Showing papers on "Electric field published in 2022"
TL;DR: Wang et al. as discussed by the authors reported a method to synthesize phosphorus-doped MoS2/g-C3N4 layer-by-layer composite, which could expose more active sites and generate a strong interaction by forming Mo-N bonds for photocatalytic sterilization.
112 citations
TL;DR: In this article, an active-site-rich 0D/1D Co3O4/TiO2 p-n heterojunction was constructed by growing p-type CoO4 nanoparticles onto the surface of n-type TiO2 porous fibers, which can increase the accessible active sites and enhance the light capture capacity.
105 citations
TL;DR: Wang et al. as discussed by the authors proposed a novel method to synthesize phosphorus-doped (P-Doped) MoS 2 /g-C 3 N 4 layer-by-layer composite, which could expose more active sites and generate a strong interaction by forming Mo-N bonds for photocatalytic sterilization.
100 citations
TL;DR: In this paper , a conformal coating of polytetrafluoroethylene (PET) was used to enhance the local electric field and temperature simultaneously and dramatically improve the electric-thermal synergy desired in electrocatalysis.
Abstract: Electrochemical CO2 reduction is a promising way to mitigate CO2 emissions and close the anthropogenic carbon cycle. Among products from CO2RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C-C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C-C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric-thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature enhancement at the tips compared with bare copper nanoneedles experimentally), resulting in an improved C2 Faradaic efficiency of over 86% at a partial current density of more than 250 mA cm-2 and a record-high C2 turnover frequency of 11.5 ± 0.3 s-1 Cu site-1. Combined with its low cost and scalability, the electric-thermal strategy for a state-of-the-art catalyst not only offers new insight into improving activity and selectivity of value-added C2 products as we demonstrated but also inspires advances in efficiency and/or selectivity of other valuable electro-/photocatalysis such as hydrogen evolution, nitrogen reduction, and hydrogen peroxide electrosynthesis.
96 citations
24 Jan 2022
TL;DR: In this article , a Pt@CoO x electrocatalyst with a large work function difference (ΔΦ) and strong BEF is presented, which shows outstanding hydrogen evolution activity in a neutral medium with a 4.5-fold mass activity higher than 20% Pt/C.
Abstract: Work function strongly impacts the surficial charge distribution, especially for metal-support electrocatalysts when a built-in electric field (BEF) is constructed. Therefore, studying the correlation between work function and BEF is crucial for understanding the intrinsic reaction mechanism. Herein, we present a Pt@CoO x electrocatalyst with a large work function difference (ΔΦ) and strong BEF, which shows outstanding hydrogen evolution activity in a neutral medium with a 4.5-fold mass activity higher than 20% Pt/C. Both experimental and theoretical results confirm the interfacial charge redistribution induced by the strong BEF, thus subtly optimizing hydrogen and hydroxide adsorption energy. This work not only provides fresh insights into the neutral hydrogen evolution mechanism but also proposes new design principles toward efficient electrocatalysts for hydrogen production in a neutral medium.
69 citations
TL;DR: In this article , electron microscopy study reveals that the non-equilibrium photo-excited electrons are collectively steered by two contiguous IEFs within binary (001)/(200) facet junctions of BiOBr platelets, and they exhibit characteristic Gaussian distribution profiles on reduction facets by using metal co-catalysts as probes.
Abstract: Construction of internal electric fields (IEFs) is crucial to realize efficient charge separation for charge-induced redox reactions, such as water splitting and CO2 reduction. However, a quantitative understanding of the charge transfer dynamics modulated by IEFs remains elusive. Here, electron microscopy study unveils that the non-equilibrium photo-excited electrons are collectively steered by two contiguous IEFs within binary (001)/(200) facet junctions of BiOBr platelets, and they exhibit characteristic Gaussian distribution profiles on reduction facets by using metal co-catalysts as probes. An analytical model justifies the Gaussian curve and allows us to measure the diffusion length and drift distance of electrons. The charge separation efficiency, as well as photocatalytic performances, are maximized when the platelet size is about twice the drift distance, either by tailoring particle dimensions or tuning IEF-dependent drift distances. The work offers great flexibility for precisely constructing high-performance particulate photocatalysts by understanding charge transfer dynamics.
