The development of sodium-ion batteries for large-scale applications requires the synthesis of electrode materials with high capacity, high initial Coulombic efficiency (ICE), high rate performance, long cycle life, and low cost. A rational design of freestanding anode materials is reported for sodium-ion batteries, consisting of molybdenum disulfide (MoS2) nanosheets aligned vertically on carbon paper derived from paper towel. The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. The as-prepared MoS2@carbon paper composites as freestanding electrodes for sodium-ion batteries can liberate the traditional electrode manufacturing procedure, thereby reducing the cost of sodium-ion batteries. The freestanding MoS2@carbon paper electrode exhibits a high reversible capacity, high ICE, good cycling performance, and excellent rate capability. By exploiting in situ Raman spectroscopy, the reversibility of the phase transition from 2H-MoS2 to 1T-MoS2 is observed during the sodium-ion intercalation/deintercalation process. This work is expected to inspire the development of advanced electrode materials for high-performance sodium-ion batteries.

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium Ion Batteries

The oxygen evolution reaction (OER) is an important bottleneck in the development of economical photoelectrodes. Herein, we firstly prepared bimetallic oxyhydroxide NiFeOOH layer on Fe2O3 photoanode through a simple electroless ligand-regulated oxidation method in order to build highly-matched semiconductor/cocatalyst interface. Benefited from the accelerated OER kinetics and low overpotential of bimetallic oxyhydroxide NiFeOOH, the resultant Fe2O3/NiFeOOH core-shell with strongly-bound heterojunction interface possesses better visible light absorption, enhanced photocurrent density (1.83 mA/cm2 at 1.23 VRHE) and good stability than bare Fe2O3 and semi-FeOOH or NiOOH decorated Fe2O3 photoanodes. We believe this work provides a new pathway for designing high-quality contact interface of various photoelectrode/catalyst.

Enhanced PEC performance of hematite photoanode coupled with bimetallic oxyhydroxide NiFeOOH through a simple electroless method

Design and synthesis of highly catalytically active, low-cost, and stable electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are the greatest challenges in electrochemical water splitting. In this work, we synthesized an efficient Ce-doped NiFe-layered double hydroxide (LDH) electrocatalyst directly on a nickel foam (NF) substrate at room temperature using an electrodeposition technique. A well-connected nanosheet array forming a three-dimensional (3D) network on the substrate provided a large electrochemical surface area with abundant catalytically active sites. Ce doping in the NiFe-LDH electrocatalyst was vital to enhancing its catalytic performance for the OER and HER. The optimized Ce-doped NiFe-LDH required overpotentials of 175 and 147 mV for the OER and HER, respectively, to achieve a current density of 10 mA cm−2 in 1 M KOH. The Ce-doped electrocatalyst outperformed bare NiFe-LDH, which required overpotentials of 197 and 175 mV for the OER and HER, respectively. However, when Ce-doped NiFe-LDH was used as a bifunctional catalyst for full water splitting, it needed only 1.59 V to achieve a current density of 10 mA cm−2 and exhibited excellent stability over 40 hours at 20 mA cm−2. The enhanced electrochemical performance of Ce-doped NiFe-LDH was ascribed primarily to its unique 3D network, which increased the electrochemical surface area, and to the number of active sites created with Ce doping. The route used in the present study to enhance the catalytic activity of NiFe-LDH can be used to develop various electrocatalysts for water splitting and other catalytic applications.

An advanced and highly efficient Ce assisted NiFe-LDH electrocatalyst for overall water splitting

Material libraries for electrocatalytic overall water splitting

For efficient water splitting and replacement of expensive Pt or Ir with the earth-abundant materials, we have designed a heterostructure based on the two-dimensional (2D) bimetallic phosphide and ...

CoMoP/NiFe-Layered Double-Hydroxide Hierarchical Nanosheet Arrays Standing on Ni Foam for Efficient Overall Water Splitting

Homogeneously Distributed NiFe Alloy Nanoparticles on 3D Carbon Fiber Network as a Bifunctional Electrocatalyst for Overall Water Splitting

Hierarchical molybdenum disulfide nanosheet arrays stemmed from nickel-cobalt layered double hydroxide/carbon cloth for highly-efficient hydrogen evolution reaction

The design of a universal synthetic strategy for long-term durable transition metal carbide catalysts with a controllable nanostructure and sufficient active sites for the hydrogen evolution reaction is challenging. Herein, the in situ growth of Mo-containing MOFs was achieved on three-dimensional (3D) nickel foam (NF) through the conversion of pre-deposited bimetal hydroxide/oxide nanosheets (Mo and Co). After pyrolysis, ultrafine Mo carbide nanoparticles encapsulated in cobalt and nitrogen-doped carbon layers were obtained. The ultrafine metal carbide nanoparticles favored the exposure of active sites, the in situ growth enhanced the binding between catalysts and substrate, and the cobalt and nitrogen-doped carbon layer facilitated charge transfer. The MoxC electrode showed a current of 10 mA cm−2 at an overpotential of 33.5 mV under alkaline conditions, which was 6 mV lower than that of the 20% Pt/C/NF electrode. The WxC electrode was also prepared. This work highlights a novel universal strategy to synthesize metal carbide electrodes.

Yanlong Lv

Papers

Homogeneously Distributed NiFe Alloy Nanoparticles on 3D Carbon Fiber Network as a Bifunctional Electrocatalyst for Overall Water Splitting

Hierarchical molybdenum disulfide nanosheet arrays stemmed from nickel-cobalt layered double hydroxide/carbon cloth for highly-efficient hydrogen evolution reaction

In situ growth of MOF-derived ultrafine molybdenum carbide nanoparticles supported on Ni foam as efficient hydrogen-evolution electrocatalysts