Electrocatalytic Mechanism Research Articles

Structural Engineering of Co-Metal-Organic Frameworks via Ce Incorporation for Improved Oxygen Evolution.

The rational design of metal-organic framework (MOF)-basedelectrocatalysts plays a key role in achieving high-efficiency oxygen evolution reaction (OER). Herein, a synergetic morphology and electronic structure engineering strategy are proposed to design a Co-MOF nanoflower grown on carbon paper via rare-earth cerium doping (CoCe-MOF/CP). Compared with Co-MOF/CP, the developed CoCe-MOF/CP exhibited superior OER performance with a low overpotential of 267mV at 10mA cm-2 and outstanding long-term stability over 100h. Theoretical calculations show that the unique 4f valence electron structure of Ce induced charge redistribution of the Co-MOF surface through the strong Co 3d-O 2p-Ce 4f orbital electronic coupling below the Fermi level. Ce-doped plays a key role in the engineering of the electronic states of the Co sites to endow them with the optimal free energy landscape for enhanced OER catalytic activity. This work provides new insights into comprehending the RE-enhanced mechanism of electrocatalysis and provides an effective strategy for the design of MOF-based electrocatalysts.

Crystalline Ni5P4/amorphous CePO4 core/shell heterostructure arrays for highly-efficient electrocatalytic overall water splitting

Exploring low-cost and highly efficient bifunctional electrocatalysts for overall water splitting has become a research focus recently. Crystalline/amorphous core/shell heterostructures have great potential for applications in the field of electrocatalytic overall water splitting. However, related research is still challenging. Herein, crystalline Ni5P4 nanosheets/amorphous CePO4 nanocrystals core/shell heterostructure arrays were developed for electrocatalytic overall water splitting. It is shown that the heterostructure array required competitive HER and OER overpotentials of 94 and 191 mV in alkaline environment (10 mA/cm2), respectively. Encouragingly, the symmetrical two-electrode system constructed with the heterostructure array only required an ultra-low cell voltage of 1.535 V to achieve a current density of 10 mA/cm2. This indicates the system has huge potential in overall water splitting. The electrocatalytic mechanism was studied systematically by combining theoretical calculation and experimental characterization. It was found that the surface coating of amorphous CePO4 could not only significantly increase the electrochemical active surface area and improve the charge transfer of crystalline Ni5P4 nanosheets, but could also regulate d-band center of Ni5P4 and optimize the adsorption towards reaction intermediates in water splitting. The results not only provide an excellent crystalline/amorphous core/shell heterostructure bifunctional electrocatalyst for overall water splitting but also greatly expand the application of rare earth metal phosphate CePO4.

Electro-catalytic adsorption mechanism of acetonitrile in water using a ME-ACFs system

Acetonitrile wastewater is difficult to treat due to its high salinity and toxicity to microorganisms. In this paper, a micro electro-activated carbon fiber coupled system (ME-ACF) was established to treat simulated acetonitrile wastewater. In the 200 ml system, the concentration of acetonitrile adsorbed by ACF was 91.3 mg/L, while that of acetonitrile adsorbed by ME-ACF was 150.6 mg/L, and the removal efficiency was increased by 65 % in comparison. The activated carbon fibers before and after the reaction were subjected to a series of characterization, and it was found that the SABET decreased from 1393.48 m2/g to 1114.93 m2/g and 900.23 m2/g, respectively, but the oxygen on the surface of the activated carbon fibers was increased, and the effect of the micro electrolytic system on the activated carbon fibers was then analyzed. The possible reasons for the formation of acetic acid contained in the products were also discussed using DFT simulations. The removal mechanism of acetonitrile by ME-ACF was considered to be electrically enhanced adsorption and electro-catalytic hydrolysis.