61 citations
TL;DR: In this article, a strong local electric field is obtained by regulating the arrangement of Cu nanoneedle arrays (CuNNAs), which leads to the accumulation of K+ ions, which benefit both *CO adsorption and C-C coupling.
Abstract: Electrocatalytic reduction of CO2 to multicarbon products is a potential strategy to solve the energy crisis while achieving carbon neutrality. To improve the efficiency of multicarbon products in Cu-based catalysts, optimizing the *CO adsorption and reducing the energy barrier for carbon-carbon (C-C) coupling are essential features. In this work, a strong local electric field is obtained by regulating the arrangement of Cu nanoneedle arrays (CuNNAs). CO2 reduction performance tests indicate that an ordered nanoneedle array reaches a 59% Faraday efficiency for multicarbon products (FEC2) at -1.2 V (vs RHE), compared to a FEC2 of 20% for a disordered nanoneedle array (CuNNs). As such, the very high and local electric fields achieved by an ordered Cu nanoneedle array leads to the accumulation of K+ ions, which benefit both *CO adsorption and C-C coupling. Our results contribute to the design of highly efficient catalysts for multicarbon products.
56 citations
TL;DR: In this paper , a first-principles-based molecular simulation reproduces the experimental capacitance peaks and reveals the origin of two peaks emerging at anodic and cathodic potentials to be an electrosorption of ions and a structural phase transition, respectively.
Abstract: Abstract To design electrochemical interfaces for efficient electric-chemical energy interconversion, it is critical to reveal the electric double layer (EDL) structure and relate it with electrochemical activity; nonetheless, this has been a long-standing challenge. Of particular, no molecular-level theories have fully explained the characteristic two peaks arising in the potential-dependence of the EDL capacitance, which is sensitively dependent on the EDL structure. We herein demonstrate that our first-principles-based molecular simulation reproduces the experimental capacitance peaks. The origin of two peaks emerging at anodic and cathodic potentials is unveiled to be an electrosorption of ions and a structural phase transition, respectively. We further find a cation complexation gradually modifies the EDL structure and the field strength, which linearly scales the carbon dioxide reduction activity. This study deciphers the complex structural response of the EDL and highlights its catalytic importance, which bridges the mechanistic gap between the EDL structure and electrocatalysis.
54 citations
TL;DR: In this paper , perylenetetricarboxylic acid nanosheets with a monolayer thickness of 1.5 nm were synthesized and shown to be active hydrogen evolution photocatalysts with production rates of 118.9 mmol g −1 h −1 .
Abstract: Abstract Highly efficient hydrogen evolution reactions carried out via photocatalysis using solar light remain a formidable challenge. Herein, perylenetetracarboxylic acid nanosheets with a monolayer thickness of ~1.5 nm were synthesized and shown to be active hydrogen evolution photocatalysts with production rates of 118.9 mmol g −1 h −1 . The carboxyl groups increased the intensity of the internal electric fields of perylenetetracarboxylic acid from the perylene center to the carboxyl border by 10.3 times to promote charge-carrier separation. The photogenerated electrons and holes migrated to the edge and plane, respectively, to weaken charge-carrier recombination. Moreover, the perylenetetracarboxylic acid reduction potential increases from −0.47 V to −1.13 V due to the decreased molecular conjugation and enhances the reduction ability. In addition, the carboxyl groups created hydrophilic sites. This work provides a strategy to engineer the molecular structures of future efficient photocatalysts.
53 citations
TL;DR: In this article , a rapid self-polarization effect of a polar dielectric material by the superhigh electric field in a charge-excitation TENG is reported, by which the permittivity of the polar material realizes self-increase to a saturation, and thus enhances the output charge density.
Abstract: Boosting output charge density is top priority for achieving high‐performance triboelectric nanogenerators (TENGs). The charge‐excitation strategy is demonstrated to be a superior approach to acquire high output charge density. Meanwhile, the molecular charge behaviors in the dielectric under a strong electric field from high charge density bring new physics that are worth exploring. Here, a rapid self‐polarization effect of a polar dielectric material by the superhigh electric field in a charge‐excitation TENG is reported, by which the permittivity of the polar dielectric material realizes self‐increase to a saturation, and thus enhances the output charge density. Consequently, an ultrahigh charge density of 3.53 mC m−2 is obtained with 7 µm homemade lead zirconate titanate−poly(vinylidene fluoride) composite film in the atmosphere with 5% relative humidity, which is the highest charge density for TENGs with high durability currently. This work provides new guidance for dielectric material optimization under charge excitation to boost the output performance of TENGs toward practical applications.
