CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Yang Yang,Yunhua Song,Shudi Mo,Mingyang Liu
Morphological design to expose more active sites and surface defect engineering to regulate the electronic structure are the two main methods to improve material properties. It is also well documented that metal sites in high valence states are beneficial to the OER process. Herein, we combine the advantages of the above three methods to fabricate extraordinary catalysts just by facile adjusting the Fe content. The catalysts with different Fe contents exhibit excellent activity and outstanding stability beyond the yardstick material (RuO 2 ) in alkaline condition. The resultant FeCoNi (oxy)hydroxide nanosheets is one of the most active trimetal-based oxygen evolution catalysts to date. Specifically, the resultant Fe 1.25 (Co 2 Ni 1 ) 2.5 (oxy)hydroxide can deliver a minimum overpotential of 212 mV to reach the current density of 10 mA cm −2 with a small Tafel slope of 52 mV dec −1 and a negligible activity attenuation after excess 72 h long-term test at 100 mA cm −2 . Most importantly, when use Fe 1.25 (Co 2 Ni 1 ) 2.5 (oxy)hydroxide as a water splitting anode, an electrolyzer delivers a current density of 10 mA cm −2 at a very low cell voltage of 1.51 V. This excellent performance is attributed to the large number of active sites exposed by the nanosheets, the active center of the catalyst to the higher valence state and the large number of oxygen defects produced. This work can provide more valuable insights to promote the development of the highly efficient oxygen evolution for applications.
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ACS Sustainable Chemistry & Engineering
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2020
·
IF 7.632
Qingqing Zha,Mingxia Li,Zihao Liu,Yonghong Ni
Metal–organic frameworks (MOFs) have attracted much interest in electrocatalysis as promising catalysts in recent years. However, it still remains a challenge to directly use MOF-based materials as bifunctional electrocatalysts for overall water splitting. Herein, a hierarchical Co,Fe-MOF-74/Co/carbon cloth (CC) three-layer hybrid electrode is synthesized by a simple electrochemical deposition technology with subsequent solvothermal treatment. Electrochemical performance investigations show that the as-constructed Co,Fe-MOF-74/Co/CC electrode exhibits impressive electrocatalytic activity for full water splitting, which only requires a low overpotential of 226 mV@20 mA cm–2 for the oxygen evolution reaction (OER) and 94 mV@–10 mA cm–2 for the hydrogen evolution reaction (HER), respectively. Employing the as-constructed electrode as the anode and cathode in a two-electrode setup simultaneously, only 1.65 V of the voltage is needed to deliver the current density of 20 mA cm–2. The above excellent electrochemical performances should be attributed to the specific architecture, the synergistic effect of the Co and Fe species, and the superhydrophilic surface of the catalyst. More importantly, further investigations uncover that metal hydroxides and oxyhydroxides produced in situ during electrochemical tests are the veritable active species, which promote the high catalytic activity of the present catalyst.
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Fan Zhang,Renjie Ji,Yonghong Liu,Zhijian Li,Zheng Liu,Shuaichen Lu,Yating Wang,Xinlei Wu,Hui Jin,Baoping Cai
Exploring the low-cost and high-efficient electrocatalysts with Pt-like activity for alkaline hydrogen evolution through water splitting is imperative yet challenging. Herein, a simple synthesis combined with electrodeposition and facile electro-oxidation is developed to construct the hollow dendritic self-supported electrode (HDSE). X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), and electron paramagnetic resonance (EPR) reveal that the surface of HDSE contains the abundant NiO, which is further decorated by fluorine (F)-doped and oxygen vacancies after electro-oxidation process. The resultant HDSE achieves an excellent electrocatalytic performance for hydrogen evolution reaction (HER) in alkaline condition, leading to the extremely low overpotential of 13 mV to drive a current density of −10 mA·cm −2 , and exhibits the long-time stability at the current density of −100 mA·cm −2 and −500 mA·cm −2 , which is superior to the electrocatalytic ability of Pt/C. Density functional theory (DFT) calculations illustrate the NiO modulated by F-doping and oxygen vacancy, could synergistically improve the charge distribution, enhance the conductivity of NiO structure, and optimize the adsorption energy for intermediates of HER, thus accelerating the electrocatalytic ability for hydrogen evolution. This work opens up a new avenue toward the reasonable design of high-efficient and low-cost electrocatalysts for alkaline hydrogen evolution reaction.
