Effect Of Built-in Electric Field Research Articles

Heterogeneous Interface Design with Oxygen Vacancy-Rich Assistance High-Capacity Titanium-Based Oxide Anode Materials for Sodium-Ion Batteries.

Researchers are paying more attention to sodium-ion batteries (SIBs) because of their abundant supply of sodium resources and affordable price. TiO2 offers excellent safety and a long lifespan as an anode material for SIBs. However, the process kinetics is slow due to its limited Na+ storage efficiency, weak conductivity, and irreversible Na+ capture. In order to address these issues, this review uses a mix of the template approach and the double-hydrolysis method to manage the structure and diffusion of TiO2-based anode materials by synthesizing FeTiO3/TiO2 heterostructured double-shell microspheres (FTO). Through the built-in electric field effect caused by their heterostructures, FTO materials improve reaction kinetics, boost electronic conductivity, and lower the diffusion energy barrier of Na+. Their distinctive double-shell structure can increase electrolyte infiltration, shorten the diffusion distance between ions and electrons, and accommodate volume expansion during cycling. Furthermore, the irreversible capture of Na+ and the unfavorable interactions between the surface active site and electrolyte can be successfully inhibited by FTO heterostructures. FTO has an exceptionally high capacity (reaching 362.7 mA h g-1 after 60 cycles at 20 mA g-1) and excellent cycle stability (with a decay rate of 0.0061% after 1000 cycles at 2 A g-1). The strategy of constructing heterogeneous interfaces assists with high-performance SIB anode design.

Enhanced photodegradation performance of Zn-BiPO4 on RhB and TC under the synergistic effect of oxygen vacancies and built-in electric field

In this work, Zn2+ ions doped BiPO4 photocatalyst was successfully prepared by one-step hydrothermal method for the first time. The degradation rates of the optimal sample on RhB and TC solution reached 91.5 % and 81.25 % under simulated sunlight exposure for 3 and 5 hours, respectively, while pure BiPO4 only reached 59.22 % and 49.4 %. The improved photocatalytic performance was due to the synergistic effect of oxygen vacancies and built-in electric field. The EPR test demonstrated the generation of more oxygen vacancies in the optimal sample. Additionally, the electrochemical experiments showed that the photocurrent intensity of the optimal sample was about 3 times than that of pure BiPO4, indicating an enhanced carrier separation and transfer ability after doping Zn2+ ions. Through density functional theory (DFT), the incorporated Zn2+ ions caused the contraction of crystal structure and the redistribution of charges, leading to a built-in electric field. As few studies pay attention to the relationship between oxygen vacancies and the built-in electric field. This study has enlightening significance for the construction of photocatalysts with oxygen vacancies and built-in electric field through doping engineering.

Built-in electric field construction and lattice oxygen activation for boosting alkaline electrochemical water/seawater oxidation

Oxygen evolution reaction (OER) remains a bottleneck for hydrogen production by water-alkali electrolysis at high industrial current density, but the structure–activity relationship of the catalyst and the underlying catalytic mechanism are still debated, which always limits the design of efficient catalysts. Herein, we report a proof-of-concept hierarchical hydroxide/sulfide (NiFe LDH/Ni3S2) heterostructure as model catalyst to simultaneously adjust the electronic states and activate lattice oxygen. As-activated NiFe LDH/Ni3S2 electrode displays promising OER capability with an ultra-low overpotential of 295 mV at the industrial current density of 500 mA·cm−2. The interface-induced built-in electric field effect promotes the asymmetric charge distribution on both sides. In-situ/ex-situ characterization demonstrates the adjusted intermediates adsorption/desorption and accelerated OER kinetics due to rapid electron transfer. A series of electrochemical probe experiments reveal that the OER mechanism of NiFe LDH/Ni3S2 follows the lattice oxygen mechanism. Especially, the super-strong wettability electrode design and structural advantages effectively enhance mass transfer and promote O2 desorption in alkaline water/seawater splitting systems. This work provides an avenue to break through OER limitations for efficient electrocatalytic water oxidation.

