Ferroelectric polymer nanocomposites are widely used in capacitive energy storage, electrocaloric refrigeration, and mechanical energy harvesting due to their exceptional electric polarization ...property and ease of fabrication. It is generally considered that the abnormal performance of ferroelectric nanocomposites stems from the interfacial region between the polymer matrix and embedded nanoparticles. However, direct evidence of the distinct local electric polarization property at the interfacial region is not yet accessible. Herein, a modified Kelvin probe force microscopy (KPFM) method with nanoscale spatial resolution is reported for direct detection of local polarization property at the matrix/particle interface in ferroelectric nanocomposites. Typical ferroelectric nanocomposites are studied using the present method. It is quantitatively probed that the electric polarization at matrix/particle interfacial region is higher than the polymer matrix under applied electric fields. Taking into account the enhanced local electric polarization gauged by the modified KPFM, the dielectric property of ferroelectric polymer nanocomposites matches with bulk experimental characterizations, indicating that the established method is reliable. It is anticipated that the present method, opening up new possibilities in understanding the matrix/particle interfacial region, may help with judicious design and engineering of high‐performance ferroelectric polymer nanocomposites.
A modified Kelvin probe force microscopy method is developed for direct detection of local electric polarization with nanoscale spatial resolution. It is quantitatively probed that in ferroelectric polymer nanocomposites the electric polarization at the matrix/particle interface is higher than the polymer matrix, which explains the exceptional performance of bulk materials.
Microbiologically influenced corrosion (MIC) refers to the deterioration of metal surfaces as a result of the formation of microbial biofilms and metabolic activities at the biofilm/metal interface. ...Conventional macroscopic electrochemical techniques provide limited spatial resolution to investigate MIC which often occurs at localized environment within micro-/nanoscopic levels. Localized electrochemical techniques have received increasing attention in MIC research as a potential strategy to solve this challenge. This paper provides a focused review of localized electrochemical techniques employed in MIC studies, including their fundamentals and applications. Furthermore, their advantages and challenges as well as topics to be investigated in future are discussed.
Organometal-halide perovskite solar cells have greatly improved in just a few years to a power conversion efficiency exceeding 20%. This technology shows unprecedented promise for terawatt-scale ...deployment of solar energy because of its low-cost, solution-based processing and earth-abundant materials. We have studied charge separation and transport in perovskite solar cells-which are the fundamental mechanisms of device operation and critical factors for power output-by determining the junction structure across the device using the nanoelectrical characterization technique of Kelvin probe force microscopy. The distribution of electrical potential across both planar and porous devices demonstrates p-n junction structure at the TiO2/perovskite interfaces and minority-carrier diffusion/drift operation of the devices, rather than the operation mechanism of either an excitonic cell or a p-i-n structure. Combining the potential profiling results with solar cell performance parameters measured on optimized and thickened devices, we find that carrier mobility is a main factor that needs to be improved for further gains in efficiency of the perovskite solar cells.
The Volta potential is an electron-sensitive parameter and describes the thermodynamic propensity of a metal to take part in electrochemical reactions. It has found widespread acceptance among ...corrosion researchers due to its connection to the corrosion potential and its easy measurability in local scale, being often used to study localised corrosion phenomena and micro-galvanic activities. The principle object of this paper is to provide a comprehensive, fundamental insight into the meaning of the Volta potential and to define a polarity convention of measured potentials by the scanning Kelvin probe force microscopy (SKPFM) in order to assess local nobilities in microstructures. Conditions to relate the Volta potential with the mixed-potential theory are discussed and a possible connection to corrosion phenomena explained. The limitations of the Volta potential as well as the SKPFM technique are also aimed to be explained, with some practical information to maximise the output of high quality data.
Highly luminescent CsPbBr3 perovskite quantum dots (QDs) have gained huge attention in research due to their various applications in optoelectronics, including as a light absorber in photovoltaic ...solar cells. To improve the performances of such devices, it requires a deeper knowledge on the charge transport dynamics inside the solar cell, which are related to its power-conversion efficiency. Here, we report the successful fabrication of an all-inorganic CsPbBr3 perovskite QD sensitized solar cell and the imaging of anomalous electrical potential distribution across the layers of the cell under different illuminations using Kelvin probe force microscopy. Carrier generation, separation, and transport capacity inside the cells are dependent on the light illumination. Large differences in surface potential between electron and hole transport layers with unbalanced carrier separation at the junction have been observed under white light (full solar spectrum) illumination. However, under monochromatic light (single wavelength of solar spectrum) illumination, poor charge transport occurred across the junction as a consequence of less difference in surface potential between the active layers. The outcome of this study provides a clear idea on the carrier dynamic processes inside the cells and corresponding surface potential across the layers under the illumination of different wavelengths of light to understand the functioning of the solar cells and ultimately for the improvement of their photovoltaic performances.
•Intergranular stress corrosion cracking (IGSCC) is prone to occur along α/β phase boundaries and RGBs.•IGSCC is frequently arrested at a triple junction with Σ3 TB.•The Volta potentials of α/β phase ...boundaries and RGB are higher than that of Σ3 TB.
The purpose of this study is to investigate the correlation between intergranular stress corrosion cracking (IGSCC) and grain boundary characteristics in brass. The Volta potential and nature of the grain boundaries in H62 brass were studied by scanning Kelvin probe force microscopy and Electron Backscattered Diffraction, respectively. The α/β phase boundaries and random grain boundaries with low work functions can act as anodic areas to promote IGSCC propagation. Moreover, due to a combination of the inherent characteristics and high work function of Σ3 annealing twin boundaries (ATBs), IGSCC is successfully halted at a triple junction containing Σ3 ATB.
There was always a controversy about if the mobile dislocations generated during plastic deformation could transport hydrogen atoms. In this study, the behavior of dislocation migration hydrogen was ...directly observed by combining the scanning Kelvin probe force microscopy (SKPFM) technique and slow tensile test. The quantitative analysis results revealed that the behavior of dislocation transport hydrogen could not accelerate hydrogen atom migration, while could achieve the uphill transport of hydrogen atoms. In addition, in this study, SKPFM has been confirmed to be a powerful tool for measuring hydrogen diffusion coefficient in materials with a high accuracy.
•SKPFM was a powerful tool for measuring hydrogen diffusion coefficient in materials.•The behavior of dislocation transport hydrogen was universal in general tensile tests.•Hydrogen transport could not be accelerated by the behavior of dislocation carrying.•The behavior of dislocation carrying hydrogen could achieve the uphill transport of hydrogen atoms.
PDF
