Mono-disperse MMoO(3)(.)2H(2)O (M = Mn, Co, Ni) compound nanocrystals were synthesized by a low-temperature hydrothermal reaction route using (N2H4H2O)-H-. as a reduction reagent as well as a structure-directed reagent. The physical characterizations were carried out by TGA, XRD, XPS, SEM and Photo RE The data of XRD indicate a single phase of monocline symmetry. Nanostructures of MMoO3.2H(2)O (M = Mn, Co, Ni) samples in zero, one or two dimensions were observed from SEM images, respectively. Furthermore, MMoO3-2H(2)O are luminescent, which is different from composite oxides with ordinary structure. (c) 2006 Elsevier B.V. All rights reserved.
Mixed Close-Packed Cobalt Molybdenum Nitrides as Non-noble Metal Electrocatalysts for the Hydrogen Evolution Reaction
摘要:
A two-step solid-state reaction for preparing cobalt molybdenum nitride with a nanoscale morphology has been used to produce a highly active and stable electrocatalyst for the hydrogen evolution reaction (HER) under acidic conditions that achieves an iR-corrected current density of 10 mA cm(-2) at -0.20 V vs RHE at low catalyst loadings of 0.24 mg/cm(2) in rotating disk experiments under a H-2 atmosphere. Neutron powder diffraction and pair distribution function (PDF) studies have been used to overcome the insensitivity of X-ray diffraction data to different transition-metal nitride structural polytypes and show that this cobalt molybdenum nitride crystallizes in space group P6(3)/mmc with lattice parameters of a = 2.85176(2) angstrom and c = 10.9862(3) angstrom and a formula of Co0.6Mo1.4N2. This space group results from the four-layered stacking sequence of a mixed close-packed structure with alternating layers of transition metals in octahedral and trigonal prismatic coordination and is a structure type for which HER activity has not previously been reported. Based on the accurate bond distances obtained from time-of-flight neutron diffraction data, it is determined that the octahedral sites contain a mixture of divalent Co and trivalent Mo, while the trigonal prismatic sites contain Mo in a higher oxidation state. X-ray photoelectron spectroscopy (XPS) studies confirm that at the sample surface nitrogen is present and N-H moieties are abundant.
双金属材料被认为是用于高效碱性水分解的有前景的催化剂。然而,催化前催化剂表面结构的自发重建长期以来一直被忽视。在这里,我们提出MoO 4 2-在 CoMoO 4中的原位溶解促进了碱性介质中的自发表面重建。我们的研究结果表明,CoMoO 4微棒阵列可作为预催化剂,在碱性条件下进行自发的表面重构,形成一层 Co 3 O 4 /CoMoO 4和 CoOOH/CoMoO 4异质结构。X射线光电子能谱(XPS)结合原位拉曼光谱表明,在这种活化的 CoMoO 4 (A-CoMoO 4 ) 中,从 Co 位点到 Mo 位点的部分电子转移有助于诱导 Co 中心的更高价态,并且 Co 3 O 4 /CoMoO 4的异质结构可以促进CoOOH 很可能是用于析氧反应 (OER) 催化的活性 Co 4+物质的前体。在析氢反应(HER)过程中,表面重构后产生的Co 3 O 4可以促进水的解离,这被认为是碱性HER的速率决定步骤。因此,A-CoMoO
The Fischer-Tropsch reaction was examined over reduced molybdenum catalysts using heteropoly compounds as catalyst precursors. Improvement in reducibility was realized by the use of heteropoly compounds. Metallic molybdenum powder with a very large surface area was obtained by the reduction of H3PMo12O40. Its catalytaic activity was one order higher than conventional Mo catalysts. Using different salts of 12-molybdophosphoric acid, various additives were introduced under equivalent conditions and their addition effects were studied.