Enhanced ionic transport and performance with a built-in electric field impact in LSCF-LCP double layer electrolyte

The widely used cathode La0·7Sr0·3Co0·5Fe0·5O3-δ (LSCF) perovskite and excellent electrolyte LaPr-codoped ceria (LCP) are combined into a double-layer LSCF-LCP electrolyte. Leveraging the semiconductor-ion material nature, a built-in electric field (BIEF) is established at the junction between the semiconductor LSCF and ionic conductor LCP layers to enhance ionic transport, consequently improving fuel cell power output. Comparative research on the double-layer LCP with LSCF brushing thin films, varying LSCF thickness from 50 μm to 150 μm, reveals that the LSCF layer with 100 μm thickness yields the highest fuel cell power output, 567 mW/cm2 at 450 °C. Based on analysis of experimental results, we attribute these intriguing properties to the enhanced ion transport and delves into the BIEF effect. This study presents alternative avenues for advancing fuel cell technologies, offering insights valuable for research and development.

Preparation of double S-scheme NaBiO3/BiO2-x/Bi2O2CO3 heterojunction and the enhancement mechanism of full-spectrum driven degradation activity toward antibiotics

In this work, a series of NaBiO3/BiO2-x/Bi2O2CO3 heterojunction was synthesized via a UV light-assisted chemical precipitation method. Full-solar-spectrum absorption was achieved owing to the localized surface plasmon effect induced by the presence of oxygen vacancies. Furthermore, through the synergistic effect of built-in electric fields and band bending in the interfaces, a Ⅱ-Ⅱ-type structure was successfully transformed into a double S-scheme heterojunction. Consequently, both the separation efficiency and redox ability of photogenerated carriers were simultaneously enhanced, significantly improving the full-solar-spectrum driven photocatalytic performance. Under visible and near-infrared light irradiation, the degradation rates of ofloxacin by the optimal heterojunction could reach 0.1265 min−1 and 0.0075 min−1, respectively, which were 7.27 and 3.95 times higher than those of the one-component NaBiO3. This work provides an efficient strategy for the design and preparation of high-active full-spectrum responsive heterojunction photocatalytic materials for antibiotic degradation.

Phosphorous Vacancy and Built-In Electric Field Effect of Co-Doped MoP@MXene Heterostructures to Tune Catalytic Activity for Efficient Overall Water Splitting.

Developing cost-effective, durable bifunctional electrocatalysts is crucial but remains challenging due to slow hydrogen/oxygen evolution reaction (HER/OER) kinetics in water electrolysis. Herein, a combined engineering strategy of phosphorous vacancy (Vp) and spontaneous built-in electric field (BIEF) is proposed to design novel highly-conductive Co-doped MoP@MXene heterostructures with phosphorous vacancy (Vp-Co-MoP@MXene). Wherein, Co doping regulates the surface electronic structure and charge re-distribution of MoP, Vp induces more defects and active sites, while BIEF accelerates the interfacial charge transfer rate between Vp-Co-MoP and MXene. Therefore, the synergistic integration of Vp-Co-MoP/MXene efficiently decreases activation energy and kinetic barrier, thus promoting its intrinsically catalytic activity and structural stability. Consequently, the Vp-Co-MoP@MXene catalyst displays low overpotentials of 102.3/196.5 and 265.0/320.0mV at 10/50mA cm-2 for HER and OER, respectively. Notably, two-electrode electrolyzers with the Vp-Co-MoP@MXene bifunctional catalysts to achieve 10/50mA cm-2, only need low-cell voltages of 1.57/1.64V in alkaline media. Besides, experimental and theoretical results confirm that the hetero-structure effectively reduces hydrogen adsorption free energy and rate-determining-step energy barrier of OER intermediates, thereby greatly boosting its intrinsically catalytic activity. This work verifies an effective strategy to fabricate efficient non-precious bifunctional electro-catalysts for water splitting via combination engineering of phosphorous vacancy, cation doping, and BIEF.

