Interfacial Charge Transfer Kinetics Research Articles

Single‐Atom Immobilization Boosting Oxygen Redox Kinetics of High‐Entropy Perovskite Oxide Toward High‐Performance Lithium‐Oxygen Batteries

AbstractUnderstanding and modulating the unique electronic interaction between single‐metal atoms and high entropy compounds are of great significance to enable their high‐efficiency oxygen electrocatalysis for aprotic lithium‐oxygen (Li‐O2) batteries. Herein, a novel bi‐functional electrocatalyst is for the first time created by immobilizing single‐atom ruthenium (Ru) on lanthanum‐based high entropy perovskite oxide La(Mn0.2Co0.2Fe0.2Ni0.2Cr0.2)O3 (Ru@HEPO), which demonstrates high activity and stability in Li‐O2 batteries. The heteronuclear coordination between single‐atom Ru and HEPO facilitates fast electron transfer from Ru to HEPO by establishing Ru‐O‐M (M stands for Mn, Co, Fe, Ni) bridges, which well redistributes electrons within the Ru@HEPO hence significantly improving its interfacial charge transfer kinetics and electrocatalytic activity. Additionally, the strong electron coupling between Ru and Mn atoms enhances the hybridization between Mn 3d and O 2p orbitals, which promotes the inherent affinity of Ru@HEPO toward the LiO2 intermediate, thereby reducing the reaction energy barrier of the oxygen electrode. As a result, the Ru@HEPO‐based Li‐O2 batteries deliver remarkable electrochemical performances, such as high energy efficiency (87.3% at 100 mA g−1), excellent rate capability (low overpotential of 0.52 V at 100 mA g−1) and durable cyclability (345 cycles at 300 mA g−1). This work opens up a promising avenue for the development of high entropy‐based electrocatalysts for Li‐O2 batteries by precisely tailoring the electronic distributions at an atomic scale.

Enhanced Electrochemical Activity Volcanoes in Flat-Band Twisted Trilayer Graphene

Electrochemical reactions at electrode-electrolyte interfaces are often controlled by modifying the substrate and thereby tuning the adsorption energy to reach peaks of activity volcanoes. In this work, we attempt to enhance interfacial charge transfer kinetics through modifying the electronic density of states of an electrode which offers highly tunable flat bands such as the twisted graphene system, allowing greater overlap with the redox couple states. Correspondingly, we develop a twist-dependent electrochemical activity map, combining a tight-binding electronic structure model with modified Marcus-Hush-Chidsey kinetics in trilayer graphene. We identify a counterintuitive rate enhancement region spanning the magic angle curve and incommensurate twists of the system geometry. At room temperature, we find a broad activity peak with a ruthenium hexamine redox couple in regions corresponding to both magic angles and incommensurate angles, a result qualitatively distinct from the twisted bilayer case. Flat bands and incommensurability offer new avenues for reaction rate enhancements in electrochemical transformations.

Mechanism and performance evaluation of spent-coffee grounds-derived nanocomposite materials for highly efficient photocatalytic degradation of organic pollutant

The study demonstrates a facile and environmentally friendly method for synthesizing crystalline TiO2 nanoparticles on the surface of hydrochar generated from readily available biomass waste, i.e., spent coffee grounds (SCGs), using a simple sol–gel process. The hydrochar served as a support for TiO2, reducing the rate at which electrons and holes recombine during photocatalysis, thereby facilitating the effective binding of TiO2, enhancing its adsorption capacity, and the convenient separation of the photocatalyst after usage. The materials were tested in the photocatalytic degradation of an organic pollutant, methylene blue (MB) dye. TiO2-hydrochar obtained at 210 ⁰C has the best performance, giving a degradation efficiency of 98.5 % and a mineralization efficiency of 87.1 % in 90 min at neutral pH. Radical trapping experiments showed O2.-andh+ being the dominant species, followed by HO.. Besides, it showed superior stability with an activity loss of ∼ 9.2 % after five runs. The superior performance of the HCT210 was ascribed to the enhanced interfacial charge transfer kinetics between the TiO2 and hydrochar through Ti-O-C bond formation, better light absorption, and the high surface area of the materials. Performance metrics show that synthesized nanocomposites are promising photocatalysts, providing a biomass-assisted method for robust photocatalytic wastewater treatment.