51 citations
TL;DR: This article investigated the electric field distributions at the air-water interface to understand the origin of surface reactivity and found that electric field alignments along free O-H bonds at the surface are ~16 MV/cm larger on average than that found for OH bonds in the interior of the water droplet.
Abstract: Reaction rates of common organic reactions have been reported to increase by one to six orders of magnitude in aqueous microdroplets compared to bulk solution, but the reasons for the rate acceleration are poorly understood. Using a coarse-grained electron model that describes structural organization and electron densities for water droplets without the expense of ab initio methods, we investigate the electric field distributions at the air-water interface to understand the origin of surface reactivity. We find that electric field alignments along free O-H bonds at the surface are ~16 MV/cm larger on average than that found for O-H bonds in the interior of the water droplet. Furthermore, electric field distributions can be an order of magnitude larger than the average due to non-linear coupling of intramolecular solvent polarization with intermolecular solvent modes which may contribute to even greater surface reactivity for weakening or breaking chemical bonds at the droplet surface.
TL;DR: In this article , a first-principles-based molecular simulation reproduces the experimental capacitance peaks and reveals the origin of two peaks emerging at anodic and cathodic potentials to be an electrosorption of ions and a structural phase transition, respectively.
Abstract: Abstract To design electrochemical interfaces for efficient electric-chemical energy interconversion, it is critical to reveal the electric double layer (EDL) structure and relate it with electrochemical activity; nonetheless, this has been a long-standing challenge. Of particular, no molecular-level theories have fully explained the characteristic two peaks arising in the potential-dependence of the EDL capacitance, which is sensitively dependent on the EDL structure. We herein demonstrate that our first-principles-based molecular simulation reproduces the experimental capacitance peaks. The origin of two peaks emerging at anodic and cathodic potentials is unveiled to be an electrosorption of ions and a structural phase transition, respectively. We further find a cation complexation gradually modifies the EDL structure and the field strength, which linearly scales the carbon dioxide reduction activity. This study deciphers the complex structural response of the EDL and highlights its catalytic importance, which bridges the mechanistic gap between the EDL structure and electrocatalysis.
TL;DR: In this article , a room-temperature skyrmion-like polar nanodomains in lead titanate/strontium titanate bilayers transferred onto silicon were realized.
Abstract: Topological domains in ferroelectrics1-5 have received much attention recently owing to their novel functionalities and potential applications6,7 in electronic devices. So far, however, such topological polar structures have been observed only in superlattices grown on oxide substrates, which limits their applications in silicon-based electronics. Here we report the realization of room-temperature skyrmion-like polar nanodomains in lead titanate/strontium titanate bilayers transferred onto silicon. Moreover, an external electric field can reversibly switch these nanodomains into the other type of polar texture, which substantially modifies their resistive behaviours. The polar-configuration-modulated resistance is ascribed to the distinct band bending and charge carrier distribution in the core of the two types of polar texture. The integration of high-density (more than 200 gigabits per square inch) switchable skyrmion-like polar nanodomains on silicon may enable non-volatile memory applications using topological polar structures in oxides.
TL;DR: Wang et al. as discussed by the authors introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoride) trifluoroethylene-chlorofluoro methylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it.
Abstract: Electromechanical (EM) coupling—the conversion of energy between electric and mechanical forms—in ferroelectrics has been used for a broad range of applications. Ferroelectric polymers have weak EM coupling that severely limits their usefulness for applications. We introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it. Under a low–dc bias field of 40 megavolts per meter, the relaxor tetrapolymer has an EM coupling factor (k33) of 88% and a piezoelectric coefficient (d33) >1000 picometers per volt. These values make this solution-processed polymer competitive with ceramic oxide piezoelectrics, with the potential for use in distinct applications. Description Polymer piezo The best-performing piezoelectric materials are oxide ceramics, which are widely used for sensors and actuators. X. Chen et al. added two additional components to poly(vinylidene difluoride) trifluoroethylene to improve the electromechanical coupling (see the Perspective by Wang and Liao). The resulting tetrapolymer has piezoelectric properties that are dramatically improved and it appears to be competitive with traditional oxides. The pliability and relative ease of fabrication of this tetrapolymer piezoelectric makes it attractive for a range of interesting applications. —BG An improved polymer has properties that make it competitive with commercially available ceramic piezoelectrics.
