Large Active Area Research Articles

Surfactant-Assisted Synthesis of Metallic-Ag/Nickel Oxide on Graphitic Carbon Nitride Composite: An Electrochemical Investigation of Synthetic Vanillin.

In this study, we developed a sensor based on surfactant-assisted synthesis of metallic silver-enriched nickel oxide confined on graphitic carbon nitride (Ag/NiO/g-CN)-modified electrode to construct a sensitive and selective voltammetric sensor for detecting vanillin in confectionaries samples. The X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy analyses confirmed the crystal structure and respective functional groups of the synthesized Ag/NiO/g-CN composite. The valence states of silver, nickel, oxygen, carbon, and nitrogen were analyzed using X-ray photoelectron spectroscopy (XPS), while energy-dispersive X-ray analysis (EDX) and morphological investigations revealed the elemental distribution and nano-structured particles, respectively. The electrocatalyst-modified electrode properties and electrochemical sensing performances were evaluated using different voltammetric and spectroscopic techniques. The Ag/NiO/g-CN composite, exhibiting a large active surface area, excellent conductivity, and synergistic interaction, proved to be a suitable electrode material for electrochemical sensor applications. The sensor demonstrated a detection limit of 0.9 nM and a broad linear range of 0.004-366.8 μM. Electrochemical investigations further highlighted the sensor's excellent reproducibility, repeatability, fast response, and functional stability. The constructed sensor also exhibited outstanding selectivity against potential interferents and demonstrated its practical applicability by successfully detecting vanillin in spiked food samples.

Adsorption Isotherm Analysis for Hybrid Molecularly Imprinted Polymeric Gold-Decorated Nanoparticles Suitable for Reliable Quantification of Gluconic Acid in Wine

A class of hybrid molecularly imprinted polymeric nanoparticles (nanoMIPs) comprising the in situ formation of gold nanoparticles (AuNPs) immobilised in a molecularly imprinted D-gluconate polymer has been designed with the objective of attempting the electrochemical quantification of gluconic acid (GA) in a wine setting. The imprinted polymers were synthesised in the presence of AuNP precursors in a pre-polymerisation mixture, which were confined to one another during the polymerisation of the chains. This allowed the formation of hybrid electroactive responsive imprinted nanoparticles (hybrid AuNPs@GA-nanoMIP), which exhibited enhanced electron conductivity. The morphological characterisation of the produced nanoMIPs revealed a fully decorated Au spherical surface of 200 nm in diameter. This resulted in a large active surface area distribution, as well a pronounced electrochemical peak response at the commercial screen-printed platinum electrode (SPPtE), accompanied by enhanced electron kinetics. The AuNPs@GA-nanoMIP sensor demonstrated the ability to detect a broad range of GA concentrations (0.025–5 mg/mL) with exceptional selectivity and reproducibility. The calibration curves were fitted with different isotherm models, such as the Langmuir, Freundlich and Langmuir–Freundlich functions. Moreover, the efficacy of the detection method was demonstrated by the recovery rates observed in real samples of Italian red wine. This research contributes to the development of a robust and reliable electrochemical sensor for the on-site determination of gluconic acid in food analysis.

Unveiling the Potential of Metal Diborides for Electrocatalytic Water Splitting: A Comprehensive Review

Electrocatalytic water splitting (EWS) driven by renewable energy is vital for clean hydrogen (H2) production and reducing reliance on fossil fuels. While IrO2 and RuO2 are the leading electrocatalysts for the oxygen evolution reaction (OER) and Pt for the hydrogen evolution reaction (HER) in acidic environments, the need for efficient, stable, and affordable materials persists. Recently, transition‐metal borides (TMBs), particularly metal diborides (MDbs), have gained attention due to their unique layered crystal structures with multicentered boron bonds, offering remarkable physicochemical properties. Their nearly 2D structures boost electrochemical performance by offering high conductivity and a large active surface area, making them well‐suited for advanced energy storage and conversion technologies. This review provides a comprehensive overview of the critical factors for water splitting, the crystal and electronic structures of MDbs, and their synthetic strategies. Furthermore, it examines the relationship between catalytic performance and intermediate adsorption as elucidated by first‐principle calculations. The review also highlights the latest experimental advancements in MDb‐based electrocatalysts and addresses the current challenges and future directions for their development.

