It is of vital importance to design efficient and low-cost bifunctional catalysts for the electrochemical water splitting under alkaline and neutral pH conditions. In this work, we report an ...efficient and stable NiCo
2
S
4
/N, S co-doped reduced graphene oxide (NCS/NS-rGO) electrocatalyst for water splitting, in which NCS microspheres are composed of one-dimentional (1D) nanorods grown homogeneously on the surface of NS-rGOs). The synergetic effect, abundant active sites, and hybridization of NCS/NS-rGO endow their outstanding electrocatalytic performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both alkaline and neutral conditions. Furthermore, NCS/NS-rGO employed as both anode and cathode in a two-electrode alkaline and neutral system electrolyzers deliver 10 mA/cm
2
with the low cell voltage of 1.58 V in alkaline and 1.91 V in neutral condition. These results illustrate the rational design of carbon-supported nickel-cobalt based bifunctional materials for practical water splitting over a wide pH range.
In the present work, we report a convenient method for preparing non-stoichiometric cobalt sulfide with one-pot solvothermal method. Different Co
x
S
y
nanomaterials are synthesized for ...supercapacitor application. This experiment explores the influence of ethanol and
N
,
N
-dimethylformamide (DMF) on the microstructure and properties of Co
x
S
y
. X-ray diffraction (XRD), scanning electron microscopy, and Brunner–Emmet–Teller (BET) measurements demonstrated that Co
x
S
y
(ethanol) and Co
x
S
y
(DMF) have different structures and morphologies. Electrochemical supercapacitor performance of Co
x
S
y
(ethanol) and Co
x
S
y
(DMF) is characterized via cyclic voltammetry, galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. These results show that Co
x
S
y
(DMF) has better electrochemical performance than Co
x
S
y
(ethanol), and its capacitance can reach 347.4 F/g at the current density of 0.5 A/g. Moreover, Co
x
S
y
(DMF) also delivers a better cycling stability of about 70.8% capacity retention after 3000 cycles at a current density of 4 A/g. In addition, the assembled asymmetric supercapacitor of Co
x
S
y
(DMF)//active carbon shows an excellent energy density of 66.4 Wh/kg at a power density of 483.1 W/kg. These results indicate that Co
x
S
y
(DMF) has a good application prospect in the field of supercapacitor.
•Zn/Co co-doped MnO/C is prepared by ZnCoMn-BTC.•Ti3C2Cl2 helps the construction of dendrite-free zinc anode.•ZnCo-MnO/C//Ti3C2@Zn full cell has excellent cycle stability.
Mn-based aqueous zinc ion ...batteries (AZIBs) are promising energy storage devices due to its low cost and high performance. However, Jahn–Teller effect of discharge process and Mn2+ dissolution restricts its practical application. Herein, we report a Zn/Co co-doped MnO/C (ZnCo-MnO/C) derived from metal organic framework (MOF) with high specific capacity and cyclic stability, which benefits from the synergistic effect of Zn/Co ions. The doping of Zn ions improves the low specific capacity of MnO in the initial activation process, and Co ions can effectively inhibit the Jahn–Teller effect of discharge products and enhance the structural stability. The synergistic effect of Zn/Co co-doped further enhances the conductivity and ion diffusion rate of MnO. In addition, the interface protection layer of the zinc anode is constructed by Ti3C2Cl2 (Ti3C2@Zn), which can effectively inhibit dendrite growth and further improve the cycle life of AZIBs. Specifically, the assembled ZnCo-MnO/C//Ti3C2@Zn full battery has a specific capacity of 428.9 mAh·g−1 at 0.1 A·g−1. With 3000 cycles at 3.0 A·g−1, the capacity retention rate is 98.7 %. This work emphasizes the significance of co-doped on the electronic structure of MOF derived MnO/C for efficient AZIBs.
NCO/N, S-rGO is successfully synthesized for multifunctional applications, and the mechanisms of HMIs detection and HER are further explained.
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•NiCo2O4 decorated N, S codoped reduced ...graphene oxides are synthesized.•The synergetic effect, oxygen vacancies and hybridization of NCO/N, S-rGO improve its excellent electrocatalytic performance.•NCO/N, S-rGO has multifunctional applications for the electrochemical detection of HMIs and HER activity.
