Mesoporous Octagonal Microplates Co 2– x Ni x P 2 O 7 ( x = 0.00, 0.50, 1.00, 1.50, and 2.00) Metal Pyrophosphates for High-Performance Asymmetric Supercapacitors
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Monoclinic Co 2– x Ni x P 2 O 7 ( x = 0.00–2.00) pyrophosphates were synthesized and composition-tuned to reveal an optimal morphology/porosity at x = 1.00 that delivered high-performance supercapacitor electrodes. Across the series, X-ray diffraction (XRD) results confirmed a pure phase of Co 2– x Ni x P 2 O 7 ( P 21/c), with Ni substitution providing acceptable crystallite-size shifts and a systematic lattice shrinkage. Field emission scanning electron microscopy (FE-SEM) showed that x = 1.00 specimen formed well-faceted octagonal microplates with the highest specific surface area (11.381 m 2 /g) and mesoporous surfaces with average pore sizes of ∼10 nm and mesopore volume of 0.0909 cm 3 /g, as revealed by Brunauer–Emmett–Teller/Barett–Joyner–Halenda (BET/BJH) analysis. X-ray photoelectron spectroscopy (XPS) identified Co 2+, Ni 2+, and P 5+, which is consistent with OH – -coupled M 2+ /M 3+ pseudocapacitance observed using cyclic voltammetry (CV)/galvanostatic charge–discharge (GCD) in 3 M KOH. The x = 1.00 electrode achieved 654 F/g at 0.5 A/g and maintained 84.6% of its initial state after a 3000-cycle GCD test at 5 A/g. An asymmetric device (Co 1.00 Ni 1.00 P 2 O 7 //rGO) delivered 56.68 Wh/kg at 938.36 W/kg. Electrochemical enhancement resulted from a combination of mixed-metal redox centers and optimized meso-porosity/microstructure, as evidenced by CV, GCD, and electrochemical impedance spectroscopy (EIS). The findings demonstrated that compositional control presented an effective strategy for controlling mesoporousity and enhancing redox utilization in Co–Ni pyrophosphate electrodes.
Source: ACS Omega
Institutions: Khon Kaen University, Suranaree University of Technology
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,935
Funder: Khon Kaen University
OpenAlex ID: W4415980241