Research

11 pages, 2727 KiB

Open AccessArticle

Plasma-Engineered CeO_x Nanosheet Array with Nitrogen-Doping and Porous Architecture for Efficient Electrocatalysis

by Zhou Wang, Tong Li and Qi Wang

Nanomaterials 2024, 14(2), 185; https://doi.org/10.3390/nano14020185 - 13 Jan 2024

Viewed by 583

Surface engineering has been proved efficient and universally applicable in improving the performance of CeO₂ in various fields. However, previous approaches have typically required high-temperature calcination or tedious procedures, which makes discovery of a moderate and facile modification approach for CeO₂ [...] Read more.

Surface engineering has been proved efficient and universally applicable in improving the performance of CeO₂ in various fields. However, previous approaches have typically required high-temperature calcination or tedious procedures, which makes discovery of a moderate and facile modification approach for CeO₂ an attractive subject. In this paper, porous CeO₂ nanosheets with effective nitrogen-doping were synthesized via a low-temperature NH₃/Ar plasma treatment and exhibited boosted hydrogen evolution reaction performance with low overpotential (65 mV) and long-term stability. The mechanism of the elevated performance was investigated by introducing Ar-plasma-treated CeO₂ with no nitrogen-doping as the control group, which revealed the dominant role of nitrogen-doping by providing abundant active sites and improving charge transfer characteristics. This work illuminates further investigations into the surface engineering methodologies boosted by plasma and the relative mechanism of the structure–activity relationship. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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22 pages, 2616 KiB

Open AccessArticle

Exploring the Potential of Heteroatom-Doped Graphene Nanoribbons as a Catalyst for Oxygen Reduction

by Eduardo S. F. Cardoso, Guilherme V. Fortunato, Clauber D. Rodrigues, Marcos R. V. Lanza and Gilberto Maia

Nanomaterials 2023, 13(21), 2831; https://doi.org/10.3390/nano13212831 - 26 Oct 2023

Cited by 1 | Viewed by 999

Abstract

In this study, we created a series of N, S, and P-doped and co-doped carbon catalysts using a single graphene nanoribbon (GNR) matrix and thoroughly evaluated the impact of doping on ORR activity and selectivity in acidic, neutral, and alkaline conditions. The results [...] Read more.

In this study, we created a series of N, S, and P-doped and co-doped carbon catalysts using a single graphene nanoribbon (GNR) matrix and thoroughly evaluated the impact of doping on ORR activity and selectivity in acidic, neutral, and alkaline conditions. The results obtained showed no significant changes in the GNR structure after the doping process, though changes were observed in the surface chemistry in view of the heteroatom insertion and oxygen depletion. Of all the dopants investigated, nitrogen (mainly in the form of pyrrolic-N and graphitic-N) was the most easily inserted and detected in the carbon matrix. The electrochemical analyses conducted showed that doping impacted the performance of the catalyst in ORR through changes in the chemical composition of the catalyst, as well as in the double-layer capacitance and electrochemically accessible surface area. In terms of selectivity, GNR doped with phosphorus and sulfur favored the 2e⁻ ORR pathway, while nitrogen favored the 4e⁻ ORR pathway. These findings can provide useful insights into the design of more efficient and versatile catalytic materials for ORR in different electrolyte solutions, based on functionalized carbon. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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14 pages, 7812 KiB

Open AccessArticle

Binary Ni-Co-Based Layered Double Hydroxide Nanoneedle Arrays for High Performance of Oxygen Evolution Reaction

by Zhi Lu, Zhihao Zhou, Shilin Li, Gongliang Tan, Hangtian Chen, Zishuo Ge, Chong Chen and Guangxin Wang

Nanomaterials 2023, 13(13), 1941; https://doi.org/10.3390/nano13131941 - 26 Jun 2023

Cited by 1 | Viewed by 984

Abstract

Low-cost and high-performance electrocatalysts are crucial for water-splitting reactions. Some non-precious metal electrocatalysts are proved to be good replacements for noble metal due to the unique electronic structure features and excellent performance. In this work, binary Ni-Co-based layered double hydroxide nanoneedle arrays electrocatalysts [...] Read more.

