Multiple Valence States Research Articles

MOF-on-MOF Derived Co2P/Ni2P Heterostructures for High-Performance Supercapacitors.

Metal-organic frameworks (MOFs) have been widely used as versatile precursors to fabricate functional nanomaterials with well-defined structures for various applications. Herein, the presynthesized Ni-MOF nanosheets were grown on a Ni foam (NF) substrate, which then guided the nucleation and further growth of Prussian blue analogues (PBA) nanocubes to form MOF-on-MOF of the PBA/Ni-MOF film. This film was subsequently converted into a Co2P/Ni2P heterostructure. The NF-supported Co2P/Ni2P composites exhibited excellent supercapacitor performance, delivering a high specific capacity of 5124.2 mF cm-2 at 1 mA cm-2 and a remarkable capacity retention of 80.69% after 3000 cycles at 10 mA cm-2. An asymmetric supercapacitor assembled using Co2P/Ni2P/NF as the cathode and activated carbon as the anode yielded a maximum energy density of 0.34 mWh cm-2 at a power density of 1.50 mW cm-2. The enhanced supercapacitor performance is attributed to the synergistic effects of the Ni2P and Co2P components with multiple valence states as well as the unique hierarchical structure, which provides efficient pathways for electron and ion transport while mitigating volume expansion during energy storage. This synthetic strategy demonstrates an effective approach to fabricate phosphide-based hybrid materials for high-performance supercapacitor applications.

Study on the combustion of toluene by acid etching assisted ultrasonic supported low content Pt catalyst

Catalytic combustion technology is an effective method for the treatment of volatile organic compounds (VOCs). However, the catalytic activity of loaded noble metal catalysts is limited by factors such as high noble metal dosage and poor stability. In this study, a method for the preparation of acid etching assisted ultrasonic loaded low-content Pt-cordierite catalysts was proposed. By comparing with the 0.5 % Pt/cordierite catalyst prepared without acid etching, it was found that the catalytic activity of toluene of the 0.5 % Pt/cordierite-HNO3 catalyst was significantly improved, and the T90 of toluene combustion was only 201 ℃, which indicated that the acid etching effectively promoted the interfacial bonding between the active component Pt and the carrier. Finally, it was confirmed by XPS that the active component Pt in the 0.5 % Pt/cordierite-HNO3 catalyst existed in multiple valence states, which effectively promoted the catalytic combustion of toluene.

Synthesis of porous Mg2MnO4 spinel microspheres and enhanced lithium storage properties

Porous Mg2MnO4 spinel microspheres were synthesized by a facile solvothermal method. Various techniques such as X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, were used to characterize the phase composition, morphology and electronic structure of materials. The results show that Mg2MnO4 spinel material was obtained at the temperature of 600–800 °C and has a microsphere structure. The microspheres were assembled by nanoparticles, and the particle size increases with the increase of annealing temperature. Analyses of XPS spectra reveal that Mn exists in multiple valence states (+2, +3, +4) in Mg2MnO4 materials, and all the materials are mixed spinel with Mg2+ and Mn2+/3+/4+ ions occupy both tetrahedral and octahedral sites of spinel structure, and the degree of inversion decreases with increasing annealing temperature. Mg2MnO4 microspheres exhibit excellent lithium storage performance, the first discharge specific capacity of M2MO-8 is 835.3 mAh g−1 under a voltage window of 0–3 V and with a current density of 100 mA g−1, and after 100 cycles the discharge capacity of the material is as high as 406.5 mAh g−1. In addition, this material shows high cyclic reversibility. The enhanced lithium storage properties of the material can be attributed to its porous structure, which promote the transport of lithium ions and reduce the damage to the structure caused by the volume change during the charge and discharge process.

Novel three-dimensional architectured ZnMgAl ternary layered double hydroxide@reduced graphene oxide nanocomposites as electrode material for high-performance supercapacitor

