Modulating Co-Co bonds average length in Co_(0.85)Se_(1-x)S_(x) to enhance conversion reaction for potassium storage

While alloying transition metal chalcogenides(TMCs)with other chalcogen elements can effectively improve their conductivity and electrochemical properties,the optimal alloying content is still uncertain.In this study,we study the influence of dopant concentration on the chemical bonds in TMC and reveal the associated stepwise conversion reaction mechanism for potassium ion storage.According to density function theory calculations,appropriate S-doping in Co0.85Se(Co_(0.85)Se_(1-x)S_(x))can reduce the average length of Co-Co bonds because of the electronegativity variation,which is thermodynamically favourable to the phase transition reactions.The optimal Se/S ratio(x=0.12)for the conductivity has been obtained from experimental results.When assembled as an anode in potassium-ion batteries(PIBs),the sample with optimized Se/S ratio exhibits extraordinary electrochemical performance.The rate performance(229.2 mA h g^(-1)at 10 A g^(-1))is superior to the state-of-the-art results.When assembled with Prussian blue(PB)as a cathode,the pouch cell exhibits excellent performance,demonstrating its great potential for applications.Moreover,the stepwise K+storage mechanism caused by the coexistence of S and Se is revealed by in-situ X-ray diffraction and ex-situ transmission electron microscopy techniques.Hence,this work not only provides an effective strategy to enhance the electrochemical performance of transition metal chalcogenides but also reveals the underlying mechanism for the construction of advanced electrode materials.

Retinal ganglion cells regenerate long-distance axons through neural activity stimulation and find their way back to the brain

Human central nerve system(CNS)is an extremely complex and delicate structure.While regeneration is possible in some reptiles and fish CNS,the regeneration capacity seems completely lost in adult mammals.Therefore,the classic concept is that once neurons in mammal

Fabricate organic thermoelectric modules use modified PCBM and PEDOT：PSS materials

In this paper, we fabricated an organic thermo- electric （TE） device with modified [6,6]-phenyl-C61- butyric acid methyl ester （PCBM） and poly（3,4-ethylene- dioxythiophene） polystyrene sulfonate （PEDOT：PSS）; the device showed good stability in air condition. For n-leg, PCBM were doped with acridine orange base （3,6-bis （dimethylamino）acridine） （AOB） and 1,3-dimethyl-2,3- dihydro- 1H-benzoimidazole （N-DMBI）. Co-doped PCBM utilizes synergistic effects of AOB and N-DMBI, resulting in excellent electrical conductivity and Seebeck coefficient values reaching 2 S/cm and -500 μV/K, respectively, at room temperature with dopant molar ratio of 0.11. P-type leg used modified PEDOT：PSS. Based on modified PCBM and PEDOT：PSS materials, we fabricated a TE module device with 48 p-type and n-type thermocouple and tested their output voltage, short current, and power. Output voltage measured -0.82 V, and generated power reached almost 945 μW with 75 K temperature gradient at 453 K hot-side temperature. These promising results showed potential of modified PEDOT and PCBM as TE materials for application in device optimization.