Bifunctional Electrocatalysts Research Articles

A facile dual isolation and protection strategy for preparation of PtFe intermetallic compound in biomass-derived carbon with high activity and durability for pH-universal bifunctional electrocatalysts

A facile dual isolation and protection strategy is developed to prepare PtFe intermetallic electrocatalyst (PtFe–N–C@bioC) on porous biomass carbon (bioC) derived from peanut shell. In preparation, meso-tetraphenylporphyrine (H2TPP) together with platinum (II)-tetraphenylporphyrin (PtTPP) are in-situ fabricated on the porous peanut shell-derived bioC matrixes and then further absorbed Fe (III) tetraphenyl porphyrin (FeTPP) molecules through π−π interactions between PtTPP/H2TPP and FeTPP to form a mixed precursor of FeTPP/PtTPP/TPP-bioC. Upon pyrolysis of FeTPP/PtTPP/TPP-bioC, PtFe bimetallic-containing N-doped carbon formed on bioC (PtFe–N–C@bioC). The resultant PtFe–N–C@bioC showed excellent oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) activity across a wide pH range. In particular, under alkaline medium, PtFe–N–C@bioC shows the ORR performance with an onset potential (Eonset) of 0.989 V, a half-wave potential (E1/2) of 0.901 V and a limiting current density (JL) of −6.214 mA cm−2. Meanwhile, PtFe–N–C@bioC delivers an enhanced mass activity (1.197 A mg−1Pt), which is 13 times larger than commercial Pt/C. For HER, PtFe–N–C@bioC shows an impressive overpotential (η10) of 17 mV at a current density of 10 mA cm−2 under acidic medium. Further, it is applied to Zn-Air batteries with a power density performance of 98.7 mW cm−2 and good durability.

Biosynthesis of CuFe2O4@Ag hybrid nanocomposite: Ultrasensitive detection and catalytic reduction of 4-nitrophenol

Due to the dearth of extremely capable, sensitive, and stable catalysts, the efficient detection and catalytic removal of 4-nitrophenol (4-NP) in industrial wastewater remains a serious challenge. The detection and determination of 4-nitrophenol (4-NP) presence in the environment is a matter of paramount importance because it is a high-priority hazardous pollutant that can affect people, animals, and plants. Here, we present a promising and economically viable green synthetic route for fabricating CuFe2O4 and CuFe2O4@Ag hybrid nanocomposites from the leaf extract of Senna didymobotrya. The UV–Vis, FTIR, XRD, FE-SEM, EDXA, BET and VSM analysis were performed to characterize the synthesis of CuFe2O4@Ag nanocomposite. To evaluate the electrocatalytic capacity of CuFe2O4@Ag, electrochemical sensing stratergy was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified CuFe2O4@Ag glassy carbon electrode (GCE) (CuFe2O4@Ag/GCE) demonstrated a linear response in the range of 0.01-15 μg/ml (71 nm-107 μM) and the ability to detect 4-NP at low concentration (0.006 μg/ml (43 nM)). Due to the increased surface area of CuFe2O4@Ag/GCE by ̴ 1.5-fold, a greater cathodic current response (-16 μA/cm2) at a low potential of -0.81 V was observed compared to CuFe2O4/GCE alone for the detection of 4-NP. Additonally, CuFe2O4@Ag showed excellent reduction ability towards 4-NP using NaBH4 with an efficiency of 96.4 % which was higher than the CuFe2O4 (only 87.3 %) in 12 min due to the synergistic relationship among Ag NPs and CuFe2O4 nanostructures. The outcomes from this study shows that the bi-functional electrocatalyst holds vast potential for environmental remediation.