TL;DR: In this paper , an effective method was reported to enhance the built-in electric field (BEF) intensity of silicon heterojunction solar cells by doping an organic ferroelectric material, poly(vinylidene fluoride):dabcoHReO4 (PVDF:DH) with high polarizability, that can be driven even by the BEF of the device itself.
Abstract: The built‐in electric field (BEF) intensity of silicon heterojunction solar cells can be easily enhanced by selective doping to obtain high power conversion efficiencies (PCEs), while it is challenging for perovskite solar cells (pero‐SCs) because of the difficulty in doping perovskites in a controllable way. Herein, an effective method is reported to enhance the BEF of FA0.92MA0.08PbI3 perovskite by doping an organic ferroelectric material, poly(vinylidene fluoride):dabcoHReO4 (PVDF:DH) with high polarizability, that can be driven even by the BEF of the device itself. The polarization of PVDF:DH produces an additional electric field, which is maintained permanently, in a direction consistent with that of the BEF of the pero‐SC. The BEF superposition can more sufficiently drive the charge‐carrier transport and extraction, thus suppressing the nonradiative recombination occurring in the pero‐SCs. Moreover, the PVDF:DH dopant benefits the formation of a mesoporous PbI2 film, via a typical two‐step processing method, thereby promoting perovskite growth with high crystallinity and a few defects. The resulting pero‐SC shows a promising PCE of 24.23% for a 0.062 cm2 device (certified PCE of 23.45%), and a remarkable PCE of 22.69% for a 1 cm2 device, along with significantly improved moisture resistances and operational stabilities.
TL;DR: In this paper , the authors presented an atomic-level insight into interfacial charge flow steering and showed that the interfacial Fe-O bond not only serves as atomic level charge flow highway but also lowers charge transfer energy barrier, thereby accelerating Z-scheme charge transfer and realizing effective spatial charge separation.
Abstract: Inferior contact interface and low charge transfer efficiency seriously restrict the performance of heterojunction. Herein, chemically bonded α-Fe2O3/Bi4MO8Cl (M=Nb, Ta) dot-on-plate Z-scheme junctions with strong internal electric field are crafted by in situ growth route. Experimental and theoretical results co-unravel that internal electric field provides a powerful driving force for vectorial migration of photocharges between Bi4MO8Cl and α-Fe2O3, and interfacial Fe-O bond not only serves as atomic-level charge flow highway but also lowers charge transfer energy barrier, thereby accelerating Z-scheme charge transfer and realizing effective spatial charge separation. Impressively, α-Fe2O3/Bi4MO8Cl manifests enormously reinforced photocatalytic activity for selective oxidation of aromatic alcohols into aldehydes (Con. ≥92%，Sel. ≥96%), with a performance improvement of one to two orders of magnitude. This work presents an atomic-level insight into interfacial charge flow steering.
TL;DR: In this paper , the effect of Au decorated bismuth oxybromide (BiOBr) was investigated to elucidate the regulation of built-in electric field on charge carrier dynamics and exploit the potential of multi-field coupled environmental purification.
Abstract: The piezo-photocatalytic effect of Au decorated bismuth oxybromide (BiOBr) was investigated to elucidate the regulation of built-in electric field on charge carrier dynamics and exploit the potential of multi-field coupled environmental purification. Physicochemical properties of Au-BiOBr such as the piezoelectricity, photoresponse characteristics, and charge separation efficiencies were thoroughly analyzed, meanwhile the degradation of carbamazepine (CBZ) was chosen to evaluate the catalytic performance of this system. The piezo-photocatalytic removal of CBZ reached 95.8% within 30 min, and the rate constant is 1.73 times higher than the sum of individual piezo- and photocatalytic ones. The results attribute to not only the modification of Au nanoparticles that accelerates charge transfer and improves light absorption, but also, more importantly, the piezoelectric effect of BiOBr that amplifies the built-in electric field and modulates the band structure alignment. This work demonstrates a promising environmental remediation strategy via the co-utilization of solar and mechanical energy in nature.
