High Electrocatalytic Activity Research Articles

A Hierarchical Polyoxometalate/Pd/Mos2 Hybrid: Developing an Efficient Novel Bifunctional Catalyst for Water Splitting

AbstractCatalytic water splitting is a promising approach to produce clean hydrogen fuel from renewable energy sources. However, developing hybrid heterostructures capable of efficiently breaking down water into its constituent elements, hydrogen, and oxygen, presents a considerable challenge. In this study, a novel hierarchical POM/Pd/MoS2 hybrid heterostructure, composed of sheets of MoS2 modified with Pd nanoparticles and combined with a cobalt‐based polyoxometalate (POM), serving as bifunctional catalyst for water splitting is reported. Through a synergistic synthetic approach, MoS2, acting as a reducing agent, triggers the nucleation and growth of Pd nanoparticles, which, in turn, serve as anchoring sites for the polymerization of the cobalt‐based POM into fibers. POM/Pd/MoS2 hybrid exhibits an enhanced oxygen evolution reaction (OER) activity, comparable to the benchmark catalysts Ir/C and IrO2/C in alkaline media, being its hydrogen evolution reaction (HER) activity similar to the activated Pd/MoS2 hybrid. The intriguing electrocatalytic capability of the resulting material for producing hydrogen and oxygen through electrochemical means arises from the enhanced charge storage capacity and conductivity of MoS2, the multi‐electron transfer facilitated by the POM, and the high electrocatalytic activity of the metals.

Enhanced stability and conductivity of montmorillonite and sucrose loaded Fe-MOFs for degradation of chlortetracycline hydrochloride via electrochemically activated persulfate

Ferreous metal-organic frameworks (Fe-MOFs) have provided excellent platforms for the removal of refractory contaminants from water, whereas poor conductivity and intrinsically fragile limit applications in electrochemistry and heterogeneous catalyst, respectively. Hence, we synthesized a novel Fe-based MOFs(Mt@Fe-MOFs@C) obtained through introducing sucrose to improve conductivity and montmorillonite (Mt) to enhance cycling stability, and combined with persulfate (PS) and electrochemical (EC) method to remove chlortetracycline hydrochloride(CTC) from water environment. The electrochemical impedance spectroscopy (EIS) demonstrated Mt.@Fe-MOFs@C was more conductive than pure Fe-MOFs. Mt.@Fe-MOFs@C showed high electrocatalytic activity for degradation of CTC in EC/Mt.@Fe-MOFs@C/PS system. The mechanism study indicated that SO4•− and HO• played dominant role in the elimination of CTC. Mt.@Fe-MOFs@C also exhibited excellent reusability with 83% removal efficiency after 5 cycle degradation. This work demonstrated that Mt.@Fe-MOFs@C would have potential for electrochemical wastewater remediation.

(Invited) Mixed Conductors for Advanced Solid Oxide Fuel Cells

Developing innovative electrode materials with high electrocatalytic activity is essential to advance the commercial viability of solid oxide fuel cells (SOFCs). Perovskite-type metal oxides have shown great potential as electrocatalysts for the oxygen reduction reaction and fuel oxidation. Mixed ionic and electronic conducting (MIECs) perovskites are being explored as electrodes which have demonstrated excellent chemical stability and provide more electrochemically active surface area. Here, we discuss our strategies towards the rational design of compositions to develop cost-effective and high-performance electrode materials for intermediate-temperature solid oxide fuel cells. Particular attention is centred on cathode materials and the role of thermal compatibility, electrical conductivity, and chemical stability towards improving the electrochemical performance of the cathode materials has been discussed.

The Durability of the Platinum/Polypyrrole Nanotubes' Catalysts in Oxygen Reduction Reaction

