Enhancing stability of Co9S8 by iron incorporation for oxygen evolution reaction and supercapacitor electrodes

Facile synthesis of mesoporous NixCo9−xS8 hollow spheres for high-performance supercapacitors and aqueous Ni/Co–Zn batteries

“…The capacity of Ni-Co 9 S 8 -0.6 electrode attenuate to 74.5% after 5000 repeated cycles. More importantly, the mesoporous hollow Ni-Co 9 S 8 -0.6 electrode exhibited a performance comparable to or higher than the recently reported sulfide-related electrodes such as rGO/Co 9 S 8 (575.9 F g −1 , 2 A g −1 ), 36 CoNi 2 S 4 /Co 9 S 8 composites (1183.3 F g −1 , 2 A g −1 ), 37 Ni 3 S 4 @Co 9 S 8 tubes (1002.2 F g −1 , 1 A g −1 ), 38 CoO/Co 9 S 8 hollow microspheres (1100 F g −1 , 2 A g −1 ), 39 GH@NC@Co 9 S 8 composite (540 F g −1 , 1 A g −1 ), 40 Co 9 S 8 nanowire/Ni (1191.17 F g −1 , 2 mV s −1 ), 41 0.3 cP/rGO/Co 9 S 8 (788.9 F g −1 , 1 A g −1 ), 42 Co 9 S 8 @N-C@MoS 2 (410 F g −1 , 10 A g −1 ), 43 Co 3 (OH) 2 (HPO 4 ) 2 @Co 9 S 8 /Co electrode (1279.4 F g −1 , 5 mA cm −2 ), 44 CoS@NSC-800 (289 F g −1 , 1 A g −1 ), 45 Co 9 S 8 @NiCo 2 S 4 @NF electrode (1026 F g −1 , 1 A g −1 ), 46 (Co 0.94 Fe 0.06 ) 9 S 8 hollow spheres (454 F g −1 , 1 A g −1 ), 47 Co 9 S 8 -2@CN/NF (471.1 F g −1 , 0.5 A g −1 ), 48 Co 9 S 8 –aCNT–NiCoLDH (1185.5 F g −1 , 1 A g −1 ), 49 and MnCo 2 S 4 /Co 9 S 8 /Ni composites (1058.0 F g −1 , 1 A g −1 ). 50 A more extensive comparison of super-capacitance performance of Ni-Co 9 S 8 -0.6 with other related electrodes are listed in Table S2 †.…”

Two-Dimensional Cobalt Sulfide/Iron–Nitrogen–Carbon Holey Sheets with Improved Durability for Oxygen Electrocatalysis

“…The two-dimensional holey sheet structure is completely collapsed into the nanoplatelet aggregates (Figures S8 and S9), of which the lattice distances at 0.44 nm are assigned to the (003) planes of CoOOH, in agreement with the XRD pattern (JCPDS 00-007-0169) in Figure S10. As seen from XPS spectra in Co 2p and S 2p regions (Figures S11a and S11b), the Co 2p 3/2 peak at 778.4 eV and S 2p peaks at 161.9 and 163.0 eV, which are indexed to the Co–S bond, completely disappear in Co 9 S 8 -5th. , The main Co 2p 3/2 peaks at 780.2 and 782.7 eV in Co 9 S 8 -5th correspond to Co 3+ and Co 2+ species. , Moreover, the O 1s peak located at 531.2 eV attributed to the Co–O bond is significantly enhanced, and the peak at 529.8 eV corresponding to the Co–O bond appears in Co 9 S 8 -5th (Figure S11c), suggesting that CoOOH is the predominant species. ,, Hence, above results disclose that Co 9 S 8 holey sheets are transformed into CoOOH during cycling, leading to poor stability performance.…”

“…The Co 2p 3/2 peak at 778.4 eV and S 2p peaks at 161.9 and 163.0 eV, which are contributed by Co 9 S 8 species, , are weakened from Co 9 S 8 /FeNC to Co 9 S 8 /FeNC-ADT (Figure d,e), in well agreement with the XRD pattern. The Co 3+ 2p 3/2 peak and O 1s peak at 531.2 eV corresponding to the Co–O bond are substantially enhanced, accompanied with the appearance of the O 1s peak at 529.8 eV that belonged to oxidized Co species (Figure f), , indicative of the formation of CoOOH species. It is consistent with that in Co 9 S 8 -5th.…”

“…The sluggish kinetics toward oxygen reduction reaction (ORR) and oxygen evolution reactions (OER) is an insurmountable technical hurdle for the future practical applications of rechargeable metal-air batteries. − Although platinum-group metals (PGMs) including Pt, RuO 2 , and IrO 2 are suggested as the benchmark catalysts, besides the high cost and scarcity, the passivation at high anodic potentials and the imbalanced ORR/OER activity lead to poor durability, large discharge–charge voltage gap, and low power density . Transition-metal sulfides (TMSs) have been developed by precisely modulating the structures and components for optimizing the adsorption/desorption of oxygen intermediates − and pursued as alternative electrocatalysts to PGMs. However, the durability that is a prime concern for future commercialization is still insufficient to meet the requirements.…”

Nickel–Copper Alloy Nanoparticles Embedded in N-Doped Porous Carbon Nanosheets for Supercapacitors and Hydrogen Evolution Reaction

“…Recently, the problems of the global energy crisis and environmental pollution caused by the rapid depletion of nonrenewable fossil sources has instantly triggered the research on green energy production and highly effective energy storage devices in the technology industry. − In terms of energy storage devices, the electrochemical supercapacitor is an ideal candidate due to its robust cyclic behavior, high power density, and fast charge/discharge capacity. Nevertheless, its widespread applications are limited by the low energy density.…”