Organic-inorganic p-type PEDOT:PSS/CuO/MoS2 photocathode with in-built antipodal photogenerated holes and electrons transfer pathways for efficient solar-driven photoelectrochemical water splitting

Organic PEDOT:PSS thin film and n-type MoS2 flakes were incorporated on CuO photocathode as the underlying layer and surface co-catalysts, respectively, establishing a rationally-designed novel integrated structure of PEDOT:PSS/CuO/MoS2. The organic-inorganic interface of PEDOT:PSS/CuO effectively shuttles photogenerated holes towards the FTO/PEDOT:PSS junction. Furthermore, the surface MoS2 co-catalysts form a p-n junction with CuO, which accelerates the transport of photogenerated electrons towards the photocathode/electrolyte junction, in addition to providing more reactive sites for the H2 evolution reaction. These synergistically formed antipodal charge transfer pathways have led to improved charge separation, rapid interfacial charge transfer kinetics and impeded electron-hole recombination in the PEDOT:PSS/CuO/MoS2 photocathode, which can achieve a photocurrent density of – 2.26 mA/cm2 at −0.6 V vs Ag/AgCl (2.1 times higher than that of the bare CuO photocathode). Analytical characterisations, electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS), also provide supporting evidence for its dramatically enhanced PEC water splitting performance.

Enhanced hydrogen evolution performance of Co/CoP in electrolysis of water by interfacial regulation of crystal plane orientation

Modulating the heterojunction interface is an effective way to improve the electrocatalytic efficiency of water electrolysis, and the metal centers with preferred crystal plane orientation offer the potential to enhance the interfacial charge transfer and electrode reaction kinetics. In this study, a Co/CoP modified hydrogen evolution electrode with selective exposure of the metal-centered Co(002) crystal face was prepared using a one-step electrodeposition method by adjusting the P/Co molar ratio. Results demonstrate that the preferential orientation of Co(002) crystal face in Co/CoP leads to an increased electrochemical active surface area, significantly reduced interfacial impedance and Tafel slope. Moreover, it brings the d-band center closer to the Fermi level, which is thermodynamically favorable for hydrogen evolution reaction (HER). Under optimized conditions, Co/CoP exhibits overpotentials of 85 mV and 183 mV at 10 mA cm−2 and 100 mA cm−2, respectively. After long-term and cyclic stability tests, no significant activity decay is observed, demonstrating excellent hydrogen evolution activity and cyclic stability.

Synergizing Spatial Confinement and Dual-Metal Catalysis to Boost Sulfur Kinetics in Lithium-Sulfur Batteries.

Sluggish kinetics and parasitic shuttling reactions severely impede lithium-sulfur (Li-S) battery operation; resolving these issues c ould enhance the capacity retention and cyclability of Li-S cells. Therefore, an effective strategy featuring core-shell-structured Co/Ni bimetal-doped metal-organic framework (MOF)/sulfur nanoparticles is reported herein for addressing these problems; this approach offers unprecedented spatial confinement and abundant catalytic sites by encapsulating sulfur within an ordered architecture. The protective shells exhibit long-term stability, ion screening, high lithium-polysulfide adsorption capability, and decent multistep catalytic conversion. Additionally, the delocalized electrons of the MOF endow the cathodes with superior electron/lithium-ion transfer ability. Via multiple physicochemical and theoretical analysis, the resulting synergistic interactions are proved to significantly promote interfacial charge-transfer kinetics, facilitate sulfur conversion dynamics, and inhibit shuttling. The assembled Li-S batteries deliver a stable, highly reversible capacity with marginal decay (0.075% per cycle) for 400 cycles at 0.2C, a pouch-cell areal capacity of 3.8 mAh cm-2 for 200 cycles under a high sulfur loading, as well as remarkably improved pouch-cell performance. This article is protected by copyright. All rights reserved.

