Interface-Assisted Synthesis of 2D Materials: Trend and Challenges

Chemical Reviews, Journal Year: 2018, Volume and Issue: 118(13), P. 6189 - 6235

Published: June 18, 2018

The discovery of graphene one decade ago has triggered enormous interest in developing two-dimensional materials (2DMs)—that is 2D allotropes various elements or compounds (consisting two more covalently bonded elements) molecular frameworks with periodic structures. At present, synthesis strategies have been exploited to produce 2DMs, such as top-down exfoliation and bottom-up chemical vapor deposition solution methods. In this review article, we will highlight the interfacial roles toward controlled inorganic organic 2DMs varied structural features. We summarize state-of-the-art progress on address their advancements structural, morphological, crystalline control by direction arrangement molecules precursors at a confined space. First, provide an overview interfaces introduce advantages uniqueness for followed brief classification achieved synthesis. Next, currently developed combined representative are summarized, including description method details, corresponding features, insights into limitations methods, along some recommendable characterization methods understanding assembly crystal growth 2DMs. After that, discuss several classes emerging particular emphasis strategies. Note not be categorized separately due fact that number articles covered synthesis, structure, processing, applications. Finally, challenges perspectives provided regarding future development interface-assisted diverse functional control.

Language: Английский

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Ultrafine Co Nanoparticles Encapsulated in Carbon‐Nanotubes‐Grafted Graphene Sheets as Advanced Electrocatalysts for the Hydrogen Evolution Reaction

Advanced Materials, Journal Year: 2018, Volume and Issue: 30(30)

Published: June 10, 2018

The rational design of an efficient and inexpensive electrocatalyst based on earth-abundant 3d transition metals (TMs) for the hydrogen evolution reaction still remains a significant challenge in renewable energy area. Herein, novel effective approach is developed synthesizing ultrafine Co nanoparticles encapsulated nitrogen-doped carbon nanotubes (N-CNTs) grafted onto both sides reduced graphene oxide (rGO) (Co@N-CNTs@rGO) by direct annealing GO-wrapped core-shell bimetallic zeolite imidazolate frameworks. Benefiting from uniform distribution nanoparticles, in-situ-formed highly graphitic N-CNTs@rGO, large surface area, abundant porosity, as-fabricated Co@N-CNTs@rGO composites exhibit excellent electrocatalytic (HER) activity. As demonstrated electrochemical measurements, can achieve 10 mA cm-2 at low overpotential with only 108 87 mV 1 m KOH 0.5 H2 SO4 , respectively, much better than most reported Co-based electrocatalysts over wide pH range. More importantly, synthetic strategy versatile be extended to prepare other binary or even ternary TMs@N-CNTs@rGO (e.g., Co-Fe@N-CNTs@rGO Co-Ni-Cu@N-CNTs@rGO). here may open new avenue toward development nonprecious high-performance HER catalysts.

Language: Английский

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Phosphorus-Doped Co₃O₄ Nanowire Array: A Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(3), P. 2236 - 2241

Published: Feb. 6, 2018

It is vitally essential to design highly efficient and cost-effective bifunctional electrocatalysts toward water splitting. Herein, we report the development of P-doped Co3O4 nanowire array on nickel foam (P-Co3O4/NF) from through low-temperature annealing, using NaH2PO2 as P source. As a 3D catalyst, such P-Co3O4/NF demonstrates superior performance for oxygen evolution reaction with low overpotential (260 mV at 20 mA cm–2), small Tafel slope (60 dec–1), satisfying durability in 1.0 M KOH. Density functional theory calculations indicate that P-Co3O4 has free-energy value much smaller than pristine potential determining step reaction. Such also performs efficiently hydrogen reaction, two-electrode alkaline electrolyzer assembled by P8.6-Co3O4/NF both anode cathode needs only 1.63 V reach water-splitting current 10 cm–2.

Language: Английский

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Heterostructured Electrocatalysts for Hydrogen Evolution Reaction Under Alkaline Conditions

Nano-Micro Letters, Journal Year: 2018, Volume and Issue: 10(4)

Published: Oct. 1, 2018

The hydrogen evolution reaction (HER) is a half-cell in water electrolysis for producing gas. In industrial electrolysis, the HER often conducted alkaline media to achieve higher stability of electrode materials. However, kinetics medium slow relative that acid because low concentration protons former. Under latter conditions, entire process will require additional effort obtain by dissociation near or on catalyst surface. Heterostructured catalysts, with fascinating synergistic effects derived from their heterogeneous interfaces, can provide multiple functional sites overall process. At present, activity most active known heterostructured catalysts surpasses (platinum-based heterostructures) approaches (noble-metal-free commercial Pt/C under demonstrating an infusive potential break through bottlenecks. This review summarizes representative and recent medium. basics principles conditions are first introduced, followed discussion latest advances with/without noble-metal-based heterostructures. Special focus placed enhancing rate accelerating Volmer step. aims overview current developments as well design future development nano- micro-sized electrocatalysts.

Language: Английский

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Enhanced Catalysis of Electrochemical Overall Water Splitting in Alkaline Media by Fe Doping in Ni₃S₂ Nanosheet Arrays

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(6), P. 5431 - 5441

Published: May 3, 2018

The development of bifunctional electrocatalysts with high performance for both hydrogen evolution reaction (HER) and oxygen (OER) earth-abundant elements is still a challenge in electrochemical water splitting technology. Herein, we fabricated free-standing electrocatalyst the form vertically oriented Fe-doped Ni3S2 nanosheet array grown on three-dimensional (3D) Ni foam (Fe-Ni3S2/NF), which presented activity durability HER OER alkaline media. On basis systematic experiments calculation, Fe-doping was evidenced to increase surface area, improve adsorption ability, optimize energy Ni3S2, resulted enhancement Fe-Ni3S2/NF. Moreover, metal sites Fe-Ni3S2/NF were proved play significant role process. During catalysis OER, formation Ni–Fe (oxy)hydroxide observed near-surface section Fe-Ni3S2/NF, introduction Fe element dramatically enhanced Ni3S2. overall electrolyzer assembled by exhibited low cell voltage (1.54 V @ 10 mA cm–2) 1 M KOH. This work demonstrated promising electrolysis media potential application future.

Language: Английский

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