Strong Internal Electric Field Research Articles

Enhancing Pollutant Mineralization through Organic-Inorganic Defect-Transit Dual S-scheme with a Robust Internal Electric Field.

Achieving superior photomineralization of pollutants relies on a rational design of a dual S-scheme with a robust internal electric field (IEF). In this study, to tackle the low mineralization rate in type-II In2 O3 /In2 S3 (IO/IS) systems, an organic-inorganic dual S-scheme In2 O3 /PDI/In2 S3 (IO/PDI/IS) nanostructured photocatalyst is synthesized via a method combining solvent-induced self-assembly and electrostatic forces. Due to the unique energy band position and strong IEF, the photoinduced defect-transit dual S-scheme IO/PDI/IS facilitates the degradation of lignin and antibiotics. Notably, a promising mineralization rate of 80.9% for sodium lignosulfonate (SL) is achieved. The charge transport pathway of IO/PDI/IS are further validated through the analysis of in situ X-ray photoelectron spectroscopy (in situ XPS), density functional theory calculations, and radical trapping experiments. In-depth, two possible pathways for the photocatalytic degradation of lignin are proposed based on the intermediates monitored by liquid chromatography-mass spectrometry (LC-MS). This study presents a new strategy for the design of organic-inorganic dual S-scheme photocatalysts with a robust IEF for pollutant degradation.

Strong Rashba parameter of two-dimensional electron gas at CaZrO3/SrTiO3 heterointerface

We synthesized a CaZrO3/SrTiO3 oxide heterostructure, which can serve as an alternative to LaAlO3/SrTiO3, and confirmed the generation of 2-dimensional electron gas (2-DEG) at the heterointerface. We analyzed the electrical-transport properties of the 2-DEG to elucidate its intrinsic characteristics. Based on the magnetic field dependence of resistance at 2 K, which exhibited Weak Anti-localization (WAL) behaviors, the fitted Rashba parameter values were found to be about 12–15 × 10–12 eV*m. These values are stronger than the previous reported Rashba parameters obtained from the 2-DEGs in other heterostructure systems and several layered 2D materials. The observed strong spin–orbit coupling (SOC) is attributed to the strong internal electric field generated by the lattice mismatch between the CaZrO3 layer and SrTiO3 substrate. This pioneering strong SOC of the 2-DEG at the CaZrO3/SrTiO3 heterointerface may play a pivotal role in the developing future metal oxide-based quantum nanoelectronics devices.

Ultra-fast magnetic catalytic degradation of organic dyes by the Fe-doped metallic 1T/1T′ MoS2 nanocomposites

This study presents a novel approach to degrading pollutants through the ultra-fast magnetic catalytic degradation of organic dyes in the dark using Fe-doped metallic 1 T/1 T′ MoS2 nanocomposites produced by the hydrothermal method. The nanocomposites demonstrated a degradation rate of 97.8% for Rhodamine B in a mere 2 min under magnetic stirring, which was 12 times and 7.65 times higher than the ZnO/MoS2 and ZnO/ZnS/(2 H) MoS2 nanocomposites respectively for Methylene Blue. This rapid magnetic catalysis could be attributed to the high magnetoelectric conversion efficiency, the MoS2 semiconductor-metal phase junction and the MoS2/FeS2 heterojunction, the strong internal electric field generated by the piezoelectric effect, and the high electrical conductivity of the metallic 1 T/1 T′ MoS2.

Fabrication of Internal Electric Field Sns/Sb2S3 with Engineered Porous Structure for Fast Kinetics Sodium Ion Storage