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Sustainable Energy & Fuels
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2020
·Vol. 4
·期 6
·2775-2781
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IF 5.503
Lingjie Li,Liu Cao,Qiudong He,Bo Shang,Jinlong Chen,Jinglei Lei,Nianbing Li,Fusheng Pan
To improve the electrocatalytic performance of CuCo hybrid oxides, here we report a novel and facile strategy to simultaneously tailor the morphology and electronic structure of CuCoOx by incorporation of CeO2. The as-synthesized CeO2-CuCoO/NF shows urchin-like morphology that is composed of numerous nanofibers, endowing the surface with superaerophobicity and massive active sites. Density functional theory calculation elucidates the crucial role of CeO2 in boosting the electron transfer and decreasing the free energy of intermediates during water splitting. As expected, CeO2-CuCoO/NF shows attractive bifunctional electrocatalytic activity with overpotentials of 266 and 93 mV at 10 mA cm−2 for oxygen and hydrogen evolution reactions in 1 M KOH, respectively, which are superior to most reported catalysts. A water-splitting electrolyzer consisted of CeO2-CuCoO/NF electrodes as both anode and cathode displays better performance than the noble-metal counterpart IrO2/NF‖Pt/C/NF. The present work undoubtedly sheds new insight on designing advanced bifunctional catalysts for practical water splitting.
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JOURNAL OF CATALYSIS
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2020
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IF 7.888
Lei Lei,Danlian Huang,Chen Zhang,Rui Deng,Sha Chen,Zhihao Li
As a member of the transition metal sulfide family, cobalt sulfides (CoS x ) are considered as highly-activity, cost-effectively, as well as stable electrocatalysts with huge potential for the application of water splitting. Combining experiments and theoretical calculations, we demonstrated that F dopants could activate the Co and S sites of CoS 2 in CoS 2 @NF composites prepared via one-step hydrothermal method and contribute to enhance the intrinsic electrical conductivity, achieving a significantly improved activity of water splitting. The improved surface wettability in F-doped CoS 2 @NF composites ensures rapid electrolyte penetration and accelerates migration of hydroxyl as well as oxygen release. Furthermore, the F-doped CoS 2 @NF composites exhibit remarkable electrocatalytic activity and excellent long-term operational stability for overall water splitting in alkaline and neutral media. Predominantly, our work could be explored to enhance and understand the catalytic properties of other transition metal sulfides, and be also expected for further progress achieved with other nonmetal element dopants.
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JOURNAL OF SOLID STATE CHEMISTRY
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2020
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IF 2.726
Yan Zhou,Jingtong Zhang,Fengchao Sun,Xinping Yu,Wenpei Kang,Jun Zhang
In this work, sheet-like Co 9 S 8 was directly grown on Ni 3 S 2 spheres (donate as Co 9 S 8 @Ni 3 S 2 ) via a one-step hydrothermal synthetic approach. The structural characterization of Co 9 S 8 @Ni 3 S 2 revealed that the Co 9 S 8 nanosheets were perpendicularly arrayed on Ni 3 S 2 spheres. This heterostructure thus fixes the two-dimensional Co 9 S 8 in position on Ni 3 S 2 spheres to obtain a stable heterostructural material. Due to the strengthened morphological structure, high surface area, metallic feature of Co 9 S 8 and Ni 3 S 2 , and the synergetic effect, the Co 9 S 8 @Ni 3 S 2 showed excellent performance in sodium ion battery (SIB) anode and HER cathode. The electrochemical tests showed that Co 9 S 8 @Ni 3 S 2 can demonstrate excellent HER catalytic activity with only −0.16 V and −0.23 V overpotential needed to achieve 10 mA cm −2 and 100 mA cm −2 current density in acidic condition. Besides, Co 9 S 8 @Ni 3 S 2 heterostructure as an anode in SIB also delivered high discharge capacity of 699 mAh g −1 at 0.5 A g −1 current density in the first cycle, with 92% Columbic efficiency.