It is anenormous challenge to explore multifunctional electrocatalysts for simultaneous detection of Cd(II), Cu(II), Hg(II) and hydrogen evolution reaction (HER). In this work, NiCo2O4 decoratedN,Sco-doped reduced grapheneoxide composites (NCO/N, S-rGO) are synthesized via hydrothermal followed calcination process. The synergetic effect, oxygen vacancies and hybridization of NCO/N, S-rGO improve its excellent electrocatalytic performance for simultaneous and individual detection of Cd(II), Cu(II), Hg(II) and HER activity. When NCO/N, S-rGO is acted as heavy metal ions (HMIs) electrochemical sensors, it exhibits the high sensitivity and low detection limit for Cd(II) with 2.38 μA μM−1 and 123 nM, Cu(II) with 10.90 μA μM−1 and 14.4 nM, as well as Hg(II) with 5.41 μA μM−1 and 67 nM. NCO/N, S-rGO has outstanding stability and anti-interference performance and has been successfully implemented in the actual water environment. Furthermore, NCO/N, S-rGO also exhibits HER activity with overpotential and Tafel slope of 107 mV and 71.35 mV dec-1, respectively. The electrochemical detection and HER activity mechanism of NCO/N, S-rGO are further investigated and demonstrated that the synergetic effect of NCO/N, S-rGO can improve its electronic microstructure and promote electrocatalytic performance. This work not only provides a simple method for the preparation of multifunctional electrocatalysts, but also enhances the comprehension of HMIs detection and HER mechanism.
Metal–organic frameworks (MOFs) are considered potential electrocatalysts for efficient water splitting. However, the structure–activity relationship of most MOFs is not systematically analyzed for ...electrocatalysis for anodes and cathodes. In this paper, we provide a strategy to modulate the electronic microstructure of iron-based bimetallic MOFs (MFe-BDC (M: Mg, Zn, Cd)) grown on the nickel foam (NF) as bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The optimal bimetallic CdFe-BDC via modulating appropriate metal cations of IIA and IIB possesses excellent OER and HER performance with the lowest overpotentials of 290 mV at 100 mA cm–2 and 148 mV at 10 mA cm–2, respectively. The overall water splitting performance of the as-prepared CdFe-BDC requires 1.68 V to achieve a current density of 10 mA cm–2 in the real seawater media, and it exhibits the competitive H2 and O2 production rates of 6.4 and 3.1 μL s–1, respectively, in ambient alkaline conditions, suggesting its potential practical applications. Density functional theory (DFT) calculations demonstrate the relationship between microstructure and electrocatalytic performance of bimetallic MFe-BDC. This work emphasizes the significance of tailoring the electronic microstructure of bimetallic MOFs for efficient overall water splitting in alkaline and seawater environment.
MXene is a highly latent capacity electrode material for supercapacitors, but its capacity limits its development. Herein, we have constructed an independently cross-linked three-dimensional (3D) ...Ti3C2T X MXene film (Zn-A-MXene) with a hydroxylation surface through a zinc ion (Zn2+) and NaOH. The alkalization of NaOH is used to replace the –F functional group that is not conducive to electrochemical reactions and cross-link the MXene nanosheets through the electrostatic interaction of zinc ions. The synergistic effect can greatly improve the effective area of the electrode, the accessibility of the electrolyte, and the specific capacitance. The 3D Zn-A-MXene films exhibit an extremely high capacity (465.1 F g–1 at 1 A g–1). The all-solid-state flexible supercapacitor assembled using a 3D Zn-A-MXene thin film also has a high energy density of 9.55 Wh kg at a power density of 603.16 W kg. After 5000 cycles, the flexible supercapacitor still has 81.25% of its initial capacity, demonstrating good cycling stability. This work furnishes the innovative idea for constructing high-capacity MXene flexible supercapacitors.
Prussian blue analogues, as prospective electrode materials, play a crucial role in detecting heavy metal ions (HMIs), a process closely related to their electron transfer capacities and active ...surfaces. Here, etched copper-iron Prussian blue analogues (CuFe-PBA) are synthesized through a combination of flash nanoprecipitation (FNP) and an alkali etching process. Furthermore, this study investigates the impact of ammonia on the electronic structure of CuFe-PBA and its electrochemical detection capabilities for HMIs. The etched CuFe-PBA (e-CuFe-PBA) exhibits excellent detection performance for Cd
, Pb
and Hg
with 17.6 μA μM
, 24.2 μA μM
and 26.2 μA μM
, respectively, due to the fact that the ammonia etching not only modulates the electronic properties of the surface of CuFe-PBA but also reduces the degree of agglomeration and enhances the accessible surface area. Additionally, it demonstrates excellent stability and resistance to interference, having been successfully applied to detect HMIs in food samples such as preserved eggs and apple juice. These results provide a new strategy for the use of Prussian blue analogues as electrochemical sensors for food safety applications.