Ternary layered double hydroxides (LDH) have recently attracted immense attention owing to their stupendous features, such as fine compositional tuning, multiple valence states, and superior electrochemical activity. Moreover, their intriguing structures and distinctive physiochemical properties delineate them as an exemplary material to serve as electrodes for high-performance supercapacitors (SCs). The present work reports the in-situ synthesis of Zinc Magnesium Aluminium LDH (ZMA) integrated with reduced graphene oxide (rGO) through a single-step hydrothermal approach. The resulting novel ternary ZMA@rGO nanocomposite (ZMAG) possesses a unique architecture incorporating hierarchical 3D nanoflowers of ZMA embedded on graphene nanosheets. The porous morphology of LDH improves interfacial charge transport, which results in more faradaic reactions at the electrochemically active sites. In addition, the conductive graphene nanosheets render a high specific surface area, endowing excellent capacitive behavior. The amalgamated electrochemical properties of ZMA and rGO develop a competent electrode material (ZMAG) for SCs. The ZMAG2 nanocomposite having ZMA and rGO in 1:1, evinces a specific capacitance (Cs) of 656.7 F/g at a current density (Id) of 1 A/g. Furthermore, the asymmetric supercapacitor (ASC) features admirable cycle stability (retains 89% of initial capacitance after 15,000 charge/discharge cycles). Herein, the real-time application of ZMA@rGO//AC ASC has also been demonstrated. Therefore, hierarchical porous nanostructure proclaims new prospects for fabricating proficient electrode materials for energy storage devices.

In suit decorating PdPt bimetals on titanium dioxide nanosheets for detecting ppb level of carbon monoxide and hydrogen

The catalyst with strong metal-support interactions often exhibits high catalytic activity. This study aims to prepare sensitive materials with strong metal-MOS interactions and explore their sensitization mechanism. Sn-PdPt/TiO2 was obtained by in-situ decorating PdPt bimetals on the surface of TiO2 NSs using Sn2+ as the reducing agent, and PdPt/TiO2 was prepared by traditional reduction method. Compared with TiO2 sensor, PdPt/TiO2 and Sn-PdPt/TiO2 sensors exhibited higher sensitivity, selectivity, lower operating temperature (200 °C) and detection limit (ppb level) to CO and H2. The sensitization of PdPt bimetal to TiO2 should be ascribed to the high catalytic activity of PdPt bimetal towards O2, H2 and CO, Schottky barrier at the interface between TiO2 and PdPt NPs, and the multiple valence states (Pd0, Pd2+ and Pd4+) of Pd will undergo mutual transformation during gas sensing reactions. And Sn-PdPt/TiO2 sensor exhibited higher sensitivity, selectivity and better stability than those of PdPt/TiO2 sensor, which can be attributed to the introduction of SnO2 and the stronger interaction between PdPt and TiO2 due to the in-situ reduction reaction. This study can provide some reference for preparing the MOS based gas sensing materials with strong metal-support interactions and understanding the sensitization mechanism of PdPt bimetal.

Surface nickel gradient tunes anionic redox activity to stabilize cobalt-free Li-rich cathodes

Constructing a gradient structure of transition metals is promising to improve the electrochemical performance of layered oxide cathodes. However, the nickel gradient spinel layer on the surface of layer Li-rich cathodes is barely successful. Herein, we present a refining strategy of reductive gas to induce a Ni-gradient spinel layer on the surface of Li1.2Mn0.6Ni0.2O2 (LRNMO). The formed gradient spinel layer stabilizes the coordination environment at the interface and reduces oxygen loss. Moreover, the Ni gradient further maintains the reversibility of the Mn3+/Mn4+ redox couple, while the multiple valence states of Mn ions in the gradient layer enhance the electrochemical kinetics. The LRNMO with Ni-gradient spinel layer achieves an initial coulomb efficiency reaching 86.1% and maintaining an energy density of 667.9 Wh kg−1 after 200 cycles at 1 C. The surface gradient strategy is conducive to maintaining structural stability and provides support for the continued development of Li-ion batteries.

Preparation of Thermochromic Vanadium Dioxide Films Assisted by Machine Learning.

