High performance g-C3N4 @NiMoO4/CoMoO4 electrode for supercapacitors

Lattice Strain-Modulated Trifunctional CoMoO4 Polymorph-Based Electrodes for Asymmetric Supercapacitors and Self-Powered Water Splitting

Developing efficient, multifunctional electrodes for energy storage and conversion devices is crucial. Herein, lattice strains are reported in the β-phase polymorph of CoMoO4 within CoMoO4@Co3O4 heterostructure via phosphorus doping (P-CoMoO4@Co3O4) and used as a high-performance trifunctional electrode for supercapacitors (SCs), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) in alkaline electrolytes. A tensile strain of +2.42% on the β-phase of CoMoO4 in P-CoMoO4@Co3O4 results in superior electrochemical performance compared to CoMoO4@Co3O4. The optimized P-CoMoO4@Co3O4 achieves a high energy density of 118 Wh kg-1 in an asymmetric supercapacitor and low overpotentials of 189 mV for the HER and 365 mV for the OER at a current density of 500 mA cm-2. This results in a low overall water splitting voltage of 1.71 V at the same current density making it an effective bifunctional electrode in a 1 m KOH freshwater electrolyte. Theoretical analysis shows that the excellent performance of P-CoMoO4@Co3O4 can be attributed to interfacial interactions between CoMoO4 and Co3O4, and the β-phase of CoMoO4, which lead to strong OH- adsorption and low energy barriers for reaction intermediates. Practical application is demonstrated by using P-CoMoO4@Co3O4-based ASCs to self-generate hydrogen (H2) in a P-CoMoO4@Co3O4||P-CoMoO4@Co3O4 alkaline seawater electrolyzer, showcasing its potential for future energy technologies.

Exploring the potential of CoMoO4-modified graphitic carbon nitride to boost oxidation of amoxicillin micropollutants in hospital wastewater

This study investigates the removal of amoxicillin micropollutants (AM) from hospital wastewater using CoMoO4-modified graphitic carbon nitride (CMO/gCN). Consequently, CMO/gCN exhibits notable improvements in visible light absorption and electron-hole separation rates compared to unmodified gCN. Besides, CMO/gCN significantly enhances the removal efficiency of AM, attaining an impressive 96.5%, far surpassing the performance of gCN at 48.6%. Moreover, CMO/gCN showcases outstanding reusability, with AM degradation performance exceeding 70% even after undergoing six cycles of reuse. The removal mechanism of AM employing CMO/gCN involves various photoreactions of radicals (•OH, •O2-) and amoxicillin molecules under light assistance. Furthermore, CMO/gCN demonstrates a noteworthy photodegradation efficiency of AM from hospital wastewater, reaching 92.8%, with a near-complete reduction in total organic carbon levels. Detailed discussions on the practical applications of the CMO/gCN photocatalyst for removal of micropollutants from hospital wastewater are provided. These findings underline the considerable potential of CMO/gCN for effectively removing various pollutants in environmental remediation strategies.

Decoration of Ag nanoparticles on CoMoO4 rods for efficient electrochemical reduction of CO2

Hydrothermal and photoreduction/deposition methods were used to fabricate Ag nanoparticles (NPs) decorated CoMoO4 rods. Improvement of charge transfer and transportation of ions by making heterostructure was proved by cyclic voltammetry and electrochemical impedance spectroscopy measurements. Linear sweep voltammetry results revealed a fivefold enhancement of current density by fabricating heterostructure. The lowest Tafel slope (112 mV/dec) for heterostructure compared with CoMoO4 (273 mV/dec) suggested the improvement of electrocatalytic performance. The electrochemical CO2 reduction reaction was performed on an H-type cell. The CoMoO4 electrocatalyst possessed the Faraday efficiencies (FEs) of CO and CH4 up to 56.80% and 19.80%, respectively at  - 1.3 V versus RHE. In addition, Ag NPs decorated CoMoO4 electrocatalyst showed FEs for CO, CH4, and C2H6 were 35.30%, 11.40%, and 44.20%, respectively, at the same potential. It is found that CO2 reduction products shifted from CO/CH4 to C2H6 when the Ag NPs deposited on the CoMoO4 electrocatalyst. In addition, it demonstrated excellent electrocatalytic stability after a prolonged 25 h amperometric test at  - 1.3 V versus RHE. It can be attributed to a synergistic effect between the Ag NPs and CoMoO4 rods. This study highlights the cooperation between Ag NPs on CoMoO4 components and provides new insight into the design of heterostructure as an efficient, stable catalyst towards electrocatalytic reduction of CO2 to CO, CH4, and C2H6 products.