Large-scale acoustic single cell trapping and selective releasing.

Recent advancements in single-cell analysis have underscored the need for precise isolation and manipulation of individual cells. Traditional techniques for single-cell manipulation are often limited by the number of cells that can be parallel trapped and processed and usually require complex devices or instruments to operate. Here, we introduce an acoustic microfluidic platform that efficiently traps and selectively releases individual cells using spherical air cavities embedded in a polydimethylsiloxane (PDMS) substrate for large scale manipulation. Our device utilizes the principle of acoustic impedance mismatches to generate near-field acoustic potential gradients that create trapping sites for single cells. These single cell traps can be selectively disabled by illuminating a near-infrared laser pulse, allowing targeted release of trapped cells. This method ensures minimal impact on cell viability and proliferation, making it ideal for downstream single-cell analysis. Experimental results demonstrate our platform's capability to trap and release synthetic microparticles and biological cells with high efficiency and biocompatibility. Our device can handle a wide range of cell sizes (8-30 μm) across a large active manipulation area of 1 cm2 with 20 000 single-cell traps, providing a versatile and robust platform for single-cell applications. This acoustic microfluidic platform offers a cost-effective and practical method for large scale single-cell trapping and selective releasing with potential applications in genomics, proteomics, and other fields requiring precise single-cell manipulation.

Cuprous oxide-functionalized activated porous carbon-modified screen-printed carbon electrode integrated with a smartphone for portable electrochemical nitrate detection.

Nitrate (NO3-) is a widespread contaminant in drinking water. An electrochemical NO3- sensor was developed based on a first-time application of materials. Activated porous carbon (APC) was synthesized by carbonizing orange peel (OP) activated with KOH. Cuprous oxide crystals were uniformly decorated by electrodeposition on a screen-printed carbon electrode modified with the synthesized APC (Cu2O@APC/SPE). The modified electrode was integrated with a portable potentiostat interfaced with a smartphone to create a chronoamperometric nitrate sensor. The modified electrodes were structurally and morphologically characterized using conventional techniques, while electrochemical tests were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). The electrode material exhibited a highly porous structure, large accessible active surface areas, and excellent conductivity, which enhanced electrocatalytic performances. The developed NO3- sensor displayed a wide linear range (4-1000μM) and a low limit of detection (LOD) of 1.2μM. The sensor demonstrated good precision, selectivity, and reasonable recoveries. The real-world application of the NO3- sensor was validated using water samples. The sensor shows promise for applications in pharmaceuticals, agriculture, forensic investigations, and environmental monitoring.

Impact of Coolant Operation on Performance and Heterogeneities in Large Proton Exchange Membrane Fuel Cells: A Review

PEMFCs’ operation entails the presence of heterogeneities in the generation of current, heat and water along the active surface area. Indeed, PEMFCs are open systems, and as such, operating heterogeneities are inherent to their operation. A review of the literature reveals numerous attempts to achieve uniform current density distribution. These attempts are primarily focused on bipolar plate design and operating conditions, with the underlying assumption that uniform current density correlates with enhanced performance. Most studies focus on the influence of gas flow-field design and inlet hydrogen and air flow conditioning, and less attention has been paid to the coolant operating condition. However, uncontrolled temperature distribution over a large cell active surface area can lead to performance loss and localized degradations. On this latter point, we notice that studies to date have been confined to a narrow range of operating conditions. It appears that complementary durability studies are needed in order to obtain in-depth analyses of the coupled influence of temperature distribution and gas humidification in large PEMFCs.

Advanced aqueous phenazine redox flow battery enhanced by selective interfacial water behavior on Co/NC modified electrode.