Indoor water splitting for hydrogen production through electrocatalysis using composite metal oxide catalysts

This study explores an optimistic approach for large-scale hydrogen production by employing electrocatalysts based on nickel, cobalt, iron, and aluminum oxides as alternatives to costlier metals. This approach offers a cost-effective solution to electrolysis in water media for hydrogen production. This investigation is focused on the electrolysis process, engaging NiO–Al2O3–CoO–Fe2O3 in 1M solution of NaOH and KOH. The environmental and economic analyses are conducted to evaluate the overall effect and cost-effectiveness of the electrolysis process. These findings provide valuable insights into the performance, feasibility, and challenges of using oxides of aluminum, nickel, iron, and cobalt in electrolysis for hydrogen production. The structural and morphological analyses of metal oxides are conducted using XRD and SEM tools, which showed reduced crystallinity and open pore structure of the samples. Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and Linear Sweep Voltammetry (LSV) revealed a higher electrocatalytic activity, a larger electrochemical active surface area, a higher current density, and a high density of active sites of NiO–Al2O3–CoO–Fe2O3 composite. Electrode 1 of the composite catalyst produced 500 ml of hydrogen after 30 min of the process, while electrodes 2 and 3 produced 263 and 249 ml of hydrogen, respectively. This study also elucidated the electrocatalytic mechanism involved in water splitting using these composite materials.

The Elements Selection of High Entropy Alloy Guided by Thermodynamics and the Enhanced Electrocatalytic Mechanism for Oxygen Reduction Reaction

AbstractOwing to their exceptional properties, high‐entropy alloys (HEAs) have received considerable attention in the field of electrocatalysis. However, few studies focus on the origin of their outstanding performance. Here, carbon‐supported PtFeCoNiMn (with an atomic ratio of 21:20:20:20:19) HEA nanoparticles via shock‐heating and shock‐cooling strategy are rationally designed and successfully prepared. The above five metal elements are rationally selected from the perspective of thermodynamics and geometric effects. Subsequently, the alloying process of the PtFeCoNiMn HEA is investigated via operando X‐ray diffraction characterizations. The electronic structures of each metal atom on the PtFeCoNiMn HEA and monometallic nanoparticles surface are revealed by density function theory calculations for illustrating the performance enhancement mechanism. It is found that Pt atoms on the PtFeCoNiMn HEA surface exhibit a wider range of d‐band center distribution range than the corresponding monometallic nanoparticles, which contributes to the enhanced selective adsorption of O2 reactants/intermediates. Importantly, some Fe, Co, Ni, and Mn atoms on the HEA surface manifest less positive d‐band center values than the corresponding monometallic nanoparticles, with similar d‐band center positions to some Pt atoms. This indicates that the inactive atoms in monometallic nanoparticles can be transformed into ORR active sites in the HEA matrix owing to the electronic interaction between adjacent atoms.

MOF-derived CoP nanoparticles anchored on P, N co-doped carbon nanoframework as robust electrocatalyst for rechargeable Li-O2 batteries

Currently, transition-metal phosphides (TMPs) coupled with heteroatom-doped carbon materials have attracted promising prospects in lithium‑oxygen (Li-O2) batteries. The CoP electrocatalysts have been extensively studied as popular electrode materials because of their efficient catalytic activity. However, numerous obstacles remain in optimizing synthetic techniques and exploring electrocatalytic mechanisms for CoP-based electrocatalysts. Herein, metal-organic frameworks (MOFs)-derived CoP nanoparticles anchored on P, N co-doped carbon nanoframeworks (CoP@PNCFs) are successfully designed at different phosphorization temperatures. The effects of the concentration of CoP active species, and the amount of P and N doping on the electrochemical performances are comparatively investigated and compared for different catalysts. The optimal catalyst, CoP@PNCF-700, displays high CoP active component, pyridinic-N and graphitic-N content, and abundant defect structures to enhance the electrochemical activity. More importantly, the CoP@PNCF-700 catalytic Li-O2 batteries deliver a high discharge specific capacity of 9630.5 mAh g−1 at 100 mA g−1 and a prominent long cycling stability of 187 cycles with a fixed capacity of 500 mAh g−1 at 200 mA g−1. This effort provides a facile strategy for designing cost-effective electrocatalysts for other energy-storage systems.