Platinum (Pt) catalysts supported on carbon-based materials are effective catalysts for fuel cells. However, the durability of the carbon supports in acidic media needs to be improved. Platinum/polypyrrole (PPy) nanotubes have emerged as promising catalysts for the oxygen reduction reaction (ORR) due to their high surface area and good electrocatalytic activity. Furthermore, the nitrogen atoms within the chemical structure of PPy nanotubes are expected to improve their durability.In this study, we investigated the performance and durability of Pt catalysts during ORR by decorating different carbon-based materials with Pt nanoparticles. The catalytic activity and durability were analyzed using the rotation ring-disk electrode (RRDE) technique. We also examined the influence of the different supports on the electrochemical degradation of the catalysts.Our results showed that Pt/PPy nanotubes exhibited high activity and durability in ORR reactions. We paid particular attention to the chemical changes of the catalysts' surfaces, including both the metal and support components, during the ex-situ electrochemical measurements. The surface of the catalysts was characterized using photoelectron X-ray spectroscopy (XPS), synchrotron radiation photoelectron spectroscopy (SRPES), and near-edge X-ray absorption fine structure (NEXAFS) analysis before and after electrochemical degradation. Based on our findings, we proposed degradation mechanisms of the Pt/PPy nanotubes catalysts.In addition, we tested the Pt/PPy nanotubes catalysts in fuel cells and observed their high performance. These findings suggest that Pt/PPy nanotubes catalysts can serve as durable and effective catalysts for ORR reactions, even under harsh conditions. Further research is needed to optimize the synthesis conditions and operating parameters of these catalysts to improve their performance and durability.

Non-PGM Cathode Electrocatalysts for PEM Fuel Cells

Polymer electrolyte membrane fuel cells, PEMFCs, are considered the most ideal next generation energy conversion device, able to provide power to a broad range of applications; automotive, combined heat and power, portable electronic devices. Pt-based electrocatalysts are regarded as ideal for promoting the desired redox reactions of a fuel cell, especially the sluggish oxygen reduction at the cathode, ORR. High expense and scarcity of Pt are the greatest impediments to successful commercialization of this technology. The replacement of unsustainable noble-metal catalysts with platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) is essential for material wise and market value viable PEMFCs.Among the different attempts towards non-PGM catalysts, incorporating atomically dispersed transition metal atoms (Fe, Mn, etc.) and heteroatoms (N, S, etc.) into carbon frameworks is the most promising [1,2]. Large specific surface area, high intrinsic ORR electrocatalytic activity, efficient porosity and sufficient stability in acid media and/or in the actual working environment are the least requirements to consider when designing the catalysts. So far, despite the tremendous efforts, many drawbacks still persist that include poor understanding of the nature of active centres and their control over the synthesis, as well as fast decay of the structure under operation.In this work, we will present a rationally designed strategy to prepare hybrid composite catalysts by developing Fe–N–C materials onto different 2D and 3D templates [3,4] with differentiated surface chemistry (silicon and heteroatom-doped carbon structures). Despite structural and physicochemical characterization, the study includes extensive electrochemical characterization in terms of activity and durability in relative to the application conditions. An example is depicted in Figure 1 for a single atom Fe-N-C catalyst synthesized using porous silica nanotubes as the sacrificial template resulting in a hierarchically porous structure with a surface area of 370 m2/g. Electrochemical study revealed a half-wave potential of 0.72 V and an onset potential of 0.88 V with high stability in acidic environment.Very importantly, the different findings are correlated to one another, thereby establishing a composition to function relationship to provide a pathway for the integrated engineering of novel structures with improved performance. Acknowledgments Funding from the Operational Program “Competitiveness, Entrepreneurship & Innovation” (EPAnEK), NSRF 2014-2020 through the project Solar2HyP Τ2ΕΔΚ-01877 References [1] L. Osmieri, et al., Current Opinion in Electrochemistry 25 (2020) 100627.[2] T. Asset, et al., Joule 4 (2019) 33-44.[3] Jin-Cheng Li et al., Asia Materials 10 (2018) e461[4] Nan Zhang et al., Energy Environ. Sci. 13 (2020) 111-118 Figure 1

(Invited) Materials Challenges for the Green Hydrogen Economy at Scale

Research and development projects over the last 30 years have successfully shown the value of hydrogen as a fuel and energy storage medium, and now hydrogen is seen as a key solution to decarbonization. Green hydrogen can be made by electrolysis anywhere that there is ample hydroelectric, solar and wind electric power. The hydrogen energy can be converted back to useful work in a fuel cell, turbine, or engine, or directly to manufacture products such as ammonia, cement, and steel. However, world decarbonization at scale also requires the demonstration of hydrogen at scale, and the widescale adoption of hydrogen for a green economy requires a reimagining of how energy is created, stored and used.Leading technologies for the green hydrogen economy include proton exchange membrane fuel cells (PEMFCs) and PEM water electrolyzers (PEMWE), both which operate under acidic conditions. In addition to high electrocatalytic activity, the electrode materials must be designed for two- phase flow of water and gas. All of the materials should be durable, low cost, manufacturable, recyclable, and have the appropriate electronic and thermal properties.This talk will describe some of the materials challenges needed to meet commercialization goals for PEMFCs and PEMWEs, and some of the constraints of manufacturing and recycling.