Low-cost and high-performance electrocatalysts are crucial for water-splitting reactions. Some non-precious metal electrocatalysts are proved to be good replacements for noble metal due to the unique electronic structure features and excellent performance. In this work, binary Ni-Co-based layered double hydroxide nanoneedle arrays electrocatalysts are synthesized on Ni foam (NF) via a hydrothermal process. The microstructure and the catalytic performance of the catalyst changes significantly by regulating the molar ratio of Ni/Co. The theoretical analysis confirmed that the as-prepared NiCo-LDH nanoneedle arrays reveal a potential behavior in oxygen evolution reaction (OER) at a lower overpotential of 305 mV at 10.0 mA cm⁻² and a Tafel slope of 110.38 mV dec⁻¹. The double-layer capacitance (C_dl) is 776 mF cm⁻², which indicates that there are many active sites that are exposed on the surface for the electrocatalytic reaction. The results provide an obvious reference value to other types of LDH catalysts for the development of water electrolysis. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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12 pages, 6609 KiB

Open AccessEditor’s ChoiceArticle

One-Step Electrochemical Dealloying of 3D Bi-Continuous Micro-Nanoporous Bismuth Electrodes and CO₂RR Performance

by Wenqin Lai, Yating Liu, Mingming Zeng, Dongmei Han, Min Xiao, Shuanjin Wang, Shan Ren and Yuezhong Meng

Nanomaterials 2023, 13(11), 1767; https://doi.org/10.3390/nano13111767 - 30 May 2023

Cited by 1 | Viewed by 1178

Abstract

The rapid development of electrochemical CO₂ reduction offers a promising route to convert intermittent renewable energy into products of high value-added fuels or chemical feedstocks. However, low faradaic efficiency, low current density, and a narrow potential range still limit the large-scale application [...] Read more.

The rapid development of electrochemical CO₂ reduction offers a promising route to convert intermittent renewable energy into products of high value-added fuels or chemical feedstocks. However, low faradaic efficiency, low current density, and a narrow potential range still limit the large-scale application of CO₂RR electrocatalysts. Herein, monolith 3D bi-continuous nanoporous bismuth (np-Bi) electrodes are fabricated via a simple one-step electrochemical dealloying strategy from Pb-Bi binary alloy. The unique bi-continuous porous structure ensures highly effective charge transfer; meanwhile, the controllable millimeter-sized geometric porous structure enables easy catalyst adjustment to expose highly suitable surface curvatures with abundant reactive sites. This results in a high selectivity of 92.6% and superior potential window (400 mV, selectivity > 88%) for the electrochemical reduction of carbon dioxide to formate. Our scalable strategy provides a feasible pathway for mass-producing high-performance and versatile CO₂ electrocatalysts. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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11 pages, 2665 KiB

Open AccessArticle

Iron-Doped Monoclinic Strontium Iridate as a Highly Efficient Oxygen Evolution Electrocatalyst in Acidic Media

by Mengjie Li, Jiabao Ding, Tianli Wu and Weifeng Zhang

Nanomaterials 2023, 13(5), 797; https://doi.org/10.3390/nano13050797 - 22 Feb 2023

Cited by 1 | Viewed by 1484

Abstract

Ir-based perovskite oxides are efficient electrocatalysts for anodic oxygen evolution. This work presents a systematic study of the doping effects of Fe on the OER activity of monoclinic SrIrO₃ to reduce the consumption of Ir. The monoclinic structure of SrIrO₃ was [...] Read more.

