H2O2 Electroreduction Research Articles

FeNi-MIL-88B-based electrochemiluminescence immunosensor for ultra-sensitive detection of CD44 protein via dual-quenching strategy

BackgroundCluster of Differentiation 44 (CD44) is considered an important biomarker for various cancers, and achieving highly sensitive detection of CD44 is crucial, which plays a significant role in tumor invasion and metastasis, providing essential information for clinical tumor diagnosis. Commonly used methods for analysis include fluorescence spectroscopy (FL), photoelectrochemical analysis (PEC), electrochemical analysis (EC), and commercial ELISA kits. Although these methods offer high sensitivity, they can be relatively complex to perform experimentally. Electrochemiluminescence (ECL) has gained widespread research attention due to its high sensitivity, ease of operation, effective spatiotemporal control, and close to zero background signal. ResultsIn this work, a sandwich-type ECL immunosensor for detecting CD44 was constructed using luminol as a luminophore. In this sensing platform, bimetallic MOFs (Pd@FeNi-MIL-88B) loaded with palladium nanoparticles (Pd NPs) were used as a novel enzyme mimic, exhibiting excellent catalytic performance towards the electroreduction of H2O2. The hybrids provided a strong support platform for luminol and antibodies, significantly enhancing the initial ECL signal of luminol. Subsequently, core-shell Au@MnO2 nanocomposites were synthesised by gold nanoparticles (Au NPs) encapsulated in manganese dioxide (MnO2) thin layers, as labels. In the luminol/H2O2 system, Au@MnO2 exhibited strong light absorption in the broad UV–vis spectrum, similar to the black body effect, and the scavenging effect of Mn2+ on O2•−, which achieved the dual-quenching of ECL signal. Under the optimal experimental conditions, the immunosensor demonstrated a detection range of 0.1 pg mL−1 − 100 ng mL−1, with a detection limit of 0.069 pg mL−1. SignificanceBased on Pd@FeNi-MIL-88B nanoenzymes and Au@MnO2 nanocomposites, a dual-quenching sandwich-type ECL immunosensor for the detection of CD44 was constructed. The proposed immunosensor exhibited excellent reproducibility, stability, selectivity, and sensitivity, and provided a valuable analytical strategy and technical platform for the accurate detection of disease biomarkers, and opened up potential application prospects for early clinical treatment.

Electrodeposition of CoFeS nanoflakes on Cu2O nanospheres as an ultrasensitive sensing platform for measurement of the hydrazine and hydrogen peroxide in seawater sample

Nanoarchitectured design of the metal sulfides with highly available surface and abundant electroactive centers and using them as electrocatalyst for fabricate the electrochemical sensors for the detection of hydrazine (N2H4) and hydrogen peroxide (H2O2) is challenging and desirable. Herein, Cu2O nanospheres powder is firstly prepared using chemical reduction of copper chloride and then drop-casted on the glassy carbon electrode (GCE) surface. In the next step, CoFeS nanoflakes are electrodeposited on Cu2O nanospheres by cyclic voltammetry method to form CoFeS/Cu2O nanocomposite as a detection platform for measuring N2H4 and H2O2. Accordingly, Cu2O nanospheres are not only used as substrate, but also guided the CoFeS nanoflakes to adhere to the electrode surface without need to any binder or conductive additive, which enhances the electrical conductivity of the sensing active materials. As the hydrazine sensor, the CoFeS/Cu2O/GCE displayed wide linear ranges (0.0001–0.021 mM and 0.021–1.771 mM), low detection limit (0.12 μM), very high sensitivities (103.33 and 21.23 mA mM−1 cm−2), and excellent selectivity. The as-made nanocomposite also exhibited low detection limit of 1.26 μM for H2O2 sensing with very high sensitivities (12.31 and 3.96 mA mM−1 cm−2) for linear ranges of 0.001–0.03 mM and 0.03–2.03 mM, respectively, and negligible response against interfering substances. The superior analytical performance of the CoFeS/Cu2O for N2H4 electro-oxidation and H2O2 electro-reduction can be attributed to structure stability, high electroactive surface area, and good availability to analyte species and electrolyte diffusion. Moreover, to examine the potency of the prepared nanocomposite in real applications, the seawater sample was analyzed and results display that the CoFeS/Cu2O/GCE can be utilized as a reliable and applicable platform for measuring N2H4 and H2O2.

