jointly discussed, along with demonstrating their practical electrocatalytic applications in overall water splitting, metal–air batteries, lithium–sulfur batteries, etc. In the end, some underpinning issues and research orientations of TMPs toward efficient energy‐related electrocatalysis are briefly proposed.
This review summarizes the recent modulated strategies of transition metal phosphides upon elemental doping, interfacial regulation, phase modification, structural engineering, and nanocarbon incorporation. Benefitted from the optimized structure and composition, transition metal phosphides (TMPs) display excellent performance in electrocatalytic hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, etc., along with their practical applications in water electrolyzer, metal–air batteries, and lithium–sulfur batteries, etc.
Sodium‐ion batteries (SIBs) have recently emerged as one of the favored contenders for use in medium and large‐scale stationary energy storage owing to the abundance of the resources required to ...fabricate them, their low cost, and the fact that have properties similar to equivalent Li batteries. However, their development also faces challenges such as poor cycling stability and unsatisfying rate performance. In traditional electrodes, binders are commonly used to integrate individual active materials with conductive additives. Unfortunately, binders are generally electrochemically inactive and insulating, which reduces the overall energy density and leads to poor cycling stability. Therefore, binder‐free electrodes provide great opportunity for high‐performance SIBs in terms of both improved electronic conductivity and electrochemical reaction reversibility. This Progress Report provides an overview of the recent progress in binder‐free electrodes for SIBs. It focuses on the current challenges of binder‐free electrodes and provides an outlook for their future in energy conversion and storage.
Binder‐free electrodes possess great merits with fast electron transport and increased energy density, and so provide a fascinating opportunity for the creation of high‐performance sodium‐ion batteries. Template‐free methods mainly combine with graphene, carbon nanotubes, and carbon nanofibers, while template‐assisted methods are based on carbon (e.g., carbon paper, carbon cloth, etc.) and metal substrates (e.g., Cu foil, Ti foil, Ni foam, etc.).
Sodium–ion batteries (SIBs) have received extensive attention as ideal candidates for large‐scale energy storage systems (ESSs) owing to the rich resources and low cost of sodium (Na). However, the ...larger size of Na+ and the less negative redox potential of Na+/Na result in low energy densities, short cycling life, and the sluggish kinetics of SIBs. Therefore, it is necessary to develop appropriate Na storage electrode materials with the capability to host larger Na+ and fast ion diffusion kinetics. 1D materials such as nanofibers, nanotubes, nanorods, and nanowires, are generally considered to be high‐capacity and stable electrode materials, due to their uniform structure, orientated electronic and ionic transport, and strong tolerance to stress change. Here, the synthesis of 1D nanomaterials and their applications in SIBs are reviewed. In addition, the prospects of 1D nanomaterials on energy conversion and storage as well as the development and application orientation of SIBs are presented.
1D nanomaterials (e.g., nanofibers, nanorods, nanowires, nanobelts, etc.) are considered promising electrode materials due to their orientated electronic and ionic transport, short radial distance, and strong tolerance to stress change. The success of numerous 1D nanomaterials fabricated via various methods and their application in sodium–ion batteries is described.
•The Ni2P/NiMoP exhibits excellent HER activity and stability due to the cooperative effect of interfaces.•Adopting UOR to replace OER could significantly reduce the oxidation potential.•An ultralow ...cell voltage of 1.35 V was required to acquire the current density of 10 mA cm−2 in a two-electrode system, much lower than traditional overall water splitting (1.50 V).
Electrochemical water splitting is a sustainable and feasible strategy for hydrogen production but is hampered by the sluggish anodic oxygen evolution reaction (OER). Herein, an effective approach is introduced to significantly decrease the cell voltage by replacing the anodic OER with a urea oxidation reaction (UOR). A Ni2P/NiMoP nanosheet catalyst with a hierarchical architecture is uniformly grown on a nickel foam (NF) substrate through a simple hydrothermal and phosphorization method. The Ni2P/NiMoP achieves impressive HER activity, with a low overpotential of only 22 mV at 10 mA cm–2 and a low Tafel slope of 34.5 mV dec–1. In addition, the oxidation voltage is significantly reduced from 1.49 V to 1.33 V after the introduction of 0.33 M urea. Notably, a two-electrode electrolyzer employing Ni2P/NiMoP as a bifunctional catalyst exhibits a current density of 10 mA cm–2 at a cell voltage of 1.35 V and excellent long-term durability after 80 h.