Prussian blue analogues, as prospective electrode materials, play a crucial role in detecting heavy metal ions (HMIs), a process closely related to their electron transfer capacities and active ...surfaces. Here, etched copper-iron Prussian blue analogues (CuFe-PBA) are synthesized through a combination of flash nanoprecipitation (FNP) and an alkali etching process. Furthermore, this study investigates the impact of ammonia on the electronic structure of CuFe-PBA and its electrochemical detection capabilities for HMIs. The etched CuFe-PBA (e-CuFe-PBA) exhibits excellent detection performance for Cd2+, Pb2+ and Hg2+ with 17.6 μA μM−1, 24.2 μA μM−1 and 26.2 μA μM−1, respectively, due to the fact that the ammonia etching not only modulates the electronic properties of the surface of CuFe-PBA but also reduces the degree of agglomeration and enhances the accessible surface area. Additionally, it demonstrates excellent stability and resistance to interference, having been successfully applied to detect HMIs in food samples such as preserved eggs and apple juice. These results provide a new strategy for the use of Prussian blue analogues as electrochemical sensors for food safety applications.
The e-CuFe-PBA is successfully synthesized via flash nanoprecipitation and alkali etching. The mechanism of e-CuFe-PBA for HMIs detection is further explained, and shows a good detection performance of HMIs in apple juice and preserved eggs. Display omitted
•Novel ammonia etching method elucidated for improved HMI detection.•The effect of ammonia on the surface electrons of e-CuFe-PBA is explained.•e-CuFe-PBA enables simultaneous detection of multiple heavy metal ions.•The mechanism of e-CuFe-PBA for HMIs detection is further explained.•Successful real-world application of e-CuFe-PBA in food safety analysis.
The ZIF-67-derived Cu-Co3O4 MCNS is successfully synthesized via the Lewis acid etching and microwave carbon bath. The mechanism of Cu-Co3O4 multichannel nanosheets for HMIs and glucose detection is ...further explained, and show a excellent performance of HMIs and glucose in apple juice and wine.
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•CMetal-doped Co3O4 nanosheets are prepared for the detection of small biological molecules.•Oxygen vacancy and multi-channel nanosheet structure enhance detection performance.•Cd(II), Pb(II) and glucose are successfully detected in apple juice and wine.•The mechanism of Cu-doped Co3O4 for HMIs and glucose detection is further explained.
Excessive small biological molecules such as Cd(II), Pb(II) and glucose in food pose a non-negligible threat to its inherent quality and human health, which makes it imperative to develop the highly sensitive sensor for Cd(II), Pb(II) and glucose detection. Metal cation-doped Co3O4 modified electrode materials have attracted vital interest in the electrochemical detection of Cd(II), Pb(II) and glucose because of their synergetic effect on Cu/Co and oxygen vacancies. Herein, a simple morphology and defect modulation strategy is proposed to synthesize multi-channel-like M-doped Co3O4 nanosheets (M = Cu, Mn, Fe, Ni, and Zn) via the Lewis acid etching process. The Cu/Co interaction and oxygen vacancies of Cu-Co3O4 multichannel nanosheets play an important role in the simultaneous detection of small biological molecules. The Cu-Co3O4 multichannel nanosheets exhibit the sensitivity of 20.59 µA µM−1 for Pb(II), 8.73 µA µM−1 for Cd(II) as well as 1613.86 µA mM−1 cm−2 for glucose, which is successfully applied in food applications such as apple juice and wine and maintain excellent stability and anti-interference. This design not only successfully constructs oxygen vacancies enriched M-Co3O4 multichannel nanosheets, but also demonstrates the application potential of electrochemical sensors in food safety.
Ultra-trace electrochemical determination of various heavy metal ions (HMIs) in water environment is of vital significance. Z-type heterojunction modified electrode materials have attracted vital ...interest in the electrochemical detection of HMIs because of its valence change and electron transfer capability. Herein, a facile and novel strategy is proposed to synthesize Co/CoO/Co3O4 polyvalent cobalt heterojunction via modified hydrothermal followed microwave carbon bath process. The strong valence change cycle of polyvalent cobalt (Co0, Co2+ and Co3+) plays a significant role in the electrochemical detection for Cd(II), Cu(II) and Hg(II) compared with other cobalt valence states according to the experiment characterizations and density functional theory (DFT) calculation. Co/CoO/Co3O4 exhibits the sensitivity of 4.31 μA/µM for Cd(II), 19.34 μA/µM for Cu(II) and 13.25 μA/µM for Hg(II), which are successfully applied in the real water environment and maintain excellent stability and anti-interference. The results of DFT calculations show that the adsorption energies of Co/CoO/Co3O4 heterojunction for Cu(II), Hg(II) and Cd(II) are − 1.147, − 1.016 and − 0.999 eV, respectively, showing an excellent adsorption capacity for HMIs. This design not only successfully constructs Z-type heterostructures with cobalt multivalence change cycle, but also demonstrates low cost and high efficient electrochemical sensors for simultaneous detection of HMIs.
•The Co/CoO/Co3O4 heterojunction is successfully synthesized.•The construction of Z-type heterojunctions can enhance the detection performance of HMIs.•Co0/Co2+/Co3+ multivalent interaction plays an important role in the detection of HMIs.