Ir-based perovskite oxides are efficient electrocatalysts for anodic oxygen evolution. This work presents a systematic study of the doping effects of Fe on the OER activity of monoclinic SrIrO₃ to reduce the consumption of Ir. The monoclinic structure of SrIrO₃ was retained when the Fe/Ir ratio was less than 0.1/0.9. Upon further increases in the Fe/Ir ratio, the structure of SrIrO₃ changed from a 6H to 3C phase. The SrFe_0.1Ir_0.9O₃ had the highest activity among the investigated catalysts with the lowest overpotential of 238 mV at 10 mA cm⁻² in 0.1 M HClO₄ solution, which could be attributed to the oxygen vacancies induced by the Fe dopant and the IrOx formed upon the dissolution of Sr and Fe. The formation of oxygen vacancies and uncoordinated sites at the molecular level may be responsible for the improved performance. This work explored the effect of Fe dopants in boosting the OER activity of SrIrO₃, thus providing a detailed reference to tune perovskite-based electrocatalyst by Fe for other applications. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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12 pages, 3572 KiB

Open AccessArticle

Enhancement of the Electrochemical Performances of Composite Solid-State Electrolytes by Doping with Graphene

by Xinghua Liang, Dongxue Huang, Linxiao Lan, Guanhua Yang and Jianling Huang

Nanomaterials 2022, 12(18), 3216; https://doi.org/10.3390/nano12183216 - 16 Sep 2022

Viewed by 1568

Abstract

With high safety and good flexibility, polymer-based composite solid electrolytes are considered to be promising electrolytes and are widely investigated in solid lithium batteries. However, the low conductivity and high interfacial impedance of polymer-based solid electrolytes hinder their industrial applications. Herein, a composite [...] Read more.

With high safety and good flexibility, polymer-based composite solid electrolytes are considered to be promising electrolytes and are widely investigated in solid lithium batteries. However, the low conductivity and high interfacial impedance of polymer-based solid electrolytes hinder their industrial applications. Herein, a composite solid-state electrolyte containing graphene (PVDF-LATP-LiClO4-Graphene) with structurally stable and good electrochemical performance is explored and enables excellent electrochemical properties for lithium-ion batteries. The ionic conductivity of the composite electrolyte membrane containing 5 wt% graphene reaches 2.00 × 10⁻³ S cm⁻¹ at 25 °C, which is higher than that of the composite electrolyte membrane without graphene (2.67 × 10⁻⁴ S cm⁻¹). The electrochemical window of the composite electrolyte membrane containing 5 wt% graphene reaches 4.6 V, and its Li⁺ transference numbers reach 0.84. Assembling this electrolyte into the battery, the LFP/PVDF-LATP-LiClO4-Graphene /Li battery has a specific discharge capacity of 107 mAh g⁻¹ at 0.2 C, and the capacity retention rate was 91.58% after 100 cycles, higher than that of the LiFePO₄/PVDF-LATP-LiClO₄/Li (LFP/PLL/Li) battery, being 94 mAh g⁻¹ and 89.36%, respectively. This work provides a feasible solution for the potential application of composite solid electrolytes. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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9 pages, 26330 KiB

Open AccessArticle

In Situ Grown Vertically Oriented Graphene Coating on Copper by Plasma-Enhanced CVD to Form Superhydrophobic Surface and Effectively Protect Corrosion

by Xiaohang Zheng, Yaqian Yang, Yi Xian, Heng Chen and Wei Cai

Nanomaterials 2022, 12(18), 3202; https://doi.org/10.3390/nano12183202 - 15 Sep 2022

Cited by 2 | Viewed by 1371

Abstract

Graphene exhibits great potential for the corrosion protection of metals, because of its low permeability and high chemical stability. To enhance the anticorrosion ability of Cu, we use plasma-enhanced chemical vapor deposition (PECVD) to prepare a vertically oriented few-layer graphene (VFG) coating on [...] Read more.

Graphene exhibits great potential for the corrosion protection of metals, because of its low permeability and high chemical stability. To enhance the anticorrosion ability of Cu, we use plasma-enhanced chemical vapor deposition (PECVD) to prepare a vertically oriented few-layer graphene (VFG) coating on the surface of Cu. The Cu coated with VFG shows superhydrophobic surface with a contact angle of ~150°. The VFG coating is used to significantly increase the anticorrosion ability, enhanced by the chemical stability and the unique geometric structure of vertically oriented graphene. The corrosion rate of VFG-Cu was about two orders of magnitude lower than that of bare Cu. This work highlights the special synthesized way of PECVD and superhydrophobic surface of vertical structures of graphene as coatings for various applications. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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14 pages, 3222 KiB

