Synthesis of randomly oriented self-assembled WO3 and WO3-WS2 nanoplates for selective oxygen sensing

Facile preparation of electrodes based on WO3 nanostructures modified with C and S used as anode materials for Li‐ion batteries

“…The C 1s XPS spectrum of WO 3 /C and WO 3 /WS 2 samples (seen Figure 4G,H) presents three peaks at 284.68, 285.88, and 287.08 eV for the WO 3 /C sample and 284.68, 286.28, and 286.68 eV for the WO 3 /WS 2 electrode. The second peak (at 285.88 eV in the WO 3 /C sample) is associated with surface carbon deposited in the samples, and the minor C 1s (287.08 eV) peak and the second O 1s (532.28 eV) peak imply the existence of oxygen atoms bonded to carbon atoms to form compounds like carbonyl groups 5,39 . The peak is shown asymmetrically, indicating the presence of carbon bonds as sp 2 and sp 3 .…”

“…However, the peaks’ intensity is decreased in this case, even totally disappearing, as is the case with the peaks corresponding to (1 0 1), (1 1 0), (2 2 2), and (1 1 4) crystal planes that have been totally diminished. This happens because the WO 3 concentration is lower than that of WS 2 , the latter being the majority species 39 …”

“…From CV curves, it can be seen that there is a great variation between the first cycle and the following ones in the three samples analyzed. In the first electrode (WO 3 , Figure 7A), two reduction peaks can be seen around 1.5 and 0.59 V, related to the electrochemical production of amorphous Li 2 O (as shown in Equation ), and the development of a partially irreversible solid electrolyte interphase (SEI) layer 39 . The disappearance of the cathodic peak at 0.59 V in the following cycles suggests that during the first cycle, an irreversible reaction of lithium insertion in the crystalline structure is taking place.…”

“…The second peak (at 285.88 eV in the WO 3 /C sample) is associated with surface carbon deposited in the samples, and the minor C 1s (287.08 eV) peak and the second O 1s (532.28 eV) peak imply the existence of oxygen atoms bonded to carbon atoms to form compounds like carbonyl groups. 5,39 The peak is shown asymmetrically, indicating the presence of carbon bonds as sp 2 and sp 3 . Moreover, the peak area of the WO 3 /C sample is greater than the area corresponding to the WO 3 /WS 2 sample (as shown in Table 2), indicating a higher amount of carbon on the surface, which means that the interfacial resistance of the electrode will decrease, producing improved electrochemical performance.…”

“…This happens because the WO 3 concentration is lower than that of WS 2 , the latter being the majority species. 39…”