Oxygen Reduction Reaction Activity of Platinum Nanosheets Derived from Layered Platinic Acid

Platinum nanoparticles are mainly utilized as the cathode catalyst for polymer electrolyte fuel cells. However, the utilization of platinum for the oxygen reduction reaction (ORR) is insufficient and one must tackle the trade-off between high surface area and high stability. We have previously shown that metallic nanosheets such as ruthenium nanosheets exhibit high electrocatalytic activity and stability owing to the two-dimensional structure with an atomic scale thickness.1, 2 Platinum nanosheets, if available, should also have the potential to increase the utilization of the atoms and durability. While a few studies have reported the synthesis of platinum nanosheets,3 the thickness of the nanosheets is more than 1 nm, and the utilization of platinum has so far been lower than that of the Pt nanoparticles.In this study, we report double-layered platinum nanosheets derived from layered platinic acid.4 Layered platinic acid was synthesized through a solid-state-reaction and subsequent acid treatment. From the layered platinic acid, platinum oxide nanosheets were obtained as a colloid via chemical exfoliation. The thickness of the platinum oxide nanosheet was ~0.9 nm, consistent with the thickness of a single PtO6 octahedron. The platinum oxide nanosheets on silicon wafer were topotactically reduced to platinum nanosheets by mild thermal treatment in hydrogen. The thickness of the platinum nanosheet was ~0.5 nm, corresponding to a two atomic layer platinum nanosheet.Carbon supported platinum nanosheets were prepared by the reduction of platinum oxide nanosheets supported on carbon. The electrochemically active surface area (ECSA) of the carbon supported platinum nanosheets was 100 to 120 m2 (g-Pt)-1, which was considerably larger than that of 3 nm platinum nanoparticle (80 m2 (g-Pt)-1). In addition, the platinum nanosheet showed 1.7 times higher mass activity towards the oxygen reduction reaction compared to that of 3 nm platinum nanoparticles.Various methods for the topotactic reduction of platinum oxide nanosheets on carbon was studied. In addition to the mild thermal treatment in hydrogen gas, electrochemical reduction was also conducted. The ECSA of the platinum nanosheet prepared by electrochemical reduction at constant potential was 100 to 120 m2 (g-Pt)-1, which was almost same as the platinum nanosheet reduced by the mild thermal treatment in hydrogen. The specific activity was 1.2 to 1.3 times higher than that of the platinum nanosheet reduced by the mild thermal treatment in hydrogen. Therefore, the platinum nanosheet reduced by electrochemical reduction showed high mass activity for ORR.AcknowledgementThis work was supported as part of the “Polymer Electrolyte Fuel Cell Program” and the FC-Platform projects from the New Energy and Industrial Technology Development Organization (NEDO) of Japan (20001201-0, 22101136-0).

Interface engineering of N, P and S-doped hollow/porous Co3O4@Co3V2O8 heterostructure nanocube for high-activity supercapacitor and oxygen evolution reaction

Cobalt-based materials exhibit high theoretical specific capacitance and desirable electrocatalytic activity. However, their practical specific capacitance and electrocatalytic activity are significantly constrained by a lack of active sites and limited conductivity. Herein, N, P and S-doped hollow Co3O4@Co3V2O8 heterostructure nanocube is reasonably constructed via in-situ ion exchange method combined with calcination strategy. Besides, the relationship of heterogeneous interface and heteroatom doping on electrochemical performance is explored. The heterogeneous interface provides rich active sites and accelerates electron transfer. Additionally, N, P, and S-doping regulate the internal electronic structures, boost ion transfer rates, and increase active sites. The hollow structure accelerates the adsorption and desorption processes due to the increased electrochemical reaction sites. Benefiting from internal electronic structure and structural advantages, N, P, S-Co3O4@Co3V2O8 exhibits low overpotentials (561 mV and 649 mV at the current density of 50 mA/cm2 and 100 mA/cm2), low Tafel slopes (100.9 mV/dec), prospective specific capacitance (550.2 F/g) and outstanding charge/discharge behavior with remarkable life span. N, P, S-Co3O4@Co3V2O8 based device delivers favorable energy density (21.3 Wh/kg at 802.3 W/kg), which surpasses most of the latest cobalt-based materials. Overall, this work provides novel insights into the development of highly active and durable bifunctional electrode materials.

