α-NaFeO2 is promising as minor-metal free cathode materials for low cost sodium-ion batteries. It has a flat voltage plateau at 3.3 V vs. Na metal and a stable reversible capacity of 85 mAh g−1. Fe3+/Fe4+ redox reaction on charge/discharge cycle was confirmed by 57Fe Mössbauer spectrometer. The thermal stability of NaFeO2 cathodes with/without 1 mol dm−3 NaClO4/EC-DMC electrolyte was investigated by DSC measurements. The fully-charged Na0.58FeO2 powder decomposed thermally at a temperature higher than 300°C, with Fe2O3 as a possible product. On the other hand, the mixture of Na0.58FeO2 powder and electrolyte showed exothermic heat in a temperature range of 220–300°C. However, NaFeO2 showed better thermal stability in the electrolyte than LiCoO2 counterparts in Li ion battery systems, including less heat generation and higher exothermic onset temperature. This indicated that the Na-ion batteries might have comparable thermal stability with Li-ion batteries.

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Rapid and specific identification of tumor metabolic markers is of great significance. Herein, a convenient, reliable and specific strategy was proposed to screen prostate cancer (PCa) individuals through indirectly quantifying sarcosine, an early indicator of PCa, in the clinical urine samples. The success roots in the rational design of a cascade response model, which takes integrated sarcosine oxidase (SOX) as a specific recognition unit and oxygen-sensitive molecule as a signal reporter. The newly developed hierarchical mesoporous Zr-based metal–organic frameworks with continuously tunable mesopore size ensure the synergetic work of the SOX and response unit spatially separated in their neighboring mesoporous and microporous domains, respectively. The large mesopore up to 12.1 nm not only greatly enhances the loading capacity of SOX but also spares enough space for the free diffusion of sarcosine. On this basis, the probe is competent to specifically check out the tiny concentration change of sarcosine in the urine sample between PCa patients and healthy humans. Such a concept of enzyme-assisted substrate sensing could be simply extended by altering the type of immobilized enzymes, hopefully setting a guideline for the rational design of multiple probes to quantify specific biomarkers in complex biological samples.