Cobalt molybdate hollow spheres decorated graphitic carbon nitride sheets for electrochemical sensing of dimetridazole

In the present work, a cobalt molybdate (CoMoO4) hollow spheres-incorporated graphitic carbon nitride (g-CN) composite is prepared for the electrochemical detection of dimetridazole (DZ). The synergistic effect between the hollow-structured CoMoO4 and g-CN nanosheets facilitates the transportation of electrons through kinetic barriers, thereby providing a high electrical conductivity with increased electroactive sites. The proposed CoMoO4@g-CN-modified electrode displayed a wide linear range (0.001-492.77 μM) and a lower detection limit (LOD: 0.4 nM) for the determination of DZ through the amperometry (i-t) method. In addition, the CoMoO4@g-CN-modified electrode achieved good operational stability, anti-interfering ability (five-fold excess amount of co-interfering compounds) and reproducibility. These results demonstrate the increased electrocatalytic activity of CoMoO4@g-CN modified glassy carbon electrode (GCE) towards the detection of DZ in food samples with satisfactory recovery ranges.

A high mass loading flexible electrode with a sheet-like Mn3O4/NiMoO4@NiCo LDH on a carbon cloth for supercapacitors

Mass loading is an important parameter to evaluate the application potential of active materials in high-capacity supercapacitors. Synthesizing active materials with high mass loading is a promising strategy to improve high performance energy storage devices. Preparing electrode materials with a porous structure is of significance to overcome the disadvantages brought by high mass loading. In this work, a Mn3O4/NiMoO4@NiCo layered double hydroxide (MO/NMO/NiCo LDH) positive electrode is fabricated on a carbon cloth with a high mass loading of 20.4 mg cm-2. The MO/NMO/NiCo LDH presents as a special three-dimensional porous nanostructure and exhibits a high specific capacitance of 815 F g-1 at 1 A g-1. Impressively, the flexible supercapacitor based on the MO/NMO/NiCo LDH positive electrode and an AC negative electrode delivers a maximum energy density of 22.5 W h kg-1 and a power density of 8730 W kg-1. It also retains 60.84% of the original specific capacitance after bending to 180° 600 times. Moreover, it exhibits 76.92% capacitance retention after 15 000 charge/discharge cycles. These results make MO/NMO/NiCo LDH one of the most attractive candidates of positive electrode materials for high-performance flexible supercapacitors.

Coupling of Nd doping and oxygen-rich vacancy in CoMoO4@NiMoO4 nanoflowers toward advanced supercapacitors and photocatalytic degradation

In this paper, we successfully prepared rare earth element-doped 0.8% Nd-CoMoO4@NiMoO4 nanoflowers with a large specific surface area using the sol-gel method for the first time. In the experiment, we added a structure-directing agent to successfully assemble the nanosheets into a three-dimensional ordered micro-flower shape. By using the strategy of forming a flower-shaped morphology with a structure-directing agent and doping Nd elements to generate oxygen vacancies, the problems of the collapse of the active material structure and slow reaction kinetics were solved. Through relevant electrochemical performance tests, it was found that when the rare earth element Nd was doped at a concentration of 0.8%, the material exhibited exceptional specific capacitance (2387 F g-1 at 1 A g-1) and cycling stability (99.3% after 10 000 cycles at 5 A g-1). These performance characteristics far surpassed those of the other synthesized products. We assembled 0.8% Nd-CoMoO4@NiMoO4 with hydrophilic CNTs into an asymmetric device, 0.8% Nd-CoMoO4@NiMoO4//CNTs. This device exhibited high specific capacitance (262 F g-1 at 1 A g-1) and cycling stability (99.2% after 3000 cycles), with a good energy storage effect. In addition, 0.8% Nd-CoMoO4@NiMoO4 has a low band gap, which broadens the absorption range of the product and improves the utilization rate of visible light. The photocatalyst showed good degradation efficiency (all exceeding 96%) and cycling stability (96%) for all four dyes. This paper provides a new strategy and method for preparing doped polymetallic mixtures, which has potential application value.