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KOREAN JOURNAL OF CHEMICAL ENGINEERING
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2020
·Vol. 37
·期 2
·224-230
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IF 2.69
Si Zhihao,Zhang Xin,Zuo Miao,Wang Tao,Sun Yong,Tang Xing,Zeng Xianhai,Lin Lu
2, 5-furandicarboxylic acid (FDCA) is a one of the most promising biomass-derived chemicals to substitute the non-renewable terephthalic acid as the monomer for producing polyethyleneterephthalate. At present, the oxidation of HMF is regarded as a prevalent way to prepare FDCA. Nevertheless, the isolation and storage of HMF is still a challenge. Herein, based on the higher stability of 5-formyloxymethylfurfural (FMF) than 5-hydroxymethylfurfural (HMF), we present an effective preparation route to prepare FDCA by substituting HMF with FMF as feedstock. A complete conversion of FMF and a 93.55% selectivity of FDCA were obtained in the mixed solvent of water and 1, 2-dioxane using Ru/C as catalyst and O 2 as oxidant. An improved process was developed for preparing FDCA using FMF as feedstock. The investigation of conversion pathway showed that FMF and HMF were simultaneously oxidized to 2, 5-diformylfuran (DFF) in a case of the existence of the reversible equilibrium between FMF and HMF. Then DFF was oxidized to 5-formyl-2-furancarboxylic acid (FFCA). Subsequently, FFCA was oxidized to FDCA. In this process, the oxidation of FFCA to FDCA was determined as the rate-determining step. Furthermore, appropriate alkalinity favored the selectivity of FDCA and the conversion of FMF.
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Nanoscale
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2020
·Vol. 12
·期 7
·4374-4382
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IF 6.895
Xingmei Guo,Cheng Qian,Xiaohan Wan,Wei Zhang,Haowei Zhu,Junhao Zhang,Hongxun Yang,Shengling Lin,Qinghong Kong,Tongxiang Fan
Streptococcus thermophilus, a Gram-positive (G+) bacterium featuring a teichoic acid-rich cell wall, has been employed as both a phosphorus source and template to synthesize a biomorphic Co2P-Co3O4/rGO/C composite as an efficient electrocatalyst for the oxygen reduction reaction (ORR). Different from the conventional method for the synthesis of phosphides, bio-derivative phosphorus vapor was emitted from the inside out, which facilitated the in situ transformation of the chemically adsorbed Co precursor on the bacteria into Co2P-Co3O4 heterogeneous nanoparticles, which featured a Co2P-rich body and Co3O4-rich surface. Besides, reduced graphene oxide (rGO) was also introduced in the synthetic process to keep Co2P-Co3O4 scattered and further promote the electron transport efficiency. All the Co2P-Co3O4 nanoparticles and rGO sheets were supported on the bacteria-derived carbon substrate with submicron-spherical morphology. The as-obtained Co2P-Co3O4/rGO/C composite exhibited excellent electrocatalytic performance for ORR with onset and half-wave potentials of 0.91 and 0.80 V vs. RHE, respectively. Furthermore, its long-term stability and methanol tolerance were better than those of commercial Pt/C. Thus, this work presents a new strategy of using an interior bio-phosphorus source to obtain heterojunction particles featuring a phosphide-rich body and oxide-rich surface, which may provide some insights for the construction of efficient heterogeneous electrocatalysts.