Although aqueous organic redox flow battery (RFBs) is a highly promising energy storage device, the redox reaction kinetics of the anode organic electrolyte material, especially for phenazine derivatives, are limited by low electrochemical activity of traditional porous carbon electrodes. Herein, Co/NC composite electrocatalyst was elaborated to significantly enhance the redox reaction kinetics of phenazine derivatives, in which Co/NC electrocatalyst could improve energy efficiency of aqueous phenazine RFBs by 43.2% compared to pure carbon felt electrodes at current density of 100mA/cm2. Control experiments combined with density functional theory calculations identified that in addition to the more reactive sites provided by relatively large electrochemical active surface area accelerate the redox reaction of phenazine derivatives, the Co and CoNC reaction sites provided by Co modification not only reduce the energy barrier, but also provide new convenient reaction pathways based on selective interfacial water behavior, further promoting the reduction reaction of phenazine derivatives. This study gives an in-depth understanding of the synergistic effects between phases in composite electrocatalysts and proposes a new behavioral mechanism for the redox reactions of organic electroactive species on the surface of catalytic electrodes.

The role of masking and aperture size for accurate measurement of performance parameters of DSSCs

DSSC efficiency is often reported with very little or no consideration of the cell area for which they are reported. Area masking of cells is almost always used for the measurement of cell performance parameters (Jsc, Voc, and FF). Although edge masking is required to exclude edge effects, a variety of masking including masking a major portion of the cells are frequently used to boost the apparent efficiency of the cell. In this work, it will be shown that the reported efficiency of a cell is strongly dependent on the exposed area. Two different kinds of cells have been considered in this work to elucidate the area effect: first is a large active area cell whose performance metrics are obtained by masking various fraction of the active area. Second, cells were fabricated with active areas ranging from small to large. A comparison of these two kinds of cells demonstrates that the cells with smaller areas show area-dependent performance parameters. A cell with a 4 mm2 exposed area will show a higher efficiency of 10.47 % while the efficiency will drop to ∼ 3 % as the area increases to 60 mm2 or higher. Such area dependence can be avoided if the cell area/exposed area selected is 60 mm2 or above. The reason for the area dependence has been identified to be due to the presence of trap states and not due to scattering which is sometimes used in the literature to explain the area dependence.

MoOX–Graphene Nanocomposite Electrode As a High-Performance Bifunctional Electrocatalyst for All Vanadium Redox Flow Battery

As one of the most promising electrochemical energy storage systems, vanadium redox flow batteries (VRFBs) have received increasing attention owing to their attractive features for large-scale storage applications. However, their high production cost and relatively low energy efficiency still limit their feasibility. One of the critical components of VRFBs that can significantly influence the effectiveness and final cost is the electrode. Therefore, the development of an ideal electrocatalyst with low cost, high electrical conductivity, large active surface area, good chemical stability, and excellent electrochemical reaction activity toward the VO2+/VO2 + and V2+/V3+ redox reactions is essential for the design of VRFBs. Extensive research has been carried out on electrode modification routes for VRFBs to improve the energy density and overall performance for large-scale applications. In the present work, we reported the successful preparation of low-cost MoOX–reduced graphene oxide nanocomposite (MoOX–rGO) acts as the electrode material for all-vanadium redox flow battery (VRFB). MoOX–rGO composite exhibits excellent electrocatalytic redox reversibility for V3+/V2+ and VO2 +/VO2+ and higher anodic and cathodic peak currents than those of other individual MoOX and rGO samples. The voltage efficiency of the VRFB using the optimized MoOX–rGO nanocomposite electrode at 80 mA cm−2 is 82.14%, which is 4.23% and 13.56% higher than the VRFBs using the rGO-coated graphite felt electrode and the graphite felt electrode, respectively. It still shows the voltage efficiencies of 73.83% and 68.50% at 120 mA cm−2 and 140 mA cm−2, respectively, but other samples have no effective discharge. This improvement is attributed to the uniform distribution of MoOX nanoparticles on the rGO surface, avoiding the restacking of the rGO sheets and suppressing nanoparticle aggregation, which might increase the effective surface area and improve mass transport at the electrode-electrolyte interface. Furthermore, oxygen vacancies on MoOX, the high electrical conductivity of rGO, and the high content of oxygen functional groups act as active sites for the vanadium ion redox reaction. References W. Bayeh, G-Y. Lin, Y-C. Chang, D.M. Kabtamu, G-C. Chen, H-Y. Chen, K-C. Wang, Y-M. Wang, T-C. Chiang, H-C. Huang and C-H. Wang, ACS Sustain. Chem. Eng., (2020).Zhou, Y. Shen, J. Xi, X. Qiu and L. Chen, ACS Appl. Mater. Interfaces, 8, 15369- 15378 (2016).M. Kabtamu, J-Y. Chen, Y-C. Chang and C-H. Wang, J. Power Sources, 341, 270-279 (2017).Amini, J. Gostick and M.D. Pritzker, Adv. Funct. Mater., 30, 1910564 (2020).M. Kabtamu, J-Y. Chen, Y-C. Chang and C-H. Wang, J. Mater. Chem. A, 4, 11472-11480 (2016).