Experimental and computational insight into the role of cobalt and phosphorus in boosting Volmer and Heyrovsky steps of Ni in alkaline hydrogen evolution reaction

Deep insight into the role of doped hetero atoms in boosting the alkaline hydrogen evolution reaction (HER) activity is of significance for designing the low-cost electrocatalysts to produce hydrogen. Herein, we designed, synthesized, and optimized the Co and P co-doped Ni (NCP) electrocatalysts and evaluated the HER performance in alkaline medium. It was found that the NCP exhibited the enhanced hydrogen evolution performance, only need an overpotential of 57.0 mV to afford 10 mA·cm−2. The calculation results of density functional density revealed that the doped P plays an important role in modulating electron distribution of Ni and Co atoms, which reduce the Gibbs free energy of water molecule dissociation at Co sites in Volmer step, and optimize the ab/desorption of hydrogen at Ni site that bonded to P and Ni atoms in Heyrovsky step, respectively. The obtained results are conductive to understanding the electrocatalytic mechanism of alkaline HER.

High-Performance Hydrogen Evolution Reaction Catalysts in Two-Dimensional Nodal Line Semimetals.

The discipline of topological quantum catalysts (TQCs) is developing due to the emergence of exotic quantum materials and their corresponding catalysts. Although a series of 3D TQCs with different topological signatures are proposed, the emergence of 2D TQCs in 2D topological semimetals is still rarely touched by others. As a typical example, we proposed that the 2D nodal line semimetal Cu2Si monolayer is a superior TQC for hydrogen evolution reaction (HER). Using first-principles calculations, we find that the Cu2Si monolayer exhibits two Γ-centered nodal lines (L1 and L2) in the kz = 0 plane. The Gibbs free energy (ΔGH*) of Cu2Si is as low as 0.195 eV, comparable to that of Pt, and better than other conventional catalysts. Moreover, it is found that changing the position of nodal lines (relative to the Fermi level) under different electron/hole conditions can effectively affect the catalytic activity of HER. Besides Cu2Si, the emergence of high HER performance in other 2D nodal line semimetals, Ti3C2, Cr2S3, ScCl, and CuSe, is also theoretically determined. These results highlight the critical role of nodal lines in studying electrocatalytic mechanisms for TQCs and benefit the seeking of high-performance HER catalysts without noble metals on a 2D scale.

Porous carbon/minerals interwoven particle electrodes co-constructed by residual carbon and ash from coal gasification fine slag and its synergistic electrocatalytic mechanism

Complex distribution forms of carbon/ash in coal gasification fine slag (GFS) make it impossible to separate precisely. A combined alkali fusion-polymerization-hydrothermal process was designed to synthesize porous carbon/minerals interwoven particle electrodes (FSAPH) co-constructed by carbon/ash from GFS for electrooxidation treatment of m-cresol wastewater. Based on the hydrogen bonding and coordination capabilities of polyaniline (PAIN), the deconstructed aluminosilicate was regenerated in sheet-like form dispersedly on carbon matrix, effectively enhancing synergistic behavior of carbon and minerals. The electrochemical assessment exhibited superior properties, including a large voltammetry charge of 9.533 mC/cm3, high oxygen evolution potential of 2.15 V, low charge-transfer resistance of 0.36 Ω, and excellent cycle stability. The three-dimensional electrode filled with 0.15 g FSAPH performed pre-adsorption of m-cresol without electricity. Intraparticle diffusion is mainly controlled by SiOSi/AlOH groups on the mineral surface, and the adsorption rate constant KS1 reached 0.491·min−1. After being electrified, AlOH converted H2O2 via three pathways to generate reactive oxygen species (ROS). The rate-determining step in path 2 was the entry of oxygen atoms in OH into the AlOH lattice with the lowest energy barrier of 1.71 kcal/mol. 79.61 mg/L m-cresol can be rapidly degraded within 24 min, 2.6 times that of the two-dimensional electrode system. The electrostatic attraction of carbon ensured the continuous and rapid supply of H2O2 near mineral active sites due to the carbon/minerals interwoven structure. Extensive catalytic sites in thin sheet-like minerals accelerated the electrooxidation of m-cresol on carbon, boosting the catalytic reaction kinetics. Hence, the study realized the comprehensive utilization of carbon/ash in GFS and waste treatment with waste.