Sustainable energy generation: High-performance NiCo2S4@S-g-C3N4 bifunctional electrocatalyst advances water splitting efficiency

Efforts to create cost-effective electrocatalysts from abundant materials, for the utilization of water electrolysis reactions, are viewed as promising sources for sustainable clean energy generation. This article describes the synthesis of cobalt sulphide (CoS) nanoparticles using a straightforward and environmentally friendly one-pot hydrothermal process. The series of nickel-doped CoS (NiCo2-x S4) introduced with varying the weight percentage of Ni (1, 2, 4, 8, 6, and 10 wt%), and the composite Ni-dopped CoS on varying the weight percentage (10, 30, 50, 70, and 90 wt %) of sulfur-doped graphitic carbon nitride (NiCo2S4@S-g-C3N4) was created. Utilizing X-ray diffraction analysis (XRD), EDS, FTIR, and scanning electron microscopy (SEM) synthesized electrocatalysts were characterized. Doped with Fluorine After being changed with an electrocatalyst, tin oxide was used as the working electrode to monitor the electrochemical activity of the whole water splitting process using chronopotentiometry, cyclic voltammetry (CV), linear sweep voltammetry (LSV), and EIS. NiCo2S4@S-g-C3N4 exhibited higher electrocatalytic performance with an overpotential 370 mV for OER and 415 mV for HER at the current intensity of 10 mAcm−2. Transition metal sulfide electrocatalysts exhibit good electrolytic performance, due to their high surface areas and intrinsically high catalytic activity. These findings suggest that the NiCo2S4@S-g-C3N4 composite possesses a significant role for use in energy conversion and energy storage applications.

NiMn layered double hydroxides with promoted surface defects as bifunctional electrocatalysts for rechargeable zinc–air batteries

Layered double hydroxides (LDHs) are attractive bidimensional materials for electrochemical applications because of their high activity in the oxygen evolution reaction (OER). However, their limited bifunctionality due to the slow kinetics of the oxygen reduction reaction (ORR) is a bottleneck for their use in secondary Zn-air batteries (ZABs). In this work, cobalt-free NiMn LDHs were rationally designed by optimizing the Ni composition and incorporating surface defects onto the LDH (oxygen vacancies, Ov) while performing interface engineering using a carbonaceous support enriched with nitrogen heteroatoms. The LDHs without induced defects presented the optimal activity for the OER at a 3:1 Ni/Mn atomic ratio (onset potential 1.47 V vs. 1.45 V for IrO2/C), while the ORR was unfavorable. However, the further optimization by introducing Ov and N–heteroatoms (labeled as Ov-NiMn LDH/NCNTG) allowed bifunctionality by improving the onset potential to 0.90 V while decreasing the half-wave potential difference from 180 mV for the material without induced defects to 100 mV, and by improving the limiting current density by a factor of two. In this regard, density of states (DOS) calculations suggested that surface defects improved the electronic transfer while decreasing the oxygen adsorption energy. ZAB tests indicated that the interface-engineered material allowed a battery voltage of 1.47 V, and a power density of 64 mW cm−2. The battery also maintained stability over 180 charge/discharge cycles at 10 mA cm−2 (50 h), with ΔV below 150 mV between the initial and final cycles.

Mo-doped SrCo0.5Fe0.5O3-δ perovskite oxides as bifunctional electrocatalysts for highly efficient overall water splitting

Perovskite oxides with high electrocatalytic activities and cost-effectiveness can be developed by rational doping. Here, we fabricate a series of perovskite oxides comprising SrCo0.5Fe0.5-xMoxO3-δ (x = 0, 0.05, 0.10, 0.15) doped with different proportions of Fe and Mo elements to enhance the long-term stabilities and electrocatalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Among them, SrCo0.5Fe0.4Mo0.1O3-δ (SCFM10) exhibits the optimum electrocatalytic activity for water splitting, exhibiting overpotentials at −10 mA cm−2 and 10 mA cm−2 of ∼200 mV for HER and ∼310 mV for OER, respectively, generating a current density of 10 mA cm−2 using only 1.68 V in a two-electrode electrolytic cell. Additionally, SCFM10 demonstrates outstanding stability, maintaining continuous operation for 100 h without visible decay. These results give some new points of view into the development of bifunctional catalysts for the purpose of efficient water splitting in a sensible way.

