Electrocatalytic Electrode Research Articles

High-Efficiency Photo-Assisted Large Current-Density Water Splitting with Mott-Schottky Heterojunctions.

The development of bifunctional photogenerated carrier-assisted electrocatalytic (PCA-EC) electrodes that operate with stability at large current-density remains a significant challenge. Herein, we demonstrate a simple sputtering-deposition process to synthesize a novel MnWO4/FeCoNi Mott-Schottky heterojunction coating and deposit it on a pure Ti substrate to prepare high-performance PCA-EC electrodes, which exhibits enhanced light absorption range/intensity and rapidly separated photogenerated electron-hole pairs. This design allows photogenerated electrons to directly participate in the hydrogen evolution reaction (HER), while the strong oxidation of photogenerated holes significantly reduces the defect formation energy of active metals, thereby facilitating the rapid reconstruction of highly active Ni(FeCo)OOH/MnOOH species for the oxygen evolution reaction (OER). As expected, the as-prepared electrode demonstrates the overpotentials of 64 mV for the HER and 204 mV for the OER at 10 mA cm-2 under illumination. Benefiting from the stable interface with Fe/Co/Ni-O-Mn/W bonding units, the dual-electrode photoassisted electrolytic cell achieves long-term stability at current densities of 500 and 1000 mA cm-2. This work provides detailed insights into the enhancement mechanism of PCA-EC and contributes to the development of photo-assisted water splitting electrodes for large current-density applications.

High‐Efficiency Photo‐Assisted Large Current‐Density Water Splitting with Mott‐Schottky Heterojunctions

The development of bifunctional photogenerated carrier‐assisted electrocatalytic (PCA‐EC) electrodes that operate with stability at large current‐density remains a significant challenge. Herein, we demonstrate a simple sputtering‐deposition process to synthesize a novel MnWO4/FeCoNi Mott‐Schottky heterojunction coating and deposit it on a pure Ti substrate to prepare high‐performance PCA‐EC electrodes, which exhibits enhanced light absorption range/intensity and rapidly separated photogenerated electron‐hole pairs. This design allows photogenerated electrons to directly participate in the hydrogen evolution reaction (HER), while the strong oxidation of photogenerated holes significantly reduces the defect formation energy of active metals, thereby facilitating the rapid reconstruction of highly active Ni(FeCo)OOH/MnOOH species for the oxygen evolution reaction (OER). As expected, the as‐prepared electrode demonstrates the overpotentials of 64 mV for the HER and 204 mV for the OER at 10 mA cm−2 under illumination. Benefiting from the stable interface with Fe/Co/Ni‐O‐Mn/W bonding units, the dual‐electrode photoassisted electrolytic cell achieves long‐term stability at current densities of 500 and 1000 mA cm−2. This work provides detailed insights into the enhancement mechanism of PCA‐EC and contributes to the development of photo‐assisted water splitting electrodes for large current‐density applications.

A Green and Efficient Electrocatalytic Route for the Highly‐Selective Oxidation of C–H Bonds in Aromatics over 1D Co3O4‐Based Nanoarrays

Electrocatalytic oxidation of C‐H bonds in hydrocarbons represents an efficient and sustainable strategy for the synthesis of value‐added chemicals. Herein, a highly selective and continuous‐flow electrochemical oxidation process of toluene to various oxygenated products (benzyl alcohol, benzaldehyde, and benzyl acetate) is developed with the electrocatalytic membrane electrodes (ECMEs). The selectivity of target products can be manipulated via surface and interface engineering of Co3O4‐based electrocatalysts. We achieved a high benzaldehyde selectivity of 90% at a toluene conversion of 47.6% using 1D‐Co3O4 nanoneedles (NNs) loaded on a microfiltration (MF) titanium (Ti) membrane, i.e, Co3O4 NNs/Ti. In contrast, the main product shifted to benzyl alcohol with a selectivity of 90.1% at conversion of 32.1% after modifying MnO2 nanosheets (NSs) on Co3O4 NNs/Ti (Co3O4@MnO2/Ti) catalyst. Moreover, benzyl acetate product can be obtained with selectivity of 92% at a conversion of 58.5% at high current density (> 1.5mA cm‐2), demonstrating that the pathway of toluene oxidation is readily maneuvered. DFT results reveal that modifying MnO2 on Co3O4 optimizes the electron structure of Co3O4@MnO2/Ti and modulates the adsorption behavior of intermediate species. This work demonstrates a sustainable, and continuous‐flow process for precise control over production selectivity of value‐added oxygenated derivatives in electrochemical oxidation of aromatic hydrocarbons.

