ABSTRACT
Electrochemical nitrate reduction (NO3RR) to ammonia production is regarded as one of the potential alternatives for replacing the Haber-Bosch technology for realizing artificial ammonia synthesis. In this study, a CuCo2O4/CuO-Ar heterostructure in the shape of dandelion nanospheres formed by nanoarrays has been successfully constructed, demonstrating excellent NO3RR performance. Experimental results indicate that Ar plasma etching of CuCo2O4/CuO-Ar significantly increases the content of oxygen vacancies compared to the sample of CuCo2O4/CuO-Air etched by air plasma, resulting in improved NO3RR performance. Density functional theory calculations further confirm that the existence of more oxygen vacancies effectively decreases the energy barrier of nitrate adsorption, which is due to the generation of more oxygen vacancies facilitating nitrate adsorption and weakening the N-O bonds of nitrate after plasma treatment. As a result, CuCo2O4/CuO-Ar exhibits a high NH3 yield of 0.55 mmol h-1 cm-2 and a Faraday efficiency of 95.07% at the optimal potential of -0.9 V (vs RHE) in a neutral medium. Importantly, CuCo2O4/CuO-Ar also showcases excellent electrocatalytic stability. This study presents new views on the design and structure regulation of NO3RR electrocatalysts and their potential applications in the future.
ABSTRACT
The electrochemical nitrate reduction reaction (ENO3RR) is a green ammonia synthesis method under ambient conditions relative to the traditional Haber-Bosch technology, which does not require high-temperature or high-pressure conditions and can convert nitrate pollutants in the environment into value-added NH3, thus achieving a dual purpose. However, more electrocatalysts with a remarkable performance towards high-efficiency ENO3RR need to be developed. In this work, a Cu/NiO-NF composite electrocatalyst with a nanorod structure on nickel foam was successfully fabricated, which contains heterogeneous interfaces between Cu and NiO toward selective electrocatalytic nitrate reduction for ammonia synthesis. The steric nanorod morphology of the catalyst can significantly increase the surface area, expose more active sites, and improve the reaction activity. Moreover, the construction of the composite and the interface effectively boosts the synergistic effect of the active species Cu and NiO, which can regulate the electronic structure of the catalyst, expose more active sites, enhance the conductivity of the material, and accelerate the interfacial electron transfer, thereby further promoting the ENO3RR performance. This Cu/NiO-NF composite exhibits a high NH3 yield of 0.6 mmol h-1 cm-2 and up to 97.81% faradaic efficiency at the optimal applied potential of -1.0 V (vs. RHE) in a concentration of 0.1 M NO3--containing 0.1 M PBS. Furthermore, it demonstrates excellent electrochemical cycle stability. This work provides insights into the rational design and fabrication of ENO3RR electrocatalysts for potential electrocatalytic applications.
ABSTRACT
OBJECTIVE: To study the effect of parenteral plus enteral nutrition (PN+EN) and total parenteral nutrition (TPN) support on the postoperative immune function in renal recipients with severe pulmonary infection. METHODS: Twenty renal recipients with severe postoperative pulmonary infection were randomly assigned into two equal groups to receive PN+EN or standard TPN, both supplied with equal nitrogen and calorie. The plasma levels of total protein, albumin, hemoglobin and peripheral blood IgA, IgG, IgM, total lymphocyte count, and CD4/CD8 ratio were measured before and after the treatment. RESULTS: The total lymphocyte count, CD4/CD8 ratio and IgG were significantly increased in patients receiving PN+EN as compared with those in TPN group (P<0.05). In both of the groups, the total protein and albumin levels underwent no significant changes after the nutritional support (P>0.05). CONCLUSION: PN+EN can better improve the immune function than TPN in renal recipients with severe pulmonary infection.
