Nanoporous networks as caging supports for uniform, surfactant-free Co₃O₄ nanocrystals and their applications in energy storage and conversion

Abstract

We report a new, surfactant-free method to produce Co3O4 nanocrystals with controlled sizes and high dispersity by a caging templation of nanoporous networks. The morphologies of Co3O4 nanoparticles differ from wires to particulates by simply varying solvents. The composites of nanoparticles within network polymers are highly porous and show promise in many applications where accessible surface and aggregation prevention is important. The electrochemical performance of the composites demonstrates superior capacity and cyclic stability at a high current density (~980 mAh g -1 at 60 th cycle at current density of 1000 mA g -1 ). In a catalytic oxidation reaction of carbon monoxide, the composites exhibit a remarkable stability (in excess of 35 hours) and catalytic performance (T100 = 100 o C).

Solvent-Free Chemical Approach to Synthesize Various Morphological Co3O4 for CO Oxidation

“…As shown in Figure a, the Co 3 O 4 -rods exhibited the best catalytic performance, and the 100% CO conversion was achieved at 80 °C, lower than Co 3 O 4 -octahedrons of 160 °C and Co 3 O 4 -plates of 180 °C, namely, Co 3 O 4 -rods exhibited the highest catalytic activity of CO oxidation. Here, the catalytic performance of Co 3 O 4 nanomaterials was comparable or better than their composites and Au nanoparticles supported on metal oxide in reported literatures, such as 3D porous hierarchical Co 3 O 4 nanostructures ( T 100 = 140 °C), Cu-doped Co 3 O 4 nanowires ( T 100 = 125 °C), Co 3 O 4 –COP composites ( T 100 = 100 and 110 °C), Co 3 O 4 nanomaterials with pretreatment ( T 100 = 120 °C), and Au/h-, Au/c-, and Au/t-Co 3 O 4 ( T 100 = 80, 90, and 110 °C), MnO 2 /CeO 2 –MnO 2 ( T 100 = 206 °C), Au 144 (SR) 60 /CeO 2 ( T 100 = 80 °C), and even better than gold supported on metal oxides (CuO, NiO, Y 2 O 3 , and La 2 O 3 ) (Table ). In addition, the stability test of CO oxidation over Co 3 O 4 -rods was carried out at 80 °C (Figure b).…”

Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications

“…A significant advantage of solid-state grinding is its facile operation and omission of organic solvents. Covalent organic frameworks (COFs) or porous organic polymers (POPs) having high stability to thermal treatment, water, and most organic solvents comprise another class of microporous host materials that can stabilize and confine metal NCs (Figure C). − Similarly to MOFs, methods like impregnation–reduction and CVD can also be used for such organic host materials. − The functional groups and surface charges of the COF/POP cavities engage in strong interactions with the metal precursors. In addition to the aforementioned synthetic strategies, ALD is an excellent method for fabricating catalytic NCs confined within porous materials by directly depositing highly dispersed metal or metal-oxide species into the materials. − ALD is based on a reaction between two or more gaseous precursors, which are pulsed alternately to avoid the occurrence of gas-phase reactions.…”

Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal

“…This is mainly due to the presence of free-standing ZVI nanoparticles formed near and around the COPs, making additional pores by self-stacking of nanoparticles themselves. 33 ICP-MS analysis of the composites revealed that iron had indeed been impregnated into the COP matrix. For the most part, the composites contained roughly 10% iron, by mass.…”