A Green and Efficient Electrocatalytic Route for the Highly-Selective Oxidation of C-H Bonds in Aromatics over 1D Co3O4-Based Nanoarrays.

Electrocatalytic oxidation of C-H bonds in hydrocarbons represents an efficient and sustainable strategy for the synthesis of value-added chemicals. Herein, a highly selective and continuous-flow electrochemical oxidation process of toluene to various oxygenated products (benzyl alcohol, benzaldehyde, and benzyl acetate) is developed with the electrocatalytic membrane electrodes (ECMEs). The selectivity of target products can be manipulated via surface and interface engineering of Co3O4-based electrocatalysts. We achieved a high benzaldehyde selectivity of 90% at a toluene conversion of 47.6% using 1D-Co3O4 nanoneedles (NNs) loaded on a microfiltration (MF) titanium (Ti) membrane, i.e, Co3O4 NNs/Ti. In contrast, the main product shifted to benzyl alcohol with a selectivity of 90.1% at conversion of 32.1% after modifying MnO2 nanosheets (NSs) on Co3O4 NNs/Ti (Co3O4@MnO2/Ti) catalyst. Moreover, benzyl acetate product can be obtained withselectivity of 92% at a conversion of 58.5% at high current density (> 1.5mA cm-2), demonstrating that the pathway of toluene oxidation is readily maneuvered. DFT results reveal that modifying MnO2 on Co3O4 optimizes the electron structure of Co3O4@MnO2/Ti and modulates the adsorption behavior of intermediate species. This work demonstrates a sustainable,and continuous-flow process for precise control over production selectivity of value-added oxygenated derivatives in electrochemical oxidation of aromatic hydrocarbons.

Superhydrophilic and Underwater Superaerophobic Dual-Function Peony-Shaped Selenide Micro-nano Array Self-Supported Electrodes for High-Efficiency Overall Water Splitting Driven by Renewable Energy.

With the intensification of global environmental pollution and resource scarcity, hydrogen has garnered significant attention as an ideal alternative to fossil fuels due to its high energy density and nonpolluting nature. Consequently, the urgent development of electrocatalytic water-splitting electrodes for hydrogen production is imperative. In this study, a superwetting selenide catalytic electrode with a peony-flower-shaped micronano array (MoS2/Co0.8Fe0.2Se2/NixSey/nickel foam (NF)) was synthesized on NF via a two-step hydrothermal method. The optimal catalytic activity of cobalt-iron selenide was achieved by adjusting the Co/Fe ratio. The intrinsic catalytic activity of the electrodes was enhanced by incorporating transition metal selenides, which then served as a precursor for the subsequent loading of MoS2 nanoflowers on the surface to fully expose the active sites. Furthermore, the superwetting properties of the electrode accelerated electrolyte penetration and electron/mass transfer, while also facilitating bubble detachment from the electrode surface, thereby preventing "bubble shielding effect". This resulted in superior oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance, as well as overall water splitting capabilities. In a 1.0 M KOH solution, the electrode required only 166 and 195 mV overpotential to achieve a current density of 10 mA cm-2 for OER and HER, respectively. When functioning as a bifunctional catalytic electrode, only 1.60 V of voltage was necessary to drive the electrolyzer to reach a current density of 10 mA cm-2. Moreover, laboratory simulations of wind and solar energy-driven water splitting validated the feasibility of establishing a sustainable energy-to-hydrogen production chain. This work provides new insights into the preparation of low-overpotential, high-catalytic-activity superhydrophilic and underwater superaerophobic catalytic electrodes by rationally adjusting elemental ratios and exploring changes in electrode surface wettability.