In recent years, smart windows have attracted widespread attention due to their ability to respond to external stimuli such as light, heat, and electricity, thereby intelligently adjusting the ultraviolet, visible, and near-infrared light in solar radiation. VO2(M) undergoes a reversible phase transition from an insulating phase (monoclinic, M) to a metallic phase (rutile, R) at a critical temperature of 68 °C, resulting in a significant difference in near-infrared transmittance, which is particularly suitable for use in energy-saving smart windows. However, due to the multiple valence states of vanadium ions and the multiphase characteristics of VO2, there are still challenges in preparing pure-phase VO2(M). Machine learning (ML) can learn and generate models capable of predicting unknown data from vast datasets, thereby avoiding the wastage of experimental resources and reducing time costs associated with material preparation optimization. Hence, in this paper, four ML algorithms, namely multi-layer perceptron (MLP), random forest (RF), support vector machine (SVM), and extreme gradient boosting (XGB), were employed to explore the parameters for the successful preparation of VO2(M) films via magnetron sputtering. A comprehensive performance evaluation was conducted on these four models. The results indicated that XGB was the top-performing model, achieving a prediction accuracy of up to 88.52%. A feature importance analysis using the SHAP method revealed that substrate temperature had an essential impact on the preparation of VO2(M). Furthermore, characteristic parameters such as sputtering power, substrate temperature, and substrate type were optimized to obtain pure-phase VO2(M) films. Finally, it was experimentally verified that VO2(M) films can be successfully prepared using optimized parameters. These findings suggest that ML-assisted material preparation is highly feasible, substantially reducing resource wastage resulting from experimental trial and error, thereby promoting research on material preparation optimization.

Core-shell organic frameworks to activate peroxymonosulfate for the simultaneous removal of SO2 and NO

Advanced oxidation process is a simple and cost-effective approach for the simultaneous removal of SO2 and NO from the flue at low temperatures. Herein, two core–shell hierarchical metal organic frameworks (MOFs), namely FeBDC@CuBDC (Iron terephthalate@Copper terephthalate) and FeBDC@CuBTC (Iron terephthalate@Copper triphenylenetriate), were successfully synthesized through Cu partial exchange and the secondary growth on surface of FeBDC, respectively. These MOFs were utilized to activate efficiently peroxymonosulfate (PMS). In the two MOFs, the metals existed in multiple valence states, specifically Fe(II)/Fe(III) and Cu(I)/Cu(II), favoring the high catalytic activity. In these MOFs/PMS solutions, more than 85% NO was removed and SO2 was completely eliminated. FeBDC@CuBTC and FeBDC@CuBDC were recovered and regenerated for at least 5 cycles. The high catalytic activity of these MOFs was attributed to the high content of Fe(II)/Cu(I) achieved by the rapid reduction of Fe(III)/Cu(II) with O2•-. Through the analysis of reactive oxygen species in the MOFs/PMS, it was observed the NO removal was influenced by both free radical processes (SO4•-,•OH) and non-free radical processes(1O2), whereas the SO2 removal was controlled primarily by free radical processes (SO4•- and •OH).

Space-confined growth of two-dimensional manganese oxide nanosheets in plant-cell structures for efficient tetracycline degradation

Manganese oxides (MnxOy) stand out as promising candidates for various redox reaction involved applications due to their diverse valence states. The expansive surface area of two-dimensional (2D) materials offers an abundance of active sites for reactions, thereby gathering significant interest for catalytic applications. Nonetheless, facile synthesis of 2D nano metal oxides remains a challenge. In this study, cabbage leaf cells were employed as bio-scaffolds to fabricate 2D MnxOy nanomaterials, leveraging the confined space within the cells. The resulting 2D MnxOy nanosheets, featured by multiple valence states and composed of Mn2O3 and Mn3O4 nanocrystals, exhibit a planar size of 32 nm and a lamellar thickness of about 3.95 nm. The distinctive 2D structure, coupled with the material’s multivalent manganese, facilitates efficient electron transfer, enhancing its function as a hetero-catalyst. Consequently, 2D MnxOy nanosheets demonstrate remarkable efficiency, achieving an 89 % removal of tetracycline (40 mg·L–1) with the assistance of H2O2. This study paves the way for employing biological templates to meticulously synthesize nanomaterials with precise morphologies, with applications extending across various fields.

Computational Comparative Study of the Binding of Americium with N-Donor Ligands.

The accessibility of multiple valence states of americium (Am) inspired redox-based protocols aimed at efficient separation of trivalent Am (Am3+) from trivalent lanthanides (Ln3+) alternative to the traditional liquid-liquid extraction. This requires an extensive understanding of the coordination chemistry of Am in its various accessible valence states in the aqueous phase. In this work, by means of DFT calculations, the coordination of AmIII-VI with five typical N-donor ligands, i.e., terpyridine (tpy), bispyrazinylpyridine (dpp), bistriazinylpyridine (BTP), bistriazinyl bipyridine (BTBP), and bistrazinyl phenanthroline (BTPhen), was studied in terms of energy and topological analysis. The results show that the exchange of aqua ligands of hydrated ions by N-donor ligands is an entropy-driven process and enthalpically unfavorable. Topological analysis suggests a distinct mechanism of BTP to modulate the redox potential of Am(III) in that BTP can assist the relay of the leaving electron of AmIII, while the other N-donor ligands can detain the oxidation of Am by offering their electron instead. This comparative study enriches our understanding of the coordination chemistry of high-valent Am with N-donor ligands and recommends the ligand design toward the modulation of redox potentials of hydrated Am(III) ions.