Open AccessArticle

Plasma-Engineered N-CoO_x Nanowire Array as a Bifunctional Electrode for Supercapacitor and Electrocatalysis

by Qi Wang, Tongtong Zhong and Zhou Wang

Nanomaterials 2022, 12(17), 2984; https://doi.org/10.3390/nano12172984 - 29 Aug 2022

Cited by 5 | Viewed by 1046

Abstract

Surface engineering has achieved great success in enhancing the electrochemical activity of Co₃O₄. However, the previously reported methods always involve high-temperature calcination processes which are prone to induce agglomeration of the nanostructure, leading to the attenuation of performance. In [...] Read more.

Surface engineering has achieved great success in enhancing the electrochemical activity of Co₃O₄. However, the previously reported methods always involve high-temperature calcination processes which are prone to induce agglomeration of the nanostructure, leading to the attenuation of performance. In this work, Co₃O₄ nanowires were successfully modified by a low-temperature NH₃/Ar plasma treatment, which simultaneously generated a porous structure and efficient nitrogen doping with no agglomeration. The modified N-CoO_x electrode exhibited remarkable performance due to the synergistic effect of the porous structure and nitrogen doping, which provided additional active sites for faradic transitions and improved charge transfer characteristics. The electrode achieved excellent supercapacitive performance with a maximum specific capacitance of 2862 mF/cm² and superior cycling retention. Furthermore, the assembled asymmetric supercapacitor (N-CoO_x//AC) device exhibited an extended potential window of 1.5 V, a maximum specific energy of 80.5 Wh/kg, and a maximum specific power of 25.4 kW/kg with 91% capacity retention after 5000 charge–discharge cycles. Moreover, boosted hydrogen evolution reaction performance was also confirmed by the low overpotential (126 mV) and long-term stability. This work enlightens prospective research on the plasma-enhanced surface engineering strategies. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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12 pages, 2861 KiB

Open AccessArticle

Pearson’s Principle-Inspired Robust 2D Amorphous Ni-Fe-Co Ternary Hydroxides on Carbon Textile for High-Performance Electrocatalytic Water Splitting

by Rong Hu, Huiyu Jiang, Jinglin Xian, Shiyun Mi, Liyun Wei, Guangyu Fang, Jiayue Guo, Siqi Xu, Ziyang Liu, Huanyu Jin, Huimin Yu and Jun Wan

Nanomaterials 2022, 12(14), 2416; https://doi.org/10.3390/nano12142416 - 14 Jul 2022

Cited by 1 | Viewed by 1670

Abstract

Layered double hydroxide (LDH) is widely used in electrocatalytic water splitting due to its good structural tunability, high intrinsic activity, and mild synthesis conditions, especially for flexible fiber-based catalysts. However, the poor stability of the interface between LDH and flexible carbon textile prepared [...] Read more.

Layered double hydroxide (LDH) is widely used in electrocatalytic water splitting due to its good structural tunability, high intrinsic activity, and mild synthesis conditions, especially for flexible fiber-based catalysts. However, the poor stability of the interface between LDH and flexible carbon textile prepared by hydrothermal and electrodeposition methods greatly affects its active area and cyclic stability during deformation. Here, we report a salt-template-assisted method for the growth of two-dimensional (2D) amorphous ternary LDH based on dip-rolling technology. The robust and high-dimensional structure constructed by salt-template and fiber could achieve a carbon textile-based water splitting catalyst with high loading, strong catalytic activity, and good stability. The prepared 2D NiFeCo-LDH/CF electrode showed overpotentials of 220 mV and 151 mV in oxygen evolution and hydrogen evolution reactions, respectively, and simultaneously had no significant performance decrease after 100 consecutive bendings. This work provides a new strategy for efficiently designing robust, high-performance LDH on flexible fibers, which may have great potential in commercial applications. Full article

(This article belongs to the Special Issue Modification Strategies on Engineering Electrocatalysts Related to Nanomaterials)

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