The electrocatalytic degradation of 1,4-dioxane by Co-Bi/GAC particle electrode.

Efficient degradation of industrial organic wastewater has become a significant environmental concern. Electrochemical oxidation technology is promising due to its high catalytic degradation ability. In this study, Co-Bi/GAC particle electrodes were prepared and characterized for degradation of 1,4-dioxane. The electrochemical process parameters were optimized by response surface methodology (RSM), and the influence of water quality factors on the removal rate of 1,4-dioxane was investigated. The results showed that the main influencing factors were the Co/Bi mass ratio and calcination temperature. The carrier metals, Co and Bi, existed mainly on the GAC surface as Co3O4 and Bi2O3. The removal of 1,4-dioxane was predominantly achieved through the synergistic reaction of electrode adsorption, anodic oxidation, and particle electrode oxidation, with ·OH playing a significant role as the main active free radical. Furthermore, the particle electrode was demonstrated in different acid-base conditions (pH = 3, 5, 7, 9, and 11). However, high concentrations of Cl- and NO3- hindered the degradation process, potentially participating in competitive reactions. Despite this, the particle electrode exhibited good stability after five cycles. The results provide a new perspective for constructing efficient and stable three-dimensional (3D) electrocatalytic particle electrodes to remove complex industrial wastewater.

High Electrocatalytic Activities of the Electrochemically Exfoliated Graphene Deposited Carbon Paper Electrodes for Vanadium Redox Flow Batteries

The cost-effective and process-efficient preparation of highly electrocatalytic carbon electrodes on a large scale is crucial for enhancing the competitiveness of vanadium redox flow batteries (VRFBs). In this work, electrochemically exfoliated graphene oxides (Exf-GOs) are prepared form graphite foil at large scale with a multi-electrodes equipped continuous Exf-GOs production system. The Exf-GOs are deposited on the activated carbon paper (A-CP) substrate by a direct infiltration-deposition approach. Collective electro-kinetics analysis applying cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed that the resulting Exf-GO/A-CP electrodes exhibit two orders magnitude greater intrinsic electrocatalytic activities than the A-CP electrode for the VO2+/VO2 + redox reactions. A trade-off between the Exf-GO deposition amount and the open pore volume through the Exf-GO/A-CP electrodes was found that have critical impacts on the overall electro-kinetic performance of the electrodes. Compared to the A-CP electrode, the Exf-GO/A-CP electrode provided the VRFB with more than two-fold enhancements in the energy storage capacity and at least 10 – 15 % higher voltage and energy efficiencies. The results collectively demonstrate the high effectiveness of the Exf-GO/A-CP electrodes for VRFBs that can be prepared cost and process efficient approach at large scales.

Emerging Electrocatalytic Textile Electrodes for Highly Efficient Alkaline Water Electrolysis

Emerging Electrocatalytic Textile Electrodes for Highly Efficient Alkaline Water Electrolysis

Facile top-down fabrication of integrated amorphous NiFe-based electrocatalytic electrodes for high current and long-life oxygen evolution

Developing an industrially relevant electrode with high catalytic activity, stability, and tunable composition/size for large-scale water electrolysis is a significant challenge. We have created an integrated electrode (NFM30-N) for the oxygen evolution reaction (OER) using a facile top-down approach that combines arc melting with dealloying-oxidation. Due to the dealloying-oxidation effect, the as-derived porous amorphous M–O, M–OH, and M–OOH (M = Ni, Fe) nanocones cover the basic NiFeMn alloy. This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities, requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm−2, respectively. It also displays a small Tafel slope of 44.1 mV dec−1 and remarkable stability for over 100 h at 100 and 500 mA cm−2. When used as an anode, a two-electrode electrolyzer cell with NFM30-N at 500 mA cm−2 only requires a cell voltage of 1.619 V and exhibits excellent stability, with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm−2. This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability, the presence of numerous active sites due to dealloying and the amorphous structure, and the promotion of the OER process by M–O, M–OH, and M–OOH species. This work offers a novel idea for fabricating integrated, industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.