Benefiting from the abundance and low cost of sodium, sodium-ion batteries show great potential as lithium-ion batteries in application of large-scale energy storage. However, anode material graphite with high theoretical capacity 372 mAh g-1, low charge-discharge plateau potential and good cyclability, widely applied in lithium-ion batteries, exhibited poor electrochemical performance. The larger radius of Na-ion compared to Li-ion hinders the mass and ion transfer during charge-discharge cycling. Thus, anode material with large abundance, stability and high conductivity is crucial for the development and further application of sodium-ion batteries.Sodium-ion batteries have the potential to benefit greatly from metallic sulfide anodes, which offer high theoretical capacities. Unfortunately, the practical use of these anodes is limited by poor electrochemical performance, as sulfides tend to expand significantly in volume and Na+ ions exhibit sluggish kinetics during cycling. We have developed a facile and scalable approach to synthesizing a SnS/Sb2S3 heterostructure that is porous and bimetallic, with an additional sulfur and nitrogen co-doped carbon matrix encapsulation (SnS/Sb2S3@SNC). The PAN precursor is mixed homogeneously with SnSbx and S with a ball milling process. The sulfur evaporates from the mixture and reacts with the SnSbx alloy, leading to the formation of bimetallic sulfides SnS/Sb2S3. As a result, voids are generated, which in turn contributes to the development of a porous structure. At the same time, the PAN is carbonized, generating a S, N co-doped carbon matrix. SnS and Sb2S3 are two highly promising anode materials for sodium-ion batteries, with high theoretical specific capacity of 1022 mAh g-1 and 947 mAh g-1, respectively. Moreover, bimetallic sulfides possess different bandgap make them ideal components for generating a strong internal electric field on the hetero-interface, which allows to improve the charge carrier transport and interface reaction kinetics. The porous nature of the structure can contain the volume expansion of sulfides during cycling, thereby ensuring superior structural stability. The distinctive heterostructure, in combination with the S, N co-doped carbon matrix, enables fast-charge transport and accelerate Na-ion storage kinetics.The SnS/Sb2S3@SNC anode demonstrates impressive electrochemical performance, with high capacities of 425 mAh g-1 at 200 mA g-1 after 100 cycles, and 302 mAh g-1 at 500 mA g-1 after 400 cycles. Additionally, the SnS/Sb2S3 @SNC anode exhibits remarkable rate capability, with a capacity of over 200 mAh g-1 at a high current density of 5000 mA g-1. Figure 1

High-Performance Self-Driven SnSe/Si Heterojunction Photovoltaic Photodetector

Tin monoselenide (SnSe), which belongs to group IV–VI monochalcogenides, has obtained significant attention in the field of photodetection owing to its ultrahigh carrier mobilities. However, the great challenges of preparing high-quality films and high-performance devices still need to be conquered. Herein, high-density continuous SnSe films were deposited on a Si substrate using magnetron sputtering technology, and a self-driven photovoltaic-type broadband photodetector from the visible light range (VIS) to the near-infrared (NIR) range based on SnSe/Si heterojunction was constructed. Owing to its high carrier mobility, narrow band gap structure, and strong internal electric field, the SnSe/Si heterojunction device exhibits an ultrafast response and high responsivity (R), which achieves a wide spectral response of 405–980 nm. Under zero bias voltage, the greatest R and detectivity (D*) of the heterojunction were 704.6 mA/W and 3.36 × 1011 Jones at 405 nm. Furthermore, the device had a fast response time (rise time) of 20.4 μs at 980 nm of illumination. This work provides a new strategy for the fabrication of high-performance, low-cost, and self-driven photodetectors.

Functional Group Modulation in Carbon Quantum Dots for Accelerating Photocatalytic CO2 Reduction.

This study investigates the mechanism behind the enhanced photocatalytic performance of carbon quantum dot (CQD)-induced photocatalysts. Red luminescent CQDs (R-CQDs) were synthesized using a microwave ultrafast synthesis strategy, exhibiting similar optical and structural properties but varying in surface functional group sites. Model photocatalysts were synthesized by combining R-CQDs with graphitic carbon nitride (CN) using a facile coupling technique, and the effects of different functionalized R-CQDs on CO2 reduction were investigated. This coupling technique narrowed the band gap of R1-CQDs/CN, made the conduction band potentials more negative, and made photogenerated electrons and holes less likely to recombine. These improvements greatly enhanced the deoxygenation ability of the photoinduced carriers, increased light absorption of solar energy, and raised the carrier concentration, resulting in excellent stability and remarkable CO production. R1-CQDs/CN demonstrated the highest photocatalytic activity, with CO production up to 77 μmol g-1 within 4 h, which is approximately 5.26 times higher than that of pure CN. Our results suggest that the superior photocatalytic performance of R1-CQDs/CN arises from its strong internal electric field and high Lewis acidity and alkalinity, attributed to the abundant pyrrolic-N and oxygen-containing surface groups, respectively. These findings offer a promising strategy for producing efficient and sustainable CQD-based photocatalysts to address global energy and environmental problems.