Display omitted
MnFe2O4 nanodots (∼3.3 nm) homogeneously dispersed in porous nitrogen-doped carbon nanofibers (denoted as MFO@C) were prepared by a feasible electrospinning technique. Meanwhile, MFO@C with the ...character of flexible free-standing membrane was directly used as binder- and current collector-free anode for sodium-ion batteries, exhibiting high electrochemical performance with high-rate capability (305 mA h g–1 at 10000 mA g–1 in comparison of 504 mA h g–1 at 100 mA g–1) and ultralong cycling life (ca. 90% capacity retention after 4200 cycles). The Na-storage mechanism was systematically studied, revealing that MnFe2O4 is converted into metallic Mn and Fe after the first discharge (MnFe2O4 + 8Na+ + 8e– → Mn + 2Fe + 4Na2O) and then to MnO and Fe2O3 during the following charge (Mn + 2Fe + 4Na2O → MnO + Fe2O3 + 8Na+ + 8e–). The subsequent cycles occur through reversible redox reactions of MnO + Fe2O3 + 8Na+ + 8e– ↔ Mn + 2Fe + 4Na2O, of which the reduction/oxidation of MnO/Mn takes place at a lower potential than that of Fe2O3/Fe. Furthermore, a soft package sodium-ion full battery with MFO@C anode and Na3V2(PO4)2F3/C cathode was assembled, delivering a stable capacity of ∼400 mA h g–1 for MFO@C (with 100 cycles at 500 mA g–1) and a promising energy density of 77.8 Wh kg–1 for the whole battery. This is owing to the distinctive structure of very-fine MnFe2O4 nanodots embedded in porous N-doped carbon nanofibers, which effectively improves the utilization rate of active materials, facilitates the transportation of electrons and Na+ ions, and prevents the particle pulverization/agglomeration upon prolonged cycling.
Designed as a high‐capacity, high‐rate, and long‐cycle life anode for sodium‐ion batteries, ultrasmall Sn nanoparticles (≈8 nm) homogeneously embedded in spherical carbon network (denoted as 8‐Sn@C) ...is prepared using an aerosol spray pyrolysis method. Instrumental analyses show that 8‐Sn@C nanocomposite with 46 wt% Sn and a BET surface area of 150.43 m2 g−1 delivers an initial reversible capacity of ≈493.6 mA h g−1 at the current density of 200 mA g−1, a high‐rate capacity of 349 mA h g−1 even at 4000 mA g−1, and a stable capacity of ≈415 mA h g−1 after 500 cycles at 1000 mA g−1. The remarkable electrochemical performance of 8‐Sn@C is owing to the synergetic effects between the well‐dispersed ultrasmall Sn nanoparticles and the conductive carbon network. This unique structure of very‐fine Sn nanoparticles embedded in the porous carbon network can effectively suppress the volume fluctuation and particle aggregation of tin during prolonged sodiation/desodiation process, thus solving the major problems of pulverization, loss of electrical contact and low utilization rate facing Sn anode.
Sn@C composite with ultrasmall Sn nanoparticles (≈8 nm) homogeneously embedded in spherical carbon network is prepared by aerosol spray pyrolysis, and further evaluated as anode material for rechargeable Na‐ion batteries. The nanocomposite exhibits excellent electrochemical performance with high reversible capacity, high‐rate capability, and long cycling stability.