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PubMed
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Nanoscale Research Letters
·
2020
·Vol. 15
·期 1
·1-14
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IF 3.578
Guo Chaozhong,Li Yanrong,Li Zhaoxu,Liu Yao,Si Yujun,Luo Zhongli
Designing appropriate methods to effectively enhance nitrogen-doping efficiency and active-site density is essential to boost the oxygen reduction reaction (ORR) activity of non-platinum Fe/N/C-type electrocatalysts. Here, we propose a facile and effective strategy to design a mesopore-structured Fe/N/C catalyst for the ORR with ultrahigh BET surface area and outstanding conductivity via nanochannels of molecular sieve-confined pyrolysis of Fe 2+ ions coordinated with 2,4,6-tri(2-pyridyl)-1,3,5-triazine complexes as a novel precursor with the stable coordination effect. Combining the nanochannel-confined effect with the stable coordination effect can synergistically improve the thermal stability and stabilize the nitrogen-enriched active sites, and help to control the loss of active N atoms during pyrolysis process and to further obtain a high active-site density for enhancing the ORR activity. The as-prepared Fe/N/C electrocatalyst has exhibited excellent catalytic activity with an onset potential of ~ 0.841 V (versus RHE) closely approaching the Pt/C catalyst and high long-term stability in alkaline electrolyte. Besides, low-hydrogen peroxide yield (< 6.5%) and high electron transfer number (3.88–3.94) can be found on this catalyst, indicating that it is a valuable substitute for traditional Pt/C catalysts. This work paves a new way to design high-performance Fe/N/C electrocatalysts and deepens the understanding of active site and ORR catalysis mechanism.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2020
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IF 3.807
Jianpeng Li,Xianfeng Li,Hongyan Chen,Dingshu Xiao,Jiajia Li,Dekang Xu
In this paper, we present a facile and one-step way for synthesizing Fe, N dual doped highly porous graphitic biomass carbon (FeNC) by using K 2 FeO 4 to fulfill the activated process and catalytic graphitization of straws. The FeNC demonstrates hierarchically porous structure with large surface area of 1034 m 2 g −1 , Fe, N dual doping with certain amount of Fe-N x , and graphitic structure. With these favorable features, the electrocatalytic activity for oxygen reduction reaction (ORR) reveals that the FeNC exhibits positively onset potential with highly comparable limiting current density when comparing with the sample using conventional KOH activated agent. In additional, the assembled Zn-air battery using FeNC as air-cathode catalyst delivers a maximal power density of 128.4 mW cm −2 . Considering the abundance of straws on the earth and the low-cost and green prepared process, the present FeNC materials are highly promising in application in ORR catalysts for Zn-air battery and other energy-related fields.
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ACS Applied Materials & Interfaces
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2020
·
IF 8.758
Zonghua Pu,Tingting Liu,Weiyue Zhao,Xiudong Shi,Yanchen Liu,Gaixia Zhang,Weihua Hu,Shuhui Sun,Shijun Liao
Highly active catalyst for the hydrogen oxidation/evolution reactions (HOR and HER) plays an essential role for the water-to-hydrogen reversible conversion. Currently, increasing attention has been concentrated on developing low-cost, high-activity, and long-life catalytic materials, especially for acid media due to the promise of proton exchange membrane (PEM)-based electrolyzers and polymer electrolyte fuel cells. Although non-precious-metal phosphide (NPMP) catalysts have been widely researched, their electrocatalytic activity toward HER is still not satisfactory compared to that of Pt catalysts. Herein, a series of precious-metal phosphides (PMPs) supported on graphene (rGO), including IrP2-rGO, Rh2P-rGO, RuP-rGO, and Pd3P-rGO, are prepared by a simple, facile, eco-friendly, and scalable approach. As an example, the resultant IrP2-rGO displays better HER electrocatalytic performance and longer durability than the benchmark materials of commercial Pt/C under acidic, neutral, and basic electrolytes. To attain a current density of 10 mA cm–2, IrP2-rGO shows overpotentials of 8, 51, and 13 mV in 0.5 M dilute sulfuric acid, 1.0 M phosphate-buffered saline (PBS), and 1.0 M potassium hydroxide solutions, respectively. Additionally, IrP2-rGO also exhibits exceptional HOR performance in the 0.1 M HClO4 medium. Therefore, this work offers a vital addition to the development of a number of PMPs with excellent activity toward HOR and HER.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Shasha Zhu,Jinglei Lei,Lina Zhang,Jianxin He
The exploration of catalysts with high activity and low cost for water splitting is still necessary. Herein, a nanowire-like morphology CoO/NF electrode is synthesized using facile hydrothermal reaction and calcination treatment. The urea can regulate its morphology during the synthetic process of CoO/NF. Electrochemical studies reveal that the as-obtained CoO/NF exhibits excellent electrocatalytic performance with overpotential of 307 mV at current density of 10 mA cm −2 and Tafel slope of 72 mV dec −1 for oxygen evolution reaction , and CoO/NF delivers current density of 10 mA cm −2 at overpotential of 224 mV for hydrogen evolution reaction . The results of the oxygen evolution reaction stability show that the overpotential of CoO/NF electrode is only increased by 4 mV at current density of 10 mA cm −2 . The two-electrode water splitting with CoO/NF electrodes as both anode and cathode needs a cell potential of 1.76 V to reach 10 mA cm −2 . Therefore, this simple method to prepare CoO/NF electrode can enhance the properties of electrocatalysts , which makes CoO/NF a promising material to replace noble metal-based catalysts.
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