Amorphous B-Doped Ni/Crystalline Ni Porous Foil Derived from Chinese Rice Paper as High-Performance Bifunctional Electrocatalytic Electrode for Oxidation of Methanol and Urea

Amorphous B-Doped Ni/Crystalline Ni Porous Foil Derived from Chinese Rice Paper as High-Performance Bifunctional Electrocatalytic Electrode for Oxidation of Methanol and Urea

Porous TiN-based ceramic electrode with N-modified Co-based Nanorods/TiN heterointerfaces for efficient overall water splitting

The development of high-performance electrocatalytic electrodes for overall water splitting is a crucial issue to realize renewable hydrogen production. This paper presents the in situ growth of N-modified Co-based nanorods on porous TiN ceramic membranes using the hydrothermal method and thermal NH3 treatment, resulting in a novel self-supported electrocatalytic electrode with abundant heterointerfaces, denoted as NCTN-x-y (x: nitridation temperature; y: nitridation time). In the alkaline medium (1 M KOH), the NCTN-350-2 electrode displays the best hydrogen evolution reaction (HER) activity (ƞ10 = 66 mV), and the NCTN-250-3 electrode manifests the best oxygen evolution reaction (OER) performance (ƞ10 = 270 mV). Accordingly, these two electrodes comprise an electrolyzer, which features a current density of 10 mA cm−2 at a low cell voltage of 1.63 V. The good electrocatalytic performance can be attributed to the abundant heterointerfaces formed between the porous TiN ceramic membrane and the N-modified Co-based nanorods, in conjunction with the hierarchical pore structure of the TiN ceramic membrane. Theoretical calculations identify that the construction of heterointerfaces modulates the electronic structure of active sites, thereby promoting the dissociation of H2O, optimizing the H* adsorption energy (ΔGH*), and accelerating the reaction kinetics, which ultimately improve the electrocatalytic activity of electrode.

Sulfur-doped manganese-cobalt hydroxide with promoted surface reconstruction for glycerol electrooxidation assisted hydrogen production

Glycerol electrooxidation reaction (GOR), as an attractive alternative to oxygen evolution reaction, not only produces value-added formic acid but also facilitates H2 production. However, its practical application suffers from the lack of efficient electrocatalysts with high activity at low potentials. Herein, sulfur doped manganese-cobalt hydroxide nanosheets on nickel foam (Mn-Co-S/NF) has been demonstrated as a promising electrocatalytic electrode for GOR, showing high current density at low potentials and high Faradaic efficiency for formate production. The combination of ex situ characterization, operando Raman analysis, and in situ electrochemical impedance spectroscopy measurement unveils that S doping leads to the formation of hierarchically porous structure with abundant oxygen vacancies during the reaction, enabling the surface reconstruction to proceed in an easier manner and to a higher degree. As a result, the reconstructed Mn-Co-S/NF possesses highly enhanced charge/mass transfer capability and enriched high valence Co active species. Impressively, in a practical flow electrolyzer, an industrial-level current density of 900 mA cm−2 can be achieved at a cell voltage of 2.0 V. It also exhibits H2 yield rate of 3.5 mmol cm−2 h−1 at 200 mA cm−2, realizing up to 30.2% energy saving efficiency compared to water electrolysis.

Solar-integrated binary chemical cracking of heavy oil for efficient high-order fuel transformation and extra hydrogen storage

Solar energy is an attractive alternative to fossil fuels (electricity and coke) for petroleum products generation. A solar-integrated binary chemical cracking of heavy oil system integrates solar energy into oil processing for carbon neutrality，in which pyrolysis and electrolysis benefit heavy oil conversion and hydrogen storage. This system has been studied in terms of solar chemical engineering, electrolyte engineering and electrode engineering. The results show improved hydrogen yield and cracking rate of heavy oil and a significant reduction in the operating temperature compared to catalytic cracking. The performance of molten salt electrolytes is as follows: binary NaOH–KOH > ternary KCl–LiCl + NaOH > ternary KCl–LiCl + NaHCO3. In electrode engineering, the electro-catalytic electrodes are in an order of Inconel 718> Ni > Incoloy 825 electrodes in the cracking rate, Ni > Inconel 718>Incoloy 825 electrodes in the hydrogen yield, and Incoloy 825>Inconel 718>Ni electrodes in the ability, for sustainable and stable efficient production.

