Two‐Dimensional Porous Molybdenum Phosphide/Nitride Heterojunction Nanosheets for pH‐Universal Hydrogen Evolution Reaction

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 60(12), P. 6673 - 6681

Published: Dec. 18, 2020

Abstract Herein, we present a new strategy for the synthesis of 2D porous MoP/Mo 2 N heterojunction nanosheets based on pyrolysis [PMo 12 O 40 ] 3− ‐melamine (PMo ‐MA) nanosheet precursor from polyethylene glycol (PEG)‐mediated assembly route. The heterostructure are ca. 20 nm thick and have plentiful pores (<5 nm). These structure features offer advantages to promote HER activity, including favorable water dissociation kinetics around as confirmed by theoretical calculations, large accessible surface nanosheets, enhanced mass‐transport ability pores. Consequently, exhibit excellent activity with low overpotentials 89, 91 89 mV achieve current density 10 mA cm −2 in alkaline, neutral acidic electrolytes, respectively. performance is superior commercial Pt/C at >55 medium >190 alkaline medium.

Language: Английский

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Boosting Activity on Co₄N Porous Nanosheet by Coupling CeO₂ for Efficient Electrochemical Overall Water Splitting at High Current Densities

Advanced Functional Materials, Journal Year: 2020, Volume and Issue: 30(32)

Published: June 11, 2020

Abstract Developing highly active nonprecious electrocatalysts with superior durability for both the hydrogen evolution reaction (HER) and oxygen (OER) is crucial to improve efficiency of overall water splitting but remains challenging. Here, a novel superhydrophilic Co 4 N‐CeO 2 hybrid nanosheet array synthesized on graphite plate (Co /GP) by an anion intercalation enhanced electrodeposition method, followed high‐temperature nitridation. Doping CeO into N can favor dissociation H O adsorption hydrogen, reduce energy barrier intermediate reactions OER, compositional stability, thereby dramatically boosting HER performance while simultaneously inducing OER activity. Furthermore, self‐supported electrode in situ grown conductive substrate expedites electron conduction between catalyst, promotes bubble release from timely impedes catalyst shedding, ensuring high stable working state. Consequently, /GP shows exceptionally low overpotentials 24 239 mV at 10 mA cm −2 respectively. An alkaline electrolyzer using as cathode anode requires cell voltage 1.507 V drive , outperforming Pt/C||RuO (1.540 V@10 ). More significantly, has extraordinary long‐term large current density 500 50 h, revealing its potential large‐scale applications.

Language: Английский

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Efficient Alkaline Water/Seawater Hydrogen Evolution by a Nanorod‐Nanoparticle‐Structured Ni‐MoN Catalyst with Fast Water‐Dissociation Kinetics

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(21)

Published: April 1, 2022

Achieving efficient and durable nonprecious hydrogen evolution reaction (HER) catalysts for scaling up alkaline water/seawater electrolysis is desirable but remains a significant challenge. Here, heterogeneous Ni-MoN catalyst consisting of Ni MoN nanoparticles on amorphous nanorods that can sustain large-current-density HER with outstanding performance demonstrated. The hierarchical nanorod-nanoparticle structure, along large surface area multidimensional boundaries/defects endows the abundant active sites. hydrophilic helps to achieve accelerated gas-release capabilities effective in preventing degradation during water electrolysis. Theoretical calculations further prove combination effectively modulates electron redistribution at their interface promotes sluggish water-dissociation kinetics Mo Consequently, this requires low overpotentials 61 136 mV drive current densities 100 1000 mA cm-2 , respectively, 1 m KOH stable operation 200 h constant density or 500 . This good also works well seawater electrolyte shows toward overall ultralow cell voltages.

Language: Английский

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A durable and pH-universal self-standing MoC–Mo2C heterojunction electrode for efficient hydrogen evolution reaction

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: Nov. 22, 2021

Efficient water electrolyzers are constrained by the lack of low-cost and earth-abundant hydrogen evolution reaction (HER) catalysts that can operate at industry-level conditions be prepared with a facile process. Here we report self-standing MoC-Mo2C catalytic electrode via one-step electro-carbiding approach using CO2 as feedstock. The outstanding HER performances low overpotentials 500 mA cm-2 in both acidic (256 mV) alkaline electrolytes (292 mV), long-lasting lifetime over 2400 h (100 d), high-temperature performance (70 oC) due to hydrophilic porous surface, intrinsic mechanical strength self-grown MoC (001)-Mo2C (101) heterojunctions have ΔGH* value -0.13 eV condition, energy barrier 1.15 for dissociation solution. preparation large (3 cm × 11.5 cm) demonstrates possibility scaling up this process prepare various carbide electrodes rationally designed structures, tunable compositions, favorable properties.

Language: Английский

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Reconstruction‐Determined Alkaline Water Electrolysis at Industrial Temperatures

Advanced Materials, Journal Year: 2020, Volume and Issue: 32(40)

Published: Sept. 2, 2020

Evaluating the alkaline water electrolysis (AWE) at 50–80 °C required in industry can veritably promote practical applications. Here, thermally induced complete reconstruction (TICR) of molybdate oxygen evolution reaction (OER) pre-catalysts 51.9 and its fundamental mechanism are uncovered. The dynamic processes, real active species, stereoscopic structural characteristics identified by situ low-/high-temperature Raman, ex microscopy, electron tomography. completely reconstructed (CR) catalyst (denoted as cat.-51.9) is interconnected thermodynamically stable (oxy)hydroxide nanoparticles, with abundant boundaries low crystallinity. For OER, cat.-51.9 exhibits a overpotential (282.3 mV 20 mA cm−2, 25.0 °C) ultrastable catalysis (250 h, negligible activity decay 19.6 µV h−1). experimental observations combined theoretical analyses confirm fast catalytic kinetics enabled co-effect vacancies. coupled MoO2-Ni hydrogen-evolving arrays provide operation for 220 h. This work uncovers new phenomenon under realistic conditions exceptional durability CR catalysts toward high-temperature AWE.

Language: Английский

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