Fabrication of MXene-TiO2 nanotube composite and their electrochemical study in acidic and alkaline medium

MXenes, a novel class of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, have emerged as promising electrocatalysts for the hydrogen evolution reaction (HER) due to their remarkable electrical conductivity, exceptional structural and chemical stability, and large active surface area. In this study, we synthesized a 1D/2D Ti3C2 MXene-TiO2 nanotube (TNT) composite via electrostatic self-assembly method. Field emission scanning electron microscopy (FE-SEM) confirmed the distinctive accordion-like, multilayered morphology of Ti3C2Tx MXene, while X-ray diffraction (XRD) provided the crystalline phase of the composite. High-resolution transmission electron microscopy (HR-TEM) revealed an average particle size of 38.41 nm for the MXene-TNT nanocomposite. Additionally, X-ray photoelectron spectroscopy (XPS) confirmed the composite composition, highlighting the synergistic integration of MXene and TiO2 nanotube that enhances electrical interactions and contributes to superior catalytic performance. Electrochemical performance was assessed using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) in both acidic and alkaline media. Among the composites, the MXene-TNT (1:10) loading demonstrated a low Tafel slope of 65 mV/dec in acidic media, indicative of enhanced mass transfer properties. In alkaline media, the MXene-TNT (1:5) composite exhibited a Tafel slope of 160 mV/dec for HER, with kinetic performance proving more favorable in the acidic environment. Additionally, the composite displayed a Tafel slope of 149 mV/dec for the oxygen evolution reaction (OER) in acidic media. This study demonstrates a feasible approach for developing high-performance, cost-effective electrocatalytic materials for efficient hydrogen production, utilizing MXene as a co-catalyst.

Photoresponse characteristics of bulk gallium nitride schottky barrier metal-semiconductor-metal ultraviolet photodetectors

In this work, bulk gallium nitride (GaN) Schottky barrier metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated, and their key performance metrics such as photoresponse, photosensitivity, gain, external quantum efficiency, detectivity, noise equivalent power, rise time, and fall time were thoroughly evaluated. The Schottky barrier was formed using platinum (Pt) metal with two different sizes of interdigitated electrode on the bulk GaN samples.The effects of mask size on the photoresponse characteristics were investigated. The Pt/bulk GaN MSM UV PDs exhibited outstanding performance under 365 nm UV light. At a bias voltage of 5 V, the PDs with smaller active areas (0.238 cm²) achieved a responsivity of 13.6 mA/W and a fast rise time of 174 ms, while those with larger active areas (0.412 cm²) demonstrated a responsivity of 2.62 mA/W and a rise time of 286 ms. Even at 0 V bias, these devices showed responsivities of 1.34 µA/W and 3.40 µA/W for the small and large masks, respectively, indicating that they possess self-powered device capabilities.

Turning properties of Ni/Al2O3 catalyst to improve catalytic ammonia decomposition for green hydrogen production: pH does matter!