A dual flow-through electrochemical system coupled electrocatalytic membrane electrode and heterogeneous electro-Fenton for organic wastewater treatment

In this work, a dual flow-through heterogeneous electrochemical system was proposed in which a porous Ti/SnO2-Sb membrane and graphite felt (GF) were used as anode and cathode, respectively. By combining of anodic oxidation (AO) and electro-Fenton (EF), this electrochemical system obtained a synergism effect on organic pollutants degradation resulted in a high removal efficiency. In addition，attributed to the application of dual flow-through mode, mass transfer was improved which is also beneficial for organic pollutants degradation. The results illustrated that this dual flow-through electrochemical system exhibited a brilliant treatment performance for BPA wastewater treatment. It can be observed that the dual flow-through electrochemical system owned a removal efficiency of 99.2 % under optimum condition (2.5 V voltage at pH=3 using 0.05 M Na2SO4 as electrolyte). The mechanism investigation results indicated that the good treatment performance was due to the ·OH generated from both EF and AO processes and O2-· produced through AO process. In addition, this dual flow-through electrochemical system also exhibited a good reusability and application. It reveals a potential for factual wastewater application.

Stainless steel as gas evolving electrodes in water electrolysis: Boosting the electrocatalytic hydrogen evolution reaction on electrodeposited Ni@CoP modified stainless steel electrodes

High efficient and durable electrocatalytic electrodes play a vital role in energy conversion and storage. In this concern, water electrolysis technology needs high performance electrodes with high activity and stability to implement this technology for green hydrogen production. Here, this study reports on the development of self-supported electrodes for the hydrogen evolution reaction (HER) based on sequential electrodeposition technique. First, the CoP has been deposited on stainless steel mesh (SSM) electrode followed by deposition of Ni to form Ni@CoP electrocatalysts standing on SSM. The loading amount of Ni was studied to achieve a high catalytic activity. The developed electrodes have been investigated with FE-SEM, EDX, XRD and XPS to identify their morphological properties as well as their chemical states and compositions. Electrocatalytic activity and durability have been studied in alkaline media by different electrochemical methods, such as LSV, EIS and CP. The results showed that the optimum deposition time of 10 min (10Ni@CoP) exhibited the higher catalytic activity in term of overpotential and Tafel slope giving a overpotential of 188 mV at 10 mA cm−2 with a small Tafel slope of 69 mV.dec−1 compared to CoP electrode with overpotential 266 mV and Tafel slope of 105 mV.dec−1 highlighting the role of Ni in enhancing the catalytic activity of the developed electrodes towards HER. Moreover, the Ni@CoP showed high stability under continues electrolysis at 50 and 100 mA.cm−2. These findings have been discussed in light of porous structure of the electrodes and introducing of Ni particles which led to creating more active sites and enhancing the hydrogen adsorption/desorption and thus facilitating the HER kinetics. The facial preparation method of self-supported electrodes and the obtained activity and stability of Ni@CoP electrodes render them as potent electrodes for HER in alkaline water electrolysis.

Ambient electrosynthesis of urea from carbon dioxide and nitrate over Mo2C nanosheet

Electrocatalytic synthesis of urea through CN bond formation, converting carbon dioxide (CO2) and nitrate (NO3–), presents a promising, less energy-intensive alternative to industrial urea production process. In this communication, we report the application of Mo2C nanosheets-decorated carbon sheets (Mo2C/C) as a highly efficient electrocatalyst for facilitating CN coupling in ambient urea electrosynthesis. In CO2-saturated 0.2 mol/L Na2SO4 solution containing 0.05 mol/L NO3–, the Mo2C/C catalyst achieves an impressive urea yield of 579.13 µg h–1 mg–1 with high Faradaic efficiency of 44.80% at –0.5 V versus the reversible hydrogen electrode. Further theoretical calculations reveal that the multiple Mo active sites enhance the formation of *CO and *NH2 intermediates and facilitate their CN coupling. This research propels the use of Mo2C-based electrodes in electrocatalysis and accentuates the capabilities of binary metal-based catalysts in CN coupling reactions.

