Co₃O₄–CuCoO₂ Nanomesh: An Interface-Enhanced Substrate that Simultaneously Promotes CO Adsorption and O₂ Activation in H₂ Purification

Abstract

Nanomaterials are widely used as redox-type reaction catalysts, while reactant adsorption and O2 activation are hardly to be promoted simultaneously, restricting their applications in many important catalytic fields such as preferential CO oxidation (CO-PROX) in H2-rich stream. In this work, an interface-enhanced Co3O4–CuCoO2 nanomesh was initially synthesized by a hydrothermal process using aluminum powder as a sacrificial agent. This nanomesh is systematically characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, Raman spectroscopy, X-ray absorption near-edge spectroscopy, hydrogen temperature-programmed reduction, and oxygen temperature-programmed desorption. It is demonstrated that the nanomesh possesses high-density nanopores, enabling a large number of CO adsorption sites exposed to the surface. Meanwhile, electron transfer from O2– to Co3+/Co2+ and the weakened bonding strength of Co–O bond at surfaces promoted the oxygen activation and redox ability of Co3O4. When tested as a catalyst for CO-PROX, this nanomesh with an optimized pore structure and a surface electronic structure, exhibits a strikingly high catalytic oxidation activity at low temperatures as well as a broader operation temperature window (i.e., CO conversion >99.0%, 100–200 °C) in the CO selective oxidation reaction. The present finding should be highly useful in promoting the quest for better CO-PROX catalysts, a hot topic for proton exchange membrane fuel cells and automotive vehicles.

Oxygen Vacancy-Induced Nonradical Degradation of Organics: Critical Trigger of Oxygen (O2) in the Fe–Co LDH/Peroxymonosulfate System

“…As shown in Figure e, after efficient reduction (307.2 °C, the peak of Co (III) to Co (II) disappears), , two typical peaks (449.6 and 594.4 °C), respectively indexed as reduction of Fe (III) to Fe (II) or Co (II) to Co, and Fe (II) to Fe in 200Fe–Co LDH, exhibit a slightly shift towards low temperature in comparison with Fe–Co LDH . It indicates that the generation of Vo will improve the reducibility of the catalyst, which facilitates the enhancement of catalytic activity in PMS activation . Moreover, peak II in 200Fe–Co LDH becomes wider, which is attributed to the reduction of the adsorbed O 2 /O – , suggesting the high potential of Vo to capture oxygen species .…”

Facile Synthesis of Two‐Dimensional Iron/Cobalt Metal–Organic Framework for Efficient Oxygen Evolution Electrocatalysis

“…Raman Angewandte spectra was also used to confirm the structural evolution of the 2D MOF nanosheets.T he typical vibrational peaks from the pristine MOF-Fe/Co(1:2) nanosheets at 1612, 1421, 1133, 858, and 633 cm À1 disappeared after 30 cycles of OER, accompanying by the emergence of five characteristic peaks at about 190, 469, 515, 610, and 670 cm À1 (Figure 3f). [34] Theb ands at 190, 515, and 610 cm À1 could be attributed to the F 2g mode, and the bands at 190 cm À1 was related to F 2g (3) mode of the tetrahedral sites (CoO 4 ). The band at 469 cm À1 was associated with the E g symmetry,a nd the strong band at 670 cm À1 corresponded to the characteristics of octahedral CoO 6 sites, matching well with the A 1g mode.T his result shows that the MOF-Fe/Co completely transformed into CoO,r ather than merely the superficial region as reported for other Cobased catalysts.…”

Facile Synthesis of Two‐Dimensional Iron/Cobalt Metal–Organic Framework for Efficient Oxygen Evolution Electrocatalysis

“…Forschungsartikel spectra was also used to confirm the structural evolution of the 2D MOF nanosheets.T he typical vibrational peaks from the pristine MOF-Fe/Co(1:2) nanosheets at 1612, 1421, 1133, 858, and 633 cm À1 disappeared after 30 cycles of OER, accompanying by the emergence of five characteristic peaks at about 190, 469, 515, 610, and 670 cm À1 (Figure 3f). [34] Theb ands at 190, 515, and 610 cm À1 could be attributed to the F 2g mode, and the bands at 190 cm À1 was related to F 2g (3) mode of the tetrahedral sites (CoO 4 ). The band at 469 cm À1 was associated with the E g symmetry,a nd the strong band at 670 cm À1 corresponded to the characteristics of octahedral CoO 6 sites, matching well with the A 1g mode.T his result shows that the MOF-Fe/Co completely transformed into CoO,r ather than merely the superficial region as reported for other Cobased catalysts.…”