查看更多>>摘要：Radio-photovoltaic cell is a micro nuclear battery for devices operating in extreme environments,which converts the decay energy of a radioisotope into electric energy by using a phosphor and a photovoltaic converter.Many phosphors with high light yield and good environmental stability have been developed,but the performance of radio-photovoltaic cells remains far behind expectations in terms of power density and power conversion efficiency,because of the poor photoelectric conversion efficiency of traditional photovoltaic converters under low-light conditions.This paper reports an radio-photovoltaic cell based on an intrinsically stable formamidinium-cesium perovskite photovoltaic converter exhibiting a wide light wavelength response from 300 to 800 nm,high open-circuit voltage(Voc),and remarkable efficiency at low-light intensity.When a He ions accelerator is adopted as a mimicked α radioisotope source with an equivalent activity of 0.83 mCi cm-2,the formamidinium-cesium perovskite radio-photovoltaic cell achieves a Voc of 0.498 V,a short-circuit current(Jsc)of 423.94 nA cm-2,and a remarkable power conversion efficiency of 0.886％,which is 6.6 times that of the Si reference radio-photovoltaic cell,as well as the highest among all radio-photovoltaic cells reported so far.This work provides a theoretical basis for enhancing the performance of radio-photovoltaic cells.
查看更多>>摘要：Low-temperature,ambient processing of high-quality CsPbBr3 films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr2 precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr3 films.Such a novel strategy is proceeded by adding CsBr species into PbBr2 precursor,which can tailor the preferred crystal orientation of PbBr2 film from[020]into[031],with CsBr additive staying in the film as CsPb2Br5 phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr2 with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr3 films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150 ℃.Carbon-electrode PSCs with these desired CsPbBr3 films yield the record-high efficiency of 10.27％coupled with excellent operation stability.Meanwhile,the 1 cm2 area one with the superior efficiency of 8.00％as well as the flexible one with the champion efficiency of 8.27％and excellent mechanical bending characteristics are also achieved.
查看更多>>摘要：Tin-based perovskite solar cells(TPSCs)have received great attention due to their eco-friendly properties and high theoretical efficiencies.However,the fast crystallization feature of tin-based perovskites leads to poor film quality and limits the corresponding device performance.Herein,a chlorofullerene,C60Cl6,with six chlorine attached to the C60 cage,is applied to modulate the crystallization process and passivate grain boundary defects of the perovskite film.The chemical interactions between C60Cl6 and perovskite components retard the transforming process of precursors to perovskite crystals and obtain a high-quality tin-based perovskite film.It is also revealed that the C60Cl6 located at the surfaces and grain boundaries can not only passivate the defects but also offer a role in suturing grain boundaries to suppress the detrimental effects of water and oxygen on perovskite films,especially the oxidation of Sn2+to Sn4+.As a result,the C60Cl6-based device yields a remarkably improved device efficiency from 10.03％to 13.30％with enhanced stability.This work provides a new strategy to regulate the film quality and stability of TPSCs using functional fullerene materials.
查看更多>>摘要：Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase.Herein,we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates,including carbon nanotubes(CNTs),graphene oxide(GO),MXene,layered double hydroxides(LDHs),MOFs,and SiO2.The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity(Vmeso/Vmicro∶2.4),ultrahigh N content of 12.4 at.％and"dual electrical conductive networks."The assembled aqueous zinc-ion hybrid capacitor(ZIC)with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g-1 at 0.5 A g-1,great rate performance of 98 F g-1 at 100 A g-1,and especially,an ultralong cycling stability up to 230 000 cycles with the capacitance retention of 90.1％.This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.
查看更多>>摘要：In this study,ZnO formation during the dissolution-passivation process of Zn anodes is observed via in situ Raman and optical characterization.The Zn passivation during galvanostatic anodization merely follows the dissolution-precipitation model,whereas that of potentiodynamic polarization exhibits different behaviors in different potential ranges.Initially,the Zn electrode is gradually covered by a ZnO precipitation film and then undergoes solid-state oxidation at～255 mV.The starting point of solid-state oxidation is well indicated by the abrupt current drop and yellow coloration of the electrode surface.During the pseudo passivation,an intense current oscillation is observed.Further,blink-like color changes between yellow and dark blue are revealed for the first time,implying that the oscillation is caused by the dynamic adsorption and desorption of OH groups.The as-formed ZnOs then experience a dissolution-reformation evolution,during which the crystallinity of the primary ZnO film is improved but the solid-state-formed ZnO layer becomes rich in oxygen vacancies.Eventually,oxide densification is realized,contributing to the Zn passivation.This study provides new insights into the Zn dissolution-passivation behavior,which is critical for the future optimization of Zn batteries.
