Electronic Buffer Research Articles

Interstitial Oxygen Acts as Electronic Buffer Stabilizing High-Entropy Alloys for Trifunctional Electrocatalysis.

Understanding the effect of elements' oxygen affinity is essential for comprehending high-entropy alloys' (HEAs) complete properties. However, the origin of HEAs' oxygen-containing structure and stability remains poorly understood, primarily due to their diverse components, hindering synthesis and analysis. Herein, the O-doping HEAs (HEA-O) have demonstrated outstanding performance and stability in electrolyzed water and Zinc-air batteries which can be reassembled after being stable for more than 1600h when the zinc consumption is over. The experiment and DFT simulation demonstrate that Cr with strong oxygen affinity can introduce more oxygen into the system of HEAs. Consequently, interstitial oxygens act as electronic buffers making the binding energy of other metal elements move to a higher level. Additionally, O-doping lowers the d-band center promoting electrochemical activity and increasing vacancy formation energies of metal active sites leading to super stability. The study provides significant insights into the design and comprehension of interstitial oxygen-doped HEAs.

Research Progress in Structure Evolution and Durability Modulation of Ir- and Ru-Based OER Catalysts under Acidic Conditions.

Green hydrogen energy, as one of the most promising energy carriers, plays a crucial role in addressing energy and environmental issues. Oxygen evolution reaction catalysts, as the key to water electrolysis hydrogen production technology, have been subject to durability constraints, preventing large-scale commercial development. Under the high current density and harsh acid-base electrolyte conditions of the water electrolysis reaction, the active metals in the catalysts are easily converted into high-valent soluble species to dissolve, leading to poor structural durability of the catalysts. There is an urgent need to overcome the durability challenges under acidic conditions and develop electrocatalysts with both high catalytic activity and high durability. In this review, the latest research results are analyzed in depth from both thermodynamic and kinetic perspectives. First, a comprehensive summary of the structural deactivation state process of noble metal oxide catalysts is presented. Second, the evolution of the structure of catalysts possessing high durability is discussed. Finally, four new strategies for the preparation of stable catalysts, "electron buffer (ECB) strategy", combination strength control, strain control, and surface coating, are summarized. The challenges and prospects are also elaborated for the future synthesis of more effective Ru/Ir-based catalysts and boost their future application.

Synergistic Sr Activation and Cr Buffering Effect on RuO2 Electronic Structures for Enhancing the Acidic Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) performance of ruthenium-based oxides strongly correlates with the electronic structures of Ru. However, the widely adopted monometal doping method unidirectionally regulates only the electronic structures, often failing to balance the activity and stability. Here, we propose an "elastic electron transfer" strategy to achieve bidirectional optimization of the electronic structures of Sr, Cr codoped RuO2 catalysts for acidic OER. The introduction of electron-withdrawing Sr intrinsically activates the Ru sites by increasing the oxidation state of Ru. Simultaneously, Cr acts as an electron buffer, donating electrons to Ru in the presence of Sr in the as-prepared catalysts and absorbing excess electrons from Sr leaching during the OER. Such a bidirectional regulation feature of Cr prevents overoxidation of Ru and maintains its high oxidation state during the OER. The optimal Ru3Cr1Sr0.175 catalyst exhibits a low overpotential (214 mV @ 10 mA cm-2) and excellent stability (over 300 h).

Si/Graphite@C Composite Fabricated by Electrostatic Self-Assembly and Following Thermal Treatment as an Anode Material for Lithium-Ion Battery.

Commercial graphite anode has advantages such as low potential platform, high electronic conductivity, and abundant reserves. However, its theoretical capacity is only 372 mA h g-1. High-energy lithium-ion batteries have been a research hotspot. The Si anode has an extremely high specific capacity, but its application is hindered by defects such as large volume changes, poor electronic conductivity, and a small lithium-ion diffusion coefficient. Here, the Si/thermally reduced graphite oxide@carbon (Si/RGtO@C) composite was fabricated by electrostatic self-assembly followed by thermal treatment. The RGtO synergistic carbon coating layer can effectively compensate for the low electronic conductivity and buffer the volume expansion effect of the Si nanoparticles during charge/discharge cycles. The Si/RGtO@C anode demonstrated a significantly increased capacity compared to the RGtO. After 300 cycles, Si/RGtO@C kept a discharged capacity of 367.6 mA h g-1 at a high current density of 1.0 A g-1. The Si/RGtO@C anode shows an application potential for commercial high-energy lithium-ion batteries.