In situ anchored ternary hierarchical hybrid nickel@cobaltous sulfide on poly(3,4-ethylenedioxythiophene)-reduced graphene oxide for highly efficient non-enzymatic glucose sensing.

A ternary hierarchical hybrid Ni@CoxSy/poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (Ni@CoxSy/PEDOT-rGO) is rationally designed and in situ facilely synthesized as electrocatalyst to construct a binder-free sensing platform for non-enzymatic glucose monitoring through traditional electrodeposition procedure. The as-prepared Ni@CoxSy/PEDOT-rGO presents unique hierarchical structure and multiple valence states as well as strong and robust adhesion between Ni@CoxSy/PEDOT-rGO and GCE. Profiting from the aforementioned merits, the sensing platform constructed under optimal conditions achieved a wide detection range (0.2μM ~ 2.0mM) with high sensitivity (1546.32 μA cm-2mM-1), a rapid response time (5s), an ultralow detection limit (0.094μM), superior anti-interference performance, excellent reproducibility and considerable stability. Furthermore, the sensor demonstrates an acceptable accuracy and appreciable recoveries ranging from 90.0 to 102.0% with less than 3.98% RSDin human blood serum samples, indicating the prospect of the sensor for the real samples analysis. It will provide a strategy to rationally design and fabricate ternary hierarchical hybrid as nanozyme for glucose assay.

Thermodynamics of mantle minerals – III: the role of iron

SUMMARY We expand the scope of HeFESTo by encompassing the rich physics of iron in the mantle, including the existence of multiple valence and spin states. In our previous papers, we considered iron only in its most common state in the mantle: the high-spin divalent (ferrous) cation. We now add ferric iron end-members to six phases, as well as the three phases of native iron. We also add low-spin states of ferrous and ferric iron and capture the behaviour of the high-spin to low-spin transition. Consideration of the multi-state nature of iron, unique among the major elements, leads to developments of our theory, including generalization of the chemical potential to account for the possibility of multiple distinguishable states of iron co-existing on a single crystallographic site, the effect of the high-spin to low-spin transition on seismic wave velocities in multiphase systems, and computation of oxygen fugacity. Consideration of ferric iron also motivates the addition of the chromia component to several phases, so that we now consider the set of components: Ca, Na, Fe, Mg, Al, Si, O and Cr (CNFMASO+Cr). We present the results of a new global inversion of mineral properties and compare our results to experimental observations over the entire pressure–temperature range of the mantle and over a wide range of oxygen fugacity. Applications of our method illustrate how it might be used to better understand the seismic structure, dynamics and oxygen fugacity of the mantle.

Understanding the mechanism of propane dehydrogenation over coordinatively unsaturated Co-O acid-base pairs and the inhibition effect of trace oxygen

High temperature and a reducing atmosphere are characteristic of propane dehydrogenation (PDH) reaction. Under such condition, the real surface structure of catalysts often differs from that in the ambient environment, particularly for CoOx species with multiple valence states and coordination. Here, a combination of in situ/operando Raman spectroscopy, in situ UV–Vis diffuse reflectance spectroscopy (DRS), and density functional theory (DFT) calculations reveal that coordinatively unsaturated Co-O (Cocu-O) acid-base pairs via lattice oxygen consumption are the PDH active sites of CoOx/Al2O3 catalysts. This highly dispersed Cocu-O species exhibit a C3H6 formation rate and C3H6 selectivity as high as 2 mmol‧gcat−1‧min−1 and 95 %, respectively, which is comparable to most state-of-the-art CoOx-based catalysts. However, industrial C3H8 raw gases typically contain 10–1000 ppm oxygen gas, and the complete eliminating oxygen increases costs. PDH catalytic performance of CoOx/Al2O3 catalysts is sensitive to the extremely low concentration of oxygen gas and is significantly inhibited by it. The fundamental reason is that the concentration of Cocu active sites is determined by the competitive reaction between the filling of trace oxygen on oxygen vacancies and lattice oxygen consumption. The reaction rate of the former is significantly higher than that of the latter. The higher reducibility of CoOx species leads to relatively weaken inhibition of trace oxygen for PDH activity. The oxygen content in the propane feed gas is a non-negligible factor in the development of new Co-based PDH catalysts, especially for their industrial applications.

