《Advanced Materials Interfaces》2017,4(13)

A series of porous La_0.6Sr_0.4Co_1–x Fe_x O_3–δ (x = 0–1) nanofibers with diameters of 54–71 nm are synthesized by electrospinning using appropriate polymers and different processing parameters. When tested as a catalyst for oxygen evolution reaction (OER), an La_0.6Sr_0.4Co_0.6Fe_0.4O_3–δ (LSCF6464) nanofiber catalyst (with a specific surface area of 24.2 m² g⁻¹) exhibits a potential (vs Ag/AgCl) of 647 mV at 10 mA cm⁻²_disk, which is much smaller than that of a powder‐type commercial LSCF (786 mV) and also smaller than that of the state‐of‐the‐art IrO₂ catalysts (660 mV). The LSCF6464 nanofiber catalyst further delivers an outstanding durability, with almost no observable change in potential at a current density of 10 mA cm⁻²_disk for more than 3 h. In contrast, the performance of an IrO₂ catalyst degrades continuously under the same testing conditions. The findings suggest that the LSCF nanofiber is a promising OER electrocatalyst for metal–air batteries and water electrolysis.  相似文献   

    

《Advanced Materials Technologies》2017,2(12)

A new hydrogen peroxide detection sensitive material, boron doped carbonized ZIF‐67@graphene (Co‐N/C@G‐B) is synthesized through pyrolysis of a sandwich‐like ZIF‐67 coating graphene material. After doping boron atoms by using chemical vapor deposition method, new active sites such as Co₂B and B N C bonds are created, and mesopores are significantly increased. Most importantly, this Co‐N/C@G‐B material is found to exhibit excellent performance as an enzyme‐free biosensor for detecting hydrogen peroxide with a very wide detection range (from 0.5 × 10⁻⁶ to 60 × 10⁻³m ), a low detection limit (0.19 × 10⁻⁶m ), and a rapid response time (≈3 s). The prepared biosensor also shows strong anti‐interference ability in the complex working occasions. Furthermore, for real application of the materials, an electronic device of biosensor is developed by using technologies of screen printing electrode, integrated circuit, 3D printed shell, and custom‐developed program, which shows high sensitivity and portability to detect hydrogen peroxide. Such device paves a way for further practical application of advanced materials in commercial scale.  相似文献   

    

《Small Methods》2017,1(12)

Zinc–air batteries (ZABs) have attracted extensive attention due to their remarkable high theoretical energy output. They represent one of the most promising future power sources. However, many barriers restrict their application on a large scale. One of the main challenges is the sluggish rates of the oxygen‐reduction reaction (ORR) and oxygen‐evolution reaction (OER), which govern the discharging and charging processes of the battery, respectively. Here, recent advances related to oxygen electrocatalyst materials for ZABs are discussed. Detailed discussions will focus on unifunctional ORR electrocatalysts and bifunctional ORR and OER electrocatalysts. Pt‐based nanomaterials, as the best ORR electrocatalysts, possess the virtue of high activity, but have the disadvantages of high cost, scarcity, and poor stability. Thus, materials based on transition metals (alloys, metal oxides, metal nitrides, and spinel oxides) and metal‐free materials are widely investigated as nonprecious ORR catalysts owing to their promising catalytic activities. As for bifunctional ORR and OER electrocatalysts, the following two categories are introduced: (i) metal‐based materials, including single metal/metal‐oxides‐based materials and mixed‐metal/metal‐oxides‐based materials; and (ii) metal‐free materials. Finally, perspectives on the continuous research and limitation of the current ZAB technology are provided.  相似文献   

    

Lin Ye  Guoliang Chai  Zhenhai Wen 《Advanced functional materials》2017,27(14)

It is of increasing importance to explore new low‐cost and high‐activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy conversion system, including various fuel cell and metal–air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt‐based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal‐free electrocatalysts in pH‐universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen‐doped porous carbon (NPC) with high yields and exceptional quality is described. The as‐prepared NPC shows advantages of high activity, high durability, and methanol‐tolerant as an efficient pH‐universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen‐doping species and favorable pores in the as‐designed NPC synergistically contribute to the significantly improved catalytic activity in pH‐universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells.  相似文献   