Enhanced photocatalytic degradation of organic pollutants via black phosphorus-mediated electron transfer in g-C3N4/BiOI: Degradation mechanisms and biotoxicity assessment

Photocatalysis is a promising strategy for organic pollutant removal, yet developing a capable photocatalyst remains challenging. Using black phosphorus (BP) as an electron buffer material, the ternary composite photocatalysts of xBP/g-C3N4/BiOI were prepared through a straightforward hydrothermal method. Tetracycline (TC) and Rhodamine B (RhB) removals were 100 % (120 min) and 99 % (90 min) by photocatalytic process on 2.5 %BP/g-C3N4/BiOI under xenon lamp irradiation. Photoluminescence and electrochemical measurements confirmed BP's role in reducing charge transfer barriers between g-C3N4 and BiOI, achieving effective separation of photogenerated electrons. The degradation mechanisms of TC and RhB on 2.5 %BP/g-C3N4/BiOI were revealed by the quenching experiments, electron paramagnetic resonance spectroscopy tests, three-dimensional excitation-emission matrix fluorescence spectrum, and liquid chromatography-mass spectrometry analyses. Plant toxicity assessment experiments confirmed the non-toxic nature of the TC and RhB degradation solutions. Plants grown in the treated solutions exhibited declining trends in both Malondialdehyde and Peroxidase indices compared to untreated solutions. This study offers a fresh approach to advanced photocatalyst design using charge transfer buffer materials.

Dual engineering of hetero-interfaces and architecture in MoSe2/VSe1.6@N[sbnd]C nanoflower for fast and stable sodium/potassium storage

Rational structure design is significant for the selenide anodes in the sodium/potassium ion batteries (SIBs/PIBs). Herein, dual engineering of hetero-interfaces and architecture is proposed to design SIB/PIB anodes. Attributed to the coordination binding with Mo7O246- and VO3-, the polydopamine assembly is demonstrated as an ideal template to produce bimetallic selenide of MoSe2/VSe1.6 anchoring on the in-situ N-doped carbon matrix (MoSe2/VSe1.6@NC). This ingenious hierarchical nanoflower structure can shorten the Na+/K+ diffusion length, increase the electron conductivity and buffer the volume changes, which can promote Na+/K+ reaction kinetics and stabilize the cycling performance. Consequently, the sodium/ potassium storage performance of MoSe2/VSe1.6@NC can be boosted. In SIBs, it achieves a capacity of 202 mAh/g at 10.0 A/g for 5000 cycles. Meanwhile, stable capacities of 207.1 mAh/g can be reached at 1.0 A/g over 1000 cycles in the PIBs. Furthermore, impressive capacities of 222.1 mAh/g and 100.4 mAh/g are delivered in the full cells of MoSe2/VSe1.6@NC//Na3V2(PO4)3@C and MoSe2/VSe1.6@NC//FePBA, respectively. This proves the potential practical application for the MoSe2/VSe1.6@NC anode in SIBs/PIBs.

Cerium Dioxide as an Electron Buffer to Stabilize Iridium for Efficient Water Electrolysis

AbstractSustaining the steady state for highly active non‐stoichiometric iridium (Ir)‐based oxide (IrOx) at low Ir loading remains challenging primarily due to the continuous oxidation and sequent dissolution of Ir active sites during the oxygen evolution reaction (OER). In this context, a new iridium–cerium (Ce) substitution solid solution oxide (SSO) has been developed, featuring uniformly dispersed Ir atoms within Ce dioxide (CeO2) matrix as electron buffer, which delivers remarkable acidic OER catalytic activity and enhanced stability. The electron‐buffering capacity of CeO2 facilitates the charge transfer toward Ir atoms, leading to abundant active low‐valence Ir sites and effectively prevent their oxidation and dissolution. As a result, Ir─Ce SSO demonstrates an overpotential of merely 238 mV@10 mA cm−2. Proton exchange membrane water electrolyzer employing Ir─Ce SSO at a low Ir loading of 396 µgIr cm−2 operates consistently for over 100 h@500 mA cm−2. Density functional theory (DFT) calculations corroborate that the electron‐buffering effect of CeO2 enriches the density of IrIII and substantially increases the dissolution energy barrier of Ir atoms. This study presents a viable approach to addressing the issues of instability and low efficiency in Ir‐based OER electrocatalysts for acidic water electrolysis.

Rational design of cuprofullerene bipyridine nanozyme with high peroxidase-like activity for colorimetric sensing of bleomycin.

