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Chemical looping reforming (CLR) technique is a prospective option for hydrogen production. Improving oxygen mobility and sintering resistance are still the main challenges of the development of high-performance oxygen carriers (OCs) in the CLR process. This paper explores the performance of Ni/CeO 2 nanorod (NR) as an OC in CLR of ethanol. Various characterization methods such as N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (TPR), and H 2 chemisorption were utilized to study the properties of fresh OCs. The characterization results show the Ni/CeO 2 -NR possesses high Ni dispersion, abundant oxygen vacancies, and strong metal-support interaction. The performance of prepared OCs was tested in a packed-bed reactor. H 2 selectivity of 80% was achieved by Ni/CeO 2 -NR in 10-cycle stability test. The small particle size and abundant oxygen vacancies contributed to the water gas shift reaction, improving the catalytic activity. The covered interfacial Ni atoms closely anchored on the underlying surface oxygen vacancies on the (111) facets of CeO 2 -NR, enhancing the anti-sintering capability. Moreover, the strong oxygen mobility of CeO 2 -NR also effectively eliminated surface coke on the Ni particle surface.

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Supercapacitors that can withstand extremely low temperatures have become desirable in applications including portable electronic devices, hybrid electric vehicles, and renewable energy conversion systems. Graphene is considered as a promising electrode material for supercapacitors owing to its high specific surface area (up to 2675 m 2 •g −1 ) and electrical conductivity (approximately 2 × 10 2 S•m −1 ). However, the restacking of graphene sheets decreases the accessible surface area, reduces the ion diffusion rate and prolongs the ion transport pathways, thereby limiting the energy storage performance at low temperatures (typically < 100 F•g −1 at sub-zero temperatures). Herein, we fabricate a supercapacitor based on holey graphene and mixed-solvent organic electrolyte for ultra-low-temperature applications (e.g., −60 °C). Reduced holey graphene oxide (rHGO) was synthesized as the electrode material via an oxidative-etching process with H2O2. Methyl formate was mixed with propylene carbonate to improve the electrolyte conductivity at temperatures ranging from −60 to 25 °C. The as-fabricated supercapacitor showed a high room-temperature capacitance of 150.5 F•g −1 at 1 A•g −1 , which was almost 1.5 times greater than that of the supercapacitor using untreated reduced graphene oxide (rGO; 101.4 F•g −1 ). The improved capacitance could be attributed to the increased accessible surface rendered by the abundant mesopores and macropores on the holey surface. As the temperature decreased to −60 °C, the rHGO supercapacitor still delivered a high capacitance of 106.2 F•g −1 with a retention of 70.6%, which was superior to other state-of-the-art graphene-based supercapacitors. Electrochemical impedance spectra tests revealed that the ion diffusion resistance in rHGO was significantly smaller than that in rGO and less influenced by temperature with a lower activation energy. This was because the holey morphology can provide transport pathways for ions and reduce the ion diffusion length during charging/discharging, consequently diminishing the diffusion resistance at low temperatures. Specifically, at −60 °C, the energy density of supercapacitor reached up to 26.9 Wh•kg −1 at 1 A•g −1 with a maximum power density of 18.7 kW•kg −1 at 20 A•g −1 , surpassing the low-temperature performance of conventional carbon-based supercapacitors. Moreover, after 10000 cycles at −60 °C with a current density of 5 A•g −1 , 89.1% of capacitance was retained, suggesting the stable and reliable power output of the current supercapacitor at extremely low temperatures.