Liquid-phase exfoliation of NH4Co0.4Ni0.6PO4·H2O for energy storage device

Rational Construction of a N, F Co‐doped Mesoporous Cobalt Phosphate with Rich‐Oxygen Vacancies for Oxygen Evolution Reaction and Supercapacitors

“…In addition, the cycling stability of the electrodes is also one of the important factors to evaluate the performance of supercapacitors, therefore, we investigated its cycling performance at 2 A ⋅ g −1 for 3000 cycles, which remains 80 % (Figure 6d), also indicating its excellent cycling stability. Figure S17b exhibits the Ragone plots of the fabricated supercapacitors using NCoHPOF‐450 as electrode, which can reach 20.89 Wh kg −1 at the power density of 810 W kg −1 and 20.17 Wh kg −1 at the power density of 4050 W kg −1 , respectively, which is higher than other as‐prepared materials and some reported phosphate‐based supercapacitors [60] . These results demonstrated that this facile reconstruction of N, F co‐doped mesoporous monometallic cobalt phosphate with oxygen vacancies has potential practical applications in electrochemical energy conversion and storage.…”

“…From the N 1s spectrum (Figure S14c), the peak intensity slightly decreased after OER test, which might be ascribed to the formation of (oxy)hydroxides on the surface via in‐situ electrochemical activation, consistent with the broad band at 3240 cm −2 from FTIR (Figure S15), while, there is no significant change for the O 1s and P 2p peaks, while, the peak intensity of F 1s increased should be ascribed to the adsorbed Nafion on its surface, which also demonstrated that the existence of N, O, F and Co on the surface of this electrocatalyst after OER test (Figure S16). Further, we applied NCoHPOF‐450 as the electrode material of supercapacitors using a three‐electrode system in a 3.0 M KOH since electrocatalysts as pseudo‐capacitors have similar reversible reaction with the initialized reaction steps of OER in the alkaline system [11,55–60] . The CV test was measured at various scan rates with a voltage range of 0.0–0.6 versus Hg/HgO.…”

“…Further, we applied NCoHPOF-450 as the electrode material of supercapacitors using a three-electrode system in a 3.0 M KOH since electrocatalysts as pseudo-capacitors have similar reversible reaction with the initialized reaction steps of OER in the alkaline system. [11,[55][56][57][58][59][60] The CV test was measured at various scan rates with a voltage range of 0.0-0.6 versus Hg/HgO. Figure 6a shows the galvanostatic charge-discharge (GCD) curves at different current densities from 0.5 to 10 A • g À 1 , which exhibits nearly symmetrical shapes and obvious potential plateaus, indicating NCoHPOF-450 as pseudocapacitors is highly reversible.…”

“…Figure 6a shows the galvanostatic charge-discharge (GCD) curves at different current densities from 0.5 to 10 A • g À 1 , which exhibits nearly symmetrical shapes and obvious potential plateaus, indicating NCoHPOF-450 as pseudocapacitors is highly reversible. [55][56][57][58][59][60] Besides, from Figure 6b, the cyclic voltammetry curves at different scan rates, it can be seen the current density increase with the scan rate gradually increasing from 20 to 100 mV s À 1 , besides, the larger the integral areas of the CV curves in non-Faraday region at different scan rate rates (Figure S7) generally suggested the more active sites involved in OER process and a higher specific capacity, which should be ascribed to its mesoporous and amorphous structure associated with anisotropy and defect, consequently, causing its abundant electroactive sites as well as the effectively mass/ charge transfer and diffusion; especially, its oxidation and reduction peaks are slightly shifted with the scan rate gradually increasing from 20 to 100 mV s À 1 , indicating its excellent rate capability and low polarization. According to the GCD curves, the corresponding specific capacitances were calculated to be 239.…”

Metal Phosphides and Phosphates‐based Electrodes for Electrochemical Supercapacitors

“…Hybrid Materials : Transition metal phosphates can provide abundant active sites for redox reactions in principle, which may not be effectively realized given the intrinsically high electrical resistance . The integration of a proper conducting phase, such as graphene, into transition metal phosphates can act as not only a desired charge transfer medium, and also a buffer zone of the volume change of active materials .…”