An insight into the structural, magnetic and dielectric properties of modified SrFe12-xPbxO19 (x = 0–0.3)

Effect of Pb2+ substitutions on the structural, magnetic and dielectric properties of SrFe12O19 in the form of SrFe12-xPbxO19 (x = 0, 0.1, 0.2 and 0.3) is carried out. All the samples crystalize in hexagonal magneto-plumbite structure with P63/mmc symmetry. An irregular but randomly distributed particles with average particle size increased from 0.791 μm to 1.131 μm due to substitutions. A characteristics Hopkinson peak is observed just below the transition temperature, may be stems from the superparamagnetic relaxations. The isothermal magnetization depicts an increase in coercivity (Hc) and decrease in saturation magnetization (Ms) due to Pb substitutions, which is further explained in the framework of site symmetry of the Fe and its multiple valence states. Mossbauer study reflects that, Fe3+/ Fe2+ present in the systems are associated with different electric environment. Furthermore, the shifting of dielectric transition by 50 °C upon substitutions is associated to dipole formation in presence of lone pair of Pb2+. A relaxor type of behavior is acquired by the system with a non-Debye type of relaxation is explained on the basis of complexity of the dipoles associated with each crystallographic sites.

Self-reduced MXene-Metal interaction electrochemiluminescence support with synergistic electrocatalytic and photothermal effects for the bimodal detection of ovarian cancer biomarkers

Novel two-dimensional MXene with unique optical and electrical properties has become a new focus in the field of sensing. In particular, their metallic conductivity, good biocompatibility and high anchoring ability to biomaterials make them attractive candidates. Despite such remarkable properties, there are certain limitations, such as low oxidative stability. MXene-Metal interactions are an effective strategy to maintain the long-term stability of MXene, while also improving the electrochemical activity and optical properties. Herein, a series of MXene/Ag nanocomposites including Ti3C2/Ag, Nb2C/Ag and V2C/Ag were designed based on the surface chemistry characteristics of MXene, where MXene served as the substrate for in-situ growth of silver nanoparticles via self-reduction of Ag(NH3)2+. The results showed that V2C MXene has the strongest self-reducing ability due to its multiple variable valence states, larger interlayer space and more reactive groups. Moreover, V2C/Ag exhibited unexpected oxygen reduction reaction catalytic activity and photothermal performance. In view of which, an electrochemiluminescence-photothermal (ECL-photothermal) immunosensor was developed using V2C/Ag as ECL anchor and photothermal reagent for ultrasensitive detection of Lipolysis stimulated lipoprotein receptor. This work not only provides a simple and effective synthesis method of MXene supported metal nanocomposites, but also provides more inspirations for exploring the efficient biosensing strategies.

Dual-Valence Characteristics of Be11: Tin/Lead-like Superatom.

To enhance the superatom family, the new superatom analogue Be11 of group IVA elements has been developed. Be11 can exhibit multiple valence states (+2 and +4), similar to carbon-group elements, and is capable of forming stable ionic compounds with other atoms such as carbon, chalcogen, (super)halogen, and hydroxyl. This resembles how tin and lead atoms combine with these elements to form stable molecules. Their special stability can be rationalized from the perspective of a cluster shell model. Sn or Pb could be the nearest atomic analogue to Be11 in group IVA, as the +2 oxidation state is more stable than the +4 oxidation state. This comparative investigation highlights the resemblance between Be11 and carbon-group elements, which encourages additional exploration within the superatom family.