Constructing heterojunction on N-doped porous carbon nanofibers for Li-S batteries: Effect of built-in electric field on efficient catalytic transformation kinetics

In this study, the CoP-Co2P heterojunction nanoparticles embedded in N-doping porous carbon nanofibers (CoP-Co2P/NPCNFs) are designed and prepared. The highly conductive grid of NPCNFs can physically confining lithium polysulfide (LiPS) and provide facilitated channels for Li+ transport. Furthermore, due to the spontaneous built-in electric field (BIEF) based on at the formed heterogeneous interfaces of CoP-Co2P, the heterojunction can significantly catalyze bi-directional conversion of LiPS and chemically adsorb LiPS which confirmed by the DFT calculations, suppressing the “shuttle effect” of LiPS. Thus, the Li-S batteries with the CoP-Co2P/NPCNFs modified separators exhibit a high initial specific capacity of 1322.86 mAh g−1 at 1 mA cm−2 and stable 695 cycles with a low decay rate (0.069 %). More importantly, the assembled pouch cell also can run with ultra-low specific capacity decay rate. Additionally, the pouch battery can also be applied to the operation of fans, temperature and humidity meters, mobile phone charging, etc.

Synergistic Regulation of Built-In Electric Field and Interface Effect to Enhance the Reaction Kinetics and Stability of Lithium-Ion Batteries

Synergistic Regulation of Built-In Electric Field and Interface Effect to Enhance the Reaction Kinetics and Stability of Lithium-Ion Batteries

Simultaneous photocatalytic removal of tetracycline and hexavalent chromium by BiVO4/0.6CdS photocatalyst: Insights into the performance, evaluation, calculation and mechanism

In this study, a novel Z-scheme heterojunction on bismuth vanadium/cadmium sulfide (BiVO4/0.6CdS) was developed and evaluated for simultaneous photocatalytic removal of combined tetracycline (TC) and hexavalent chromium Cr(Ⅵ) pollution under visible light. Based on the analysis of intermediate products and theoretical calculation, the property of the intermediate products of TC degradation and the effect of built-in electric field (IEF) of composite materials on photo-generated carrier separation were illustrated. According to the experiments and evaluation results, the performance of BiVO4/0.6CdS is higher than CdS 2.83 times and 4.82 times under the visible light conditions, with the aspect of simultaneous oxidizing TC and reducing Cr(Ⅵ), respectively. The catalyst has a faster removal rate in the binary composite pollution system than the single one. Therefore, the photocatalytic degradation of TC using BiVO4/0.6CdS can reduce the toxic effect of TC on the environment. The aforementioned evaluation provides a new design strategy for Z-scheme heterojunction to simultaneous photocatalytic degradation of composite organic and inorganic pollutants.

Tailoring Built-In Electric Field in a Self-Assembled Zeolitic Imidazolate Framework/MXene Nanocomposites for Microwave Absorption.

Heterointerface engineering, which plays a pivotal role in developing advanced microwave-absorbing materials, is employed to design zeolitic imidazolate framework (ZIF)-MXene nanocomposites. The ZIF-MXene composites are prepared by electrostatic self-assembly of negatively charged titanium carbide MXene flakes and positively charged Co-containing ZIF nanomaterials. This approach effectively creates abundant Mott-Schottky heterointerfaces exhibiting a robust built-in electric field (BIEF) effect, as evidenced by experimental and theoretical analyses, leading to a notable attenuation of electromagnetic energy. Systematic manipulation of the BIEF-exhibiting heterointerface, achieved through topological modulation of the ZIF, proficiently alters charge separation, facilitates electron migration, and ultimately enhances polarization relaxation loss, resulting in exceptional electromagnetic wave absorption performance (reflection loss RLmin = -47.35 dB and effective absorption bandwidth fE = 6.32 GHz). The present study demonstrates an innovative model system for elucidating the interfacial polarization mechanisms and pioneers a novel approach to developing functional materials with electromagnetic characteristics through spatial charge engineering.