Aluminium, Nitrogen-Dual-Doped Reduced Graphene Oxide Co-Existing with Cobalt-Encapsulated Graphitic Carbon Nanotube as an Activity Modulated Electrocatalyst for Oxygen Electrocatalyst for Oxygen Electrochemistry Applications.

There is a rising need to create high-performing, affordable electrocatalysts in the new field of oxygen electrochemistry. Here, a cost-effective, activity-modulated electrocatalyst with the capacity to trigger both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in an alkaline environment is presented. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with cobalt-encapsulated carbon nanotube units. Based on X-ray Absorption Spectroscopy (XAS) studies, it is established that the superior reaction kinetics in Al, Co/N-rGCNT over their bulk counterparts can be attributed to their electronic regulation. The Al, Co/N-rGCNT performs as a versatile bifunctional electrocatalyst for zinc-air battery (ZAB), delivering an open circuit potential ≈1.35V and peak power density of 106.3mWcm-2, which are comparable to the system based on Pt/C. The Al, Co/N-rGCNT-based system showed a specific capacity of 737mAhgZn -1 compared to 696mAhgZn -1 delivered by the system based on Pt/C. The DFT calculations indicate that the adsorption of Co in the presence of Al doping in NGr improves the electronic properties favoring ORR. Thus, the Al, Co/N-rGCNT-based rechargeable ZAB (RZAB) emerges as a highly viable and affordable option for the development of RZAB for practical applications.

Phosphorus-doped nickel cobalt oxide (NiCo2O4) wrapped in 3D hierarchical hollow N-doped carbon nanoflowers as highly efficient bifunctional electrocatalysts for overall water splitting

Properly design and fabricate capable electrocatalysts with 3D hierarchical hollow framework to realize cost-effective and efficacious overall water splitting (OWS) are particularly meaningful for the large-scale arrangement of pivotal energy technology. In this study, P-doped NiCo2O4 nanoparticles encapsulated in N-doped carbon hierarchical hollow nanoflowers (P-NiCo2O4@NCHHNFs) were constructed using the hydrothermal-pyrolysis-phosphorization approach. This fascinating architecture can not merely serve as a conductive pathway for electron transfer, but at the same time effectively inhibited the aggregation and corrosion of the NiCo2O4 nanoparticles. Additionally, the P doping not only regulates electronic structure configuration to boost the intrinsic activity of the catalyst, but also enhance electrochemical surface areas to reveal more accessible active sites. Attributing to these characteristics, the as-prepared P-NiCo2O4@NCHHNFs exhibit preeminent electrocatalytic performance with low overpotentials of 283 mV and 162 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) (at 10 mA cm−2), respectively. Specifically, by using the P-NiCo2O4@NCHHNFs as bifunctional catalysts, a low potential of 1.56 V (at 10 mA cm−2) is sufficient to drive overall water splitting with splendid durability. This study proposed an innovative strategy for the conceiving and fabricating high-performance catalysts via heteroatom-doping.

Multi-Active Sites Loaded NiCu-MOF@MWCNTs as a Bifunctional Electrocatalyst for Electrochemical Water Splitting Reaction.

Water can be sustainably and ecologically converted by electrocatalysts into hydrogen and oxygen, which, in turn, can be converted into energy. However, the advancement of using water as green energy is hampered by limitations in the study of high-performance catalysts. The purpose of this study was to construct an electrocatalyst by anchoring well-dispersed multiwalled carbon nanotubes (MWCNTs) on nickel-copper (NiCu-MOF) nanoblocks through a simple solvothermal method. The synthesis of NiCu-MOF@MWCNTs demonstrated exceptional electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. At 10 mA cm-2 in 1.0 M KOH, the OER and HER performance of the catalyst displays a relatively low overpotential, with only 220 and 78 mV, respectively. Furthermore, the catalytic activity remained unchanged for 24 h in 1.0 M KOH. This performance was superior to the majority of electrocatalysts that have been reported. This was achieved by utilizing the strong synergy that exists between MWCNTs and bimetallic (Ni-Cu) nano blocks present in the metal-organic framework. The enhanced electrocatalytic activity of the nanocomposite can be attributed to the synergistic impact caused by its various components.