In this study, the influence of solution pH (6.0–12.5) of the cation–anion double hydrolysis (CADH) method in the formation of Ni/Al2O3 catalyst and its catalytic performance for green hydrogen production from NH3 decomposition was studied for the first time. The physicochemical properties of the prepared catalysts were systematically characterized by various analysis techniques. The results indicated that pH conditions significantly influenced both the structural properties and catalytic activity of the derived Ni/Al2O3 catalysts. The better catalytic activity for NH3 decomposition over catalysts prepared under high pH conditions (pH ≥ 10.0) is mainly due to the appropriate synergic effect of the interaction between Ni and Al2O3 support, large active Ni surface area, and suitable porosity, particle size, and basicity of the catalyst. The correlation analysis and density functional theory (DFT) calculations confirm that the percentage of surface metallic Ni plays a crucial role in controlling the catalytic activity of Ni/Al2O3 catalysts. The 40Ni/Al2O3 catalyst (Ni = 40 wt%) could achieve over 94.5% NH3 conversion under the harsh reaction conditions of 600 °C and NH3 WHSV of 54000 mL/gcat./h, and that stably maintained for 200 h without any obvious deactivation. Overall, our work not only highlights the critical role of pH conditions in the CADH solution for cost-effective Ni/Al2O3 catalyst preparation but also proposes a promising strategy for developing a highly active, stable, and Ru-free catalyst for practical hydrogen production via NH3 decomposition.

Optimization Strategies of Hybrid Lithium Titanate Oxide/Carbon Anodes for Lithium-Ion Batteries.

Lithium-ion batteries, due to their high energy density, compact size, long lifetime, and low environmental impact, have achieved a dominant position in everyday life. These attributes have made them the preferred choice for powering portable devices such as laptops and smartphones, power tools, and electric vehicles. As technology advances rapidly, the demand for even more efficient energy storage devices continues to rise. In lithium-ion batteries, anodes play a crucial role, with lithium titanate oxide standing out as a highly promising material. This anode is favored for its exceptional cycle stability, safety features, and fast charging capabilities. The impressive cycle stability of lithium titanate oxide is largely due to its zero-strain nature, meaning it undergoes minimal volume changes during lithium-ion insertion and extraction. This stability enhances the anode's durability, leading to longer battery life. In addition, the lithium titanate oxide anode operates at a voltage of approximately 1.55 V vs. Li+/Li, significantly reducing the risk of dendrite formation, a major safety concern that can cause short circuits and fires. The material's spinel structure, with its large active surface area, further allows fast electron transfer and ion diffusion, facilitating fast charging. This review explores the characteristics of lithium titanate oxide, the various synthesis methods employed, and its integration with carbon materials to enhance cycle stability, coulombic efficiency, and safety. It also proposes strategies for optimizing lithium titanate oxide properties to create sustainable anodes with reduced environmental impact using eco-friendly routes.

Sol-gel preparation and visible-light-driven photocatalytic activity of the double perovskite Sr2FeMoO6

Sr2FeMoO6 was synthesized as a visible-light-driven photocatalytic double perovskite by a simple sol-gel preparation method. In-depth experimental techniques were used to characterize morphological and optical properties. Scanning and transmission electron microscopy revealed a tubular shape morphology, resulting in a large active surface area for improved photocatalysis. Optimization of Sr2FeMoO6 achieved a narrow bandgap of 1.77 eV, capable of interacting with visible light. The decomposition of methylene blue (MB) under visible-light irradiation was employed to assess the photocatalytic performance of as-synthesized samples.The Sr2FeMoO6 samples exhibited excellent degradation performance, demonstrating a 95.6% degradation of MB within 35 min of irradiation. This work has certain research significance by revealing the potential mechanism of double perovskite photocatalysts.

Novel Octa-Structure Metamaterial Architecture for High Q-Factor and High Sensitivity in THz Impedance Spectroscopy.

