Metal-Organic Frameworks Derived Cobalt Phosphide Architecture Encapsulated into B/N Co-Doped Graphene Nanotubes for All pH Value Electrochemical Hydrogen Evolution
Metal-Organic Frameworks Derived Cobalt Phosphide Architecture Encapsulated into B/N Co-Doped Graphene Nanotubes for All pH Value Electrochemical Hydrogen Evolution
复制标题
金属有机框架衍生的磷化钴结构封装在 B/N 共掺杂石墨烯纳米管中，适用于所有 pH 值电化学析氢
DOI：
10.1002/aenm.201601671
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发表时间：
2017-05-10
影响因子：
27.8
通讯作者：
Zou, Ruqiang
中科院分区：
文献类型：
--
作者：
Tabassum, Hassina;Guo, Wenhan;Zou, Ruqiang
DOI：10.1002/aenm。 201601671在大电流和长期HER测试下容易团聚，稳定性较差，无论pH值如何，HER活性较低。 [7]最近，研究人员利用碳壳来保护金属或其化合物纳米颗粒免受酸性大气降解和与邻近纳米颗粒的团聚。 [8]这些新型金属/碳复合材料不仅使金属纳米粒子在环境大气中不稳定的催化应用成为可能，而且在一定程度上改善了它们的电子传输。然而，如果活性物质上的碳层太厚或孔隙率低，可能会阻碍所需的传质通道，从而导致金属的催化活性显着下降。 [9]在这方面，最近开发的利用金属有机框架（MOF）作为前体制备金属@碳的原位技术突出了此类应用的新功能。 [10] MOFs是通过金属离子与有机连接体偶联制备的结晶规则多孔材料，[11]及其衍生的复合材料，如氮掺杂多孔碳，表现出大表面积和分级孔结构，这对丰富各种催化反应，如HER、氧还原和演化反应发挥着重要作用。 [12]然而，此类材料的石墨化程度较低，活性金属纳米粒子与衍生碳之间的键合相互作用较差。 [13]为了改善 HER 的电子传输和有效的质量扩散路径，我们通过使用 B/N 共掺杂石墨烯 (BCN) 纳米管来限制 MOF 衍生的 CoP NPs 来应用这一概念。此外，有充分证据表明，用氮 (N) 和硼 (B) 化学取代碳原子可以调节碳纳米管的电荷极化。 [14]特别是，这两种元素的电负性与碳相反，因为 B 和 N 共掺杂可以激活杂原子和相邻碳原子之间的电子自旋密度。因此，BCN纳米管三元体系的协同效应大大扩大了催化表面积。[14a, 15]同时，预计在石墨烯纳米管封装的金属磷化物纳米颗粒中共掺杂B和N不仅可以防止金属的团聚，还可以产生额外的活性位点以增强HER性能。据我们所知，将金属磷化物纳米粒子封装在杂原子石墨纳米管中是一项具有挑战性的任务，并且很少有报道。在此，我们引入了一种自下而上的策略，通过热解和磷化合成封装在BCN纳米管中的CoP结构（CoP@BCN），如图所示。由于近年来世界范围内对能源危机和环境问题的日益关注，通过电催化反应开发清洁高效的能源转换和存储技术引起了人们的极大关注。 [1]作为未来能源供应的有希望的候选者，分子氢 (H2) 具有最高的重量能量密度，由电催化水分解产生。高效电催化剂对于降低过电势以提高析氢反应（HER）中的能量转移效率至关重要。 [2]传统上，稀土金属 Pt 被认为是加速 HER 动力学的最佳电催化剂，这是加速 HER 动力学的先决条件。 [3]不幸的是，它们的商业应用受到高成本和稀缺性的阻碍。[4]用地球上丰富的金属取代贵重铂催化剂的关键策略将促进此类潜在清洁能源应用的全球可扩展性。[5…
DOI: 10.1002/aenm. 201601671 easy for the agglomeration under high current and long-term testing for HER, which showed poor stability and exhibited low HER activity irrespective of pH value.[7] Recently, researchers employed carbon shell to protect the metal or their compounds NPs from acidic atmospheric degradation and agglomeration with neighboring NPs.[8] These new metal/carbon composites not only enabled the catalytic applications of metal NPs which are also not stable as the naked in ambient atmosphere, but also improved their electron transport to certain extent. However, if the carbon layers on active species are too thick or with low porosity, it could hinder the desired access of mass transport, and as a result catalytic activity of metal is significantly decreased.[9] In this regard, recently developed in situ technology to prepare metal@ carbon by using metal–organic frameworks (MOFs) as precursors has highlighted new functionality for such application.[10] MOFs are crystalline regular porous materials prepared by the coupling of metal ions with organic linkers,[11] and their derived composites, like nitrogendoped porous carbon, exhibit large surface area and hierarchical pore structures, which play important roles to ample the various catalytic reactions, such as HER, oxygen reduction, and evolution reaction.[12] However, such kind of materials consisted of some low degree of graphitization and poor bonding interactions between active metal NPs and derived carbon.[13] To improve the electron transport and valid mass diffusion path for HER, we apply this concept by using B/N co-doped graphene (BCN) nanotubes to confine MOF-derived CoP NPs. Furthermore, it is well documented that chemical replacement of carbon atom by nitrogen (N) and boron (B) can modulate the charge polarization of carbon nanotubes.[14] In particular, the two elements are reverse in electronegativity to that of carbon as B and N co-doping could activate the electron spin density between heteroatom and adjacent carbon atom. Thus, synergistic effect of ternary system of BCN nanotubes greatly enlarges the catalytic surface area.[14a, 15] Meanwhile, it is anticipated that co-doping of B and N in graphene nanotubes encapsulated metal phosphide NPs will not only prevent the agglomeration of metal but also produce the additional active sites to enhance the HER performance. To the best of our knowledge, encapsulation of metal phosphide NPs in heteroatom graphitic nanotubes is a challenging task and has rarely been reported. Herein, we introduce a bottom-up strategy for synthesis of CoP architecture encapsulated into BCN nanotubes (CoP@ BCN) through pyrolysis and phosphidation as shown inOwing to the increasing worldwide concern over energy crisis and environmental issues, great attention has been triggered for the development of clean and highly efficient energy conversion and storage techniques by electrocatalytic reaction in recent years.[1] As a promising candidate for the future energy supply, molecular hydrogen (H2) possess the highest gravimetric energy density and produced from electrocatalytic water splitting. The highly efficient electrocatalysts are crucial for lower overpotential to improve the energy transfer efficiency in hydrogen evolution reaction (HER).[2] Traditionally, rare earth metal Pt has been regarded as the best electrocatalyst to accelerate the kinetics in HER which is a prerequisite.[3] Unfortunately, their commercial applications are impeded by high cost and scarcity.[4] A key strategy to replace the precious Pt catalyst with earth abundant metals would promote global scalability of such potential clean energy applications.[5 …