Deciphering the Degradation Mechanism of High‐Rate and High‐Energy‐Density Lithium–Sulfur Pouch Cells

AbstractLithium–sulfur (Li–S) batteries are widely regarded as promising next‐generation battery systems due to their impressive theoretical energy density of 2600 Wh kg−1. However, practical high‐energy‐density Li–S pouch cells suffer from rapid performance degradation under high working rates. Herein, the performance degradation mechanism of 400 Wh kg−1 Li–S pouch cells is systematically investigated under a high cycling rate of 0.2 C. Focusing on the reduced specific capacity and increased cell polarization, the sluggish cathodic sulfur redox kinetics under lean‐electrolyte and high‐rate conditions is identified as the main limitation. Further polarization decoupling indicates the cathodic activation polarization contributes dominantly to the increased cell polarization. Accordingly, a delicately designed electrolyte using dimethyl diselenide as the kinetic promoter is proposed to enable the Li–S pouch cells to work at 0.2 C with reduced cell polarization. This work clarifies the sluggish cathodic interfacial charge transfer kinetics as the main challenge for high‐energy‐density Li–S batteries at high rates and is expected to inspire rational strategy design for achieving advanced Li–S batteries.

Ion Transport in Polymer/Inorganic Composite Electrolytes – a Comparison between Broadband Dielectric Spectroscopy and Impedance Spectroscopy

Significant efforts have been made to develop composite electrolytes combining polymer matrix with Li-ion conducting inorganic solids for feasible construction of solid-state batteries. However, the Li-ion transfer kinetics at the interface between polymer/inorganic electrolyte is unfavorable for Li-ion conduction in the composite electrolyte because of the interfacial resistance and the activation energy barrier for interfacial Li-ion transfer. The activation energy barrier for the Li-ion transfer reaction at the interface is correlated with the interaction between Li-ion and polymer matrix in the polymer electrolyte, interaction between Li-ion and anions in inorganic electrolytes and the interaction between polymer and inorganic electrolytes, therefore, the electrolyte composition significantly affects the interfacial charge transfer kinetics in composites.In this work, Li-ion transport properties in the composite electrolytes are investigated by using broadband dielectric spectroscopy (BDS) and impedance spectroscopy (IS). We particularly focus on Li-ion charge transfer at the polymer/inorganic interface from the dual ion conducting polymer to the single ion conducting polymer electrolytes with different Li-ion conducting salts such as LiN(SO2CF3)2 (LiTFSI) and (LiMTFSI) in vinyl ethylene carbonate (VEC) or polymerized vinyl ethylene carbonate (PVEC). The interfacial resistances of inorganic electrolytes Li0.34La0.56TiO3 (LLTO) in polymer electrolytes are elucidated. To further evaluate the polymer/inorganic electrolyte interfaces, various types of cell are assembled in a glove box filled with argon gas and characterized by a series of techniques such as BDS and IS. The Li-ion transfer kinetics at the interface significantly affects the Li-ion flux through the composite electrolytes and will be presented. In addition, we will present a systematic comparison between BDS and IS results in order to build connections between the two communities. Acknowledgements This work was supported as part of the Fast and Cooperative Ion Transport in Polymer-Based Materials (FaCT), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences at Oak Ridge National Laboratory under contract DE-AC05-00OR22725.

Linker Engineering for Reactive Oxygen Species Generation Efficiency in Ultra-Stable Nickel-Based Metal-Organic Frameworks.