An efficient electrode based on one-dimensional CoMoO4 nanorods for oxygen evolution reaction
作者:Xueliang Liu、Yunxu Yang、Shanyue Guan
DOI:10.1016/j.cplett.2017.02.074
日期:2017.5
Abstract We have developed the CoMoO4 nanorods (NRs) electrode with a specific one-dimensional nanostructure, which exhibited superior electrocatalytic performance for OxygenEvolutionReaction (OER), such as lower potential (343 mV at a current density of 10 mA cm−2), Tafel slope (67 mV decade−1) and excellent catalytic stability (for 10 h). Benefiting from enhancement of electrical conductivity and
摘要 我们开发了具有特定一维纳米结构的 CoMoO4 纳米棒 (NRs) 电极,该电极对析氧反应 (OER) 表现出优异的电催化性能,例如较低的电势(在 10 mA cm-2 的电流密度下为 343 mV) ,塔菲尔斜率(67 mV 十倍数-1)和优异的催化稳定性(10 小时)。受益于导电性和一维纳米结构的增强,CoMoO4 NRs 表现出比 Co3O4 立方体更高的 OER 活性,表明一维纳米结构有望实现具有优异性能的 OER 催化剂。
property of an electrocatalyst is crucial for oxygenevolutionreaction (OER). In this work, we have successfully prepared CoMoO4 nanorods (NR) with 100} facets exposed mainly and CoMoO4nanosheets (NS) with 010} exposed mainly via a facile hydrothermal route. It is found that although the CoMoO4 NS has a 7 times higher surface area (49.3 m2 g−1) than the CoMoO4 NR (7.0 m2 g−1), the CoMoO4 NR has a 5
摘要 电催化剂的表面性质对于析氧反应 (OER) 至关重要。在这项工作中,我们成功地制备了主要暴露 100} 面的 CoMoO4 纳米棒 (NR) 和主要通过简便的水热途径暴露 010} 的 CoMoO4 纳米片 (NS)。发现虽然 CoMoO4 NS 的表面积 (49.3 m2 g-1) 比 CoMoO4 NR (7.0 m2 g-1) 高 7 倍,但 CoMoO4 NR 的 OER 电流密度 (8.93 mA cmcat-) 高 5.7 倍2) 比 550 mV 的 CoMoO4 NS (1.56 mA cmcat-2)。其较高的内在 OER 活性主要归因于 CoMoO4 NR 暴露的 100} 面。与010}面(0.41 Jm-2)相比,具有更高表面能(0.54 Jm-2)的100}面更具反应性,并且(100)表面上越多的Co原子可以提供更多的OER活性位点。
Controlled Synthesis of Hollow Co–Mo Mixed Oxide Nanostructures and Their Electrocatalytic and Lithium Storage Properties
作者:Yong Yang、Shitong Wang、Caihua Jiang、Qichen Lu、Zilong Tang、Xun Wang
DOI:10.1021/acs.chemmater.6b00761
日期:2016.4.12
view of the unique heterostructure with hollow structure, the Co3O4/CoMoO4 heterostructures exhibit much better electrocatalytic activity for the oxygen evolution reaction than CoMoO4. Moreover, the as-synthesized carbon-coated Co3O4/CoMoO4 nanospheres show excellent lithium storage properties. Our result described here provides a method to fabricate other mixed metal oxides with complicated structure
空心混合金属氧化物由于其在广泛的潜在应用中的出色性能而备受关注。在这里,我们成功地制备了具有受控结构和组成的中空Co-Mo混合氧化物纳米结构,包括中空Co 3 O 4 / CoMoO 4异质结构和球中CoMoO 4纳米球。通过一锅溶剂热法制备均匀的CoMo混合前驱体,然后在热处理后转变为空心结构。重要的是,该策略可用于制备其他基于Mo的三元氧化物。鉴于具有空心结构的独特异质结构,Co 3 O 4 / CoMoO 4异质结构对氧的释放反应比CoMoO 4表现出更好的电催化活性。此外,所合成的碳包覆的Co 3 O 4 / CoMoO 4纳米球显示出优异的锂储存性能。我们在此描述的结果提供了一种制造结构复杂的其他混合金属氧化物的方法。
Molybdenum Nitrides as Oxygen Reduction Reaction Catalysts: Structural and Electrochemical Studies
作者:Bingfei Cao、Joerg C. Neuefeind、Radoslav R. Adzic、Peter G. Khalifah
DOI:10.1021/ic5024778
日期:2015.3.2
Monometallic (δ-MoN, Mo5N6, and Mo2N) and bimetallic molybdenum nitrides (Co0.6Mo1.4N2) were investigated as electrocatalysts for the oxygen reduction reaction (ORR), which is a key half-reaction in hydrogen fuel cells. Monometallic hexagonal molybdenum nitrides are found to exhibit improved activities over rock salt type molybdenum nitride (γ-Mo2N), suggesting that improvements are due to either the
研究了单金属(δ-MoN,Mo 5 N 6和Mo 2 N)和双金属氮化钼(Co 0.6 Mo 1.4 N 2)作为氧还原反应(ORR)的电催化剂,这是氢中的关键半反应燃料电池。单金属六边形钼氮化物被发现在岩盐型氮化钼表现出改善的活动(γ-沫2 N),这表明改善是由于无论是较高的钼化合价或在六方结构更有利的配位环境。发现六方双金属钴氮化钼(Co 0.6 Mo 1.4 N2),相对于可逆氢电极(RHE)产生了0.713 V的中等启动电位。Co 0.6 Mo 1.4 N 2在酸性环境中表现出良好的稳定性,并且在相对RHE低于0.5 V的电势范围内,基于对转盘电极结果的分析,ORR似乎是通过四电子机理进行的。使用中子衍射数据对二元氮化钼的结构进行了重新测定,中子衍射数据比X射线衍射数据对氮位点的位置更敏感。修改后的单金属六方氮化物结构均与Co 0.6 Mo 1.4 N 2具有许多共同特征。 这种结