Synergistic effect of donor-acceptor structure and built-in electric field in hollow-spherical carbon nitride homojunction towards effective charge transfer and excellent photocatalytic hydrogen evolution performance

Polymeric carbon nitride (PCN) is regarded as a most promising photocatalyst, but the severe recombination of electron-hole pairs restrains its photocatalytic performance. Herein, a carbon nitride gradient homojunction with donor–acceptor (D-A) structure was successfully synthesized. The D-A structure promoted the electron delocalization, while gradient K intercalation helped establish a strong internal electric field from the interior to the surface. They synergistically inhibited the recombination of electron-hole pairs and led to fast charge transfer and much enhanced photocatalytic hydrogen evolution (PHE) performance. This work developed a novel method to promote the charge carrier transfer in carbon nitrides, which could provide a new perspective for the design and development of carbon nitride-based homojunctions in the application of PHE.

Nanoarchitectonics toward Full Coverage of CdZnS Nanospheres by Layered Double Hydroxides for Enhanced Visible-Light-Driven H2 Evolution.

Nanoarchitectonics of semiconductors shed light on efficient photocatalytic hydrogen evolution by precisely controlling the surface microenvironment of cocatalysts. Taking cadmium zinc sulfide (CZS) nanoparticles as a target, the spontaneous modifications are conducted by interactions between surface Cd2+/Zn2+ atoms and thiol groups in thioglycolic acid. The capping ligand impacts the semiconductor surface with a negative electronic environment, contributing to the full coverage of CZS by nickel-cobalt hydroxides (NiCo-LDHs) cocatalysts. The obtained core-shell CZS@NiCo-LDHs, possessing a shell thickness of ≈20nm, exhibits a distinguished topology (SBET=87.65m2g-1), long surface carrier lifetime, and efficient charge-hole separation. Further photocatalytic hydrogen evaluation demonstrates an enhanced H2 evolution rate of 18.75mmolg-1h-1 with an apparent quantum efficiency of 16.3% at 420nm. The recorded catalytic performance of the core-shell sample is 44.6 times higher than that of pure CZS nanospheres under visible light irradiation. Further density functional theory simulations indicate that sulfur atoms play the role of charge acceptor and surface Ni/Co atoms are electron donors, as well as a built-in electric field effect can be established. Altogether, this work takes advantage of strong S affinity from surface metal atoms, revealing the interfacial engineering toward improved visible-light-driven photocatalytic hydrogen evolution (PHE)activity.

Unveiling the potential of two-dimensional Janus ScXAlY (X/Y=P, As) materials and heterostructures in visible-light-driven photocatalytic water splitting

Two-dimensional (2D) material with Janus-induced built-in electric field, has become a research focus arising from their characteristic physical and chemical properties, especially in photocatalytic water splitting applications. Herein, we introduce a novel family of 2D Janus materials, named ScXAlY (X/Y = P, As), and prove these Janus materials and their heterostructures as promising water splitting photocatalytic candidate materials, leveraging first-principles calculations. All Janus structures and heterostructures exhibit strong dynamical, thermal, and mechanical stabilities. These 2D Janus ScXAlY materials possess wide band gaps, excellent electronic carrier mobilities, and appropriate band edges to facilitate overall water splitting, and moreover can attain Janus-induced built-in electric field effect. Interestingly, the heterostructures (ScXAlY/ScXAlY) surpass the individual materials in performance, demonstrating enhanced solar-to-hydrogen (STH) efficiencies (>30 %) and increscent electrostatic potential differences (>0.85 eV). Furthermore, they show comprehensive photoabsorption across the visible light spectrum, with peak absorptions more than doubling those of the single materials. These heterostructures also display effective spatial separation of electrons and holes which can further boosting their photocatalytic capabilities. Our findings underscore the potential of Janus ScXAlY materials and their heterostructures, in facilitating visible-light-driven photocatalytic water splitting, showcasing a promising avenue for advancement in this burgeoning field.