TL;DR: An electron donor-acceptor interface with high charge separation between TPPS (tetra(4-sulfonatophenyl)porphyrin) and PDI (perylene diimide) is successfully constructed for boosting photocatalytic H2 evolution as discussed by the authors .
Abstract: Charge separation efficiency of photocatalysts is still the key scientific issue for solar‐to‐chemical energy conversion. In this work, an electron donor–acceptor (D‐A) interface with high charge separation between TPPS (tetra(4‐sulfonatophenyl)porphyrin) and PDI (perylene diimide) is successfully constructed for boosting photocatalytic H2 evolution. The TPPS/PDI with D‐A interface shows excellent photocatalytic H2 evolution rate of 546.54 µmol h–1 (30.36 mmol h–1 g–1), which is 9.95 and 9.41 times higher than that of pure TPPS and PDI, respectively. The TPPS/PDI has a markedly stronger internal electric field, which is respectively 3.76 and 3.01 times higher than that of pure PDI and TPPS. The D‐A interface with giant internal electric field efficiently facilitates charge separation and urges TPPS/PDI to have a longer excited state lifetime than single component. The work provides entirely new ideas for designing materials with D‐A interface to realize high photocatalytic activity.
TL;DR: In this article , the ZnIn2S4 (ZIS)-NiSe2 S-scheme heterojunctions anchored on Ti3C2 MXene (MX) with multiple internal electric fields were rationally fabricated for effective photocatalytic H2 generation.
TL;DR: Z-scheme AgIn5S8/ZnO heterojunction with superior photocatalytic activity in degrading pharmaceutical pollutants and enhancing biodegradability of pharmaceutical wastewater was reported in this paper .
TL;DR: In this paper , a liquid sacrificial substrate electric-field-driven (LS-EFD) microscale 3D printing of thin film silver paste is proposed for the fabrication of high performance transparent glass heaters.
Abstract: Transparent glass with metal mesh is considered a promising strategy for high performance transparent glass heaters (TGHs). However, the realization of simple, low-cost manufacture of high performance TGHs still faces great challenges. Here, a technique for the fabrication of high performance TGHs is proposed using liquid sacrificial substrate electric-field-driven (LS-EFD) microscale 3D printing of thick film silver paste. The liquid sacrificial substrate not only significantly improves the aspect ratio (AR) of silver mesh, but also plays a positive role in printing stability. The fabricated TGHs with a line width of 35 µm, thickness of 12.3 µm, and pitch of 1000 µm exhibit a desirable optoelectronic performance with sheet resistance (Rs ) of 0.195 Ω sq-1 and transmittance (T) of 88.97%. A successful deicing test showcases the feasibility and practicality of the manufactured TGHs. Moreover, an interface evaporator is developed for the coordination of photothermal and electrothermal systems based on the high performance TGHs. The vapor generation rate of the device reaches 10.69 kg m-2 h-1 with a voltage of 2 V. The proposed technique is a promising strategy for the cost-effective and simple fabrication of high performance TGHs.
TL;DR: In this paper , a BiOI/BiP5O14 heterostructure with enhanced interfacial internal electric field for directional charge transfer and separation effectively was constructed successfully through epitaxial growth on the surface of biOI nanosheets, which could boost the photodegradation and mineralization of phenol.
Abstract: BiOI/BiP5O14 heterostructure with enhanced interfacial internal electric field for directional charge transfer and separation effectively were constructed successfully through epitaxial BiP5O14 layer on the surface of BiOI nanosheets. Dramatical enhanced internal electric field of BiOI/BiP5O14 heterostructure was established when BiP5O14 monolayer epitaxial grow on the surface of BiOI nanosheets by adding 2% of NaH2PO4. As a result, this heterostructure could boost the photodegradation and mineralization of phenol. Compared to pristine BiOI nanosheets, the photocatalytic reaction constant rates of phenol over the BiOI/BiP5O14 heterostructure were elevated over 8.5 times, and the corresponding mineralization ability was also enhanced 8.9 times due to the effective and directional charges transfer and separation. This work provides an evidential proof of rational designing heterostructure via epitaxial growth, and confirms the internal electric field drive charge transfer and separation directionally for promoted photocatalytic performances.