A hemin/rGO/MWCNT nanocomposite-based dual signal electrochemical aptasensor for sensitive detection of NSE.

Neuron-specific enolase (NSE), a tumor marker of small cell lung cancer (SCLC), has high application value in the early diagnosis of SCLC. In this study, a dual signal electrochemical aptasensor for NSE was constructed based on hemin/reduced graphene oxide/multi-walled carbon nanotube (H-rGO-MWCNT) nanocomposites. Hemin played a dual role, functioning not only as an in situ electrochemical probe but also exhibiting excellent peroxidase-like properties, effectively catalyzing the electroreduction of H2O2. Reduced graphene oxide and multi-walled carbon nanotubes exhibited excellent conductivity. Through their binding with hemin, the nanocomposites achieved a larger specific surface area, providing numerous active sites for capturing the NSE aptamer. In the presence of NSE, the specific adsorption between the antigen and the aptamer formed a stable antigen-aptamer structure, which inhibited the performance of hemin, resulting in the weakening of the electrochemical signals of hemin and H2O2. Leveraging these characteristics, the sensitive and cost-effective dual-signal electrochemical aptasensor has been fabricated for the detection of NSE. One signal corresponded to differential pulse voltammetry (DPV) of hemin, while the other signal was derived from chronoamperometry, capturing the catalytic reduction of H2O2. The linear ranges for NSE were 1 pg mL-1 to 1 μg mL-1 and 100 pg mL-1 to 100 ng mL-1 with the limit of detection (LOD) of 0.21 pg mL-1 and 11.22 pg mL-1 by DPV and chronoamperometry, respectively. In addition, this aptasensor exhibited good reproducibility, stability and specificity. The recovery of NSE in human blood serum samples was from 89% to 131%. It provided a promising strategy for the detection of NSE in clinical diagnostics.

Metallic Ir-decorated iridium oxide nanofibers with programmable performance towards non-enzymatic detection of hydrogen peroxide

Hydrogen peroxide (H2O2) is an essential biomolecule in various fields, including clinical control and environmental protection. This present work reports a design of a non-enzymatic H2O2 electrochemical sensor. The metallic Ir-decorated iridium oxide nanofibers (IrO2@Ir NFs) are prepared using the electrospinning process followed by annealing at different temperatures (500–900 °C). The resultant materials are characterized through field emission scanning electron microscopy, X-ray diffraction analysis, and X-ray absorption spectroscopy. Furthermore, the electrochemical sensing performance of the IrO2@Ir NFs electrode is evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometric (i-t) techniques. The sensitivity of the IrO2@Ir NFs modified screen-printed electrode (SPCE) is checked to investigate the effect of annealing temperature on the H2O2 sensing. The performance of the nanofibers in the electro-reduction of H2O2 is programmable by controlling the metallic Ir contents. The IrO2@Ir NFs electrode annealed at 600 °C (IrO2@Ir-600 °C NFs) exhibits better electrocatalytic activity towards the electro-reduction of H2O2. Further, the broad linear range (0.1–1000 µM), low detection limit (LOD) of 0.16 µM with a higher sensitivity of 289 μA/cm2·mM is successfully achieved. Additionally, the IrO2@Ir-600 °C NFs modified SPCE has appreciable selectivity in the presence of potentially interfering biological molecules and the practical applicability was demonstrated in MCF-7 human breast cancer cells.

Carbon Nanotube-Supported Bimetallic Core-Shell (M@Pd/CNT (M: Zn, Mn, Ag, Co, V, Ni)) Cathode Catalysts for H2O2 Fuel Cells.