Terahertz (THz) electric inductive-capacitive (ELC) resonant metamaterials (MMs) are well established tools that can be used to detect the presence of dielectric material (e.g., nanoparticles, bioparticles, etc.) spread on their surfaces within the gap of the capacitive plates of a nanoantenna array. In THz spectroscopy, the amount of the red shift in the resonance frequency (ΔF) plays an important role in the detection of nanoparticles and their concentration. We introduce a new LC resonant MM architecture in the ELC category that maximizes dielectric sensitivity. The newly proposed architecture has an octahedral structure with uniform capacitive gaps at each forty-five-degree interval, making the structure super-symmetric and polarization independent. The inductor core is condensed into a central solid circle connecting all the eight lobes of the octahedron, thereby completing the LC circuit. This ELC resonator has very large active areas (capacitor-gaps), with hotspots at the periphery of each unit cell. The MM structure is repeated in a clustered fashion, so that the peripheral hotspots are also utilized in dielectric sensing. This results in enhancing the quality factor of MM resonance, as well as in increasing ΔF. The research comprises a combination of rigorous system-level simulations along with THz impedance spectroscopy laboratory experiments. We achieved a highly sensitive MM sensor with sensitivity reaching 1600 GHz/RIU. This sensor is fully CMOS compatible and has promising potential applications in high-sensitivity bio-sensing, characterization of nanoparticles, and ultra-low-concentration dielectrics detection, as well as in sensing differential changes in the composition of substances deposited on the metasurface.

Ir Doping Modulates the Electronic Structure of Flower-Shaped Phosphides for Water Oxidation.

Electrolysis of water to produce hydrogen is an efficient, clean, and environmentally friendly hydrogen production method with unlimited development prospects. However, its overall efficiency is hampered by the slow oxygen evolution reaction (OER) with complex electron transfer processes. Therefore, designing efficient and low-cost OER catalysts is the key to solving this problem. In this paper, Ir-doped Co2P/Fe2P (abbreviated as Ir-CoFeP/NF) was grown on nickel foam through the strategies of low amount noble-metal doping and mild phosphating. Phosphide derived from a floral metal-organic framework (MOF) exhibits regular three-dimensional (3D) morphology and large active area, avoiding the stacking of active sites. The addition of Ir can effectively adjust the electronic structure, change the position of the d-band center, and increase active sites, thus enhancing the catalytic activity. Hence, the optimized catalyst exhibits unexpected electrocatalytic OER activity with an ideal overpotential of 213 mV at 10 mA cm-2, as well as a low Tafel slope of 40.63 mV dec-1. Coupling with Pt/C for overall water splitting (OWS), the entire device only needs an ultralow cell voltage of 1.50 V to achieve a current density of 10 mA cm-2. Besides, the OWS can be maintained for more than 70 h. This study demonstrates the superiority of Ir-doped phosphide in accelerating water oxidation.

Enhancing the efficiency of wavelength-shift fiber-based detectors for optical wireless communications

A wavelength-shift fiber-based optical detector promises to revolutionize the deployment of optical wireless communication (OWC) due to its inherent advantages over traditional receivers. These advantages include a flexible structure, a wide field of view (FOV), and a large active area. Despite progress in previous studies, there remains a gap in optimizing the re-utilization of unabsorbed light within wavelength-shift fiber (WSF) and maximizing the efficiency of light focusing onto photodetectors. To address these challenges, this study explores three novel, to the best of our knowledge, approaches to enhance the light conversion and detection efficiency of WSF-based optical detectors. First, a reflective mirror is employed behind the WSF array to increase the light absorption and re-emission probability. Second, a reflective mirror is placed at one end of the WSF array to direct the light toward the opposite end. Third, a tightly bundled WSF array configuration focuses the emitted light onto the photodetector’s active area. Experimental results demonstrate that each approach significantly improves the peak-to-peak voltage. This work presents an optical detector design featuring a large active area of 0.4cm×20cm, based on a blue-to-green color-converting WSF and achieving a high 3-dB bandwidth of up to 48 MHz. This design enables real-time data transmission at rates of 275 Mbps using non-return-to-zero on-off keying (NRZ-OOK) modulation over a distance of 1 m. Additionally, the transmission link operates at over 250 Mbps, with bit error rates (BERs) below the forward error correction (FEC) limit, under a wide FOV of 60°. This work opens exciting possibilities for revolutionizing photodetection schemes in non-line-of-sight free-space optical communications.

