Multiscale Design of 3d Metal–Organic Frameworks (M-Btc, M: Cu, Co, Ni) Via Plal Enabling Bifunctional Electrocatalysts for Robust Overall Water Splitting

Multiscale design of 3D metal–organic frameworks (M−BTC, M: Cu, Co, Ni) via PLAL enabling bifunctional electrocatalysts for robust overall water splitting

Recent advances of metal-organic frameworks and their composites toward oxygen evolution electrocatalysis

Metal-organic framework (MOF)-based materials have attracted attention in recent times owing to their remarkable properties such as regulatable pore size, high specific surface area, and elasticity in their network topology, geometry, dimension, and chemical functionality. It is believed that the incorporation of a MOF network into a fibrous matrix results in the improvement of the electrocatalytic properties of the material. Herein, we have synthesized a Co-incorporated MOF-5-based fibrous material by a simple wet-chemical method, followed by an electrospinning (ES) process. The as-prepared Co-incorporated MOF-5 microfibers were employed as an electrocatalyst for the oxygen evolution reaction (OER) in 1 M KOH electrolyte. The catalyst demands a lower overpotential of 240 mV to attain a current density of 10 mA/cm2 with a lower Tafel slope value of 120 mV/dec along with a charge transfer resistance value of 2.9 Ω from electron impedance spectroscopy (EIS) analysis. From these results, it has been understood that the incorporation of Co metal into the MOF-5 microfibrous network has significantly improved the OER performance, which made them a potential entrant in other energy-related applications also.

Electrospun Cobalt-Incorporated MOF-5 Microfibers as a Promising Electrocatalyst for OER in Alkaline Media.

In this work, for the first time, the synergetic effect of CoWO4-CoMn2O4/N-doped graphene (CCNG) hybrid nanocomposites as active electrode materials with high conductivity and fast transmission of electrons/ions are investigated for high performance supercapacitor. The crumpled- paper like CCNG nanostructure is synthesized by an efficient and simple hydrothermal route via adding a certain amount of CoWO4-CoMn2O4 and a defined amount of urea as a reducing agent into the aqueous dispersion of graphene oxide (GO). The obtained CCNG hybrid nanocomposites represent excellent electrochemical efficiencies with a high specific capacitance of 4133.3 F g−1 at a current density of 2 A g−1. Besides, the proposed electrode exhibits the excellent specific energy density of 116.25 WhKg−1, specific power density of 2250 Wkg−1 and superior cycling stability by retaining 96.96% of their original capacitance after 5000 cycles. Furthermore, using CCNG as positive electrode and activated carbon (AC) as negative electrode is designed for an asymmetric supercapacitor (ASC). The assembled ASC device provides a superior specific capacitance of 281.58 mF g−1 at the applied current density of 1 mA g−1 and delivers the energy density of 56.31 mWh kg−1 at the power density of 600 mWkg−1. 

Facile synthesis of crumpled-paper like CoWO4-CoMn2O4/N-doped Graphene hybrid nanocomposites for high performance all-solid-state asymmetric supercapacitors

Copper manganese oxide-graphene (CuMn2O4-RGO) composite was prepared by sol-gel method and then synthesized by physical grinding, which was further applied to electrode materials for supercapacitors. The structure and morphology of the composites were analyzed by means of characterization, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), transmission electron microscopic (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) analysis, and Raman. The electrochemical tests including cyclic voltammetry (CV), galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and cyclic life were used to investigate electrochemical properties of CuMn2O4-RGO so as to optimize its composition. Through the comparison of electrochemical properties at different mass ratios, current densities and scan rates, it was found that when the mass ratio was m (CuMn2O4): m (RGO) =1:1, the as-prepared CuMn2O4-RGO exhibited the excellent electrochemical properties. The capacitance reached 342 F g−1 at the current density of 1.0 A g−1, which was significantly higher than that of pure CuMn2O4 and RGO. The higher capacitance performance can be comparable with the reported literature value. Meanwhile, the energy density of CuMn2O4-RGO (1:1) is significantly higher than that of CuMn2O4 and RGO. Therefore, CuMn2O4-RGO (1:1) composite has a good prospect as electrode material for supercapacitor.