Transient potential oscillation-driven vertically-aligned cobalt hydroxide nanosheet as non-noble bifunctional electrocatalyst for water splitting

Transient potential oscillation-driven vertically-aligned cobalt hydroxide nanosheet as non-noble bifunctional electrocatalyst for water splitting

FeNi alloys incorporated N-doped carbon nanotubes as efficient bifunctional electrocatalyst with phase-dependent activity for oxygen and hydrogen evolution reactions

Electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are two important half-cell reactions for overall water splitting. The rational design and fabrication of efficient electrocatalysts involving nonprecious-metals and carbon matrix is highly attractive. Herein, a series of N-doped carbon nanotubes encapsulated FeNi alloy nanoparticles (FeNi@NCNTs) are synthesized via a simple pyrolysis treatment of Fe-doped Ni(OH)2 precursors under the assistance of dicyandiamine source. The results reveal that the Fe/Ni ratio has an obvious influence on the morphology and phase composition of FeNi@NCNTs series, thus affecting the electrocatalytic performance. The highest electrocatalytic activity is achieved for the Fe1Ni4@NCNTs product with a Fe/Ni molar ratio of 1:4, which delivers low overpotentials of 278 and 279 mV for OER and HER at 10 mA cm−2 in 1.0 mol/L KOH, respectively. The intriguing electrocatalytic performance is mainly ascribed to the advantageous integration of rambutan-like hierarchically porous structure and composition optimization, significantly facilitating the fast mass/charge transfer as well as promoting the adsorption ability for intermediates. The present method may open a facile avenue for developing cost-effective, high-activity, and stable electrocatalysts for the application of overall water splitting.

Ni-Fe-P/Co-W: Nested heterostructures and multi-transition metal synergistic effect optimizing overall water splitting performance

Recently, the application of multi-component transition alloy catalysts in the water splitting field has been a popular development trend. In this work, we have proposed a multi-alloy catalyst for in-situ synthesis of nested multilayer heterostructure Co-W on Ni-Fe-P by electrodeposition way. The heterogeneous interfaces brought by the nested heterogenous structure expose abundant active sites on the catalyst, effectively enhancing the catalytic performance. Moreover, the synergistic effect of five elements (Ni, Fe, P, Co, and W) in the electrocatalysts improves electron transfer efficiently. By adjusting the proportion of Co and W of Co-W-O in the Ni-Fe-P plating solution, we have obtained optimal electrochemical performance in 1 M KOH solution. At 150 (10) mA cm−2, the HER and OER overpotentials are 157.6 (23.6) mV and 260.6 (219.9) mV respectively. Furthermore, it shows a low cell voltage (1.46 V) in overall water splitting, exceeding most of the previously reported electrocatalysts. The activity of Ni-Fe-P/Co-W has no significant decrease at 100 mA cm−2 for 100 h. Subsequently, XPS and Raman spectroscopy are used to infer the mechanism of the electrochemical reaction. This study demonstrates a kind of simple, scalable, and efficient bifunctional electrocatalyst method that has special nested heterogenous structure for overall water splitting.

Bifunctional electrocatalyst for oxygen reduction/evolution reactions based on controlled morphology of nickel–cobalt nanoprickly particles composited by graphene and carbon nanotube

Bifunctional electrocatalyst for oxygen reduction/evolution reactions based on controlled morphology of nickel–cobalt nanoprickly particles composited by graphene and carbon nanotube

Self-supported monometallic FeS2/FeOOH-ZnO@NF with abundant oxygen vacancies as efficient and stable electrocatalysts for the OER and HER