    

Jia Yang  Xu Wang  Bo Li  Liang Ma  Lei Shi  Yujie Xiong  Hangxun Xu 《Advanced functional materials》2017,27(17)

Development of efficient, low‐cost, and durable electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is of significant importance for many electrochemical devices, such as rechargeable metal–air batteries, fuel cells, and water electrolyzers. Here, a novel approach for the synthesis of a trifunctional electrocatalyst derived from iron/cobalt‐containing polypyrrole (PPy) hydrogel is reported. This strategy relies on the formation of a supramolecularly cross‐linked PPy hydrogel that allows for efficient and homogeneous incorporation of highly active Fe/Co–N–C species. Meanwhile, Co nanoparticles are also formed and embedded into the carbon scaffold during the pyrolysis process, further promoting electrochemical activities. The resultant electrocatalyst exhibits prominent catalytic activities for ORR, OER, and HER, surpassing previously reported trifunctional electrocatalysts. Finally, it is demonstrated that the as‐obtained trifunctional electrocatalyst can be used for electrocatalytic overall water splitting in a self‐powered manner under ambient conditions. This work offers new prospects in developing highly active, nonprecious‐metal‐based electrocatalysts in electrochemical energy devices.  相似文献   

    

Shuo Dou  Chung‐Li Dong  Zhe Hu  Yu‐Cheng Huang  Jeng‐lung Chen  Li Tao  Dafeng Yan  Dawei Chen  Shaohua Shen  Shulei Chou  Shuangyin Wang 《Advanced functional materials》2017,27(36)

The activity of electrocatalysts strongly depends on the number of active sites, which can be increased by downsizing electrocatalysts. Single‐atom catalysts have attracted special attention due to atomic‐scale active sites. However, it is a huge challenge to obtain atomic‐scale CoO_x catalysts. The Co‐based metal–organic frameworks (MOFs) own atomically dispersed Co ions, which motivates to design a possible pathway to partially on‐site transform these Co ions to active atomic‐scale CoO_x species, while reserving the highly porous features of MOFs. In this work, for the first time, the targeted on‐site formation of atomic‐scale CoO_x species is realized in ZIF‐67 by O₂ plasma. The abundant pores in ZIF‐67 provide channels for O₂ plasma to activate the Co ions in MOFs to on‐site produce atomic‐scale CoO_x species, which act as the active sites to catalyze the oxygen evolution reaction with an even better activity than RuO₂.  相似文献   

    

《International Journal of Hydrogen Energy》2021,46(79):39438-39456

This study demonstrates the structural properties and evaluates the electrocatalytic activity of an ethanol oxidation reaction using ternary materials composed by Pd and Sn nanoparticles combined with CeO₂ nanorods (NR) anchored on Vulcan carbon black to be used as an anode in alkaline direct ethanol fuel cells (ADEFCs). The highest open circuit voltage (1010 mV), maximum power (30 mW cm⁻²) and current densities (113 mA cm⁻²) were achieved using (Pd₁Sn₃)₁₀(CeO₂ NR)₂₀(Vn)₇₀, while the commercial anode values were 968 mV, 23 mW cm⁻² and 123 mA cm⁻². Although similar performance for both anodes was observed, the ternary hybrid electrocatalyst contains an 8-fold lower Pd content than the commercial material. This outcome may be justified by the higher defect density presented by the carbon support observed by Raman spectroscopy and the metal oxidation state modifications detected by X-ray photoelectron spectroscopy, as well as the electrochemically active surface area presented by the ternary electrocatalyst. The combination of higher vacancies, defects and oxygenated species in the carbon support and the synergistic effect between the oxyphilic Sn and CeO₂ NR species and the Pd nanoparticles results in an electrochemical performance that makes these ternary electrocatalysts promising anode materials for ADEFC applications.  相似文献   

    

Guoqiang Zhao  Jian Chen  Wenping Sun  Hongge Pan 《Advanced functional materials》2021,31(20):2010633