M@Pd/CNT (M: Zn, Mn, Ag, Co, V, Ni) core-shell and Pd/CNT nanoparticles were prepared by sodium borohydride reduction and explored as cathode catalysts for the hydrogen peroxide reduction reaction. Electrochemical and physical characterization techniques are applied to explore the characteristics of the produced electrocatalysts. The cyclic voltammetry (CV) experiments show that Zn@Pd/CNT-modified electrodes have a current density of 273.2 mA cm-2, which is 3.95 times higher than that of Pd/CNT. According to the chronoamperometric curves, Zn@Pd/CNT has the highest steady-state current density for the H2O2 electro-reduction process among the synthesized electrocatalysts. Moreover, electrochemical impedance spectroscopy (EIS) spectra confirmed the previous electrochemical results due to the lowest charge transfer resistance (35 Ω) with respect to other electrocatalysts.

Rational design of Ti3C2 MXene nanocomposite with bromophenol blue for efficient signal amplification: Sensitive electrochemical detection of cardiac troponin I in patient plasma

Today, although a new generation of two-dimensional (2D) MXenes has received considerable interest throughout several fields, the rational design of MXene-based nanocomposites and their particular applications in biosensors remain serious challenges. Herein, to avoid etched-loosely accumulated accordion-like structure of Ti3C2 MXene to restacking, delamination was conducted using bromophenol blue (BPB), which makes the resulting BPB@Ti3C2 nanocomposite as an ideal nanolable for ultrasensitive detection of acute myocardial infarction (AMI) biomarker (cardiac troponin I, cTnI). For this purpose, after sandwiching the cTnI between covalently-bonded Tro4 aptamer on the BPB@Ti3C2 and MNPs/Tro6, the electrocatalytic activity of the nanolabel towards H2O2 was followed as a tracer signal. Owing to i) high effective surface area for immobilization of the Tro4 and ii) large electrocatalytic activity of the BPB@Ti3C2 for electroreduction of H2O2, along with iii) enrichment characteristic of the MNPs/Tro6, as well as iv) the synergistic-assisted signal amplification between the Ti3C2 and BPB, high sensitive detection of cTnI has been introduced. The developed biofunctionalized BPB@Ti3C2 exhibits a wide dynamic range of 200 fg mL−1-250 ng mL−1 with a low detection limit of 20 fg mL−1. The aptasandwich form was used to quantify the cTnI in the human blood plasma of cardiovascular patients, above 90% clinical sensitivity, providing a promising strategy for clinical diagnosis and biochemistry research.

Carbon fiber cloth loaded core-shell structured Pd@AgCl-Ag as an efficient bifunctional electrode for direct hydrogen peroxide-hydrogen peroxide fuel cells

A bifunctional Pd@AgCl-Ag/O-CFC electrode was prepared on oxidized carbon fiber cloth (O-CFC) by hydrothermal method and Galvanic reaction and used for catalytic H2O2 reduction reaction (HPRR) and oxidation reaction (HPOR). The catalyst on electrode surface presents a particular core-shell structure with Ag and AgCl as the core and Pd and AgCl as the shell, facilitating the synergistic interaction between the bimetals and the exposure of the primary active substance of Pd. The Pd@AgCl-Ag/O-CFC electrode exhibited excellent catalytic performance for both HPRR and HPOR with current densities of − 733.3 mA cm−2 and 708.0 mA cm−2, respectively. For the kinetic study, the activation energy of HPRR catalyzed by the Pd@AgCl-Ag/O-CFC electrode was low (7.59 kJ mol−1), and both the electroreduction and electrooxidation reaction processes were controlled by a hybrid of substance diffusion and kinetics. The electroreduction and electrooxidation reactions of H2O2 on the surface of the Pd@AgCl-Ag/O-CFC electrode are both irreversible processes, and their reaction levels are 1 and 0.5, respectively. The direct hydrogen peroxide-hydrogen peroxide fuel cell (DPPFC) was assembled with Pd@AgCl-Ag/O-CFC as a bifunctional electrode, and the open circuit potential reached 0.75 V and power density reached 61.9 mW cm−2 at 338.15 K. In addition, due to the stability of the structure and catalytic performance of the Pd@AgCl-Ag/O-CFC electrode, the DPPFC can operate stably for a long time. This work indicates that the as-prepared Pd@AgCl-Ag/O-CFC can be a promising electrode for DPPFC.