Hollow Zn0.01Co0.99 Se2/ZnIn2S4 Z-scheme heterogeneous photocatalyst with Strong internal electric field and Excellent surface electron transfer capability for Efficient Hydrogen Production

Reasonable design and optimization of photocatalyst structure is an important strategy to realize sustainable hydrogen production. The rational design and interfacial tuning of Z-scheme heterojunctions remain challenging. Herein, a series of hollow cage-like Zn0.01Co0.99Se2/ZnIn2S4 Z-scheme heterojunction photocatalysts templated by cobalt-based bimetallic organic frameworks is successfully obtained via a hydrothermal approach. As expected, the optimized catalysts exhibit excellent hydrogen production performance without noble metal co-catalysts, which is mainly attributable to the synergistic effect of abundant active sites, strong light trapping and effective charge separation. Spectroscopic characterization and density functional theory (DFT) calculations indicate that the doping of Zn ions leading to more photogenerated carriers and faster charge transfer rates inside the heterojunction is another key factor in improving the catalytic performance. This work provides a feasible strategy for the optimization and design of Z-scheme heterojunctions through structural and interfacial engineering.

Gradient Cationic Vacancies Enabling Inner-To-Outer Tandem Homojunctions: Strong Local Internal Electric Field and Reformed Basic Sites Boosting CO2 Photoreduction.

The slow charge dynamics and large activation energy of CO2 severely hinder the efficiency of CO2 photoreduction. Defect engineering is a well-established strategy, while the function of common zero-dimensional defects is always restricted to promoting surface adsorption. In this work, a gradient layer of tungsten vacancies with a thickness of 3-4nm is created across Bi2 WO6 nanosheets. This gradient layerenables the formation of an inner-to-outer tandem homojunction with an internal electric field, which provides a strong driving force for the migration of photoelectrons from the bulk to the surface. Meanwhile, W vacancies change the coordination environment around O and W atoms, leading to an alteration in the basic sites and the mode of CO2 adsorption from weak/strong adsorption to moderate adsorption, which ultimately decreases the formation barrier of the key intermediate *COOH and facilitates the conversion thermodynamics for CO2 . Without any cocatalyst and sacrificial reagent, W-vacant Bi2 WO6 shows an outstanding photocatalytic CO2 reduction performance with a CO production rate of 30.62µmolg-1 h-1 , being one of the best catalysts in similar reaction systems. This study reveals that gradient vacancies as a new type of defect will show huge potential in regulating charge dynamics and catalytic reaction thermodynamics.

Photogenerated Defect‐Transit Dual S‐Scheme Charge Separation for Highly Efficient Hydrogen Production

AbstractThe rational design of a step‐scheme (S‐scheme) heterojunctions in hybrid semiconductors by avoiding unwanted charge transport paths is considered as an attractive way to achieve high photocatalytic activity in hydrogen evolution reaction (HER). Here, a dual S‐scheme heterojunction formed in the lychee‐shaped W18O49/CdWO4/CdS nanostructures is proposed for improving the photocatalytic performance in HER under visible light irradiation. The remarkable activity in photocatalytic HER of W18O49/CdWO4/CdS is attributed to the unique structure and effective charge separation by the photoinduced defect‐transit dual S‐scheme mechanism and strong internal electric field. The measurements of X‐ray photoelectron spectroscopy (XPS), femtosecond transient absorption (fs‐TA) spectroscopy, and electron paramagnetic resonance (EPR) further confirm the photoinduced carrier transfer pathways following the dual S‐scheme mechanism. This research can provide a new strategy for designing the dual S‐scheme heterojunctions to improve photocatalytic performance through the defect band structure engineering.