Electrocatalytic Mechanisms for an Oxygen Evolution Reaction at a Rhombohedral Boron Monosulfide Electrode/Alkaline Medium Interface.

Rhombohedral boron monosulfide (r-BS) with a layer stacking structure is a promising electrocatalyst for an oxygen evolution reaction (OER) within an alkaline solution. We investigated the catalytic mechanisms at the r-BS electrode/alkaline medium interface for an OER using hybrid solvation theory based on the first-principles method combined with classical solution theory. In this study, we elucidate the activities of the OER at the outermost r-BS sheet with and without various surface defects. The Gibbs free energies along the OER path indicate that the boron vacancies at the first and second layers of the r-BS surface (VB1 and VB2) can promote the OER. However, we found that the VB1 is easily occupied by the oxygen atom during the OER, degrading its electrocatalytic performance. In contrast, VB2 is suitable for the active site of the OER due to its structure stability. Next, we applied a bias voltage with the OER potential to the r-BS electrode. The bias voltage incorporates the positive excess surface charge into pristine r-BS and VB2, which can be understood by the relationship between the OER potential and potentials of zero charge at the r-BS electrode. Because the OH- ions are the starting point of the OER, the positively charged surface is kinetically favorable for the electrocatalyst owing to the attractive interaction with the OH- ions. Finally, we qualitatively discuss the flat-band potential at a semiconductor/alkaline solution interface. It suggests that p-type carrier doping could promote the catalytic performance of r-BS. These results explain the previous measurement of the OER performance with the r-BS-based electrode and provide valuable insights into developing a semiconductor electrode/water interface.

Electrocatalytic regulation of electrochemiluminescence: Mechanisms and sensing strategies

Electrocatalysis (EC) can reduce the overpotential and promote electrochemical reactions, leading to improved energy conversion, and electrochemiluminescence (ECL) is a convenient energy output. However, fundamental understanding of the relationship between EC and ECL performance has been very limited, hindering rational improvement and effective applications. Herein, as a proof of concept, we developed a model system composed of multi-walled carbon nanotubes (MWCNTs) as a catalyst, 6-aza-2-thiothymine protected gold nanoclusters (ATT-AuNCs) as luminophore, and tripropylamine (TPA) as coreactant, to evaluate the electrocatalytic effect on ECL by kinetic analysis of electrocatalytic reactions. A dual EC-mediated ECL enhancement was demonstrated in this system. The catalytically active sites were identified to be the carboxyl groups in the MWCNTs. We also discovered that EC could be tuned by other factors, such as wettability. Our findings were supported by density functional theory and molecular dynamics calculations as well. After understanding the EC mechanism, EC was then used to rationally regulate ECL for biosensor development for the first time. The detection of arginase with a record low limit of detection of 1.6 × 10−7 U mL−1 was achieved. This work not only enriches ECL regulation strategies, but also paves a new avenue for engineering EC guided ECL and devices.

