課題番号：

JPMXP1223NM5195

実施機関：

物質・材料研究機構

要約

The 2D WO3/WSe2 electrode demonstrates exceptional Na+ storage, with a specific capacitance of 378.1 F g−1 at 1 A g−1, excellent rate capability, and long-lasting cycling durability over 10,000 cycles. The full cell comprising WO3/WSe2 as the negative and MnSe/MnSe2 as the positive electrode achieved a peak energy density of 82.1 Wh kg−1 at a power density of 1873.5 W kg−1, along with high-rate capability and long-cycle durability.

Synthesis of WSe2 nanoflakesWSe2 nanoflakes were grown on CF substrate through the selenization of WO3. A typical synthesis protocol involves two steps. The first is the synthesis of WO3 nanostructures on CF using the hydrothermal method, according to our previous report. 0.025 M Na2WO4.2H2O was dissolved in 30 mL DI water under constant magnetic stirring for 110 min to get a transparent solution. Afterward, 3 M HCl solution was added dropwise until the pH of the solution turned to ~3. At this stage, the transparent solution turns to a slight yellow. After stirring for 15 min, 0.05 M NaCl was added to the reaction solution, and then the whole solution was transferred to a 40 mL Teflon-lined stainless steel autoclave. The well-cleaned and dried piece of CF substrate (2 X 2) cm was placed into the Teflon liner, and then the autoclave was kept for hydrothermal reaction in an oven at 180 ºC for 12 h. Subsequently the autoclave cooled to room temperature, the CF substrate with deposited material was removed and washed several times with DI water and ethanol and dried in a vacuum oven at 70 ºC overnight. The selenization of WO3 on CF to prepare WSe2 nanoflakes was performed at four different temperatures, 600 ºC, 700 ºC, 800 ºC, and 900 ºC. The piece of WO3 on CF was placed in one quartz boat at the center of the tube furnace, and a second quartz boat with 0.5 gm Se powder was kept on the front side of the tube furnace under N2 gas flow 100 sccm. The temperature of the tube furnace was varied from 600 – 900 ºC with a heating rate of 10 ºC min-1 for 2h. The N2 gas carries Se vapors to the surface of WO3 where WSe2 nanoflake growth occurs. When the tube furnace was naturally cooled down slowly to room temperature, WSe2 nanoflakes on CF were collected.
　Synthesis of MnSe nanowires　 MnSe nanowires were directly grown on CF substrate through a one-pot hydrothermal method. Se (0.1 gm) powder was dissolved in 30 mL of DI water using a bath sonicator for 10 min and kept for constant stirring on a magnetic stirrer. 0.1 gm NaBH4 was added to the Se powder solution, followed by 0.05 M MnCl2.4H2O. The reaction solution was kept stirring for another 10 min and then transferred to a 40 mL Teflon-lined stainless steel autoclave. The well-cleaned and dried piece of CF substrate (2 X 2) cm was placed into the Teflon liner, and then the autoclave was kept for hydrothermal reaction in an oven at 180 ºC for 12 h. When the autoclave cooled to room temperature, the CF substrate with deposited material was removed and washed several times with DI water and ethanol and dried in a vacuum oven at 70 ºC overnight.

Here we present the results obtained by using FE-SEM+EDX [SU8230] in EDX mode.