Functionally Graded Infiltration Triggering Ultrahigh Electrolytic Current in Robust Reversible Solid Oxide Cells

The reversible solid oxide cell (ReSOC) offers the dual capability to store electricity as chemical fuels and convert fuels to electricity, thereby enabling carbon neutral cycling. The nickel‐cermet fuel electrode exhibits high electrocatalytic activity for redox reactions while being particularly vulnerable to carbon deposition and nickel coarsening, especially at high current densities. Herein, a novel approach involving a graded infiltration onto a dendritic Ni–YSZ (yttria‐stabilized zirconia) skeleton with Pr6O11 nanoparticles/films is presented, demonstrating remarkable electrolytic current and coke tolerance in CO–CO2 conversion. At 800 °C, the current densities achieve approximately −2.0 and +2.0 A cm−2 under 1.3 and 0.6 V, respectively, showcasing robust cycling stability switching between two operational modes within 20 cycles. Notably, the attained electrolytic current density reaches an unprecedented −3.06 A cm−2 under 1.6 V. Furthermore, the button cell runs smoothly at ultrahigh electrolytic current densities ranging from −0.5 to −3.0 A cm−2 for nearly 270 h. The mechanism of high‐performance CO2 reduction is elucidated by in/ex situ experimental characterizations and theoretical calculations. These results indicate the viability of employing Ni–YSZ‐supported ReSOC for stable renewable electricity storage at previously unattainable reaction rates, and have implications for fundamental understanding of designing robust ReSOC based on the nickel‐cermet fuel electrode.

Enhanced electrocatalytic hydrodechlorination of 2,4-dichlorophenol over palladium nanoparticles loading on dendrite-like Ni-Cu-P interlayer

A new electrode with high electrocatalytic hydrodechlorination activity was prepared by pulse electrodeposition of Pd nanoparticles on a dendrite-like Ni-Cu-P interlayer with foam nickel as the substrate. The physical and chemical properties of the composite electrode were systematically investigated by various characterizations. The dechlorination performance was evaluated with 2,4-dichlorophenol as the model pollutant. The results indicated that in 150 min the dechlorination efficiency over the electrode without the Ni-Cu-P interlayer was only 52.7 %, while 100 % of 2,4-dichlorophenol could be removed by the composite electrode. The enhanced dechlorination performance was mainly attributed to the synergic effect between Pd nanoparticles and the Ni-Cu-P interlayer. The dendrite morphology of Ni-Cu-P facilitated Pd nanoparticle dispersion, thus providing more active sites and reducing the consumption of Pd. Furthermore, the Ni-Cu-P interlayer assisted Pd0 to produce more active hydrogen and increased the content of Pd2+ to promote CCl bond cleavage. Consequently, the dechlorination performance was improved.

Design and catalytic performance of Cu/γ-Al2O3 for electrocatalytic methanol oxidation reaction by using density functional theory and molecular dynamics

The electrocatalytic activity of methanol oxidation reaction (MOR) on Cu/γ-Al2O3 and the growth behavior of Cu on γ-Al2O3 are investigated by using density functional theory and molecular dynamics. It is found that the interaction between the Cu3 cluster and γ-Al2O3(110) is stronger than that between the Cu4 cluster and γ-Al2O3(110). Consequently, the d-band center of the Cu3 cluster locates close to the Fermi level compared to the d-band center of the Cu4 cluster, resulting in high electrocatalytic MOR activity on Cu3/γ-Al2O3(110). The electrocatalytic MOR pathway is non-CO pathway on Cu3/γ-Al2O3(110). The highest Gibbs free energy pathway is CH3O* → CH2O*, which the Gibbs free energy is 0.53 eV. To achieve a high proportion of 2D Cu cluster on γ-Al2O3, it is recommended to prepare the catalyst at temperatures below 500 K with Cu loading below 21.78 wt%. These findings provide valuable insights into the design of MOR catalysts.

Machine Learning-Assisted Automatically Electrochemical Addressable Cytosensing Arrays for Anticancer Drug Screening.