Electrocatalytic degradation of octadecylamine and 4-dodecylmorpholine by the Ti/SnO2-Sb/β-PbO2 anode at high salinity conditions: Activity and mechanism insights

Increased levels of octadecylamine (ODA) and 4-dodecylmorpholine (DMP) in the aqueous, primarily utilized as flotation agents in the worldwide production of potash fertilizer, imperil the stability of ecosystems and the downstream production of high-end chemicals. Nevertheless, there is a dearth of exhaustive studies pertaining to the elimination of ODA and DMP. Herein, the Ti/SnO2-Sb/β-PbO2 anode was fabricated by a thermal decomposition-electrodeposition technique for the electrocatalytic degradation of ODA and DMP. The degradation efficiency of ODA and DMP can achieve complete degradation, reaching 100%, after treatment periods of 10 min and 120 min, respectively. Meanwhile, the TOC removal efficiency of ODA and DMP is up to 85% and 61% at 30 min and 120 min, respectively. In particular, sulphate exhibits inhibitory degradation activity of ODA and DMP in comparison to chloride salt. The recycling and accelerated lifetime tests indicate excellent stability and recyclability of the Ti/SnO2-Sb/β-PbO2 electrode. The mechanism of electrocatalytic degradation involves indirect electrochemical oxidation mediated by free radicals. The primary reactive species responsible for the degradation of DMP and ODA, as determined through scavenger quenching experiments and ESR, are ·OH and Cl·. The degradation of the ODA and DMP commences with the elimination of N element, leading to the formation of the NO3-. The carbon chain subsequently undergoes the breakdown. The degradation pathways of ODA and DMP were also proposed based on the GC–MS and H-NMR analyses, respectively. Moreover, the Ti/SnO2-Sb/β-PbO2 anode performed excellently in the removal of ODA and DMP in real samples, TOC removal from ODA and DMP in natural samples was 56% and 52%, respectively, within 180 min. This study provides the first exploration of electrocatalytic degradation mechanisms and pathways of ODA and DMP based on the Ti/SnO2-Sb/β-PbO2 anode.

Highly efficient sulfur-doped Ni3Fe electrocatalysts for overall water splitting: Rapid synthesis, mechanism and driven by sustainable energy

Designing efficient electrocatalysts and insight into their electrocatalytic mechanisms are significantly important for storing and converting the intermittent sustainable energy sources into clean hydrogen. In this study, we synthesize the bifunctional sulfur-doped Ni3Fe (NiFeS) electrocatalysts by a simple electrodeposition method only taking 30 s. After optimizing the components, it was found that the synthesized NiFeS electrocatalysts exhibit the excellent hydrogen and oxygen evolution reaction performances in 1.0 M potassium hydroxide solution. The results of experimental and theoretical calculations reveal that the introduced sulfur could optimize the electronic distribution, which make Ni electron-rich and Fe electron-deficient, thereby weakening the energy barriers of potential-determining steps, i.e. the absorption of H2O molecule on Ni sites for HER and formation of *OOH on Fe sites for OER, respectively. Besides, the NiFeS electrocatalysts are used as the bifunctional electrodes to water splitting, which only need 1.51 V to reach 10 mA·cm−2, and exhibits excellent durability and a >95% Faraday efficiency. Furthermore, the intermittent kinetic, wind and solar energies are used to power the assembled electrolyzer with NiFeS bi-electrodes to verify their great application potential. This work not only proved a deep insight into mechanism of the boosted electrocatalytic activities of NiFeS, but also the synthesized NiFeS electrocatalysts have great application prospect in the conversion of intermittent and sustainable energy sources into hydrogen by water electrocatalysis.

Catalytic and Electrocatalytic Mechanisms of Cytochromes P450 in the Development of Biosensors and Bioreactors.

Cytochromes P450 are a unique family of enzymes found in all Kingdoms of living organisms (animals, bacteria, plants, fungi, and archaea), whose main function is biotransformation of exogenous and endogenous compounds. The review discusses approaches to enhancing the efficiency of electrocatalysis by cytochromes P450 for their use in biotechnology and design of biosensors and describes main methods in the development of reconstituted and electrochemical catalytic systems based on the biochemical mechanism of cytochromes P450, as well as and modern trends for their practical application.

