Interfacial Engineering in Crystalline Cobalt Tungstate/Amorphous Cobalt Boride Heterogeneous Nanostructures for Enhanced Electrochemical Performances

Abstract

Interfacial engineering is one of the feasible pathways to tune the characteristics and functions of nanomaterials. In this report, we successfully synthesized crystalline CoWO 4 /amorphous Co−B heterostructures that enable superior electrochemical performance. The electrodes overcome the defect of low conductivity of cobalt tungstate and also expose more active sites. The optimized CoWO 4 /Co−B electrode has a remarkable specific capacity of 177.4 C g −1 at 0.5 A g −1 and a great specific capacity retention of 100% at 5 A g −1 after 10,000 cycles with reasonable cycling stability. Moreover, the Co−B/CoWo 4 electrode and activated carbon electrode are combined to assemble an asymmetric supercapacitor, which achieves 22.26 W h kg −1 maximum energy density at 200 W kg −1 and a capacity retention of 95.65% after 10,000 cycles at 2 A g −1 . In general, the work shows the unique characteristics of the crystalline/amorphous nanoheterostructure and provides a direction for future studies on increasing the electrochemical character and application of nanomaterials through regulating the interface contact of composites.

Investigation of electronic structure, morphological features, optical, colorimetric, and supercapacitor electrode properties of CoWO4 crystals

“…12(c), the C s for CoWO 4 electrode film prepared by the CP method are 160.5, 173.9, 188.4, As can be presented in Table 6 above, we have noted some well significant differences in C s values for pure CoWO 4 crystals and modified CoWO 4 crystals when compared with other previous papers reported in the literature [26,39,40,43,51,52, 53,54,135,13 7-147] of the crystalline and amorphous state. These differences at minor C s values that have already been previously reported in the literature [43,51,52,138,143,145,146,147] about our CoWO 4 crystals can be possibly ascribed to the relatively slower redox rates on the cobalt actives sites, cobalt deficiencies or oxygen vacancies. Moreover, based on our previous experimental and theoretical analysis is noted the presence of the effect of order-disorder at the monoclinic lattice through Rietveld refinement data at the long-range, non-homogeneous distribution of electronic charges on surfaces mainly for CoWO 4 nanocrystals prepared by the CP method, Raman-active vibrational modes are not wellsharp or defined at Raman spectra at short-range, distortions in the between (O-W-O) and (O-Co-O) bonds found in FT-IR spectra.…”

Research Advances in Amorphous‐Crystalline Heterostructures Toward Efficient Electrochemical Applications

“…[109] Hou et al demonstrated the enhanced supercapacitor performance on the crystalline-amorphous CoWO 4 /Co-B heterostructures because of the improved conductivity and exposed more active sites. [171] As schematically illustrated in Figure 6a, Jiang et al proposed a two-step hydrothermal approach to prepare amorphouscrystalline MoO 3 -Ni 3 S 2 /NF 0.5 nanosheet arrays with abundant heterointerfaces as the battery-type electrodes for supercapacitor. [172] The crystalline Ni 3 S 2 components are designed to get enormous structural nanocrystallization and improve the efficiency of redox reaction.…”

“…demonstrated the enhanced supercapacitor performance on the crystalline‐amorphous CoWO 4 /Co‐B heterostructures because of the improved conductivity and exposed more active sites. [ 171 ]…”

Hybrid Nano-Phase Ion/Electron Dual Pathways of Nickel/Cobalt–Boride Cathodes Boosting Intercalation Kinetics for Alkaline Batteries

“…By now, plenty of research studies have reported that alkaline batteries exhibit relatively low specific capacity and poor cycling stability, which is ascribed to the low conductivity and unstable structure of nickel-based oxide and hydroxide cathode materials, such as Ni­(OH) 2 and NiO. ,− Numerous studies have been carried out to improve the intrinsic conductivity of nickel-based cathodes, such as sulfides, selenides, and phosphides, even conductive organic ligand incorporation. − Nowadays, nickel-based borides have become popular because of their relatively high conductivity and environmentally friendly nature; however, research studies have mainly focused on electrocatalytic water splitting. − As alternative to noble metal electrocatalysts, nickel-based borides exhibit long-term durability in an alkaline medium, which has aroused researchers’ interest in the development of alkaline battery energy storage. ,, The semiconductive property of nickel-based borides prompts electron transfer easily, resulting in fast kinetics during the electrochemical reaction. − For the intercalation-type battery material, intrinsic conductivity and electrolyte ion-shuttling diffusion are the two most important factors that have a great effect on the reaction kinetics of active materials. − In our previous report, the naphthalene dicarboxylate acid ligand pillared a Ni/Co layer in the NiCo metal–organic framework (MOF) to form ion intercalation/de-intercalation channels. This verified that the ion-shuttling channel enlarged linearly with the larger pillaring layer space. ,, However, more organic ligands introduced would render low conductivity, leading to slow chemical reaction kinetics. , …”