Routes to high-performance layered oxide cathodes for sodium-ion batteries.

Sodium-ion batteries (SIBs) are experiencing a large-scale renaissance to supplement or replace expensive lithium-ion batteries (LIBs) and low energy density lead-acid batteries in electrical energy storage systems and other applications. In this case, layered oxide materials have become one of the most popular cathode candidates for SIBs because of their low cost and comparatively facile synthesis method. However, the intrinsic shortcomings of layered oxide cathodes, which severely limit their commercialization process, urgently need to be addressed. In this review, inherent challenges associated with layered oxide cathodes for SIBs, such as their irreversible multiphase transition, poor air stability, and low energy density, are systematically summarized and discussed, together with strategies to overcome these dilemmas through bulk phase modulation, surface/interface modification, functional structure manipulation, and cationic and anionic redox optimization. Emphasis is placed on investigating variations in the chemical composition and structural configuration of layered oxide cathodes and how they affect the electrochemical behavior of the cathodes to illustrate how these issues can be addressed. The summary of failure mechanisms and corresponding modification strategies of layered oxide cathodes presented herein provides a valuable reference for scientific and practical issues related to the development of SIBs.

Nickel Nanoparticles Protruding from Molybdenum Carbide Micropillars with Carbon Layer-Protected Biphasic 0D/1D Heterostructures for Efficient Water Splitting.

It remains a tremendous challenge to achieve high-efficiency bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) for hydrogen production by water splitting. Herein, a novel hybrid of 0D nickel nanoparticles dispersed on the one-dimensional (1D) molybdenum carbide micropillars embedded in the carbon layers (Ni/Mo2C@C) was successfully prepared on nickel foam by a facile pyrolysis strategy. During the synthesis process, the nickel nanoparticles and molybdenum carbide were simultaneously generated under H2 and C2H2 mixed atmospheres and conformally encapsulated in the carbon layers. Benefiting from the distinctive 0D/1D heterostructure and the synergistic effect of the biphasic Mo2C and Ni together with the protective effect of the carbon layer, the reduced activation energy barriers and fast catalytic reaction kinetics can be achieved, resulting in a small overpotential of 96 mV for the HER and 266 mV for the OER at the current density of 10 mA cm-2 together with excellent durability in 1.0 M KOH electrolyte. In addition, using the developed Ni/Mo2C@C as both the cathode and anode, the constructed electrolyzer exhibits a small voltage of 1.55 V for the overall water splitting. The novel designed Ni/Mo2C@C may give inspiration for the development of efficient bifunctional catalysts with low-cost transition metal elements for water splitting.

[Epidemiological analysis of malaria prevalence in Sichuan Province, 2012-2014].

OBJECTIVE: To understand the characteristics of malaria prevalence in Sichuan Province from 2012 to 2014, so as to provide evidences for improving the work of malaria elimination. METHODS: The epidemiological data of malaria cases in Sichuan Province were collected from the Disease Surveillance Information Reporting System of Chinese Center for Disease Control and Prevention, and analyzed with the descriptive epidemiological method. RESULTS: A total of 690 imported malaria cases were reported in Sichuan Province from 2012 to 2014. In detail, 54.49% (376/690) were falciparum malaria cases, 42.03% (290/690) were vivax malaria cases, 0.58% (4/690) were malariae malaria cases, 1.88% (13/690) were ovale malaria cases, and 1.01% (7/690) were mixed infection cases with Plasmodium vivax and P. falciparum. Among them, five cases died. Totally 671 malaria cases were infected overseas, accounting for 97.25% of the total cases. Among which, 517 patients returned from Africa and 138 patients returned from Southeast Asia. There were malaria cases reported in the whole year, and 185 cases were reported in May and June, accounting for 26.81% of the total cases. The cases distributed in 20 prefecture-level cities in the whole province, and there were 137 and 105 ones reported in Guangan and Chengdu, respectively, which accounted for 35.07% of the total cases. CONCLUSIONS: The number of patients with overseas imported malaria in Sichuan Province increases year by year, and therefore effective measures should be carried out to control the overseas imported malaria.