The high-throughput and accurate screening of anticancer drugs is crucial to the preclinical assessment of candidate drugs and remains challenging. Herein, an automatically electrochemical addressable cytosensor (AEAC) for the efficient screening of anticancer drugs is reported. This sensor consists of sectionalized laser-induced graphene arrays decorated by the rhombohedral TiO2 and spherical Pt nanoparticles (LIG-TiO2-Pt) with high electrocatalytic activity for H2O2 and a homemade Ag/Pt electrode couple fixed onto the robot arm. The immobilization of laminin on the surface of LIG-TiO2-Pt can promote its biocompatibility for the growth and proliferation of various tumor cells, which empowers the in situ monitoring of H2O2 directly released from these live cells for drug screening. A machine learning (ML) algorithm is employed to eliminate the possible random or systematic errors of AEAC, realizing rapid, high-throughput, and accurate prediction of different types of anticancer drugs. This ML-assisted AEAC provides a powerful approach to accelerate the evolution of sensing-served tumor therapy.

Surface-Modified Carbon Nanotubes with Ultrathin Co3O4 Layer for Enhanced Oxygen Evolution Reaction.

Alkaline water electrolysis is a vital technology for sustainable and efficient hydrogen production. However, the oxygen evolution reaction (OER) at the anode suffers from sluggish kinetics, requiring overpotential. Precious metal-based electrocatalysts are commonly used but face limitations in cost and availability. Carbon nanostructures, such as carbon nanotubes (CNTs), offer promising alternatives due to their abundant active sites and efficient charge-transfer properties. Surface modification of CNTs through techniques such as pulsed laser ablation in liquid media (PLAL) can enhance their catalytic performance. In this study, we investigate the role of surface-modified carbon (SMC) as a support to increase the active sites of transition metal-based electrocatalysts and its impact on electrocatalytic performance for the OER. We focus on Co3O4@SMC heterostructures, where an ultrathin layer of Co3O4 is deposited onto SMCs using a combination of PLAL and atomic layer deposition. A comparative analysis with aggregated Co3O4 and Co3O4@pristine CNTs reveals the superior OER performance of Co3O4@SMC. The optimized Co3O4@SMC exhibits a 25.6% reduction in overpotential, a lower Tafel slope, and a significantly higher turnover frequency (TOF) in alkaline water splitting. The experimental results, combined with density functional theory (DFT) calculations, indicate that these improvements can be attributed to the high electrocatalytic activity of Co3O4 as active sites achieved through the homogeneous distribution on SMCs. The experimental methodology, morphology, composition, and their correlation with activity and stability of Co3O4@SMC for the OER in alkaline media are discussed in detail. This study contributes to the understanding of SMC-based heterostructures and their potential for enhancing electrocatalytic performance in alkaline water electrolysis.

Graphitic carbon nitride and its nanocomposites-based sensors for detection of pharmaceutical effluents in food, ecological and biological samples: A mini-review

Pharmaceutical effluents (PEs) have emerged as a global threat to mankind owing to their adverse health effects on humans. Generally, PEs are acquainted with the environment via direct emissions from drug manufacturing plants, unplanned disposal of unused or expired medicines, unprocessed patient/animal excretion, aquafarming, etc. Unlike other pollutions, PE-based contaminations can lead to catastrophic consequences via genotoxic, ecotoxicological, mutagenic effects, etc., causing behavioural changes, reproductive damage, and chronic damage. Therefore, a susceptible detection platform for PE traces in different sources like water bodies, human biofluids, etc., is in high demand. Owing to their high surface area, chemical stability, and electrocatalytic activity, the 2D graphitic carbon nitride (gCN) has gathered significant research interest. It has been examined for the electrochemical detection of PE traces in different ecological and biological samples. In this mini-review, we discuss the exciting advancements in the design and fabrication of gCN and its nanocomposite-based electrochemical sensors for other trace-level detection of different PEs in ecological and biological systems. The table in this review provides a clear insight into the reported gCN-based electrochemical sensors and their performance analysis towards sensing of EFs. The anticipated developments are discussed with current limitations in gCN-based electrochemical sensors for PE detection.

