Reduced Graphene Oxide Conjugated Cu2O Nanowire Mesocrystals for High-Performance NO2 Gas Sensor
Reduced Graphene Oxide Conjugated Cu2O Nanowire Mesocrystals for High-Performance NO2 Gas Sensor
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用于高性能 NO2 气体传感器的还原氧化石墨烯共轭 Cu2O 纳米线介晶
DOI：
10.1021/ja211683m
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发表时间：
2012-03-14
影响因子：
15
通讯作者：
Sow, Chorng Haur
中科院分区：
文献类型：
--
作者：
Deng, Suzi;Tjoa, Verawati;Sow, Chorng Haur
在水热条件下，以还原氧化石墨烯（GO）和邻氨基苯甲醚（o-anisidine）为催化剂，采用非经典晶化法制备了还原氧化石墨烯（GO）共轭Cu 2 O纳米线介晶.所得介晶由高度各向异性的纳米线作为构建块组成，并具有八个{111}等效晶面的独特八面体形态。介晶形成的机理是：第一，GO促进了非晶球形Cu_2 O纳米粒子的团聚，使其生长机制从传统的逐离子生长转变为粒子介导晶化;第二，无定形微球演化为分级结构，最后通过介观尺度转变为纳米线介晶，其中奥斯特瓦尔德成熟是纳米线结构单元生长的原因;第三，介晶的大规模自组织和GO的还原（在高GO浓度下）同时发生，产生一种集成的混合结构，其中多孔三维（3D）骨架结构散布在二维（2D）rGO片层中。有趣的是，从观察到的空洞Sierpinski多面体判断，通过介晶的3D取向附着形成的“超介晶”也形成。此外，这些介晶的内部纳米线结构可以通过仔细改变生长条件来动力学控制。由于高比表面积和改善的导电性，rGO-Cu 2 O介晶在室温下实现了对NO2的更高灵敏度，超过了Cu 2 O纳米线网络和rGO片的独立系统的性能。rGO-Cu_2 O介晶的独特性质使其在超灵敏环境传感器中具有广阔的应用前景。
Reduced graphene oxide (rGO)-conjugated Cu2O nanowire mesocrystals were formed by nonclassical crystallization in the presence of GO and o-anisidine under hydrothermal conditions. The resultant mesocrystals are comprised of highly anisotropic nanowires as building blocks and possess a distinct octahedral morphology with eight {111} equivalent crystal faces. The mechanisms underlying the sequential formation of the mesocrystals are as follows: first, GO-promoted agglomeration of amorphous spherical Cu2O nanoparticles at the initial stage, leading to the transition of growth mechanism from conventional ion-by-ion growth to particle-mediated crystallization; second, the evolution of the amorphous microspheres into hierarchical structure, and finally to nanowire mesocrystals through mesoscale transformation, where Ostwald ripening is responsible for the growth of the nanowire building blocks; third, large-scale self-organization of the mesocrystals and the reduction of GO (at high GO concentration) occur simultaneously, resulting in an integrated hybrid architecture where porous three-dimensional (3D) framework structures interspersed among two-dimensional (2D) rGO sheets. Interestingly, "super-mesocrystals" formed by 3D oriented attachment of mesocrystals are also formed judging from the voided Sierpinski polyhedrons observed. Furthermore, the interior nanowire architecture of these mesocrystals can be kinetically controlled by careful variation of growth conditions. Owing to high specific surface area and improved conductivity, the rGO-Cu2O mesocrystals achieved a higher sensitivity toward NO2 at room temperature, surpassing the performance of standalone systems of Cu2O nanowires networks and rGO sheets. The unique characteristics of rGO-Cu2O mesocrystal point to its promising applications in ultrasensitive environmental sensors.