TL;DR: In this article , the formation of Os-OsSe2 heterostructures with neutralized work function (WF) perfectly balances the electronic state between strong and weak adsorbents and bidirectionally optimizes the hydrogen evolution reaction (HER) activity of Os sites, significantly reducing thermodynamic energy barrier and accelerating kinetics process.
Abstract: Theoretical calculations unveil that the formation of Os-OsSe2 heterostructures with neutralized work function (WF) perfectly balances the electronic state between strong (Os) and weak (OsSe2) adsorbents and bidirectionally optimizes the hydrogen evolution reaction (HER) activity of Os sites, significantly reducing thermodynamic energy barrier and accelerating kinetics process. Then, heterostructural Os-OsSe2 is constructed for the first time by a molten salt method and confirmed by in-depth structural characterization. Impressively, due to highly active sites endowed by the charge balance effect, Os-OsSe2 exhibits ultra-low overpotentials for HER in both acidic (26 mV @ 10 mA cm-2) and alkaline (23 mV @ 10 mA cm-2) media, surpassing commercial Pt catalysts. Moreover, the solar-to-hydrogen device assembled with Os-OsSe2 further highlights its potential application prospects. Profoundly, this special heterostructure provides a new model for rational selection of heterocomponents.
TL;DR: In this article , a formamidinium tin iodide (FASnI 3 ) perovskite absorber with a vertical Sn 2+ gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovsites.
Abstract: Abstract Lead-free tin perovskite solar cells (PSCs) have undergone rapid development in recent years and are regarded as a promising eco-friendly photovoltaic technology. However, a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking. In the present study, a formamidinium tin iodide (FASnI 3 ) perovskite absorber with a vertical Sn 2+ gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites. Depth-dependent X-ray photoelectron spectroscopy revealed that the Fermi level upshifts with an increase in Sn 2+ content from the bottom to the top in this heterogeneous FASnI 3 film, which generates an additional electric field to prevent the trapping of photo-induced electrons and holes. Consequently, the Sn 2+ -gradient FASnI 3 absorber exhibits a promising efficiency of 13.82% for inverted tin PSCs with an open-circuit voltage increase of 130 mV, and the optimized cell maintains over 13% efficiency after continuous operation under 1-sun illumination for 1,000 h.
TL;DR: In this article , a homojunction carbon nitride photocatalyst integrated with three crystallization levels (tri-crystallinity) is developed to enhance the degradation activity of organic pollutants.
Abstract: Herein, a homojunction carbon nitride photocatalyst integrated with three crystallization levels (Tri-crystallinity) is developed to enhance the degradation activity of organic pollutants. The increase in crystallinity induces the Fermi level and band position to decrease. This difference constructs an internal electric field (IEF) at the interface with a lower to higher crystallinity direction. The multiple contact interfaces in Tri-crystallinity reinforce the interfacial IEF twice compared to a conventional single-interface. The interfacial IEF improves charge separation and transfer, and the degradation of antibiotics by Tri-crystallinity carbon nitride is at least 20 times greater than primary carbon nitride. Further, the Tri-crystallinity carbon nitride loading on a nonwoven fabric in a continuous-flow reactor achieves 91.0% purification of the organic wastewater at a flow rate of 14.2 L h −1 m −2 from 11:00 a.m. to 3:00 p.m. This work provides a strategy for engineering interfacial IEF of future efficient photocatalysts. • An interfacial internal electric field through CN crystallinity differences. • Enhance 20-times degradation of antibiotics by Tri-crystalline CN. • 90.0% purification of the organic wastewater at a flow rate of 20.83 L h −1 m −2 .
TL;DR: In this paper , the authors show the generation of extraordinarily large piezoelectric responses in cubic fluorite gadolinium-doped CeO2-x films, which are two orders of magnitude larger than the responses observed in the presently best-known lead-based piezel-based relaxor-ferroelectric oxide at kilohertz frequencies.