Three-dimensional Electrocatalytic Degradation of Tetracycline by Nano-Feooh

Nano-FeOOH catalysts were prepared by a co-precipitation method and characterized by XRD, SEM, XPS and BET to analyze the phase composition, surface morphology, elemental composition and specific surface area of FeOOH. Results showed that the FeOOH catalyst had large pore volume and surface area, providing more active sites for catalytic reactions. A 3D electrocatalytic system EC/PS/FeOOH was established to degrade tetracycline (TC), and the contributions of FeOOH adsorption, PS activation and electrocatalysis were investigated. It was found that the adsorption rate of TC on sole FeOOH was 42%, the degradation rate of TC in the PS/FeOOH system was 63.80%, and the degradation rate of TC in the 3D EC/PS/FeOOH system reached 72.97%, indicating the high electrocatalytic activity of FeOOH. Surface catalysis mechanism studies showed that the high catalytic activity of FeOOH could be attributed to electron transfer between Fe(II) and Fe(III) and adsorbed oxygen on its surface.

Applications, prospects and challenges of metal borides in lithium sulfur batteries

Although the lithium-sulfur (Li-S) battery has a theoretical capacity of up to 1675 mA h g−1, its practical application is limited owing to some problems, such as the shuttle effect of soluble lithium polysulfides (LiPSs) and the growth of Li dendrites. It has been verified that some transition metal compounds exhibit strong polarity, good chemical adsorption and high electrocatalytic activities, which are beneficial for the rapid conversion of intermediate product in order to effectively inhibit the “shuttle effect”. Remarkably, being different from other metal compounds, it is a significant characteristic that both metal and boron atoms of transition metal borides (TMBs) can bind to LiPSs, which have shown great potential in recent years. Here, for the first time, almost all existing studies on TMBs employed in Li-S cells are comprehensively summarized. We firstly clarify special structures and electronic features of metal borides to show their great potential, and then existing strategies to improve the electrochemical properties of TMBs are summarized and discussed in the focus sections, such as carbon-matrix construction, morphology control, heteroatomic doping, heterostructure formation, phase engineering, preparation techniques. Finally, the remaining challenges and perspectives are proposed to point out a direction for realizing high-energy and long-life Li-S batteries.

Optimization of Pt infiltrated Sr2Fe2-xMoxO6-δ-Ce0.8Sm0.2O1.9 oxygen electrode for reversible solid oxide cell and CH4-assisted electrolysis process

Sr2Fe2-xMoxO6-δ-Ce0.8Sm0.2O1.9 (SFM-SDC) is a promising composite oxygen electrode for reversible solid oxide cells. In this study, well-dispersed Pt nanoparticles are prepared by one-cycle infiltration method using H2PtCl6 aqueous solution in SFM-SDC scaffold, to form high electrocatalytic activity Pt-SFM-SDC electrode for fuel cell, steam electrolysis and CH4-assisted steam electrolysis processes. Systematic studies in concentration variation of H2PtCl6 solution demonstrate that the discharge current of the 3.14 cm2 cell infiltrated by 0.040 M solution is significantly increased from 0.4 to 1.32 A (>3 times) at 0.5 V at 800 °C while the electrolysis current is effectively enhanced from 0.8 to 3.28 A (>4 times) at 1.5 V. Moreover, cells with Pt-SFM-SDC electrode applied in CH4-assisted electrolysis process realized a remarkable reduction of power consumption. Impedance analysis and morphological observation results suggest that appropriate H2PtCl6 concentration has a positive effect on surface exchange and gas diffusion process at oxygen electrode side.

Electrochemical Detection of Hormones Using Nanostructured Electrodes

Hormones regulate several physiological processes in living organisms, and their detection requires accuracy and sensitivity. Recent advances in nanostructured electrodes for the electrochemical detection of hormones are described. Nanostructured electrodes’ high surface area, electrocatalytic activity, and sensitivity make them a strong hormone detection platform. This paper covers nanostructured electrode design and production using MOFs, zeolites, carbon nanotubes, metal nanoparticles, and 2D materials such as TMDs, Mxenes, graphene, and conducting polymers onto electrodes surfaces that have been used to confer distinct characteristics for the purpose of electrochemical hormone detection. The use of aptamers for hormone recognition is producing especially promising results, as is the use of carbon-based nanomaterials in composite electrodes. These materials are optimized for hormone detection, allowing trace-level quantification. Various electrochemical techniques such as SWV, CV, DPV, EIS, and amperometry are reviewed in depth for hormone detection, showing the ability for quick, selective, and quantitative evaluation. We also discuss hormone immobilization on nanostructured electrodes to improve detection stability and specificity. We focus on real-time monitoring and tailored healthcare with nanostructured electrode-based hormone detection in clinical diagnostics, wearable devices, and point-of-care testing. These nanostructured electrode-based assays are useful for endocrinology research and hormone-related disease diagnostics due to their sensitivity, selectivity, and repeatability. We conclude with nanotechnology–microfluidics integration and tiny portable hormone-detection devices. Nanostructured electrodes can improve hormone regulation and healthcare by facilitating early disease diagnosis and customized therapy.