Bifunctional Zinc-Molybdate or Zinc molybdenum Oxide/Metal-Nitrogen-Carbon catalytic layers with improved four-electron selectivity for oxygen reduction in acidic medium

Platinum-group-metal-free metal-nitrogen-carbon catalysts for the oxygen reduction reaction have demonstrated high initial activity and power performance in proton exchange membrane fuel cells. The main challenge facing this class of catalysts is their poor durability in operating acidic fuel cells. Their key operando degradation mechanisms involve oxidative attacks triggered by the catalysis of the oxygen reduction on atomically-dispersed 3d transition metals. Reactive oxygen species such as H2O2 or radical species are particularly aggressive to the carbon matrix. Minimizing H2O2 by-product formation during oxygen reduction or actively scavenging any formed H2O2 are therefore promising routes to improve their durability.Here, we report that Zn-molybdate and Zn molybdenum oxide have low activity towards H2O2 decomposition and electro-reduction in acid, but result in a strong synergistic effect with various M-N-C catalysts. The addition of α-ZnMoO4 or Zn3(OH)2(MoO4)2 in cathode layers resulted in improved four-electron ORR selectivity of M-N-C catalysts (M = Fe, Co, Cr) as well as moderately improved durability in accelerated stress tests in O2-saturated pH 1 electrolyte. The improvement in selectivity could be rationalized by hydrogen peroxide electro-reduction measurements and catalase enzyme-like activity tests. Both types of measurements revealed higher reactivity towards H2O2 scavenging when Metal-N-C catalysts are physically mixed (in a catalytic layer) or together in a suspension in solution with Zn-molybdate or Zn molybdenum oxide, revealing a synergy effect. Control experiments with ZnCl2 and Na2MoO4 salts however suggest that leached ions from ZnMoO4 in acidic solution are likely at the root of the synergy effect.

A Conductive Metal−Organic Framework Based on Triptycene Ligand: An Effective Electrochemical Sensor for Glucose and H2O2 Detection in Food and Human Serum

Triptycenes (TT) scaffolds have emerged as attractive organic ligands for the synthesis of MOF electrocatalytic materials because their characteristic rigid trigonal topology interferes with close molecular packing, thus favoring the formation of open structures with significant volume available for the inclusion of guests. In this work, a novel conductive metal-organic framework based on 2, 3, 6, 7, 14, 15-hexahydroxytriptycene (Cu-HHTT) is synthesized in situ by a simple hydrothermal method. As an bifunctional electrocatalyst for efficient glucose electrooxidation and H2O2 electroreduction in alkaline and neutral electrolytes, the non-enzymatic electrochemical sensor has a sensitivity of 47200 mA μM−1 cm−2 and 5170 mA μM−1 cm−2 to glucose and H2O2 with detection limits of 0.16 μM and 0.54 μM (S/N = 3) respectively, and successfully used in the detection of actual serum, orange juice and milk samples. The method provides a new idea for the preparation and application of MOF materials based on triptycene scaffolds.

Synthesis of Bimetallic Ni-Co Phosphide Nanosheets for Electrochemical Non-Enzymatic H2O2 Sensing

NiCoP nanosheets (NSs) were successfully synthesized using the hydrothermal and high-temperature phosphorization process. The obtained NiCoP NSs were immobilized on a glassy carbon electrode (GCE) and used to construct a novel sensing platform for electrochemical non-enzymatic H2O2 sensing. Physicochemical characteristics of NiCoP NSs were obtained by field-emission scanning electron microscopy (FESEM), field-emission transmission electron microscope (FETEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the electrochemical properties of NiCoP NSs were obtained by cyclic voltammetry (CV) and chronoamperometry (CA) towards the non-enzymatic detection of H2O2. FESEM and FETEM images provided a morphological insight (the unique nanosheets morphology of NiCoP) that could expose more active sites to promote mass/charge transport at the electrode/electrolyte interface. XRD and XPS results also confirmed the crystalline nature of the NiCoP nanosheets and the coexistence of multiple transitional metal oxidation states in NiCoP nanosheets. These unique physicochemical characteristics had a degree of contribution to ensuring enhancement in the electrochemical behavior. As a result, the synthesized NiCoP NSs composed of intercalated nanosheets, as well as the synergistic interaction between bimetallic Ni/Co and P atoms exhibited excellent electrocatalytical activity towards H2O2 electroreduction at neutral medium. As the results showed, the electrochemical sensing based on NiCoP NSs displayed a linear range of 0.05~4 mM, a sensitivity of 225.7 μA mM-1 cm-2, a limit of detection (LOD) of 1.190 μM, and good selectivity. It was concluded that NiCoP NSs-based electrochemical sensing might open new opportunities for future construction of H2O2 sensing platforms.