Developing non-platinum group metal (non-PGM) electrocatalysts for the hydrogen oxidation reaction (HOR) represents the efforts towards the more economical use of hydrogen fuel cells and hydrogen energy, which has attracted tremendous attention recently. However, non-PGM electrocatalysts for the HOR are still in their early development stages as compared with the significant advances in those for the oxygen reduction reaction and hydrogen evolution reaction. Herein, this paper summarizes the recent progresses and highlights the key challenges for the rational design of non-PGM electrocatalysts, aiming to promote the development of non-PGM HOR electrocatalysts. Fundamental understandings of the HOR mechanism are firstly reviewed, where theoretical interpretations on the low HOR kinetics in alkaline media, including the hydrogen binding energy theory, the bifunctional mechanism, and the water molecule reorganization, are particularly discussed. Subsequently, progresses of typical non-PGM HOR electrocatalysts in acid and alkaline media are summarized separately. For the HOR under alkaline conditions, the superiorities and challenges of Ni-based catalysts are discussed with a particular focus as they are the most promising non-PGM electrocatalysts. Finally, this paper highlights the challenges and provide perspectives on the future development directions of non-PGM HOR electrocatalysts.  相似文献   

    

Chaoqi Zhang  Ruihu Lu  Chao Liu  Ling Yuan  Jing Wang  Yan Zhao  Chengzhong Yu 《Advanced functional materials》2021,31(26):2100099

Hydrogen peroxide (H₂O₂) production by electrochemical two-electron water oxidation reaction (2e-WOR) is a promising approach, where high-performance electrocatalysts play critical roles. Here, the synthesis of nanostructured CaSnO₃ confined in conductive carbon fiber membrane with abundant oxygen vacancy (O_V) as a new generation of 2e-WOR electrocatalyst is reported. The CaSnO₃@carbon fiber membrane can be directly used as a self-standing electrode, exhibiting a record-high H₂O₂ production rate of 39.8 µmol cm⁻² min⁻¹ and a selectivity of ≈90% (at 2.9 V vs reversible hydrogen electrode). The CaSnO₃@carbon fiber membrane design improves not only the electrical conductivity and stability of catalysts but also the inherent activity of CaSnO₃. Density functional theory calculation further indicates the crucial role of O_V in increasing the adsorption free energy toward oxygen intermediates associated with the competitive four-electron water oxidation reaction pathway, thus enhancing the activity and selectivity of 2e-WOR. The findings pave a new avenue to the rational design of electrocatalysts for H₂O₂ production from water.  相似文献   

    

Rui-Qi Yao  Yi-Tong Zhou  Hang Shi  Wu-Bin Wan  Qing-Hua Zhang  Lin Gu  Yong-Fu Zhu  Zi Wen  Xing-You Lang  Qing Jiang 《Advanced functional materials》2021,31(10):2009613

Electrocatalytic hydrogen evolution in alkaline and neutral media offers the possibility of adopting platinum-free electrocatalysts for large-scale electrochemical production of pure hydrogen fuel, but most state-of-the-art electrocatalytic materials based on nonprecious transition metals operate at high overpotentials. Here, a monolithic nanoporous multielemental CuAlNiMoFe electrode with electroactive high-entropy CuNiMoFe surface is reported to hold great promise as cost-effective electrocatalyst for hydrogen evolution reaction (HER) in alkaline and neutral media. By virtue of a surface high-entropy alloy composed of dissimilar Cu, Ni, Mo, and Fe metals offering bifunctional electrocatalytic sites with enhanced kinetics for water dissociation and adsorption/desorption of reactive hydrogen intermediates, and hierarchical nanoporous Cu scaffold facilitating electron transfer/mass transport, the nanoporous CuAlNiMoFe electrode exhibits superior nonacidic HER electrocatalysis. It only takes overpotentials as low as ≈240 and ≈183 mV to reach current densities of ≈1840 and ≈100 mA cm⁻² in 1 m  KOH and pH 7 buffer electrolytes, respectively; ≈46- and ≈14-fold higher than those of ternary CuAlNi electrode with bimetallic Cu–Ni surface alloy. The outstanding electrocatalytic properties make nonprecious multielemental alloys attractive candidates as high-performance nonacidic HER electrocatalytic electrodes in water electrolysis.  相似文献