Self-polarization-enhanced oxygen evolution reaction by flower-like core–shell BaTiO3@NiFe-layered double hydroxide heterojunctions

A flower-like core–shell heterostructured oxygen evolution reaction (OER) electrocatalyst based on tetragonal BaTiO3 nanoparticles (t-BTO NPs) and NiFe-layered double hydroxide (NiFe-LDH) nanoarrays was prepared in this study. The influence from the self-polarization effect of t-BTO on the OER performance of NiFe-LDH is reported. Intriguingly, the OER activity of the t-BTO@NiFe-LDH heterojunctions in an alkaline media (1.0 M KOH) exhibited a low overpotential of 186 mV at 10 mA/cm2 and a low Tafel slope of 38.3 mV dec-1, which were far superior to those of the component materials: NiFe-LDH (267 mV and 94.8 mV dec-1) and t-BTO NPs (517 mV and 132.4 mV dec-1). Density functional theory (DFT) calculations revealed that the effective electronic modulation between t-BTO NPs and NiFe-LDH nanoplatelets narrowed the bandgap, promoted the electric conductivity, moderately raised Ed (i.e., energy level of the d-band center), optimized the adsorption ability of the oxygen-containing intermediates (*O, *OH, and *OOH), and induced an apparent reduction in the free energy barrier for the transformation from O* to OOH* in the t-BTO@NiFe-LDH heterojunctions. The PDOS result confirmed that t-BTO in the heterojunctions was easier to polarize, which can cause the rapid electron transfer in the OER process. In these heterostructures, the interface tension between BTO NPs and NiFe-LDH endowed BTO with easier self-polarization, thus leading to greater band tilting and faster electron transfer. Multiple synergistic effects of the flower-like core–shell t-BTO@NiFe-LDH heterojunctions enabled them with higher electrocatalytic activity. This work provides an in-depth understanding of the rational design of a high-efficiency, noble metal-free ferroelectric OER electrocatalyst based on the self-polarization of t-BTO NPs.

Enhanced electrochemical hydrogen storage performance of Co9S8 material by doping with cobalt nanoparticles embedded hollow porous carbon nanofibers

Co-axial electrospinning has been regarded as an effective technology to fabricate hollow or core/shell nanofibers. Herein, co-axial electrospinning was carried out employing polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN) as the core and shell components. Cobalt acetate was used as the cobalt source. The cobalt nanoparticles embedded hollow porous carbon fibers (Co/HCNF) were obtained after electrospinning and subsequent carbonization process. For comparison, the conventional carbon fibers (CNF), hollow carbon fibers (HCNF), and cobalt nanoparticles modified carbon fibers (Co/CNF) were also synthesized. Co9S8 material was manufactured via mechanical alloying. By adjusting the types of carbon fibers, a series of carbon fibers modified Co9S8 composites were obtained by ball milling and their electrochemical hydrogen storage properties were studied. As a result, the Co9S8 + Co/HCNF electrode showed the higher discharge capacity of 603.3 mAh/g than CNF, HCNF, Co/CNF modified Co9S8 and conventional Co9S8 electrodes. The Co nanoparticles within Co/HCNF provided high electrocatalytic activity. The special hollow porous structure and high specific surface area of Co/HCNF increased the conductivity, offered more electrochemical active sites and rapid channel for charge transfer. Moreover, Co9S8 + Co/HCNF also demonstrated improved high-rate dischargeability (HRD), capacity retention and kinetics properties. An advantageous solid-solid interface may be generated between Co9S8 and Co/HCNF, serving as a beneficial electron conduction path and facilitating the hydrogen diffusion, thereby enhancing the electrode performance of Co9S8 material.