High‐power microbial‐fuel‐based hybrid cells with three‐dimensional graphene‐coated iron foam as an anode control Fe3+ release

AbstractMicrobial fuel cells (MFCs) benefit from the introduction of iron in the anode, as its multiple valence states and high electron‐catalytic activity led to improved power densities in MFCs. However, the effect of long‐term Fe3+ release into the electrolyte on the power density of MFCs is often overlooked. Herein, an anode consisting of a three‐dimensional iron foam uniformly coated by reduced graphene oxide (rGO/IF) with a suitable loading density (8 g/m2) and a large specific surface area (0.05 m2/g) for high‐density bacterial loading was prepared. The hybrid cells based on the rGO/IF anode exhibit a maximum power density of 5330 ± 76 mW/m2 contributed by MFCs and galvanic cells. The rGO/IF anode enables continuous Fe3+ release for high electron‐catalytic activity in the electrolyte during the discharging of the galvanic cells. As a result, the hybrid cells showed a power density of 2107 ± 64 mW/m2 after four cycles, facilitated through reversible conversion between Fe3+ and Fe2+ in the electrolyte to accelerate electron transfer efficiency. The results indicate that the rGO/IF anode can be used for designing and fabricating high‐power MFCs by optimizing the rate of release of Fe3+ in the electrolyte.

Solid solution-typed defect concept in forming multivalent cations- and oxygen vacancy-filled MnCo2O4-z spinel bifunctional electrodes for innovative symmetrical supercapacitor

Oxygen vacancies-filled MnCo2O4-z (MCO) nanosheets prepared by a two-step process with varied NH4F content have been investigated. MCO prepared with NH4F at 10 mmol (MCO-10) shows excellent to be used not only for cathode and anode but also for a symmetric supercapacitor cell (SSC). This MCO-10 electrode as a cathode not only reaches a high specific capacitance (Cs) of 7249 F/g at 1 A/g but also performs a high value of 2515 F/g at 1 A/g as an anode. An enlarged SSC of 5 × 5 cm2 is developed. One and five light-emitter-diode (LED) bulbs and commercial 100 F supercapacitor devices are tested to authenticate our reported data. The outstanding performance of nonstoichiometric MCO spinel involving the OH− dipole interaction with oxygen vacancies, chemical redox reaction, multiple cationic valence states, and oxygen vacancies-filled defective structure are all connected with the solid solution-typed defect concept to form bifunctional spinel.

A Brief Review of MoO3 and MoO3-Based Materials and Recent Technological Applications in Gas Sensors, Lithium-Ion Batteries, Adsorption, and Photocatalysis.

Molybdenum trioxide is an abundant natural, low-cost, and environmentally friendly material that has gained considerable attention from many researchers in a variety of high-impact applications. It is an attractive inorganic oxide that has been widely studied because of its layered structure, which results in intercalation ability through tetrahedral/octahedral holes and extension channels and leads to superior charge transfer. Shape-related properties such as high specific capacities, the presence of exposed active sites on the oxygen-rich structure, and its natural tendency to oxygen vacancy that leads to a high ionic conductivity are also attractive to technological applications. Due to its chemistry with multiple valence states, high thermal and chemical stability, high reduction potential, and electrochemical activity, many studies have focused on the development of molybdenum oxide-based systems in the last few years. Thus, this article aims to briefly review the latest advances in technological applications of MoO3 and MoO3-based materials in gas sensors, lithium-ion batteries, and water pollution treatment using adsorption and photocatalysis techniques, presenting the most relevant and new information on heterostructures, metal doping, and non-stoichiometric MoO3-x.

Hydrothermal synthesis of zinc-cobalt binary hydroxide / reduced graphene oxide composite nanosheets as electrode materials with surface redox pseudocapacitive behaviour

Binary metal hydroxides have grabbed the attention of researchers in energy storage field owing to their better electrochemical properties compared to that of monometallic counterparts and metal oxides. Being an eco-friendly, abundant, and cost effective metal, Zinc has been chosen to form binary hydroxide with cobalt which can show multiple valence states during electrochemical reactions. Zinc-Cobalt binary hydroxide (ZCH) nanosheets and its nanocomposite with reduced Graphene Oxide (ZCH-rGO) were synthesized through a simple hydrothermal method. Electrochemical properties of the prepared samples were analyzed by means of cyclic voltammograms, chronopotentiograms, and Nyquist plots. ZCH-rGO nanocomposite exhibited a high specific capacitance of ⁓756.8 F/g whilst ZCH nanosheets showed relatively less specific capacitance of ⁓594.6 F/g at 1 A/g. The electrochemical performance of ZCH-rGO nanocomposite was assessed using a two-electrode system from which the energy density was found to be 10.6 Wh/kg. This electrochemical setup of ZCH-rGO nanosheets displayed a capacitance retention of 126.6 % after 2000 charge-discharge cycles. Addition of rGO changed the primary electrochemical behaviour of ZCH from battery-type to capacitive-type thereby producing an electrode material with surface redox pseudocapacitive properties.