Rational design of optimal bifunctional oxygen electrocatalyst with low cost and high activity is greatly desired for realization of rechargeable Zn–air batteries. Herein, we fabricate mesoporous ...thin-walled CuCo2O4@C with abundant nitrogen-doped nanotubes via coaxial electrospinning technique. Benefiting from high catalytic activity of ultrasmall CuCo2O4 particles, double active specific surface area of mesoporous nanotubes, and strong coupling with N-doped carbon matrix, the obtained CuCo2O4@C exhibits outstanding oxygen electrocatalytic activity and stability, in terms of a positive onset potential (0.951 V) for oxygen reduction reaction (ORR) and a low overpotential (327 mV at 10 mA cm–2) for oxygen evolution reaction (OER). Significantly, when used as cathode catalyst for Zn-air batteries, CuCo2O4@C also displays a low charge–discharge voltage gap (0.79 V at 10 mA cm–2) and a long cycling life (up to 160 cycles for 80 h). With desirable architecture and excellent electrocatalytic properties, the CuCo2O4@C is considered a promising electrocatalyst for Zn–air batteries.
Aqueous Zn‐storage behaviors of MoS2‐based cathodes mainly rely on the ion‐(de)intercalation at edge sites but are limited by the inactive basal plane. Herein, an in‐situ molecular engineering ...strategy in terms of structure defects manufacturing and O‐doping is proposed for MoS2 (designated as D‐MoS2‐O) to unlock the inert basal plane, expand the interlayer spacing (from 6.2 to 9.6 Å), and produce abundant 1T‐phase. The tailored D‐MoS2‐O with excellent hydrophilicity and high conductivity allows the 3D Zn2+ transport along both the ab plane and c‐axis, thus achieving the exceptional high rate capability. Zn2+ diffusion through the basal plane is verified by DFT computations. As a proof of concept, the wearable quasi‐solid‐state rechargeable Zn battery employing the D‐MoS2‐O cathode operates stably even under severe bending conditions, showing great application prospects. This work opens a new window for designing high‐performance layered cathode materials for aqueous Zn‐ion batteries.
In‐situ molecular engineering of structure defect manufacturing and O‐doping unlocks the MoS2 basal plane and simultaneously upgrades its interlayer spacing (from 6.2 to 9.6 Å), hydrophilicity, and electrical conductivity. These merits enable highly efficient 3D Zn‐ion transport in the MoS2 lattice along both the ab plane and c‐axis, thus leading to fast reaction kinetics and the exceptional rate performance in aqueous Zn‐ion batteries.
A novel composite of magnetite (Fe3O4) nanoparticles (NPs) grown on reduced graphene oxide (rGO) has been synthesized by a facile hydrothermal technique without any surfactants or templates. In this ...method, the growth of Fe3O4 NPs and the reduction of graphene oxide (GO) are completed in one single step. Moreover, we have prepared Fe3O4 microcubes and Fe3O4/carbon nanotubes (CNTs) composite under the same condition. The electrochemical properties of the as-prepared samples are investigated as advanced electrode materials for supercapacitors. It is found that the Fe3O4/rGO nanocomposite displays much higher specific capacitances and better cycle stability than those of pure Fe3O4 and Fe3O4/CNTs composite. Specifically, it exhibits a high specific discharge capacitance of 220.1 F ga1 at 0.5 A ga1 and remains stable after 3000 charge/discharge cycles. The improvement of the electrochemical performances of Fe3O4/rGO may be attributed to the chemical interaction between rGO and Fe3O4, lower agglomeration and smaller particle size of Fe3O4.
Transition metal oxides (TMOs) based on conversion reactions are attractive candidate anode materials for lithium-ion batteries (LIBs) because of their high theoretical capacity and safety ...characteristics. In this review, we have summarized recent progress in the rational design and efficient synthesis of TMOs with controllable morphologies, compositions, and micro-/nanostructures, along with their Li storage behaviors. Single metal oxides of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), ruthenium (Ru), chromium (Cr), molybdenum (Mo), and tungsten (W) and their common binary metal oxides have been discussed in this review. Finally, the less well-known merits of conversion reactions are put forward, and the design of metal oxide electrodes making full use of these merits has been proposed.
Single and binary metal oxides based on conversion reactions for Li-ion batteries are discussed in this review.
PDF
