Spatial Surface Charge Engineering for Electrochemical Electrodes

Xie, Lingyun; Wang, Peng; Qian, Yinping; Rao, Lujia; Yin, Hongjie; Wang, Xingyu; Chen, Hedong; Zhou, Guofu; Nötzel, R.

doi:10.1038/s41598-019-51048-5

Cited by 8 publications

(12 citation statements)

References 49 publications

(48 reference statements)

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“…Moreover, MBE-grown InGaN layers on Si substrates are N-polar with outward electric dipole. For both substrates, the experimental results are very similar 12,13 , indicating minor influence of the lattice polarity induced electric dipole. After etching, the lattice polarity induced electric dipole and the measured electric dipole both point inwards.…”

Section: Discussionmentioning

confidence: 74%

Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy

Qian

Wang

Rao

et al. 2020

Sci Rep

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We directly measure the electric dipole of inn quantum dots (QDs) grown on in-rich inGan layers by Kelvin probe force microscopy. This significantly advances the understanding of the superior catalytic performance of inn/inGan QDs in ion-and biosensing and in photoelectrochemical hydrogen generation by water splitting and the understanding of the important third-generation inGan semiconductor surface in general. the positive surface photovoltage (SpV) gives an outward QD dipole with dipole potential of the order of 150 mV, in agreement with previous calculations. After HCl-etching, to complement the determination of the electric dipole, a giant negative SpV of −2.4 V, significantly larger than the inGan bandgap energy, is discovered. this giant SpV is assigned to a large inward electric dipole, associated with the appearance of holes, matching the original QD lateral size and density. Such surprising result points towards unique photovoltaic effects and photosensitivity. Beyond the established applications of III-nitride semiconductors for blue lasers, solid state lighting and high-power amplifiers, the great potential of InGaN for electrochemical devices has been widely recognized recently. This is due to the intrinsic materials properties of InGaN, most relevant, the wide direct bandgap tunability upon In content from the ultraviolet to the near-infrared spectral region, the huge near bandgap absorption coefficient, one order of magnitude larger than that of GaAs, the large carrier mobility, the non toxicity and bio-compatibility. Moreover, InGaN exhibits unique surface properties, governing the electrochemical activity. For the c-plane of InGaN there exists a transition from negatively to positively charged surface states above about 40% In content, reaching a density of 2 × 10 13 cm −2 for InN. The associated transition from surface electron depletion to surface electron accumulation, i.e., from upward surface energy band bending to downward surface energy band bending, i.e., from positive to negative surface photovoltage (SPV) has been directly revealed by electrochemical capacitance-voltage (C-V) measurements, X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM) 1-4. The positively charged surface states are highly active to attract anions and electrons to catalytically enhance oxidation reactions. Key applications include electrochemical ion-and biosensors 5-7 and photoelectrochemical solar hydrogen generation by water splitting 8-11. In both application areas, InN/InGaN quantum dots (QDs) show superior performance 12-14. Super-Nernstian sensitivity is observed in potentiometric sensing and the efficiency of hydrogen generation by water splitting is enhanced by almost a factor of three compared to that for a bare InGaN layer. This has been explained by the existence of a large electric dipole associated with the InN QDs in addition to the pure surface charge effect. For the QDs, the high density of positively charged surface states is not fully compensated because not sufficient...

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Section: Discussionmentioning

confidence: 74%

Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy

Qian

Wang

Rao

et al. 2020

Sci Rep

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“…High-resolution transmission electron microscopy and detailed optical and electrochemical characterizations of the InN/InGaN QDs have been presented before. 34 − 36 …”

Section: Methodsmentioning

confidence: 99%

“…AFM (Bruker Multimode) and top-view and cross-sectional SEM (ZEISS Gemini 500) were performed to observe the surface morphology and layer thickness. High-resolution transmission electron microscopy and detailed optical and electrochemical characterizations of the InN/InGaN QDs have been presented before. − …”

Section: Methodsmentioning

confidence: 99%

Comparison of the Extended Gate Field-Effect Transistor with Direct Potentiometric Sensing for Super-Nernstian InN/InGaN Quantum Dots

et al. 2020

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We systematically study the sensitivity and noise of an InN/InGaN quantum dot (QD) extended gate field-effect transistor (EGFET) with super-Nernstian sensitivity and directly compare the performance with potentiometric sensing. The QD sensor exhibits a sensitivity of −80 mV/decade with excellent linearity over a wide concentration range, assessed for chloride anion detection in 10 –4 to 0.1 M KCl aqueous solutions. The sensitivity and linearity are reproduced for the EGFET and direct open-circuit potential (OCP) readout. The EGFET noise in the saturated regime is smaller than the OCP noise, while the EGFET noise in the linear regime is largest. This highlights EGFET operation in the saturated regime for most precise measurements and the lowest limit of detection and the lowest limit of quantification, which is attributed to the low-impedance current measurement at a relatively high bias and the large OCP for the InN/InGaN QDs.

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“…The primary concern relating to efficient usage of nano-enabled sensing is the surface charge characteristics of nanomaterial that influences the subsystems and biological membranes. Reports by Martin K. Rasmussen et al [ 4 ] show pioneering results on charge characterization applied to exosome-based diagnostics and Lingyun Xie et al [ 5 ], who explored the solid-state reference electrode paired with InN/InGaN QD sensing electrode generating super-Nernstian response in electrochemical sensors confirmed by Kelvin probe force microscopy, which also emphasizes the spatial surface charge engineering and the influence of charge distribution at the nanoscale sensing. The ever-growing market of nanosensors can become sustainable by a combination of competitive and complimenting development of microscopic nanomaterial research and macroscopic manufacturing techniques.…”

Section: Introductionmentioning

confidence: 99%

Sensing beyond Senses: An Overview of Outstanding Strides in Architecting Nanopolymer-Enabled Sensors for Biomedical Applications

Malini¹,

Roy

Raj³

et al. 2022

Polymers

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Nano-enabled sensing is an expanding interdisciplinary field of emerging science with dynamic multifunctional detecting capabilities, equipped with a wide range of multi-faceted nanomaterial having diverse dimensions and composition. They have proven to be highly robust, sensitive, and useful diagnostic tools ranging from advanced industrial processes to ordinary consumer products. As no single nanomaterial has proved to be unparalleled, recent years has witnessed a large number of nanomaterial-based sensing strategies for rapid detection and quantification of processes and substances with a high degree of reliability. Nano-furnished platforms, because of easy fabrication methods and chemical versatility, can serve as ideal sensing means through different transduction mechanisms. This article, through a unified experimental-theoretical approach, uses literature of recent years to introduce, evaluate, and analyze significant developments in the area of nanotechnology-aided sensors incorporating the various classes of nanomaterial. Addressing the broad interests, the work also summarizes the sensing mechanisms using schematic illustrations, attempts to integrate the performance of different categories of nanomaterials in the design of sensors, knowledge gaps, regulatory aspects, future research directions, and challenges of implementing such techniques in standalone devices. In view of a dependency of analysis and testing on sustained growth of sensor-supported platforms, this article inspires the scientific community for more attention in this field.

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Spatial Surface Charge Engineering for Electrochemical Electrodes

Cited by 8 publications

References 49 publications

Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy

Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy

Comparison of the Extended Gate Field-Effect Transistor with Direct Potentiometric Sensing for Super-Nernstian InN/InGaN Quantum Dots

Sensing beyond Senses: An Overview of Outstanding Strides in Architecting Nanopolymer-Enabled Sensors for Biomedical Applications

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