The high catalytic activity of Cu-based nanozymes mainly depends on the efficient Fenton-like reaction of Cu+/ H2O2, but Cu+ cannot exist stably. Trying to find a material that can stably support Cu+ while promoting the electron cycle of Cu2+/Cu+ still faces serious challenges. C60 is expected to be an ideal candidate to solve this problem due to its unique structure and rich physicochemical properties. Here, we designed and synthesized a C60-doped Cu+-based nanozyme (termed as C60-Cu-Bpy) by loading high catalytic active site Cu+ onto C60 and coordinating with 2,2'-bipyridine (Bpy). The single crystal diffraction analysis and a series of auxiliary characterization technologies were used to demonstrate the successful preparation of C60-Cu-Bpy. Significantly, the C60-Cu-Bpy exhibited superior peroxidase-like activity during the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Then, the catalytic mechanism of C60-Cu-Bpy as peroxidase was elucidated in detail, mainly benefiting from the dual function of C60. On the one hand, C60 acted as a carrier to directly support Cu+, which has the ability to efficiently decompose H2O2 to produce reactive oxygen species. The other was that C60 acted as an electron buffer, contributing to promoting the Cu2+/Cu+ cycle to facilitate the reaction. Furthermore, a colorimetric sensor for the quantitative analysis of bleomycin was established based on the principle of bleomycin specific inhibition of C60-Cu-Bpy peroxidase-like activity, with satisfactory results in practical samples. This study provides a new strategy for the direct synthesis of Cu+-based nanozymes with high catalytic performance.

Thermal-Driven Orderly Assembly of Ir-atomic Chains on α-MnO2 with Enhanced Performance for Acidic Oxygen Evolution.

The development of acid-stable oxygen evolution reaction electrocatalysts is essential for high-performance acidic water electrolysis. Herein, we report the results of one-dimensional (1D) nanorods (NRs) IrCeMnO@Ir containing ~20 wt . % Iridium (Ir) as an efficient anode electrocatalyst, synthesized via a one-step cation exchange strategy. Owing to the presence of 1D channels of the nanorod architecture and the unique electronic structure, the IrCeMnO@Ir exhibited 69 folds more mass activity than that of commercial IrO2 as well as over 400 h stability with only a 20 mV increase in overpotential. DFT calculations and control experiments demonstrated that CeO2 serves as an electron buffer to accelerate the kinetics of the rate-determined step for the significantly enhanced activity and suppress the over-oxidation of Ir species as well as their dissolution for impressively promoted stability under practical conditions. Our work opens up a feasible strategy to boost OER activity and stability simultaneously.

Vanadium oxide as an electron buffer to stabilize palladium for electrocatalytic hydrodechlorination

Pd/VOx/C presents 97% reduction of 4-chlorophenol in electrocatalytic hydrodechlorination after 18 h electrolysis due to the buffer function of vanadium oxide.

Coupling thulium 4f orbitals with Ni3Fe LDH loaded with Pt to form an electronic buffer band for catalyzing alkaline overall water splitting

When thulium is doped into Ni3Fe LDH, coupling thulium 4f orbitals with the Ni3Fe LDH system forms an electronic buffer band and Pt loading catalyzes alkaline overall water splitting.

C60 and Derivatives Boost Electrocatalysis and Photocatalysis: Electron Buffers to Heterojunctions

AbstractBuckminsterfullerene (C60) and derivatives are significant in the synthesis of efficient electrocatalysts and photocatalysts. This is because of electron acceptor properties and distinctive heterostructure(s) and physicochemical characteristics. High‐performance electrocatalysts and photocatalysts are important therefore in conversions for clean energy. Here a critical assessment of advances in use of C60 and derivatives as heterostructures and “electron buffers” in catalysts are reported. Methodologies for preparing C60 composite catalysts are assessed and categorized and microscopic mechanisms for boosting catalytic performance through C60 and derivatives in important catalytic materials including, semiconductors, carbon‐based metal‐free materials, metal nanoclusters, single atoms, and metal–organic skeletons are established. Important characterizations used with C60 and derivative composites are contrasted and assessed and practical challenges to development are determined. A prospective on future directions and likely outcomes in development of high efficiency electrocatalysts and photocatalysts is provided. It is concluded that C60 and derivatives are advantageous for advanced electrocatalysts and photocatalysts with high structural integrity and boosted electron transport. The findings are expected to be of interest and benefit to researchers and manufacturers for formation of heterostructures and electron buffer areas for significantly boosted catalytic performance.