Chemically bonded BiVO4/Bi19Cl3S27 heterojunction with fast hole extraction dynamics for continuous CO2 photoreduction

Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO2 photoreduction performance of photocatalysts. Herein, chemically bonded BiVO4/Bi19Cl3S27 (BVO/BCS) S-scheme heterojunction with a strong internal electric field is designed. Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO4 to Bi19Cl3S27 via the interfacial chemical bonding interactions (i.e., Bi-O and Bi-S bonds) between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation, breaking the interfacial barrier and surface charge localization of Bi19Cl3S27, and further decreasing the energy of reactive hydrogen generation, CO2 absorption and activation. The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system. As a result, BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO2 reduction and the 24 ​h CO yield reaches 678.27 ​μmol·g−1. This work provides an atomic-level insight into charge transfer kinetics and CO2 reduction mechanism in S-scheme heterojunction.

Strong interface interaction and internal electric field promote electron transfer of Bi2O2S/NiFe2O4 heterojunction for photocatalytic antibiotic degradation

Heterojunction photocatalysts have shown considerable activities for organic pollutants degradation. However, the faint connection interface and inferior charge shift efficiency critically block the property of heterojunction photocatalysis. Herein, Bi2O2S/NiFe2O4 nanosheets heterojunction with ultrastrong interface interaction and high internal electric field are designed by an in-situ growth method. Tentative and theoretical consequences prove that the interfacial interaction and internal electric field not only act as the electron flow bridge but also decrease the electrons shift energy obstacle, thus speeding up electrons transfer and achieving effective spatial electron-hole separation. Therefore, a large amount of ·O2– and holes as active species were generated. Remarkably, Bi2O2S/NiFe2O4 establishes a considerably boosted photocatalytic performance for tetracycline degradation (0.032 min–1), which is about 14.2-fold and 7.8-fold of the pristine BOS and NFO, respectively. This work provides a promising motivation for modulating charge transfer by interface control and internal electric field to boost photocatalytic performance.

Electron self-sufficient core-shell BiOCl@Fe-BiOCl nanosheets boosting Fe(III)/Fe(II) recycling and synergetic photocatalysis-Fenton for enhanced degradation of phenol

Core-shell BiOCl@Fe-BiOCl nanosheets with electron self-sufficient structure were prepared as catalysts to promote degradation and mineralization of phenol through synergetic photocatalysis-Fenton. This electron self-sufficient structure was established by engaging a strong internal electric field of BiOCl core and electron-capture centers of doped Fe(III) in Fe-BiOCl shell for electrons supplying and consuming, respectively, separating charges spatially and enriching holes on the surface of catalysts. Meanwhile, the Fe(III) transited to Fe(II), which acted as reactive sites for H2O2 activation and was further reversed to Fe(III) and hydroxyl radical (•OH) through Fenton reaction, achieving Fe(III)/Fe(II) recycling. The •OH and surface holes could synergistically boost the degradation and mineralization (∼64 %) of phenol. The reaction rate constant of BiOCl@Fe-BiOCl nanosheets was ∼41.32 and ∼95 times higher than that of BiOCl under full spectra and visible light irradiation, respectively. This work provides sophisticated structure design of catalysts, boosting Fe(III)/Fe(II) recycling, catalytic activity, and mineralization.

Hollow bi-Janus hetero-nanofibers as a bi-functional photoreforming catalyst for prominently boosting hydrogen evolution from water-pollutant system

