To realize the utilization of high-performance lithium–oxygen batteries (LOBs), a rational-designed cathode structure and efficient catalytic materials are necessary. However, side products accumulated during battery cycling seriously affects the performance. Designing a cathode catalyst that could simultaneously facilitate the catalytic efficiency of the main reaction and inhibit the side reactions will make great sense. Herein, NiCeOx was proposed for the first time as a bifunctional cathode catalyst material for LOBs. The combined action of NiO and CeO2 components was expected to facilitate the decomposition of byproducts (e.g., Li2CO3), increase the oxygen vacancy content in CeO2, and enhance the adsorption of oxygen and superoxide. NiCeOx nanorods (NiCeOx PNR) were prepared using electrospinning method. It showed a hollow and porous nanorod (PNR)-like structure, which provided a large number of catalytic active sites and facilitated the transport of reactants and the deposition of discharge products. As a result, a high specific discharge capacity (2175.9 mAh g–1) and a long lifespan (67 cycles at 100 mA g–1 with a limited capacity of 500 mAh g–1) were obtained.
Conventional catalytic pyrolysis of waste plastics for H 2 production faces challenges due to excessively high reaction temperatures. This study introduced a NiCeOx/β catalyst for low-temperature H 2 production from polyethylene (PE), aiming to enhance H 2 yield through nonthermal plasma (NTP) and catalytic active sites. Experimental results confirmed the efficacy of NTP in promoting collision between high-potential-energies active species and plasma-catalyst interactions, identifying acidic sites as primary catalytic active sites. Both experiments and density functional theory (DFT) calculations confirmed NiO and CeO 2 particles as metallic active sites, exhibiting thermodynamic and kinetic benefits for primary products from PE pyrolysis. Under optimal conditions, the highest H 2 yield and selectivity respectively reached 32.71 mmol/g and 82.10 % at a PE/(NiCeOx/β) ratio of 1:4, reaction temperature of 400 °C, and NTP discharge power of 210 W. The NiCeOx/β catalyst facilitated low-temperature pyrolysis of waste plastics, enhancing H 2 selectivity and yield.
Mengyuan Zhang,Jian Ye,Nana Lu,Xiaoyan Lu,Kongliang Luo,Jiali Dong,Qiang Niu,Pengfei Zhang,Sheng Dai
CO 2 methanation at low temperatures is still a challenge. Herein, Ni n CeO x (n = 1–3) and Ni 2.5 Pd 0.1 CeO x nanofibers by electrospinning is reported. The main advantage of this method is to obtain the highly dispersed precursor of palladium, nickel, and cerium, overcoming the difficulty of uniform mixing in conventional preparation methods. The Ni 2.5 Pd 0.1 CeO x nanofiber catalyst exhibited outstanding catalytic performance at low temperatures (CO 2 conversion rate = 90.4 %, CH 4 selectivity = 99.6 % at 230 °C) along with exceptional stability over 300 h. EPR, Raman, and O 1s XPS confirmed that Pd 2+ doping increased oxygen vacancy concentration. In-situ infrared spectroscopy indicated that CO 2 methanation on Ni 2.5 CeO x and Ni 2.5 Pd 0.1 CeO x catalysts followed the formate pathways. Pd 2+ doping increased the number of surface oxygen vacancies and hydroxyl groups, thus increasing the amount of bicarbonates and formates. DFT calculations suggested that Pd 2+ doping increased CO 2 adsorption energy, and confirmed surface hydroxyl groups and bicarbonate being beneficial for CO 2 methanation, consequently enhancing the activity of Ni 2.5 Pd 0.1 CeO x catalyst especially at low temperatures.
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