The construction of heterogeneous interfaces and oxygen vacancy (Ov) is a very useful method to enhance the catalytic activity performance of catalysts. In this work, the high-performance a monometallic iron based bifunctional electrocatalyst FeS2/FeOOH-ZnO@NF with oxygen vacancy (Ov) and heterogeneous interface is prepared by the ZnO template induced deposition method for the first time. Due to the synergistic effect of the heterogeneous interface of FeS2/FeOOH-ZnO@NF and the oxygen vacancies of the ZnO, the FeS2/FeOOH-ZnO@NF catalysts exhibited excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in alkaline media, with a low overpotential of 74 mV and 177 mV at 10 mA cm−2, respectively. It should be emphasized that the FeS2/FeOOH-ZnO@NF || FeS2/FeOOH-ZnO@NF electrolytic cell has an ultra-low decomposition voltage, only 1.41 V at 10 mA cm−2 and 1.49 V at 20 mA cm−2, which is much lower than that currently reported in most literatures. This work will provide a new strategy and idea for the improvement of HER and OER electrocatalytic performance of transition metal-based catalyst.

Fe-Doped CoS2 Nanocages as Bifunctional Electrocatalysts for Water Splitting

Fe-Doped CoS₂ Nanocages as Bifunctional Electrocatalysts for Water Splitting

Bimetal organic framework derived CoM@N–C composites as bifunctional oxygen catalysts for Zn-air batteries

Metal-loaded nitrogen-doped carbon (M@N–C) catalysts have shown promise as electrocatalysts for replacing noble metal catalysts in industrial processes. To study the influence on structural and performance caused by different bimetal doping, a family of bimetals CoM@N–C (M = Cu/Ni/Fe) composites with porous surface and abundant C defects were well-designed. After bimetallic doping, more defects are introduced into the carbon frameworks, and the metal-N species are fixed. As such, efficient utilization of active sites and rapid mass transfer make the reaction kinetics process more favorable and stable. Density functional theory calculations indicate that Cu/Ni doping optimizes the electronic environment of the Co–N, resulting in the balanced adsorption and dissociation of oxygen intermediates. While the synergy of FeCo activates the O=O, which promotes the sharp decrease in free energy of ∗OOH to ∗O, shifting the rate-determining step for oxygen reduction reaction. This indicates the adsorption site transfer of CoFe0.05@N–C in oxygen reduction and evolution reactions. The CoFe0.05@N–C catalyst exhibits superior bifunctional catalytic activity (with a potential gap of 0.80 V) than that of Pt catalysts. This work presents a simple strategy to fabricate well-defined bimetals doping in bifunctional oxygen electrocatalysts and it is expected to inspire future work on the role of electronic structure modulation and interface engineering.

γ-FeOOH Nanosheet with Enormous Cationic Defect: Efficient and Durable Bifunctional Electrocatalyst Suitable for an Industrial-Scale AEM Electrolyzer

γ-FeOOH Nanosheet with Enormous Cationic Defect: Efficient and Durable Bifunctional Electrocatalyst Suitable for an Industrial-Scale AEM Electrolyzer

Fe‐doped Ni3S2@CoSx nanoarrays derived from MOF as bifunctional electrocatalysts for efficient overall water splitting

AbstractBackgroundFabricating high‐performance bifunctional electrocatalysts remains challenging to promote the development of electrocatalytic water splitting.ResultA heterostructure Fe‐Ni3S2@CoSx/NF was successfully synthesized by using interfacial engineering strategy. Benefiting from the strong synergistic effect between highly active CoSx and Fe‐Ni3S2, Fe‐Ni3S2@CoSx/NF exhibited outstanding bifunctional performance, which showed low overpotentials of 77 mV for HER and 217 mV for OER at 10 mA cm−2, respectively.ConclusionThe CoSx nanoarrays and Fe‐Ni3S2 nanosheets respectively served as HER and OER active center. When Fe‐Ni3S2@CoSx/NF was used as both cathode and anode for overall water splitting, a low voltage of 1.52 V was required to reach the current density of 10 mA cm−2 with nearly 100% Faradic efficiency and outstanding durability.This article is protected by copyright. All rights reserved.

A data-driven bifunctional oxygen electrocatalyst with a record-breaking ΔE = 0.57 V for ampere-hour-scale zinc-air batteries

A data-driven bifunctional oxygen electrocatalyst with a record-breaking ΔE = 0.57 V for ampere-hour-scale zinc-air batteries

In-Situ Nanoarchitectonics of Fe/Co LDH over Cobalt-Enriched N-Doped Carbon Cookies as Facile Oxygen Redox Electrocatalysts for High-Rate Rechargeable Zinc-Air Batteries.

