Dong Duan

Monolithic Au/CeO2 nanorod framework catalyst prepared by dealloying for low-temperature CO oxidation

Monolithic Au/CeO2 nanorod frameworks (NFs) with porous structure were prepared by dealloying melt-spun Al89.7Ce10Au0.3 ribbons. After calcination in O2, a 3D Au/CeO2 NF catalyst with large surface area was obtained and used for low-temperature CO oxidation. The small Au clusters/nanoparticles (NPs) were in situ supported and highly dispersed on the nanorod surface, creating many nanoscale contact interfaces. XPS results demonstrated that high-concentration oxygen vacancy and Au δ+/Au0 co-existed in the calcined sample. The Au/CeO2 nanorod catalyst calcined at 400 °C exhibited much higher catalytic activity for CO oxidation compared with the dealloyed sample and bare CeO2 nanorods. Moreover, its complete reaction temperature was as low as 91 °C. The designed Au/CeO2 NF catalyst not only possessed extreme sintering resistance but also exhibited high performance owing to the enhanced interaction between the Au clusters/NPs and CeO2 nanorod during calcination.

Facile synthesis of 3D nanoporous Pd/Co2O3 composites with enhanced catalytic performance for methanol oxidation

Abstract To simultaneously reduce noble metal Pd usage and enhance electrocatalytic performance for methanol oxidation, Pd/Co2O3 composites with ultrafine three-dimensional (3D) nanoporous structures were designed and synthesized by simple one-step dealloying of a melt-spun Al-Pd-Co alloy with an alkaline solution. Their electrocatalytic activity in alkaline media was determined by a Versa-STAT MC workstation. The results indicate that the typical sizes of the ligaments and pores of the composites were approximately 8–9 nm. The Co2O3 was uniformly distributed on the Pd ligament surface. Among the as-prepared samples, the nanoporous Pd/Co2O3 composite generated from dealloying of the Al84.5Pd15Co0.5 alloy had the best electrocatalytic activity, and its activity was enhanced by approximately 230% compared with the nanoporous Pd from dealloying of Al85Pd15. The improvement of the electrocatalytic performance was mainly attributed to the electronic modification effect between Pd and Co as well as the bifunctional mechanism between Pd and Co2O3.

Sm2O3/Co3O4 catalysts prepared by dealloying for low-temperature CO oxidation

A series of Co3O4 catalysts modified by Sm were prepared by a combined dealloying and calcination approach, and the catalytic activities were evaluated using CO catalytic oxidation. The Sm2O3/Co3O4 catalysts were composed of a large number of nanorods and nanosheets, and exhibited a three-dimensional supporting structure with pores. The experimental results revealed that the addition of a small amount of Sm into the precursor AlCo alloy led to a dealloyed sample with improved catalytic activity, and the dealloyed Al90Co9.5Sm0.5 ribbons (0.5 Sm2O3/Co3O4) calcined at 300 °C showed the highest activity for CO oxidation with complete CO conversion at 135 °C, moreover, CO conversion almost no attenuation, even after 70 hours of catalytic oxidation, which is superior to that of Co3O4. The enhanced catalytic activity of the Sm2O3/Co3O4 catalyst can be attributed to the large specific surface area, more reactive oxygen species and Co3+ ion, as well as electronic interactions between Sm and Co.

Novel CeO 2 nanorod framework prepared by dealloying for supercapacitors applications

The CeO2 nanorod framework was synthesized via a facile-dealloying method coupled with calcination treatment for supercapacitors. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) characterizations identified the cubic phase and nanorod morphology of the synthesized sample. Their electrochemical performance was also evaluated by cyclic voltammetry, galvanostatic charge-discharge tests, and cycling performances. The results show that CeO2 nanorod framework possesses high-specific capacitance and superior charge/discharge stability, which are mainly ascribed to its high-Brunauer-Emmett-Tellar surface area (110.6xa0m2xa0g−1). Notably, the CeO2//AC (Active Carbon) asymmetric supercapacitor device exhibits excellent cycling stability with capacity retention of 133.6% after cycling for 30,000xa0cycles.

CeO 2 Nanorod-Supported Transition Metal Catalysts Prepared by Dealloying for CO Oxidation

In this study, Al–Ce, Al–Ce–Ni, and Al–Ce–Mn precursor alloys were prepared by melt-spinning, and then dealloyed in 20% NaOH aqueous solution and calcined in air. The catalytic activities of the as-prepared precursors were evaluated for the oxidation of CO at atmospheric pressure. The results revealed that a novel CeO2 nanorod-supported skeleton structure could be obtained by dealloying and calcining the as-quenched Al–Ce ribbons. The CO conversion temperatures for the CeO2/NiO and CeO2/MnO2 composites were reduced to about 147 and 136 °C, respectively, which indicated the superior activity of these composites as compared to pure CeO2 (Zhang et al. in Nanotechnology 28, 45602, 2017) [11]. The reason for the increased catalytic performance can be attributed to the large number of active sites provided by the composite materials. The synergistic effects at the NiO/MnO2 and CeO2 interface as well as the increase in the concentration of oxygen vacancies in the composites also play important roles in the enhancement of the catalytic performance.