CuMn2O4 spinel anchored on graphene nanosheets as a novel electrode material for supercapacitor

Metal-organic framework (MOF) materials have a topological structure, which helps the reactants to fully contact the active sites. This structure can effectively increase the number of active sites participating in the reaction and enhance their catalytic properties. Therefore, in this work, single metal MOF (Co-MOF), single metal MOF with Cu through electrodeposition (Cu/Co-MOF), and double metal MOF (CuCo-MOF) in the case of the same ligand and metal ion were prepared by a hydrothermal method and electrodeposition, which were then applied in the electrocatalytic oxygen evolution reaction (OER). A group of electrochemical tests showed that as-prepared CuCo-MOF exhibited lowest Rct value, highest electron transfer capability, and the best catalytic performance among the three catalysts. When the current density was 10 mA cm−2, the overpotential of CuCo-MOF was 0.38 V, and the slope of Tafel curve was 118 mV dec−1. Moreover, the CuCo-MOF had larger TOF values and better electrocatalytic property as compared with the other two MOF materials. Therefore, the self-assembled acicular CuCo-MOF material prepared in this work has the advantages of low overpotential, small initial potential, and good stability.

Self-assembled acicular CuCo-MOF for enhancing oxygen evolution reaction

LaFeO3 was synthesized by sol-gel method, and corresponding LaFeO3/graphene composite materials were prepared under the condition of ultrasonic dispersion. The as-prepared composite modified electrode was used as electrochemical sensor to detect sulfite content. The morphology, structure and elemental composition of the prepared composite were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray electron spectroscopy (XPS). A group of electrochemical properties of the optimal LaFeO3 were investigated by differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical test results showed that the LaFeO3/graphene composite modified electrode has a good response signal for sulfite. Its response current is proportional to the concentration of sulfite in the range of 1 ~ 200 μM. The linear relationship is I(μA) = 0.119 C(μM) + 0.135. Correlation coefficient (R2) is 0.994, and the limit of detection (LOD) (S/N = 3) is 0.21 μM. The proposed method was successfully applied to white wine samples, the recovery rate is within the range of 97.63% to 103.02% (n = 5). Therefore, the as-prepared sulfite sensor has the characteristics of high sensitivity, low LOD, good stability and reproducibility, and good anti-interference ability.

Highly Sensitive and Selective Nonenzymatic Sulfite Sensor Based on LaFeO3/Graphene

This comprehensive experiment is specially designed for the third-year and above students who are majoring in chemistry, applied chemistry, and chemical engineering. Students conduct experiments in...

Synthesizing CeO2–NiTiO3/Attapulgite and Investigating the Conversion Rate of NOx, Sulfur Resistance, N2 Selectivity, and Stability of the Catalyst through Applied SCR by Upper-Level Undergraduate Students

The invention belongs to the technical field of novel energy, and particularly relates to preparation of a two-dimensional layered Co-MOF electrode material with significantly improved water oxidationperformance, and oxygen evolution performance research. The two-dimensional layered Co-MOF electrode material is prepared through a simple and mild hydrothermal method, then the prepared electrode material is used for researching the oxidation performance of electrolyzed water; a preparation method comprises the following steps: the two-dimensional layered Co-MOF electrode material is prepared through the hydrothermal method; and study on the oxygen evolution performance of the prepared electrode material is carried out. The two-dimensional layered Co-MOF electrode material has the beneficialeffects that the two-dimensional layered Co-MOF electrode material has relatively good stability and good oxygen evolution reaction performance, and has a wide application prospect in the technical field of novel energy sources.

Duo Xiaoxiao

Papers

CuMn2O4 spinel anchored on graphene nanosheets as a novel electrode material for supercapacitor

Self-assembled acicular CuCo-MOF for enhancing oxygen evolution reaction

Highly Sensitive and Selective Nonenzymatic Sulfite Sensor Based on LaFeO3/Graphene

Synthesizing CeO2–NiTiO3/Attapulgite and Investigating the Conversion Rate of NOx, Sulfur Resistance, N2 Selectivity, and Stability of the Catalyst through Applied SCR by Upper-Level Undergraduate Students

Two-dimensional layered cobalt-based metal organic framework (Co-MOF) electrode material preparation and oxygen evolution performance research