A NEW APPROACH TO CONTROL DIABETES BY CONVERTING EXCESS BLOOD SUGAR TO ENERGY OVER ELECTROCATALYTIC METALLIC ANODE

Diabetes Mellitus, or Diabetes in short, is a group of widespread endocrine diseases characterized by high blood sugar levels. This research paper attempts to find a solution to this high sugar problem, by taking the route of electrochemistry. It was attempted to demonstrate that the excess sugar (glucose) in the bloodstream of a diabetic patient can be lowered by electro-oxidizing the excess sugar in Simulated Body Fluid (SBF) and convert it into electrical energy. For this, a sugar level detection system was developed, using a linear regression model with a coefficient of determination (R2 value) of 0.974. At first, one of the most popular as well as costly electrocatalytic materials i.e., Platinum was used to electro-oxidize the excess sugar. Upon its success, some highly electrocatalytic but cheap electrode materials were developed, such as Nickel, Nickel with nanocarbon, Manganese dioxide (MnO2) and Manganese dioxide with nanocarbon (MnO2C). And they also successfully electro-oxidized the excess glucose in SBF solution, thereby reducing the sugar levels. Thus, a potentially novel route to deal with the epidemic problem of diabetes has been proposed through this research work.

Rational design of bimetallic metal-organic framework derived three-dimensional flower-like and porous NiCoFe LDH/NF electrocatalyst for electrochemical overall water splitting

Porous structured metal–organic frameworks (MOFs) and their derivatives are desired in catalysis and energy storage. Herein, three-dimensional (3D) flower-like NiCoFe LDH/NF are first synthesized though a convenient cathodic electrodeposition strategy subsequent an ion-exchange process. And the morphology and catalytic performance of the CoFe-MOF/NF can be finely by tailoring the electrodeposition voltage, deposition time and the ratio of Co: Fe. The 3D flower-like and porous NiCoFe/NF not only retains structural integrity to promote durability but also greatly alleviates the aggregation of active sites. In addition, the 3D flower-like and porous NiCoFe/NF display remarkable results with low overpotentials of 233 mV at a current density of 50 mA cm−2 for OER and 84 mV at a current density of 10 mA cm−2 for HER in 1 M KOH, respectively. When acting as electrocatalytic electrodes for overall water splitting, NiCoFe/NF displays a low overpotential of 1.52 V to achieve a current density of 10 mA cm−2. The study provides a promising approach to design MOF electrocatalysts for electrocatalytic applications.

Simultaneous acceleration of sulfur reduction and oxidation on bifunctional electrocatalytic electrodes for quasi-solid-state Zn–S batteries

Simultaneous acceleration of sulfur reduction and oxidation on bifunctional electrocatalytic electrodes for quasi-solid-state Zn–S batteries

An effective descriptor for identifying the electrocatalytic activity and selectivity of bilayer carbon-based heterojunction catalysts

The usage of composite carbon-based materials supported by graphene has emerged as a powerful selection for designing electrocatalytic electrodes due to their agile electronic transmission and diversiform redox active sites. Here, we constructed fresh electroactive organic catalysts for hydrogen carrier synthesis by stacking a series of organic molecules on transition metal azide doped graphene substrates, in anticipation of these bilayer heterostructures to breathe new life into electrocatalysis. As expected, several promising cathodic catalysts were speculated through first principles calculations, such as Co-PMDT for H2 generation and Co-PQ for ammonia (NH3) synthesis. However, facing such an intricate interface engineering and electronic structure regulation undoubtedly poses a challenge to the time-consuming computational screening work. To tackle this, an effective descriptor was proposed as a predictive tool for identifying the activity and selectivity toward diverse chemical reactions, which allows us to systematically fine-tune the catalysts' properties in order to enhance their electrocatalytic performance. Our work may offer feasible approaches for the rational design of advanced electrocatalysts.