Interfacial charge redistribution to promote the catalytic activity of Vs-CoP-CoS2/C n-n heterojunction for oxygen evolution

Modulating surface charge redistribution based on interface and defect engineering has been considered as a resultful means to boost electrocatalytic activity. However, the mechanism of synergistic regulation of heterojunction and vacancy defects remains unclear. Herein, a Vs-CoP-CoS2/C n-n heterojunction with sulfur vacancies is successfully constructed, which manifests superior electrocatalytic activity for oxygen evolution, as demonstrated by a low overpotential of 170 mV to reach 10 mA/cm2. The experimental results and density functional theory calculations testify that the outstanding OER performance of Vs-CoP-CoS2/C heterojunction is owed to the synergistic effect of sulfur vacancies and built-in electric field at n-n heterogeneous interface, which accelerates the electron transfer, induces the charge redistribution, and regulates the adsorption energy of active intermediates during the reaction. This study affords a promising means to regulate the electrocatalytic performance by the construction of heterogeneous interfaces and defects, and in-depth explores the synergistic mechanisms of n-n heterojunction and vacancies.

The built-in electric field and spin-pinning effect in BiVO4/Fe0.4Co0.6Se2/Co(Fe)OxHy for enhanced photoelectrochemical water oxidation

Photoelectrocatalytic water splitting is a promising method for producing green and clean energy. In this research, a three-layer composite photoanode BiVO4/Fe0.4Co0.6Se2/Co(Fe)OxHy, named as M@BFOH5, is prepared by a in situ electro-oxidation reconstitution and magnetization method. Through constructing a p-n heterojunction BiVO4/Fe0.4Co0.6Se2, a built-in electric field is formed to accelerate electron transfer in the cross-layer channels. The spin-pinning effect caused by ferromagnetic semiconductor Fe0.4Co0.6Se2 induce spontaneous polarization in the ultra-thin Co(Fe)OxHy layer, which is favorable for conductivity of the passivation layer (Co(Fe)OxHy). The results demonstrate the exceptional oxygen reduction reaction performance of M@BFOH5, achieving a photocurrent density of 4.99 mA cm−2 at 1.23 V in comparison to the reversible hydrogen electrode. This represents an enhancement of 3.1 and 1.37 times over BiVO4 and BFOH5, respectively. Additionally, the charge separation and charge injection efficiencies significantly increased to 92.44 % and 82.68 %, correspondingly. This subtle catalyst is designed to help accelerate oxygen reduction reaction.

Built-in electric field and hydrostatic pressure effects on exciton states in a wurtzite (In,Ga)N/GaN coupled double quantum well

Built-in electric field and hydrostatic pressure effects on exciton states in a wurtzite (In,Ga)N/GaN coupled double quantum well

A Co2N/CoP p-n junction with modulated interfacial charge and rich nitrogen vacancy for High-Efficiency water splitting

In-depth study the regulation mechanism of p-n heterogeneous interface and vacancy defects on electrocatalytic performance remains a great challenge. Herein, a nitrogen-vacancy-rich Co2N/CoP@CC p-n junction with enhanced HER and OER activities has been successfully developed. In detail, the Co2N/CoP@CC delivers HER activity comparable to the commercial Pt/C catalyst, as demonstrated by the ultra-low overpotential of 44 mV, and also shows excellent OER activity with an overpotential as low as 227 mV at 10 mA cm−2 in alkaline medium. Meanwhile, the water splitting potential of 1.5 V for the Co2N/CoP@CC heterojunction at 10 mA cm−2 is also achieved. DFT theoretical calculations indicate the outstanding electrocatalytic activity of Co2N/CoP@CC may be attributed to the synergy effect of abundant nitrogen vacancies and built-in electric field induced by rich p-n interfaces, which can effectively promote electron transfer, realize charge redistribution, adjust the adsorption/desorption free energy of the intermediates, and thus significantly enhancing the electrocatalytic activity.