Interfacial charge transfer on the surface of heterogeneous photocatalysts dictates the efficiency of reactive oxygen species (ROS) generation and therefore the efficiency of aerobic oxidation reactions. Reticular chemistry in metal-organic frameworks (MOFs) allows for the rational design of donor-acceptor pairs to optimize interfacial charge-transfer kinetics. Herein, we report a series of isostructural fcu-topology Ni8-MOFs (termed JNU-212, JNU-213, JNU-214, and JNU-215) with linearly bridged bipyrazoles as organic linkers. These crystalline Ni8-MOFs can maintain their structural integrity in 7 M NaOH at 100 °C for 24 h. Experimental studies reveal that linker engineering by tuning the electron-accepting capacity of the pyrazole-bridging units renders these Ni8-MOFs with significantly improved charge separation and transfer efficiency under visible-light irradiation. Among them, the one containing a benzoselenadiazole unit (JNU-214) exhibits the best photocatalytic performance in the aerobic oxidation of benzylamines with a conversion rate of 99% in 24 h. Recycling experiments were carried out to confirm the stability and reusability of JNU-214 as a robust heterogeneous catalyst. Significantly, the systematic modulation of the electron-accepting capacity of the bridging units in donor-acceptor-donor MOFs provides a new pathway to develop viable noble-metal-free heterogeneous photocatalysts for aerobic oxidation reactions.

Superior Interfacial Contact Yields Efficient Electron Transfer Rate and Enhanced Solar Photocatalytic Hydrogen Generation in M/C3N4 Schottky Junctions.

Various literature studies (Table 6) have reported that dispersion of metal nanoparticles (NPs) on graphitic carbon nitride g-C3N4 (M/CN) has considerably improved the photocatalytic hydrogen yield. It is understood that metal NPs create active sites on the surface of CN and act as a cocatalyst. However, the precise changes induced by different metal NPs on the surface of CN still elude us. Here, we report a thorough understanding and comparison of the morphology, metal-support interactions, interfacial charge transfer kinetics, and band characteristics in different M/CN (M = Pt, Pd, Au, Ag, Cu) correlated with photocatalytic activity. Among all metals, Pt/CN was found to be the best performer both under sunlight and UV-visible irradiation. Under sunlight, maximum H2@ 2.7 mmol/h/g was observed over Pt/CN followed by Pd/CN > Au/CN > Ag/CN > Cu/CN ≈ CN. The present study revealed that among all metals, Pt formed superior interfacial contact with g-C3N4 as compared to other metals. The maximum Schottky barrier height (Φb,Pt) of 0.66 V was observed at Pt/CN followed by Φb,Au/CN (0.46 V) and Φb,Pd/CN (0.05 V). The presence of electron-deficient Pt in Pt-XPS, decrease in the intensity of d-DOS of Pt near the Fermi level in VB-XPS, increase in CB tail states, and cathodic shift in Vfb in MS plots sufficiently confirmed strong metal-support interactions in Pt/CN. Due to the SPR effect, Au and Ag NPs suffered from agglomeration and poor dispersion during photodeposition. Finely dispersed Pt NPs (2-4 nm, 53% dispersion) successfully competed with shallow/deep trap states and drove the photogenerated electrons to active metallic sites in a drastically reduced time period as investigated by femtosecond transient absorption spectroscopy. Typically, an interfacial electron transfer rate, KIET,avg, of 2.5 × 1010 s-1 was observed for Pt/CN, while 0.087 × 1010 s-1 was observed in Au/CN. Band alignment/potentials at M/CN Schottky junctions were derived and most favorable in Pt/CN with CB tail states much above the water reduction potential; however, in the case of Pd, these extend much below the H+/H2 potential and hence behave like deep trap states. Thus, in Pd/CN (τ0 = 4200 ps, 49%) and Ag/CN (3870 ps, 53%), electron deep trapping dominates over charge transfer to active sites. The present study will help in designing futuristic new cocatalyst-photocatalyst systems.