Electronic Health Record Usage in an Academic Orthopaedic Sports Medicine Practice

Background While the relationship between electronic health record usage and physician burnout has been investigated in other specialties, no reports exist for orthopaedic surgery. The purpose of this study was to determine the amount of time spent on the electronic health record compared to actual patient interaction in four busy orthopaedic outpatient clinics. Hypothesis We hypothesized that surgeons would spend as much time on the electronic health record as they do interacting with patients on a typical clinic day. Methods Four busy academic orthopaedic surgeons (Surgeon 1, 2, 3, and 4) at a tertiary academic institution were each followed on clinic days to determine their total time spent on Epic Hyperspace electronic health record as compared to face-to-face interactions with patients. A research assistant recorded the amount of time each surgeon spent dictating notes, writing orders, or replying to clinical inbox messages (electronic health record time) and how much time was spent on loading screens or electronic health record buffering (loading time) during which no actions could be completed. Results Surgeon 1 spent an average of 63% of their clinic days using the electronic health record. Surgeon 2 spent 50% of their time on the computer. Surgeon 3 spent 35% of his days on the computer. Surgeon 4 spent 46% of his days on the computer. Conclusion Approximately half of each surgeon’s clinic time was spent using the electronic health record. Given the known influence of electronic health record usage on orthopaedic surgeon burnout, this is an issue that needs to be addressed. The solution likely involves a multifactorial approach, including changes to electronic health records, widespread use of scribes or advanced care teams, work hour limitations, and mindfulness training for residents and faculty. Information technology quality improvements can be made to EHRs that include reducing or eliminating unnecessary information displayed on screen, providing more abundant and accessible EHR training and on-site technical support, and a more streamlined software interface that eliminates unnecessary typing and clicks to improve charting flow and efficiency. Level of Evidence Level IV Descriptive Study

Co3O4 anode for lithium-ion batteries coupled by polyoxometalates and graphene for boosting ion-/electron-conductivity

Even being promising anode materials for lithium-ion batteries (LIBs), Co3O4 is still hindered by poor redox and large volume change during dis-/charging. Herein, series of PW12 @Co3O4 @GO composites were successfully fabricated to address the aforementioned shortcomings by pinning monodispersed H3PW12O40 (PW12) on Co3O4 and then coating graphene (GO). Results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CV) show that PW12 was successfully anchored to the macromolecule Co3O4 by covalent Co-O-W bond, where, to improve the ion and charge transfer rate of Co3O4, the excellent ionic conductivity and multi-electron redox of PW12 as “Li+ migration entrance” were explored for the first time, meanwhile, the capacity retention of PW12 was greatly maintained (97.5% after 250 cycles). Moreover, GO as electronic conductor and buffer improves the overall conductivity and copes with large volume changes of Co3O4, which ensures the capacity retention rate of PW12 @Co3O4 @GO-2 of 94.9% after 250 cycles. Finally, we delved into the lithium storage process and proposed a possible lithium storage mechanism of PW12 @Co3O4 @GO-2, which provides a new insight to trigger the electrochemical activity for next-generation anode materials.

Nitrogen‐Rich WN Clusters with Atomic Disorders and Non‐Grain Boundaries Confined in Carbon Nanosheets Boosting Sodium‐Ion Storage (Small 24/2023)

Atomic Disorders The specific transport routes and rigid structures of crystalline metal compounds can limit their application in sodium ion batteries. The atomically dispersed amorphous W-N clusters confined in carbon nanosheets (W-N/CNSs) can provide abundant storage sites and isotropic transport paths for sodium ions, and the highly conductive CNSs can facilitate electron transfer and buffer structural deformations. More details can be found in article number 2300619 by Fanyan Zeng, Shenglian Luo, and co-workers.

C60‐Stabilized Cu+ Sites Boost Electrocatalytic Reduction of CO2 to C2+ Products

AbstractConstructing Cu0–Cu+ double‐active sites is significant for C–C coupling to produce multicarbon products during the CO2 electrocatalytic reduction process. However, Cu‐based precursors (including Cu+) are easily reduced to Cu0, especially at large current densities. Thus, developing a facile Cu+ stabilization method to form Cu0–Cu+ double‐active sites is highly desirable but challenging. Herein, fullerene (C60) is used as an electronic buffer to stabilize the Cu+ site. Then, a composite of copper oxide and C60 precursor is designed to obtain a catalyst consisting of in situ formed Cu0–Cu+ double‐active sites. The catalyst not only delivers up to 61% multicarbon (C2+) products Faraday efficiency at a partial current density of 366 mA cm−2 but also exhibits a good 12 h durability of the Cu+ site at −1.4 V versus reversible hydrogen electrode. Moreover, the Cu0–Cu+ double‐active sites are revealed to induce the preferential coupling of *CO and *CHO over *CO dimerization, accounting for the enhanced C2+ selectivity.