Insights into the effects of pulsed parameters on H2O2 synthesis by two-electron oxygen reduction under pulsed electrocatalysis

Pulsed electrocatalysis is emerging as a promising strategy for the improvement of electrocatalytic performance. Herein, the 2-electron oxygen reduction reaction (2eORR) for H2O2 synthesis was taken as a model reaction to explore the effects of pulsed parameters on electrocatalysis. Firstly, the key parameters of a square wave pulse were determined by theoretical analysis and electrochemical testing. Secondly, we found that the pulsed period of the square wave pulse should be neither too short nor too long due to the opposing effects of non-Faradaic and diffusion processes. The lower duty ratio was more favorable for 2eORR. Finally, the effects of the pulsed waveform were explored. We found that the enhanced effects on 2eORR under the rapid sweep potential of a triangular or sine wave were similar to those for a square wave with a short period. Under a sine wave pulse with a frequency of 0.2 Hz, the H2O2 production rate and Faradaic efficiency of 2eORR were increased by 1.4 times and 3.62 times, respectively, compared with the results obtained under constant potential, and the energy consumption was reduced by 75 %. The enhanced effects described above could be attributed to the diffusion layer becoming thinner while the pulsed potential was applied. The reaction rate was increased by the diffusion of reactants (i.e., O2, H+) to the electrode surface and the intrinsic selectivity of 2eORR was increased by the oxygen-rich environment. In addition, the ineffective electroreduction of H2O2 was also reduced by the diffusion of H2O2 toward the bulk solution. This work provides new insights into the determination of parameters, waveform effects and the mechanism of pulsed electrocatalysis.

Synthesis and Catalytic Studies of Nanoalloy Particles Based on Bismuth, Silver, and Rhenium

The work reports the synthesis and characterization of ternary nanoalloy catalysts of silver, bismuth, and rhenium from alkaline solutions containing L–cysteine as a complexing agent and sodium borohydride as a reducing agent. UV–Vis spectra and dynamic light scattering (DLS) analyses of the obtained colloids were performed. Additionally, high-resolution transmission electron microscope (HR–TEM) analysis assisted the former investigations. The influence of a stabilizer (PVA) was demonstrated for bismuth nanoparticles reaching an average size of 8 nm with PVA, whereas they grew large, 514 nm, in the case of synthesis without stabilizing agent. AgReBi nanoalloy particles reach an average size of 19 nm with PVA. The presence of two absorption maxima in the UV–Vis spectrum suggests shape anisotropy of these nanoparticles. TEM micrographs demonstrate the crystal structure of AgReBi nanoparticles. Cyclic voltamaperometry allows for deciphering of the catalytic properties for hydrogen peroxide electro-reduction. Both bismuth and AgReBi nanoalloy catalysts showed relatively high catalytic activity in H2O2 electro-reduction in the amperometric tests.

Spider chrysanthemum-like Co flowers on a Ni foam for highly efficient H2O2 electroreduction in alkaline media