Transition metal nitrides embedded in N-doped porous graphitic Carbon: Applications as electrocatalytic sulfur host materials

While transition metal nitrides (TMNs) are promising electrocatalysts, their widespread use is challenged by the complex synthetic methodology and a limited understanding of the underlying electrocatalytic mechanisms. Herein, we describe a novel synthesis of TMNs (including Mo2N, NbN, and ZrN) and explore their potential as electrocatalysts to affect sulfur cathode reactions. The TMNs were prepared in-situ using a process that simultaneously infuses nitrogen-doped porous graphitic carbon (designated as TMN@N-PGC). The methodology avoids the use of ammonia, which poses safety risks due to its flammability and toxicity. Analysis of the d-p hybridized orbitals formed between the transition metal ions and sulfur species revealed that the antibonding orbitals are empty. Thus, TMNs with more negative d-band centers exhibit stronger affinities towards polysulfides. NbN facilitated polysulfide conversion as well as Li2S detachment, and thus featured a high electrocatalytic capability for promoting cathode kinetics. Lithium−sulfur (Li–S) batteries containing NbN@N-PGC exhibited the highest performance metrics in terms of specific capacity (1488 mA h g−1 at 0.1 C), rate capacity (521 mA h g−1 at 6 C), and cycling stability (603 mA h g−1 at 0.5 C after 1300 cycles, corresponding a capacity decay of 0.030% per cycle). Li−S cells with high sulfur loadings also exhibit outstanding performance.

2D-2D Nanoheterostructure of an Exposed {001}-Facet CuO and MoS2 Based Bifunctional Catalyst Showing Excellent Surface Chemistry and Conductivity for Cathodic CO2 Reduction.

A novel CuO-MoS2 based heterostructure catalyst model system is proposed where a CuO nanosheet with exposed {001} facet with proper termination is the active surface for the catalysis and a MoS2 nanosheet is the supporting layer. Density functional theory (DFT) calculations were performed to validate the model. The MoS2 bilayer forms a stable heterostructure with {001} faceted CuO with different terminations exposing oxygen and copper atoms (active sites) on the surface. The heterostructure active sites with a low oxidation state of the copper atoms and subsurface oxygen atoms provide a suitable chemical environment for the selective production of multicarbon products from CO2 electrocatalytic reduction. Furthermore, our heterostructure model exhibits good electrical conductivity, efficient electron transport to active surface sites, and less interfacial resistance compared to similar heterostructure systems. Additionally, we propose a photoenhanced electrocatalysis mechanism due to the photoactive nature of MoS2. We suggest that the photogenerated carrier separation occurs because of the interface-induced dipole. Moreover, we utilized a machine learning model trained on a 2D DFT materials database to predict selected properties and compared them with the DFT results. Overall, our study provides insights into the structure-property relationship of a MoS2 supported 2D CuO nanosheet based bifunctional catalyst and highlights the advantages of heterostructure formation with selective morphology and properly terminated surface in tuning the catalytic performance of nanocomposite materials.

Exciting lattice oxygen of nickel–iron bi-metal alkoxide for efficient electrochemical oxygen evolution reaction

High efficiency, cost-effective and durable electrocatalysts are of pivotal importance in energy conversion and storage systems. The electro-oxidation of water to oxygen plays a crucial role in such energy conversion technologies. Herein, we report a robust method for the synthesis of a bimetallic alkoxide for efficient oxygen evolution reaction (OER) for alkaline electrolysis, which yields current density of 10 mA cm−2 at an overpotential of 215 mV in 0.1 M KOH electrolyte. The catalyst demonstrates an excellent durability for more than 540 h operation with negligible degradation in activity. Raman spectra revealed that the catalyst underwent structure reconstruction during OER, evolving into oxyhydroxide, which was the active site proceeding OER in alkaline electrolyte. In-situ synchrotron X-ray absorption experiment combined with density functional theory calculation suggests a lattice oxygen involved electrocatalytic reaction mechanism for the in-situ generated nickel–iron bimetal-oxyhydroxide catalyst. This mechanism together with the synergy between nickel and iron are responsible for the enhanced catalytic activity and durability. These findings provide promising strategies for the rational design of non-noble metal OER catalysts.