Bi-functional photoreforming catalysts are promising for synergetic hydrogen evolution and pollutant removal through a water-pollutant system. The rational energy band and interface engineering are crucial in promoting their performance but are still challenging due to finely regulating nanoscale interface difficulties. Herein, single to bi-Janus interface engineering is adopted to develop hollow bi-Janus SrTiO3/ZnO/TiO2 hetero-nanofibers with gradient energy band and spatially separated redox surfaces via electrospinning married atomic layer deposition methods. The simulations indicate that these novel structures have a stronger internal electric field (5.72 ×106 V/m) than SrTiO3/ZnO (1.84 ×106 V/m) and ZnO/TiO2 (3.98 ×106 V/m) single-Janus hetero-nanofibers (SJ-HNFs), and more ordered electric field distribution than mixed hetero-nanofibers (MHNFs). Experimentally, they have better charge separation and directional carriers transfer path, as evidenced by photoluminescence, photovoltage, and photoelectrochemical investigations, along with photo-deposition probe experiments. The gradient energy band, directional charge transfer path, and spatially separated redox surfaces promote their photoreforming performance effectively, presenting a high photoreforming hydrogen evolution rate of 104.6 μmol g−1 h−1 in 10,000 ppm propranolol (corresponding degradation of 33.1% after 5 h), about 3.62, 4.27, and 3.11 times of ZnO/TiO2 SJ-HNFs, SrTiO3/ZnO SJ-HNFs and SrTiO3/ZnO/TiO2 MHNFs. This work provides a promising interfacial engineering strategy for designing photoreforming catalyst to simultaneously achieve energy conversion and environmental pollution treatment.

Boosting non-sacrificial H2O2 production on a Bi6S2O15 photocatalyst via creating a crystal surface-dependent internal electric field

A Bi6S2O15 photocatalyst without any cocatalyst loading is reported for the first time to exhibit considerable H2O2 production (3.4 mM h−1 g−1) from only H2O and O2 under a Xe lamp by creating a strong internal electric field (IEF) via exposing the (110) surface.

L-cysteine capped CoNiSx combined with Mn-Cd-S solid solution form S-scheme heterojunction for efficient and stable H2-releasing photocatalysis

With the reduction of traditional energy sources, photocatalytic hydrogen production technology provides a practical way to solve the energy crisis. The construction of photocatalysts with high performance and excellent stability is the core of water splitting for hydrogen production. Here, L-cysteine capped CoNiSx (L-CNSx) nanoplates are used to generate Mn-Cd-S solid solution (MCS) nanomaterials in situ for the construction of efficient and robust L-CNSx/MCS S-scheme heterojunction for photocatalytic hydrogen evolution reaction (HER). As a result, the optimized L-CNSx/MCS-2 heterojunction exhibited an enhanced HER rate of 91.2 mmol∙g−1∙h−1, which was 4.8 times of the pure MCS and 690.9 times of pure CNSx. This work not only suppressed the photo-corrosion of MCS nanomaterials, but also greatly improved the charge transfer efficiency by generating a strong internal electric field. This study highlights the role of CNSx in photocatalytic HER, which provides a new method to inhibit the photocorrosion of MCS-based composites.

Enhancement of polysulfide trapping induced by faceted ferroelectric for high-performance Li-S batteries

Facet engineering is viewed as an effective approach to tune the surface structure of electrode materials and thus influence their electrochemical performances. Herein, we report the introduction of faceted lead zirconate titanate with exposed (110) plane as the additive into the cathode of Li-S batteries to restrain the shuttle effect. The findings reveal that the faceted ferroelectric with strong internal electric field and sufficient surface polar sites can achieve the more efficient anchoring towards polysulfides than its partial- and un-faceted counterparts. By combining with the porous carbon host, the elaborately designed cathode therefore delivered excellent cycling stability with a low capacity attenuation rate of 0.047% per cycle after 300 cycles at 1 C. This work advances our understanding for the engineering of ferroelectric materials and the electric field effects on the stability of Li-S batteries, which could potentially inspire new strategies for the design of high-performance ferroelectric based energy devices.

Efficient photocatalytic hydrogen peroxide production induced by the strong internal electric field of all-organic S-scheme heterojunction

Light-driven reaction of oxygen and water to hydrogen peroxide (H2O2) is an environmental protection method, which can convert solar energy into green products. In this work, perylene-3, 4, 9, 10-tetracarboxylic diimide (PDINH) could be recrystallized in situ on the surface of porous carbon nitride (PCN), to obtain an all-organic S-scheme heterojunction (PDINH/PCN). The design of the hierarchical porous photocatalyst improved the mass transfer, enhanced the light absorption and increased specific surface area. Moreover, the construction of the S-scheme heterojunction at the interface of PDINH and PCN exhibited suitable band, which facilitated the separation and transfer of carriers. The H2O2 production rate was up to 922.4 μmol g−1h−1, which was 2.6 and 53.3 times higher than that of PCN and PDINH. Therefore, the all-organic S-scheme heterojunction provides an insight for improving the photocatalytic H2O2 production.