查看更多>>摘要：We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates.The devices are based on thin films of WS2,Te,and BP(P-type semiconductors)and TiS3 and TiS2(N-type semiconductors),deposited by simply rubbing powder of these materials against paper.The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of(+1.32±0.27)mV K-1 and(-0.82±0.15)mV K-1 for WS2 and TiS3,respectively.Additionally,Peltier elements were fabricated by interconnecting the P-and N-type films with graphite electrodes.A thermopower value up to 6.11 mV K-1 was obtained when the Peltier element were constructed with three junctions.The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices.
查看更多>>摘要：Urea synthesis through the simultaneous electrocatalytic reduction of N2 and CO2 molecules under ambient conditions holds great promises as a sustainable alternative to its industrial production,in which the development of stable,highly efficient,and highly selective catalysts to boost the chemisorption,activation,and coupling of inert N2 and CO2 molecules remains rather challenging.Herein,by means of density functional theory computations,we proposed a new class of two-dimensional nanomaterials,namely,transition-metal phosphide monolayers(TM2P,TM=Ti,Fe,Zr,Mo,and W),as the potential electrocatalysts for urea production.Our results showed that these TM2P materials exhibit outstanding stability and excellent metallic properties.Interestingly,the Mo2P monolayer was screened out as the best catalyst for urea synthesis due to its small kinetic energy barrier(0.35 eV)for C-N coupling,low limiting potential(-0.39 V),and significant suppressing effects on the competing side reactions.The outstanding catalytic activity of the Mo2P monolayer can be ascribed to its optimal adsorption strength with the key*NCON species due to its moderate positive charges on the Mo active sites.Our findings not only propose a novel catalyst with high-efficiency and high-selectivity for urea production but also further widen the potential applications of metal phosphides in electrocatalysis.
Won Seok ChoDae Myung HongWan Jae DongTae Hyung Lee...
215-221页
查看更多>>摘要：Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO2 to formic acid(HCOOH),which are composed of petal-shaped Bi2O2CO3(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room temperature.During the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi domains.Lattice mismatch between both domains induces biaxial strain at the interfaces.Density functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO2 conversion to HCOOH.Together with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9％at-0.8 VRHE for the electrochemical conversion of CO2 to HCOOH.This work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO2 reduction reaction;such a strategy can be applicable in design of various electrocatalysts.
查看更多>>摘要：Flexible electronic sensors composed of flexible film and conductive materials play an increasingly important role in wearable and internet information transmission.It has received more and more attention and made some progress over the decades.However,it is still a great challenge to prepare biocompatible and highly transparent conductive films.Egg white is a pure natural protein-rich material.Hydroxypropylmethyl cellulose has a good compatibility and high transparency,which is an ideal material for flexible sensors.Here,we overcome the problem of poor mechanical flexibility and electrical conductivity of protein,and develop a high transparency and good flexibility hydroxypropylmethyl cellulose/egg white protein composite membrane-based triboelectric nanogenerator('X'-TENG).The experimental results show that the flexible pressure sensor based on'X'-TENG has a high sensitivity,fast response speed,and low detection limit.It can even be used as a touch/pressure sensing artificial electronic skin.It can also be made into an intelligent waffle keyboard for recording and tracking users of the keyboard.Our strategy may provide a new way to easily build flexible electronic sensors and move toward practical applications.
查看更多>>摘要：Rhombohedral phase HfxZr1.xO2(HZO,x from 0 to 1)films are promising for achieving robust ferroelectric polarization without the need for an initial wake-up pre-cycling,as is normally the case for the more commonly studied orthorhombic phase.However,a large spontaneous polarization observed in rhombohedral films is not fully understood,and there are also large discrepancies between experimental and theoretical predictions.In this work,in rhombohedral ZrO2 thin films,we show that oxygen vacancies are not only a key factor for stabilizing the phase,but they are also a source of ferroelectric polarization in the films.This is shown experimentally through the investigation of the structural properties,chemical composition and the ferroelectric properties of the films before and after an annealing at moderate temperature(400 ℃)in an oxygen environment to reduce the Vo concentration compared.The experimental work is supported by density functional theory(DFT)calculations which show that the rhombohedral phase is the most stable one in highly oxygen defective ZrO2 films.The DFT calculations also show that Vo contribute to the ferroelectric polarization.Our findings reveal the importance of Vo for stabilizing rhombohedral ZrO2 thin films with superior ferroelectric properties.
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