The reality of long-term rechargeable and high-performance zinc-air batteries relies majorly on cost-effective and eminent bifunctional electrocatalysts, which can perform both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Herein, we demonstrate a new approach for the synthesis of in-situ-grown layered double hydroxide of iron and cobalt over a cobalt nanoparticle-enriched nitrogen-doped carbon frame (CoL 2:1) by a simple coprecipitation reaction with facile scale-up and explore its electrocatalytic ORR and OER activity for an electrically rechargeable zinc-air battery. Consequently, the developed composite displays excellent ORR and OER activity with an ORR half-wave potential of 0.84 V, a limiting current density of 5.85 mA/cm2, and an OER overpotential of 320 mV with exceptional stability. The outstanding bifunctionality index of the catalyst (ΔE = 0.72 V) inspired us to utilize it as a cathode catalyst in an in-house developed prototype zinc-air battery. The battery could easily supply a specific capacity of 804 mAh/g with a maximum peak power density of 161 mW/cm2. The battery exhibits an attractive charge-discharge profile with a lesser voltage gap of 0.76 V at 10 mA/cm2 with durability for a period of 200 h and a voltage efficiency of 97%, which surpassed the corresponding Pt/C + RuO2-based zinc-air battery. Further, a maximum load of 50 mA/cm2 could easily be sustained during cycling, revealing its outstanding stability. A series-connected two CoL 2:1-based zinc-air batteries effortlessly enlighten a pinwheel fan and LED panel simultaneously, revealing its practicality. The high electrical conductivity and greater specific surface area of Co/N-C and its robust attachment with Fe/Co LDH preserves both active sites, thereby resulting in exceptional performance. Our method is capable of being flexible enough to create various bifunctional Co/N-C-based composite electrodes, opening up a feasible pathway to rechargeable zinc-air batteries with maximum energy density.

Bagasse derived N-doped graphitic carbon encapsulated cobalt nanoparticles as an efficient bifunctional catalyst for water splitting reactions

The utilization of non-precious metal-based electrodes to unlock cost-effective and scalable processes for the production of clean energy is highly desirable. Herein, we reported a straightforward hydrothermal carbonization method for the synthesize of nitrogen-doped graphitic carbons integrated with cobalt (Co@NGC-600, Co@NGC-700, and Co@NGC-800) from sugarcane bagasse and their electrocatalytic applications in oxygen and hydrogen evolution reactions. The graphitic nature of the Co integrated N-doped carbon materials was confirmed by Raman and XPS analysis. FESEM and HRTEM analysis confirms the dispersion of Co on N-doped carbon nanosheets. The Co@NGC-800 catalyst shows low overpotential and Tafel slope, requiring only 304 mV (84.1 mV dec−1) for oxygen electrode and 234 mV (118 mV dec−1) for HER at a current density of 10 mA cm−2. Moreover, Co@NGC-800 materials showed better activity than Co@NGC-700, Co Co@NGC-600, and Co@NC. The active Co@NGC-800 bifunctional electrocatalysts pair contributes to the fabrication of a water electrolyser with a 10 mA/cm2 current density at 1.68 V. The Co@NGC-800 // Co@NGC-800 electrocatalyst exhibits good stability over a period of 24 h with negligible potential aberration during the process of water splitting. The electrocatalytic performance of the prepared catalyst in a 1.0 M KOH solution exhibits admirable bifunctional activity and remarkable stability. In fact, it outperforms cobalt-based and carbon-supported electrocatalysts, including highly valued commercial catalysts like IrO2 and Pt@C. The solar cell configuration, utilizing the energetic bifunctional Co@NGC-800 electrocatalyst, can continuously generate hydrogen and oxygen. The overall water-splitting process of Co@NGC-800 catalyst delivered at a cell voltage of 1.68 V, enabling sustained and efficient oxygen and hydrogen evolution at a large scale.