Efficient defluorination of perfluorooctanoic acid enabled by single-atom Cu/reduced graphene oxide electrocatalytic anode and peroxymonosulfate activation

In this study, an electrocatalytic system using reduced graphene oxide supported single-atom copper (SA-Cu/rGO) anode was constructed for perfluorooctanoic acid (PFOA) defluorination. The successful doping of SA-Cu elevated the oxygen evolution potential and electrochemical active surface area of the anode and provided high electrocatalytic properties. Under optimum initial conditions with a peroxymonosulfate (PMS) concentration of 10 mM, a current density of 15 mA·cm−2, and an unadjusted pH of 7.75, the SA-Cu/rGO system achieved 98.8% removal ratio, 92.5% defluorination, and 94.4% mineralization of 20 mg·L-1 PFOA in 120 min. Kinetic studies indicate PFOA degradation following a pseudo-first-order model, with a rate constant of 4.7 × 10−2 min−1. The presence of PMS in the electrocatalytic system significantly improved the degradation rate and defluorination ratio. Radical trapping and quenching experiments confirmed that both ·OH and ·SO4- radicals contributed to PFOA degradation, with ·SO4- playing a more important role in defluorination. The system show high flexibility in initial PFOA concentrations (0.2–20 mg·L−1) and environmental pH values (3.0–10.0), as well as good durability. The electrocatalytic degradation mechanism of PFOA was proposed through determination of intermediates and density functional theory (DFT) calculation. The total short-chain perfluorocarboxylic acids (PFCAs) intermediates generated throughout the degradation were far from sufficient recovery of the PFOA loss, indicating that apart from the ·OH mediated decarboxylation-hydroxylation-elimination-hydrolysis (DHEH) pathway, the ·SO4- mediated decarboxylation-hydroxylation-oxidation-decarbonyl fluoride (DHOD) pathway may play a significant role in the near-complete defluorination and mineralization of PFOA. Moreover, DFT calculations suggest that the DHOD pathway is energetically favorable over DHEH. This study provides a further understanding of the defluorination mechanism of PFOA in electrocatalytic systems and demonstrates that electrochemical degradation with single-atom copper catalyst is an promising method for PFOA remediation in aqueous environment.

Theoretical insights on oxygen electrode reactions of YNxC4-x@Gra with hydroxylation effect

The oxygen electrode reactions (ORR/OER) are the key to electrochemical storage and conversion technologies. In this study, the bifunctional electrocatalytic mechanisms of YNxC4-x@Gra with hydroxylation effect were discussed extensively. Firstly, the configurations with N coordination have good stability. Secondly, YN1C3/N2C2hex@Gra with unstable coordination environment break the scale relationships between adsorption intermediates and exhibit outstanding OER performance with ηOER of 0.45 V and 0.46 V. Thirdly, YN2C2oppo/N2C2pen/N3C1OH@Gra with stable coordination environment demonstrate excellent bifunctional activity with ηORR of 0.48 V, 0.54 V, and 0.53 V and ηOER of 0.71 V, 0.73 V, 0.63 V. Forth, for catalysts with stable coordination environments, there are scale relationships between the adsorption of intermediates, and thus volcanic curves were constructed. Finally, the d-electron number was introduced to predict catalytic performance, saving time and computative costs for screening potential catalyst configurations. All in all, YNxC4-x@Gra catalysts are potential oxygen electrode bifunctional electrocatalysts.

Electrocatalytic Mechanism of Water Splitting by Ultralow Content of RuO2-supported on Fluorine-Doped Graphene Using a Constant Potential Method

Electrocatalytic Mechanism of Water Splitting by Ultralow Content of RuO₂-supported on Fluorine-Doped Graphene Using a Constant Potential Method