Cathode Kinetics Evaluation in Lean-Electrolyte Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries afford great promise on achieving practical high energy density beyond lithium-ion batteries. Lean-electrolyte conditions constitute the prerequisite for achieving high-energy-density Li-S batteries but inevitably deteriorates battery performances, especially the sulfur cathode kinetics. Herein, the polarizations of the sulfur cathode are systematically decoupled to identify the key kinetic limiting factor in lean-electrolyte Li-S batteries. Concretely, an electrochemical impedance spectroscopy combined galvanostatic intermittent titration technique method is developed to decouple the cathodic polarizations into activation, concentration, and ohmic parts. Therein, activation polarization during lithium sulfide nucleation emerges as the dominant polarization as the electrolyte-to-sulfur ratio (E/S ratio) decreases, and the sluggish interfacial charge transfer kinetics is identified as the main reason for degraded cell performances under lean-electrolyte conditions. Accordingly, a lithium bis(fluorosulfonyl)imide electrolyte is proposed to decrease activation polarization, and Li-S batteries adopting this electrolyte provide a discharge capacity of 985 mAh g-1 under a low E/S ratio of 4 μL mg-1 at 0.2 C. This work identifies the key kinetic limiting factor of lean-electrolyte Li-S batteries and provides guidance on designing rational promotion strategies to achieve advanced Li-S batteries.

Thermal effect on the photoelectrochemical performance and interface charge transfer of CuInS2/TiO2 NTs photoelectrode

As a photothermal material, CuInS2 can effectively use the infrared spectrum to trigger the thermal effect and provide the required endothermic energy for the reaction. Here, CuInS2/TiO2 NTs composite photoanode was constructed, and the influence of thermal effect on its photoelectrochemical properties was systematically studied. It was found that CuInS2 nanoparticles could effectively convert light energy into heat energy, which led to the local temperature rise of CuInS2/TiO2 NTs under light irradiation. Furthermore, by regulating the ambient temperature from 20 ℃ to 60 ℃, the photocurrent density and photocurrent efficiency of CuInS2/TiO2 NTs increased significantly because the thermal effect could effectively inhibit the bulk recombination of photogenerated carriers and accelerate the charge transfer. The oxygen bubbles on the surface of CuInS2/TiO2 NTs photoanode had smaller diameter and showed faster desorption. Therefore, the thermal effect was conducive to charge transfer in the interfacial charge transfer kinetics of CuInS2/TiO2 NTs. It suggests that the introduction of thermal effect plays an auxiliary role in improving the photoelectrochemical reaction, and can provide a cheap and competitive method to effectively improve the photochemical performance of the photoanode.

Porous 2D Catalyst Covers Improve Photoelectrochemical Water-oxidation Performance.

Confined catalysis under the cover of two-dimensional (2D) materials has emerged as a promising approach for achieving highly effective catalysts in various essential reactions. Here, a porous cover structure is designed to boost the interfacial charge and mass transfer kinetics of 2D-covered catalysts. The improvement in catalytic performance is confirmed by the photoelectrochemical oxidation evolution reaction (OER) on a photoanode based on an n-Si substrate modified with a NiOx thin-film model electrocatalyst covered with a porous graphene (pGr) monolayer. Experimental results demonstrate that the pGr cover enhances the OER kinetics by balancing the charge and mass transfer at the photoanode and electrolyte interface compared to the intrinsic graphene cover and cover-free control samples. Theoretical investigations further corroborate that the pore edges of the pGr cover boost the intrinsic catalytic activity of active sites on NiOx by reducing the reaction overpotential. Furthermore, the optimized pores, which can be easily controlled by plasma bombardment, allow oxygen molecules produced in the OER to pass through without peeling off the pGr cover, thus ensuring the structural stability of the catalyst. This study highlights the significant role of the porous cover structure in 2D-covered catalysts and provides new insight into the design of high-performance catalysts. This article is protected by copyright. All rights reserved.