Strong internal electric field enhanced polysulfide trapping and ameliorates redox kinetics for lithium-sulfur battery

The shuttle effect of polysulfides is a major challenge for the commercialization of lithium-sulfur battery. The systematic modification of separators has the potential to solve these problems by enhancing the adsorption and catalytic conversion of polysulfides. Herein, strong internal electric field bismuth oxycarbonate (Bi2O2CO3) nanoflowers decorated conductive carbon (DC + BOC) is proposed to be systematically modified on separator. This intermediate layer not only possesses a strong affinity for polysulfides, but also promotes the conversion of polysulfides and induces the formation of a stable solid electrolyte interphase (SEI) layer, thereby improving the rate performance and cycling stability of the battery. As expected, the modified membrane achieved a high specific capacity of 713 mA h g−1 at 5 C. At 1 C, high reversibility of 719 mA h g−1 was achieved after 550 cycles with only 0.044% decay per cycle. More importantly, under the sulfur loading of 5.1 mg cm−2, the area specific capacity remained at 4.1 mA h cm−2 after 200 cycles, and the attenuation rate per cycle was only 0.056%. This work provides a new strategy to overcome the shuttle effect of polysulfide, and shows great potential in the application of high-performance lithium-sulfur batteries.

Oxygen vacancy and Van der Waals heterojunction modulated interfacial chemical bond over Mo2C/Bi4O5Br2 for boosting photocatalytic CO2 reduction

The establishment of heterojunctions between phase interfaces is an important strategy to enhance catalytic activity, but the behavior of charge transfer and exciton dissociation is unsharpness and significant. Here, a Van der Waals heterojunction (VDWH) of Mo2C/Bi4O5Br2 composite with oxygen vacancies (BM) was synthesized via a facile method. Various experimental results and density functional theory calculations demonstrated that the compact VDWH and unsaturated oxygen vacancy induced interfacial Mo-O bonds to modulate surface electronic structure. Consequently, the electron extracted from the exciton formed a strong internal electric field, which boosted the dissociation of the excitons and charge transfer via the electron transfer channel of the Mo-O bond. Therefore, the BM shows excellent CO2 reduction performance (1277.4 µmol g−1 h−1) and stability without using sacrificial agents and cocatalysts, which is about 6 times of Mo2C/Bi4O5Br2. This work not only gives deep insights into charge separation in VWDH and oxygen vacancy but also provides an efficient photocatalyst for efficient green energy conversion.

Optical and Photocatalytic Properties of Br-Doped BiOCl Nanosheets with Rich Oxygen Vacancies and Dominating {001} Facets.

Crystal facet engineering and nonmetal doping are regarded as effective strategies for improving the separation of charge carriers and photocatalytic activity of semiconductor photocatalysts. In this paper, we developed a facial method for fabricating oxygen-deficient Br-doped BiOCl nanosheets with dominating {001} facets through a traditional hydrothermal reaction and explored the impact of the Br doping and specific facets on carrier separation and photocatalytic performance. The morphologies, structures, and optical and photocatalytic properties of the obtained products were characterized systematically. The BiOCl samples prepared by the hydrothermal reaction exhibited square-like shapes with dominating {001} facets. Photodeposition results indicated that photoinduced electrons preferred to transfer to {001} facets because of the strong internal static electric fields in BiOCl nanosheets with dominating {001} facets. Br doping not only contributed to the formation of impurity energy levels that could promote light absorption but introduced a large number of surface oxygen vacancies (VO) in BiOCl photocatalysts, which was beneficial for photocatalytic performance. Moreover, the photocatalytic activities of these products under visible light were tested by degradation of rhodamine B (RhB). Because of the synergistic effect of the dominating {001} facets, Br doping, and rich VO, oxygen-deficient Br-doped BiOCl nanosheets exhibited improved carrier separation, visible light absorption, and photocatalytic efficiency.