Tailoring stress-relieved structure for ternary cobalt Phosphoselenide@N/P codoped carbon towards high-performance potassium-ion hybrid capacitors and potassium-ion batteries

Hierarchical Architecture Engineering of Branch‐Leaf‐Shaped Cobalt Phosphosulfide Quantum Dots: Enabling Multi‐Dimensional Ion‐Transport Channels for High‐Efficiency Sodium Storage

“…[ 46,47 ] As for the P 2p spectra of the CoPS@C@N‐CNF and CoP 2 @C@N‐CNF (Figure 2g), the doublet peaks manifest the P 2p 3/2 orbital at 132.7 eV and P 2p 1/2 orbital at 134.0 eV attributing to P─O bond, while the position of the other two peaks at 128.8 and 129.8 eV were regarded as the P 2p 3/2 and P 2p 1/2 orbitals of Co─P bond. [ 21,48,49 ] In Figure 2h, the peak‐deconvoluted C 1s spectra with four clear bond signals of C─C, C═C, C═N, and C═O are, respectively, situated to the binding energies of 284.2, 284.7, 285.8, and 287.2 eV, [ 50 ] and the existing C═N bond further interprets that the N atom can be readily introduced into carbon lattice through the pyrolysis reaction of PAN and MOFs. The nitrogen state is generally treated as a vital factor to influence the electrochemical features of carbonaceous materials, therefore, the primary modalities of N‐doped carbon lattice involve pyridine‐N, pyrrolic‐N, and quaternary‐N, [ 51,52 ] reflected by the binding energies of 398.3, 399.6, and 400.5 eV (Figure 2i), respectively.…”

“…These results are analogical to previously reported CoPSe anodes. [ 21,54 ] Starting on the second loop, the well‐overlapped CV curves illustrate the remarkable reversibility on the sodiation–desodiation processes. Meanwhile, the peak signals at 1.84 and 1.09 V in the cathodic scan are, respectively, related to the sodium insertion to yield Na x CoS, and further conversion reaction of Na x CoS to Co and Na 2 S. Additionally, another shoulder peak of ≈0.63 V can be induced by the alloying process of Na 3 P. Next, ex situ XPS analysis at different initial desodiation/sodiation states was operated to further give clearer information about the change of valence state of the CoPS@C@N‐CNF upon initial cycling.…”

“…In which two pairs of apparent spin‐orbit splitting peaks at ≈779.1/793.9 eV and 781.3/797.4 eV belong to the 2p 3/2 and 2p 1/2 orbitals of Co 2+ as well as the 2p 3/2 and 2p 1/2 orbitals of Co─O band, respectively. [ 8,21,43 ] Meanwhile, every spin‐orbit involves two satellite signals at a higher binding energy, illustrating the existence of hybridization between Co 2+ levels and PS ligand orbitals. [ 20,44 ] Furthermore, the high‐resolution S 2p spectra of the CoPS@C@N‐CNF and CoS@C@N‐CNF in Figure 2f present two spin‐orbit doublets at the binding energies of 161.6 and 163.5 eV associating with the S 2p 3/2 and S 2p 1/2 , respectively, which are identified as the characteristic signal of Co─S bond.…”

“…Further charging to 3.0 V, however, the Na 2 CoS 2 peaks at 16.0 o , 33.0 o , and 38.3 o were still detected, demonstrating the CoPS cannot be completely recovered its original crystalline phase during the first desodiation process, which is consistent with the reported CoPSe anode for SIBs. [ 21 ] What is noteworthy that no characteristic reflection signals originated from phosphorus were detected, which may be thanks to its small crystallite size or amorphous feature during the whole first cycle. More significantly, the phase transformation of the CoPS@C@N‐CNF during the first sodiation‐ desodiation loop can also be verified by ex situ HRTEM and SAED (Figure S11, Supporting Information) measurements.…”

“…Meanwhile, the regulated electronic feature of MPS x is capable of atomic-level engineering, which triggers prominent chemical diversity and enhanced intrinsic activities, thereby inducing swifter charge conduction than unitary or binary layered materials. [21] Not only that the particular 2D lamella structure of MPS x is generally identified as a desired architecture for fast Na + de-/intercalating thanks to the adequately exposed surface area, adjustable morphologies, and scalable/shortened channels. [22] Until now, a few ternary MPS x hosts, such as FePS 3 /C, [23,24] MnPS 3 /rGO, [25] BiPS 4 -CNT [26] and Cu 3 PS 4 /G, [27] have been springed up and manifested good electrochemical characteristics in SIBs systems.…”