Search

Developing non-noble-metal electrocatalysts for hydrogen evolution reactions with high activity and stability is the key issue in green hydrogen generation based on electrolytic water splitting. It has been recognized that the stacking of large CoP particles limits the intrinsic activity of as-synthesized CoP catalyst for hydrogen evolution reaction. In the present study, N-Mo x C/CoP-0.5 with excellent electrocatalytic activity for hydrogen evolution reaction was prepared using N-Mo x C as decoration. A reasonable overpotential of 106 mV (at 10 mA cm−2) and a Tafel slope of 59 mV dec−1 in 1.0 M KOH solution was achieved with N-Mo x C/CoP-0.5 electrocatalyst, which exhibits superior activity even after working for 37 h. Uniformly distributed ultrafine nanoclusters of the N-Mo x C/CoP-0.5 hybrids could provide sufficient interfaces for enhanced charge transfer. The effective capacity of the hydrogen evolution reaction could be preserved in the complex, and the enlarged electrocatalytic surface area could be expected to offer more active sites for the reaction. [ABSTRACT FROM AUTHOR]

Molybdenum carbide (Mo2C) has become a promising candidate for electrocatalytic hydrogen production from water splitting due to its low price and platinum-like electrocatalytic properties. In this work, Mo2C nanotubes (Mo2C NTs) with ultrathin imbricate structure were successfully synthesized by carburizing polydopamine organic layer covered molybdenum trioxide (MoO3) nanowire templates at elevated temperature through organic–inorganic hybridization. The inner diameter and wall thickness of the as-synthesized Mo2C NTs are about 150 nm and 100 nm, respectively. Two-dimensional Mo2C nanoflakes with a thickness of about 10 nm were composed of nanoclusters with a size of 2 nm. Furthermore, N–MoxC was facilely prepared by nitrogen doping into the prepared Mo2C by chemical vapor deposition and the enhanced electrocatalytic activity was obtained with an overpotential of 120 mV at a current density of 10 mA cm−2. An enlarged specific surface area of 189 m2 g−1 was achieved for N–MoxC, which provides more electrocatalytic active sites for water reduction. More importantly, the interface optimization of Mo2C and MoC was expected to modify the electronic structure and accelerate the electron transfer for improved water splitting performance. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis techniques have enormous potential for industrial-scale hydrogen generation, but a lack of effective and low-cost bifunctional electrocatalysts capable of steady high-current density operation has hampered progress. Layered double hydroxides (LDHs) have been considered promising OER electrocatalysts, but their poor electrical conductivity impedes hydrogen evolution reaction (HER) activity. Integrating LDHs with transition metal phosphides (TMPs) can potentially achieve bifunctional capability by overcoming individual limitations. Herein, CoP@NiFe LDH/Ni heterostructured catalyst was rapidly synthesized by a scalable two-step electrodeposition method. The integration of NiFe LDH with CoP enhanced its electrical conductivity. Meanwhile, electron transfer occurred from the metal atoms to the more electronegative phosphorus, facilitating phosphorus to act as a proton acceptor and expedite the HER process. Benefiting from the synergistic integration and optimized electronic structure, CoP@NiFe LDH/Ni exhibited excellent alkaline water-splitting performances with low overpotentials of 260 mV for HER and 351 mV for OER at 400 mA/cm2. The CoP@NiFe LDH/Ni two-electrode-based alkaline electrolyzer displayed a cell voltage of 2.13 V and stable operation for 100 h at a high current density of 1000 mA/cm2. This work elucidates a strategy to tackle critical challenges impeding the design and preparation of high-current-density tolerant bifunctional electrocatalysts. [Display omitted] • CoP@NiFe LDH/Ni can be rapidly and large-scale synthesized via electrodeposition • CoP@NiFe LDH/Ni demonstrates excellent HER and OER performances • CoP@NiFe LDH/Ni exhibits remarkable durability at high current densities • CoP@NiFe LDH/Ni shows impressive overall water splitting with high current density [ABSTRACT FROM AUTHOR]

Summary: The morphology and structure of the electrocatalysts are important factors affecting their performance for electrochemical splitting water into hydrogen. Herein, the urchin‐like CoP nanomaterials with the large specific surface area (SSA) were fabricated through the solvothermal process and the solid‐gas reaction for hydrogen evolution reaction (HER). The resulting CoP nanomaterial with a diameter of approximately 4 μm was assembled by the nanowires with a length of about 10 nm. The excellent performance is accessible for HER with a small overpotential of 130 mV and a low Tafel slope of 52 mV/decade in a 0.5 M H2SO4 aqueous solution. Especially, the resulting urchin‐like CoP nanomaterials with a large SSA and electric double‐layer capacitance lower the electrochemical impedance and accelerate the electron transfer, endowing the excellent performance for HER process. [ABSTRACT FROM AUTHOR]