Improved Electrochemical Performance of Ni2P2O7 and Mn‐doped Ni2P2O7 Electrode Materials for Supercapacitor Applications

AbstractThe development of electrode materials for supercapacitors is really progressive and it still poses a huge challenge for researchers in many aspects. Doping of transition metals is indeed effective method because fast interfacial charge transfer kinetics has demonstrated their potential supercapacitive nature. The present work submits the structural, morphological and electrochemical performances of nickel pyrophosphate (Ni2P2O7) and manganese doped nickel pyrophosphate (Mn‐Ni2P2O7) thin film electrodes synthesized by chemical bath deposition method. The crystal structure of Ni2P2O7 obtained through X‐ray diffraction (XRD) is confirmed to be monoclinic which remains unaltered despite of Mn doping concentration. Morphological studies reveal that crystalline phase of Mn is intimately anchored on the surface of Ni2P2O7 which is beneficial for better charge transfer between transition metal and transition metal phosphates. A specific capacitance value of 603 F/g is obtained for 3 M concentration of Mn doped Ni2P2O7 from galvanostatic charge‐discharge curve at current density 1 A/g. This value is noticeably higher than what is obtained for the pure Ni2P2O7 indicating that Mn doping enhances the electrochemical performance of Ni2P2O7 thin films.

Non-desolvation Zn2+ storage mechanism enables MoS2 anode with enhanced interfacial charge-transfer kinetics for low temperature zinc-ion batteries

Non-desolvation Zn2+ storage mechanism enables MoS2 anode with enhanced interfacial charge-transfer kinetics for low temperature zinc-ion batteries

Probing the Functionality of Halogen-Free Electrolytes Using Succinonitrile Additive in Magnesium-Sulfur Batteries

Rechargeable magnesium batteries have attractive features as a post-lithium battery owing to their high volumetric capacity, safety, and low cost. However, the high charge density of Mg2+ causes sluggish interfacial charge transfer kinetics at the electrode/electrolyte interface. This paper is an attempt to optimize the electrochemical performance of a halogen-free liquid electrolyte (HFE)-based magnesium nitrate (Mg(NO3)2) and variable additive of succinonitrile (SN). A polymer layer interface (PLI) consisting of Mg (CF3SO3)2, polyvinylidene fluoride (PVDF), SN, and G4 has been introduced to isolate the Mg anode's surface from HFE in order to reduce the growth rate of the passivation layer at the surface of the Mg anode. The introduction of SN regulates the ionic conductivity, overpotential of Mg plating/stripping, and the ion transference number of the HFE. A prototype of the Mg/HFE_SN/S full cell delivers a high initial discharge/charge capacity of ~ 1200/500 mAh g−1 with a rapid capacity fade, while (Mg/PLI/HFE_SN/S) cell offers low capacity with long cycle life over (Mg/HFE_SN/S) counterpart. Postmortem analysis of sulfur electrodes at different electrochemical states reveals the reversible back and forth movement of Mg2+ ions in Mg/S cells via conversion reaction.

Two-Dimensional Sb Modified TiO2 Nanorod Arrays as Photoanodes for Efficient Solar Water Splitting.

As one of the widely studied semiconductor materials, titanium dioxide (TiO2) exhibits high photoelectrochemical (PEC) water-splitting performance as well as high chemical and photo stability. However, limited by a wide band gap and fast electron-hole recombination rate, the low solar-to-hydrogen conversion efficiency remains a bottleneck for the practical application of TiO2-based photoelectrodes. To improve the charge separation and water oxidation efficiency of TiO2 photoanodes, antimonene, a two-dimensional (2D) material obtained by liquid-phase exfoliation, was assembled onto TiO2 nanorod arrays (TNRAs) by a simple drop-coating assembly process. PEC measurements showed that the resulting 2D Sb/TiO2 photoelectrode displayed an enhanced photocurrent density of about 1.32 mA cm-2 in 1.0 M KOH at 0.3 V vs. Hg/HgO, which is ~1.65 times higher than that of the pristine TNRAs. Through UV-Vis absorption and electrochemical impedance spectroscopy measurements, it was possible to ascribe the enhanced PEC performances of the 2D Sb/TiO2 photoanode to increased absorption intensity in the visible light region, and improved interfacial charge-transfer kinetics in the 2D Sb/TiO2 heterojunction, which promotes electron-hole separation, transfer, and collection.