Abstract: Piezoelectrics are materials that linearly deform in response to an applied electric field. As a fundamental prerequisite, piezoelectric materials must have a noncentrosymmetric crystal structure. For more than a century, this has remained a major obstacle for finding piezoelectric materials. We circumvented this limitation by breaking the crystallographic symmetry and inducing large and sustainable piezoelectric effects in centrosymmetric materials by the electric field-induced rearrangement of oxygen vacancies. Our results show the generation of extraordinarily large piezoelectric responses [with piezoelectric strain coefficients (d33) of ~200,000 picometers per volt at millihertz frequencies] in cubic fluorite gadolinium-doped CeO2-x films, which are two orders of magnitude larger than the responses observed in the presently best-known lead-based piezoelectric relaxor-ferroelectric oxide at kilohertz frequencies. These findings provide opportunities to design piezoelectric materials from environmentally friendly centrosymmetric ones.
TL;DR: In this paper , the authors report a bistable domal hydrogel structure capable of spontaneous and reversible snapping under an electric field, where the electric field does not drive the gel directly.
Abstract: Venus flytrap and bladderwort, capable of rapid predation through a snapping transition, have inspired various designs of soft actuators and robots with fast actions. These designs, in contrast to their natural counterparts, often require a direct force or pressurization. Here, we report a bistable domal hydrogel structure capable of spontaneous and reversible snapping under an electric field. Unlike a mechanical force, the electric field does not drive the gel directly. Instead, it redistributes mobile ions that direct the migration of water molecules and bends the polyelectrolyte hydrogel. Subject to constraint from surrounding neutral gel, the elastic energy accumulates until suddenly released by snapping, just like the process in natural organisms. Several proof-of-concept examples, including an optical switch, a speedy catcher, and a pulse pump, are designed to demonstrate the versatile functionalities of this unit capable of articulate motion. This work should bring opportunities to devise soft robotics, biomedical devices, etc.
TL;DR: A highly crystalline perylene imide supramolecular photocatalyst (PDI-NH) is synthesized via imidazole solvent method with a breakthrough oxygen evolution rate and a robust built-in electric field induced by its high crystallinity, showing a new perspective for the design of organic photocatalysts.
Abstract: A highly crystalline perylene imide supramolecular photocatalyst (PDI‐NH) is synthesized via imidazole solvent method. The catalyst shows a breakthrough oxygen evolution rate (40.6 mmol g−1 h−1) with apparent quantum yield of 10.4% at 400 nm, which is 1353 times higher than the low crystalline PDI‐NH. The highly crystalline structure comes from the ordered self‐assembly process in molten imidazole solvent via π–π stacking and hydrogen bonding. Further, the excellent performance ascribes to the robust built‐in electric field induced by its high crystallinity, which greatly accelerates the charge separation and transfer. What is more, the PDI‐NH is quite stable and can be reused over 50 h without performance attenuation. Briefly, the crystalline PDI‐NH with strong built‐in electric field throws light on photocatalytic oxygen evolution, showing a new perspective for the design of organic photocatalysts.
TL;DR: In this paper , an advanced heterostructure photocatalyst constructed by hexagonal boron nitride (h-BN) and flower-ring g-C3N4 (MCN) was successfully synthesized.
TL;DR: In this article , the authors reported the direct observation of sliding ferroelectricity, using a high-quality amphidynamic single crystal, (15-Crown-5)Cd$_3$Cl$_6), which possesses a large band-gap and so allows direct measurement of P-E hysteresis.
Abstract: Sliding ferroelectricity is a recently observed polarity existing in two-dimensional materials. However, due to their weak polarization and poor electrical insulation in these materials, all available experimental evidence till now are indirect, with most based on transport properties in the nanoscale or piezoresponse force microscopy. We report the direct observation of sliding ferroelectricity, using a high-quality amphidynamic single crystal, (15-Crown-5)Cd$_3$Cl$_6$, which possesses a large band-gap and so allows direct measurement of P-E hysteresis. This coordination polymer is a van der Waals material, which is composed of inorganic stators and organic rotators as measured using XRD and NMR characterisation. From DFT calculations, we find that after the freezing of rotators an electric dipole is generated in each layer driven by the geometric mechanism, meanwhile a comparable ferroelectric polarization originates from the interlayer sliding. The net polarization of these two components can be directly measured and manipulated. Our finding provides insight into low-dimensional ferroelectrics, especially the controlling of synchronous dynamics of rotating molecules and sliding layers in solids.