Full-spectrum broad-spectrum degradation of antibiotics by BiVO4@BiOCl crystal plane S-type and Z-type heterojunctions

Based on the poor full-spectrum broad-spectrum catalytic activity of the exposed crystal faces of BiVO4, a photo-deposited crystal plane selectively induce method was used to nucleate the strong reduction-capable BiOCl on BiVO4 (010) crystal planes in the heterogeneous phase and the OVs-BiOCl on BiVO4 (110) crystal planes in the homogeneous phase. The core–shell BiVO4@BiOCl crystal plane S-type and Z-type heterojunction photocatalysts were prepared. Under the synergistic effects of the surface heterojunction built-in electric field, the interfacial electrostatic built-in electric field, the inter-heterojunction polarization charge transfer and the Localized Surface Plasmon Resonance (LSPR) effect of oxygen vacancies, the BiVO4@BiOCl exhibits strong broad-spectrum degradation ability over the entire spectral range and exhibits excellent degradation cycle stability. The degradation rates of BiVO4@BiOCl for TC are 90.32%/71.17%, the TOC removal rates are 74.07%/57.81% and degradation efficiencies of CIP, BHA, Phenol, BPA and Coumarin are 49.36 ∼ 71.32%/37.88% ∼ 62.86%, respectively, after Vis/NIR light irradiation, respectively. It also shows good degradation performance of the mixed antibiotic solutions. This study offers a feasible research proposal for surface heterogeneous crystalline facet selective induction of oxygen vacancies to induce the enhanced full-spectrum broad-spectrum degradation performance of heterojunction photocatalysts for the application of environmental purification.

Synergistic effect of oxygen vacancies and built-in electric field in GdCrO3/BiVO4 composites for boosted photocatalytic reduction of nitrate in water

As a promising approach for nitrate nitrogen removal in water, photocatalysis required sufficient photogenerated charges to achieve a high photocatalytic efficiency. Herein, a novel GdCrO3/BiVO4 composite was prepared by the solid-state combustion method combined with hydrothermal treatment. The synergistic effect of oxygen vacancies introduced by chemical reduction method and built-in electric field formed in GdCrO3/BiVO4 heterostructures suppressed the charge recombination, which eventually improved the photocatalytic activity. Effects of photocatalyst composition, HCOOH dosage and oxygen vacancy concentration on photocatalytic activity were investigated. It was found that 0.30-GdBiOVs composites exhibited highest photocatalytic activity with nitrate removal ratio of 97.05% and N2 selectivity of 92.76% in 40 min. Moreover, end-products of nitrate nitrogen elimination and stability of photocatalysts were revealed. The existences of oxygen vacancies and built-in electric field were confirmed by EPR and HRTEM analyses. Ultimately, the possible mechanisms of nitrate nitrogen elimination were clarified.

Nickel sulfide/nickel phosphide heterostructures anchored on porous carbon nanosheets with rapid electron/ion transport dynamics for sodium-ion half/full batteries

Nickel-based materials have been extensively deemed as promising anodes for sodium-ion batteries (SIBs) owing to their superior capacity. Unfortunately, the rational design of electrodes as well as long-term cycling performance remains a thorny challenge due to the huge irreversible volume change during the charge/discharge process. Herein, the heterostructured ultrafine nickel sulfide/nickel phosphide (NiS/Ni2P) nanoparticles closely attached to the interconnected porous carbon sheets (NiS/Ni2P@C) are designed by facile hydrothermal and annealing methods. The NiS/Ni2P heterostructure promotes ion/electron transport, thus accelerating the electrochemical reaction kinetics benefited from the built-in electric field effect. Moreover, the interconnected porous carbon sheets offer rapid electron migration and excellent electronic conductivity, while releasing the volume variance during Na+ intercalation and deintercalation, guaranteeing superior structural stability. As expected, the NiS/Ni2P@C electrode exhibits a high reversible specific capacity of 344 mAh g−1 at 0.1 A g−1 and great rate stability. Significantly, the implementation of NiS/Ni2P@C//Na3(VPO4)2F3 SIB full cell configuration exhibits relatively satisfactory cycle performance, which suggests its widely practical application. This research will develop an effective method for constructing heterostructured hybrids for electrochemical energy storage.