Unveiling the Synchronized Effect of Bulk and Surface Dual Modification of In Situ Nb-Doping and Microwave-Assisted Co(OH)x Cocatalyst for Boosting Photoelectrochemical Water Splitting of Fe2O3 Photoanodes

Herein, in order to improve the conductivity and slack water oxidation kinetics of the hematite (α-Fe2O3) photoanode, we propose the Nb-doped and Co(OH)x cocatalyst-deposited α-Fe2O3 thin film photoanode (Nb-HT/Co(OH)x) via in situ diluted hydrothermal and microwave-assisted methods. The as-prepared Nb-HT/Co(OH)x thin-film photoanode exhibited a photocurrent density of 1.78 mA cm–2 at 1.23 V versus a reversible hydrogen electrode (RHE), which is 1.7-fold higher than that of the Bare-Fe2O3 photoanode. The dual effect of Nb-doping and Co(OH)x deposition markedly improved the PEC performance through enhancing the charge carrier mobility and donor density in hematite, as well as accelerating the interfacial charge transfer kinetics at the electrode/electrolyte interface of the α-Fe2O3 thin film photoanode. The Nb-HT/Co(OH)x photoanode displayed a high charge separation efficiency of 90% (at 1.23 VRHE) and excellent stability over a 10 h period without any decrease. Detailed electrochemical analyses using electrochemical impedance spectroscopy (EIS), open-circuit potential (OCP), and accumulated charge density techniques disclosed the charge separation and transfer processes. This strategy of bulk and surface modification highlights a new approach to constructing a stable photoanode for sustainable solar energy conversion.

Improving Electrocatalytic Activity of MoO3 for the Oxygen Evolution Reaction by Incorporation of Li Ions

Several polymorphs of MoO3 with different crystal and electronic structures provide many opportunities to find suitable electrocatalysts for water splitting hydrogen generation. So far, promising electrocatalytic activity for hydrogen evolution reaction (HER) has been found for α-MoO3 (orthorhombic), while the polymorph has shown a poor oxygen evolution reaction (OER) activity. In this work, it is found that the intrinsic OER activity of α-MoO3 is remarkably improved by incorporating guest ions of lithium-ion (Li+). α-MoO3 nanoparticles were deposited on a carbon fiber paper (α-MoO3/CFP) by chemical vapor transport and a subsequent lithiation process was applied to prepare lithiated α-MoO3/CFP (Li-α-MoO3/CFP), showing the robust η10 of 458 mV. The improved OER activity in the lithiated electrode is attributed to the incorporation of Li+ into the MoO3, which increases the electron carrier density and the corresponding electrical conductivity, thereby improving the interfacial charge transfer kinetics as well as activating a large number of ECSA.

Ready-to-use interactive dual-readout differential lateral flow biosensor for two genotypes of human papillomavirus

Ready-to-use in vitro diagnosis of multiple genotypes is vital for the prevention and treatment of cervical cancer. Herein, a paper-film-based interactive dual readout differential lateral flow biosensor is proposed to simultaneously assay two high-risk types of human papillomavirus (HPV) within the body-fluid. The CuCo2S4/ZnIn2S4 heterostructure is fabricated on the paper-film compound chip with high thermostability, and surface sulfur vacancy is introduced by mild annealing treatment to endow unexceptionable photoexcitation activity, such structure can be served as an initial energy harvester and converter. With the assistance of differential channels, the dual-target-propelled self-assembly of annular DNA and the cleavage activity of CRISPR-Cas12a are stepwise activated by sequential solution transfer. Accordingly, the input and release of polydopamine-coated gold nanoparticles with photothermal/photoelectric characteristic were implemented. The fabricated biosensor not only realized intelligent thermal-response without large instruments, but also actuated dynamic interfacial charge separation and transfer kinetics to further transmit photoelectric-signal, resulting in desirable interactive dual-signal with low limit-of-detection (0.21 pM for HPV-18 and 42.92 pM for HPV-16). Thanks to the sophisticated design of differential lateral flow paper-film compound chip and interactive dual-signal amplification strategy, sensitive detection of two HPV genotypes is realized, which provides a promising candidate for home medical intelligent diagnosis.