Centimeter‐Scale and Honeycomb‐Like Bismuth Sulfide Film Composed of Triangular Structural Units for Flexible Photodetector

AbstractFilms with honeycomb‐like structures have became ideal network structures for the development of flexible photodetectors due to their superior mechanical stability and merits in large active surface area, high carrier transport efficiency and well light absorption capacity. In this work, a honeycomb‐like Bi2S3 film with centimeter‐scale (2 cm × 2 cm) is synthesized on an ultrathin flexible fluorophlogopite mica substrate, which consists of a well‐stabilized arrangement of triangular unit structures forming an interconnected network structure. Based on the as‐grown honeycomb‐like Bi2S3 film, a flexible photodetector with a broadband response from ultraviolet to infrared is constructed, which displays the highest responsivity (Rλ) of 611.2 mA W−1 and specific detectivity (D*) of 4.77 × 1010 Jones. And at 850 nm light illumination, there is nearly no deterioration in Rλ and D* of the Bi2S3 flexible photodetector after successive multiple bends, benefiting from the excellent structural stability of the triangular honeycomb network structure. Notably, the device maintains excellent detection performance after 1 week of prolonged bending in air without any encapsulation, and its photocurrent can still reach 90.39% of the initial photocurrent. In addition, the device also exhibits favorable durability, cycle stability, as well as high‐definition imaging ability in bending state and after bending recovery.

Innovative Air Cathode with Ni-Doped Cobalt Sulfide in Highly Ordered Macroporous Carbon Matrix for Rechargeable Zn-Air Battery.

To realize the practical application of rechargeable Zn-Air batteries (ZABs), it is imperative to develop a non-noble metal-based electrocatalyst with high electrochemical performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Ni-doped Co9S8 nanoparticles dispersed on an inverse opal-structured N, S co-doped carbon matrix (IO─NixCo9-xS8@NSC) as a bifunctional electrocatalyst is presented. The unique 3D porous structure, arranged in an inverse opal pattern, provides a large active surface area. Also, the conductive carbon substrate ensures the homogeneous dispersion of NixCo9-xS8 nanocrystals, preventing aggregation and increasing the exposure of active sites. The introduction of heteroatom dopants into the Co9S8 structure generates defect sites and enhances surface polarity, thereby improving electrocatalytic performance in alkaline solutions. Consequently, the IO─NixCo9-xS8@NSC shows excellent bifunctional activity with a high half-wave potential of 0.926V for ORR and a low overpotential of 289mV at 10mA cm-2 for OER. Moreover, the rechargeable ZAB assembled with prepared electrocatalyst exhibits a higher specific capacity (768 mAh gZn -1), peak power density (180.2mW cm-2), and outstanding stability (over 160h) compared to precious metal-based electrocatalyst.

Advanced Methodology for Simulating Local Operating Conditions in Large Fuel Cells Based on a Spatially Averaged Pseudo-3D Model

To address the performance and lifetime limitations of Proton Exchange Membrane Fuel Cells, it is essential to have a comprehensive understanding of the operating heterogeneities at the cell scale, requiring the test of a wide range of operating conditions. To avoid experimental constraints, numerical simulations seem to be the most viable option. Hence, there is a need for time-efficient and accurate cell-scale models. In this intention, previous works led to the development and the experimental calibration of a pseudo-3D model of a full-size cell in a stack. To further reduce the computation time, a new spatially averaged, multi-physics, single-phase, non-isothermal, steady state pseudo-3D model is developed and calibrated with the results of the preceding model. Particularly, it captures the influence of the coolant on temperature and water mappings in the cell. Moreover, a new methodology is proposed to calibrate the electrochemical cell voltage law for new membrane-electrode assemblies. The emulation of the local operation conditions in large active surface area is realized with a small differential cell, avoiding the testing of large single cells or stacks. Subsequently, simulations are conducted to investigate the impact of the coolant temperature gradient, coolant outlet temperature and gas relative humidity.