Transition metal oxides have shown potential as hydrogen peroxide (H2O2) reduction catalysts because of their low cost, good catalytic properties, and excellent stability in alkaline solutions. In this study, a CNF-0.25 composite electrode comprising spider chrysanthemum-like Co flowers on a Ni foam is synthesized as an efficient cathode for H2O2 electroreduction in alkaline media. CNF-0.25 exhibited superior stability and highly desirable electrocatalytic properties for H2O2 reduction with a high current density of 0.42 A cm−2 at − 0.5 V. The voltage of an Al-H2O2 semi-fuel cell prepared using CNF-0.25 as the cathode remains stable during a 50 h discharge test. The specific mechanism for the promotion of H2O2 electroreduction using CNF-0.25 is investigated according to the mechanism of H2O2 reduction over a cobalt-based catalyst. The spider chrysanthemum-like Co flowers are mainly composed of metallic Co, which improves the conductivity of the electrode. On the surface of the metallic Co, the presence of a layer of cobalt oxides or hydroxides provides sufficient catalytic active sites (Co2+/Co3+) and prevents further oxidation of internal Co. In addition, the unique spider chrysanthemum-like structure of CNF-0.25 increases the specific surface area of the electrode and facilitates electrolyte transport. This work offers another approach for designing highly efficient transition metal oxide electrodes in alkaline media.

Investigation to the impact of mutual interactions between CdS sensitized TiO2 and integrated Hemoglobin on the catalysis of H2O2 Electro-reduction

The complex of nano-TiO2 core wrapped by CdS outer shell as hemoglobin (Hb) supporter was proposed to prepare Hb based electrode. The multiple techniques were employed to study the influence of mutual interactions between nano-complex and integrated Hb on the electro-catalytic function on H2O2 reduction and the utilization efficiency of illumination of Hb based electrode. The experimental results implied that the moderate combination of Hb with CdS would lead to the formation of the intermediate species. The intermediate species would dominate the redox process of Hb based electrode with appropriate electron shuttle rate of ∼ 0.45 s−1. The combination of Hb with CdS would cripple its electro-catalytic performance on H2O2 reduction with high detection limit of 18.9 μM. The substrate diffusion process could be identified as the key factor in determining the catalytic efficiency of Hb based electrode. The as-prepared Hb based electrode is sensitive to the visible illumination.

Unveiling the effect of gas treatment on the electronic structure of carbon nanotube-supported Pd catalysts for electroreduction of H2O2 and Heck reaction

This study explored the impact of gas treatments on the structures of multi-walled carbon nanotubes supported Pd (CNT-Pd) catalysts used for electrocatalytic H2O2 reduction and the Heck cross-coupling reaction. The CNT-Pd catalyst was prepared by anchoring Pd nanoparticles on thiolated CNTs. XPS was conducted to examine the surface composition and electronic structure changes of the CNT-Pd catalyst before and after gas treatment. The XPS results revealed that as-prepared CNT-Pd contains at least two different oxidation states on the surface, whereon their proportions depend on the gas used for treatment. Treatment with H2 leads to Pd(0) enrichment near the surface, while O2 treatment causes Pd(Ⅱ) enrichment of CNT-Pd. All catalysts containing both Pd(0) and Pd(Ⅱ) were active toward H2O2 reduction, and the Heck cross-coupling reaction of n-butyl acrylate and 4-iodotoluene; increased proportion of metallic Pd(0) boosted the catalytic reaction. However, the catalyst stability increased as the amount of Pd(II) increased.

High efficiency N/C foam supported Pd electrode for direct sodium borohydride-hydrogen peroxide fuel cell

A bi-functional electrode material of self-supporting N-doped C foam grown Pd nanoparticles (Pd@N/C-8 foam) for NaBH4 electrooxidation and H2O2 reduction reaction is successfully prepared. The Pd@N/C-8 foam electrode is fabricated by sacrificial template synthesis of N/C foam followed by 8 repetitive Pd impregnation reduction cycles. The Pd@N/C-8 foam electrode exhibits an extraordinary catalytic performance (642 mA cm−2 at −0.2 V) in 2 mol L−1 NaOH and 0.3 mol L−1 NaBH4, which is due to the large electrochemical active surface area, low activation energy (Ea = 10.34 kJ mol−1) and 60.83% utilization efficiency of NaBH4. Besides, its catalytic density for H2O2 electroreduction reaches 648 mA cm−2 at −0.2 V in 2 mol L−1 H2SO4 +1.3 mol L−1 H2O2. The kinetic parameters show that the electrooxidation of BH4− and the electroreduction of H2O2 on Pd@N/C-8 foam electrode are first-order reactions, and the number of transferred electrons are 5.8 and 1.56, respectively. Further exploration of Pd@N/C-8 foam electrode on the direct sodium borohydride-hydrogen peroxide fuel cell (DBHPFC) displays the maximum power density of 137 mW cm−2 and a superior stability. In view of the excellent performance, Pd@N/C foam will be a highly efficient electrode material of DBHPFC.

