Fabrication of Co@SiO₂@C/Ni submicrorattles as highly efficient catalysts for 4-nitrophenol reduction

Abstract

In this paper, an extended Stöber method has been developed to fabricate a Ni-polydopamine (PDA) complex coated on Co[Co(CN)]@SiO composites. After one-step carbonization involving the heat treatment of a Prussian blue analogue (PBA) of Co[Co(CN)] cores and the PDA-Ni shell under a nitrogen atmosphere, homogeneous Co@SiO@C/Ni submicrorattles were synthesized. Notably, the silica interlayer played a vital role in the formation of such Co@SiO@C/Ni submicrorattle structures. Without the protection of SiO, Co-Ni@C composites were obtained instead and aggregated seriously due to sintering at high temperature. While with the silica layer as the spacer, the obtained Co@SiO@C/Ni composites were not only well dispersed in the solution, but could also be adjusted in terms of the size and density of Ni nanoparticles (NPs) on the surface. Moreover, the size of core Co and surficial Ni NPs can be facilely modulated via changing the calcination temperature, which can effectively control the catalytic performance of the as-prepared nanocomposites. The as-prepared Co@SiO@C/Ni submicrorattles were employed as the reaction catalyst for the reduction of 4-nitrophenol (4-NP), and exhibit both superior catalytic activity and cycling stability to Co@SiO and Co-Ni@C composites.

Fabrication of 3D Hierarchical Byttneria Aspera‐Like Ni@Graphitic Carbon Yolk–Shell Microspheres as Bifunctional Catalysts for Ultraefficient Oxidation/Reduction of Organic Contaminants

“…Although having no need for the high MW‐harvesting capacity like the MW‐driven catalytic process, the unique morphology characterized by 3D hierarchical byttneria aspera‐like yolk–shell structure are still favorable to the superior catalytic features, which was probably attributed to its high specific surface area as well as good mass transfer of reactant/product. Simultaneously, zero‐value metallic Ni acted as active sites plays a vital role in this reduction reaction as previous reports . Moreover, for this case, the in situ formed carbon matrix with high graphitic degree (inset of Figure a) can also help 4‐nitrophenolate ion to get close to the catalyst through π–π interactions between the aromatic regions of 4‐nitrophenolate ion and the graphitic carbon.…”

“…Additionally, a comparison of the Ni@GC and other similar catalysts is listed in Table S1 in the Supporting Information. As a result, the 3D hierarchical Ni@GC demonstrated a better catalytic activity …”

“…Likewise, transition metal NPs instead of noble metals demonstrated excellent catalytic reduction activities for the hydrogenation, reduction of oxygen, as well as hydrogen evolution, while the use alone also suffers from the similar constraints. To overcome the aforementioned shortcomings, it is highly desirable to develop transition metal‐based hybrids with characteristics of protective layer and well dispersion, guaranteeing their high activity and stability.…”

Biosynthesis of Cu nanoparticles supported on carbon nanotubes and its catalytic performance under different test conditions

“…Reduction of 4‐NP to 4‐aminophenol (4‐AP) is an effective method to remove toxic 4‐NP because 4‐AP is an important intermediate for fabricating various analgesic and antipyretic drugs . Thus, it is extremely desirable to develop cheap and highly active catalysts for converting 4‐NP to 4‐AP …”

“…[6][7][8] Thus, it is extremely desirable to develop cheap and highly active catalysts for converting 4-NP to 4-AP. 9 The reductive transformation of nitroaromatics on the surface of non-noble metal catalysts such as copper (Cu) nanoparticles attracted considerable attention owing to the excellent catalytic efficiency and lower cost of preparation of such catalysts. [10][11][12][13][14][15][16] Copper nanoparticles with a high surface-to-volume ratio can dramatically enhance the number of active sites per unit area in the catalysts.…”