Dual Charge-Transfer Channels Harmonize Carrier Separation for Efficient U(VI) Photoreduction

The low efficient transfer of photogenerated electrons to an active catalytic site is a pivotal problem for the photoreduction of highly soluble hexavalent uranium [U(VI)] to low soluble tetravalent uranium [U(IV)]. Herein, we successfully synthesized a TiO2-x/1T-MoS2/reduced graphene oxide heterojunction (T2-xTMR) with dual charge-transfer channels by exploiting the difference in Fermi levels between the heterojunction interfaces, which induced multilevel separation of photogenerated carriers. Theoretical and experimental results demonstrate that the presence of the electron buffer layer promoted the efficient migration of photogenerated electrons between the dual charge-transfer channels, which achieved effective separation of photogenerated carriers in physical/spatial dimensions and significantly extended the lifetime of photogenerated electrons. The migration of photogenerated electrons to the active catalytic site after multilevel spatial separation enabled the T2-xTMR dual co-photocatalyst to remove 97.4% of the high concentration of U(VI) from the liquid-phase system within 80 min. This work provides a practical reference for utilizing multiple co-catalysts to accomplish directed spatial separation of photogenerated carriers.

Conducting Polymers Meet Lithium–Sulfur Batteries: Progress, Challenges, and Perspectives

Lithium–sulfur (Li–S) batteries have attracted increased interest because of the high theoretical energy density, low cost, and environmental friendliness. Conducting polymers (CPs), as one of the most promising materials used in Li–S batteries, can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility, but also enable stronger physical/chemical adsorption capacity toward polysulfides (LiPSs) when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur loading. This review firstly introduces the properties of various CPs including structural CPs (polypyrrole (PPy), polyaniline (PANi), polyethylene dioxothiophene [PEDOT]) and compound CPs (polyethylene oxide (PEO), polyvinyl alcohol (PVA) and poly(acrylic acid) [PAA]), and their application potential in Li–S batteries. Furthermore, the research progress of various CPs in different components (cathode, separator, and interlayer) of Li–S batteries is systematically summarized. Finally, the application perspective of the CPs in Li–S batteries as a potential guidance is comprehensively discussed.

Boosted electrochemical performance of Na3V2(PO4)3 at low temperature through synergistical F substitution and construction of interconnected nitrogen-doped carbonaceous network

Benefitting from its unique NASICON-type framework, the Na3V2(PO4)3 (NVP) cathodes have aroused extensive interest and have been deemed as the promising cathode candidate for sodium-ion batteries (SIBs). Unfortunately, the poor electronic conductivity, combined with the undesirable volume variations, seriously hinders the practical application of NVP cathode, especially at low temperatures. Herein, a dual-strategy, F substitution accompanied by V vacancies and the construction of three-dimensional (3D) nitrogen-doped carbonaceous frameworks (NC), were employed for the NVP cathode (F-NVP/C@3DNC). The former can remarkably decrease the particle size and enhance Na+ migration capability, increasing the ionic conductivity. Meanwhile, the electronic connection and effective buffering can be obtained from the latter, strengthening the electrode integrity. Consequently, up to 100 cycles at 0.1 A g–1, a reversible capacity of 113.8 mAh g–1, approaching the theoretical value (117 mAh g–1), is demonstrated, accompanied by impressive capacity retentions at 1.0 (93.75% after 4800 cycles) and 20.0 A g–1 (92.7% after 1000 cycles). More importantly, even at –20 °C, a superior specific capacity (102.6 mAh g–1 after 100 cycles at 0.1 A g–1) and high capacity retention (86.6% at 20.0 A g–1 up to 1000 cycles) can still be obtained simultaneously. Significantly, the design of F-NVP/C@3DNC provides insights for the fabrication of polyanion cathodes for applications at low temperatures with modified structure stability and reaction kinetics.

Highly active and stable amorphous IrOx/CeO2 nanowires for acidic oxygen evolution

Development of highly active and durable electrocatalysts for acidic oxygen evolution reaction (OER) remains an unresolved grand challenge. Here, we reported the amorphous IrOx/CeO2 nanowires as highly active and acid-stable OER catalysts through a facile electro-spinning/calcination approach. The amorphous catalysts delivered a high mass activity of 167 A gIr−1 at 1.51 V, a low overpotential of 220 mV at 10 mA cm−2, and a stable performance for 300 h of continuous operation in acid. As revealed by complementary experimental and theoretical calculation results, the intimate nanoscale feature of IrOx/CeO2 creates abundant binary interfaces, at which CeO2 as an electron buffer regulates the adsorption of oxygen intermediates, lowers the activation barrier of OER, and suppresses the over-oxidation and dissolution of Ir, thereby significantly enhancing the OER activity and stability. This work provides a new strategy for designing highly active and acid-resistant OER catalysts.