The Catalytic Effect on H2O2 Electro-Reduction of an Electrode Based on MOF Material ZIF-8 as Hemoglobin Supporter via Hydrogen Bond Interaction

The Catalytic Effect on H2O2 Electro-Reduction of an Electrode Based on MOF Material ZIF-8 as Hemoglobin Supporter via Hydrogen Bond Interaction

Facile construction of a novel binder-free graphene/polyimide foam-based Au electrode for H2O2 electroreduction

Fuel cells have described their potential applications for novel-generation energy storage/conversion devices. Herein, an original 3D Au/reduced graphene oxide(RGO)@Polyimide(PI) foam (denoted as 3D ARP) electrode was constructed via a facile reduced graphene oxide and metal Au simultaneous in situ reduction and self-assembling process on the PI foam. The PI foam support material, modified with RGO nanosheets and well-dispersed Au nanoparticles, exhibits distinctive structural, ensuring a significant promotion towards hydrogen peroxide (H2O2) electroreduction under acid conditions. Such an open 3D hierarchical structures may provide a number of exposed catalytic activity sites and generate interconnected channels between solid and liquid interface for highly efficient mass transport. The electroactivity of 3D ARP electrode was systemically investigated by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) measurements. Results indicate that the as-developed electrode presented an impressive electrocatalytic behavior. As expected, the 3D ARP electrode displayed an optimized reduction current density in acid media (880 mA cm−2 at - 0.2 V). What's more, the obtained 3D ARP electrode still represented robust stability, a small apparent activation energy value (11.442 kJ mol−1), good reproducibility and repeatability (840 mA cm−2 after 1000 cycles with a 0.0053% current density decay per cycle at - 0.2 V). Such an original catalytic electrode might be an alternative for novel energy transformation systems.

Investigation on impact of mutual interactions between elements of Ag nano-particle core-MOF material shell nano-complex and incorporated hemoglobin on electro-catalysis on H2O2 electro-reduction

Investigation on impact of mutual interactions between elements of Ag nano-particle core-MOF material shell nano-complex and incorporated hemoglobin on electro-catalysis on H2O2 electro-reduction

Construction of free-standing electrode anchored on polyimide foam with a facile synergistic strategy for enhancing hydrogen peroxide reduction electrocatalysis

A rational design and selection of electrocatalytic cathode host materials are significant to achieve sustainable, efficient and stable catalysis towards H2O2 electroreduction. Herein, we described a facile synergetic strategy to generate a novel free-standing electrode (Pd-Co3O4/3D RGO@polyimide (PI) foam, PCRP) with well-developed porous and hollow structure, which derived from cobalt-based MOFs (ZIF-67) as an advanced Pd host, rooting on the 3D conductive graphene/PI foam to realize the significant promotion towards H2O2 electroreduction. Such 3D hollow structure design not only offers a high specific area to develop a number of exposed catalytic activity sites but also restricts the aggregation of nanoparticle catalysts within catalysis. Utilizing the electrode structural advantages and reducing the particle diameter of noble metal catalysts to improve the catalytic performance was possible. When evaluated as a co-catalyst for H2O2 electroreduction, the as-developed electrode displayed an optimized reduction current density of 962 mA·cm−2 at −0.8 V in alkaline due to the synergetic influence of Pd nanoparticles and Co3O4 hollow cages. Notably, the loading of noble metal on the PCRP electrode was only close to 2.0 wt% in Pd-Co3O4 hybrids. What's more, the obtained PCRP electrode also exhibited robust stability, low apparent activation energy (9.071 kJ·mol−1), good reproducibility and repeatability (903 mA·cm−2after 1000 cycles with a 0.0058% current density decay per cycle at −0.8 V) superior to that of single Co3O4 nanoparticles or Co3O4/3D RGO hybrids with simple configuration, implying its great promise for novel energy transformation systems.