1,721,214 research outputs found
Wafer-Scale Si-Based Metal−Insulator−Semiconductor Photoanodes for Water Oxidation Fabricated Using Thin Film Reactions and Multiple-layer Electrodeposited Catalysts
No full textSolar-driven photoelectrochemical (PEC) water
splitting offers a promising and environmentally friendly route for
the conversion of renewable solar energy to hydrogen gas. A
crystalline Si absorber is especially attractive due to its moderate
bandgap, high charge mobility, long carrier diffusion length, costeffectiveness,
and scalability in manufacturing. To improve the
stability of Si-based PEC cells in operation, metal−insulator−
semiconductor (MIS) structures have been widely employed. In
this work, we employ simple and highly scalable processes to
fabricate high-performance, extremely stable Si-based MIS photoanodes,
and demonstrate their application to the fabrication of
wafer-scale photoanodes. Localized conduction paths formed via an
Al/SiO2 thin-film reaction enable low-resistance charge extraction
even through thick insulating layers, yielding photoanodes with excellent stability. To improve the efficiency, we demonstrate a twostep
Ni/NiFe electrodeposition process to create efficient oxygen evolution reaction catalysts. The Ni/NiFe catalyst allows for a high
Schottky barrier between Si and Ni, lowering the photoanode onset potential, while the NiFe surface layer improves the catalytic
performance. An unassisted solar-driven water splitting system incorporating a wafer-scale photoanode and monocrystalline Si solar
cells is demonstrated and yields a solar-to-hydrogen conversion efficiency of 6.9% under simulated AM 1.5G sunlight illumination
Elucidating Piezoelectricity and Strain in Monolayer MoS2 at the Nanoscale Using Kelvin Probe Force Microscopy
No full textStrain engineering modifies the optical and
electronic properties of atomically thin transition metal dichalcogenides.
Highly inhomogeneous strain distributions in twodimensional
materials can be easily realized, enabling control of
properties on the nanoscale; however, methods for probing strain
on the nanoscale remain challenging. In this work, we characterize
inhomogeneously strained monolayer MoS2 via Kelvin probe force
microscopy and electrostatic gating, isolating the contributions of
strain from other electrostatic effects and enabling the measurement
of all components of the two-dimensional strain tensor on
length scales less than 100 nm. The combination of these methods
is used to calculate the spatial distribution of the electrostatic
potential resulting from piezoelectricity, presenting a powerful way
to characterize inhomogeneous strain and piezoelectricity that can be extended toward a variety of 2D materials
Massively Scalable Self-Assembly of Nano and Microparticle Monolayers via Aerosol Assisted Deposition
No full textAn extremely rapid process for self-assembling well-ordered, nano, and
microparticle monolayers via a novel aerosolized method is presented. The
novel technique can reach monolayer self-assembly rates as high as 268 cm2
min−1 from a single aerosolizing source and methods to reach faster
monolayer self-assembly rates are outlined. A new physical mechanism
describing the self-assembly process is presented and new insights enabling
high-efficiency nanoparticle monolayer self-assembly are developed. In
addition, well-ordered monolayer arrays from particles of various sizes,
surface functionality, and materials are fabricated. This new technique enables
a 93× increase in monolayer self-assembly rates compared to the current
state of the art and has the potential to provide an extremely low-cost option
for submicron nanomanufacturing
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Wafer-Scale Si-Based Metal−Insulator−Semiconductor Photoanodes for Water Oxidation Fabricated Using Thin Film Reactions and Multiple-layer Electrodeposited Catalysts
Get PDFSolar-driven photoelectrochemical (PEC) water
splitting offers a promising and environmentally friendly route for
the conversion of renewable solar energy to hydrogen gas. A
crystalline Si absorber is especially attractive due to its moderate
bandgap, high charge mobility, long carrier diffusion length, costeffectiveness,
and scalability in manufacturing. To improve the
stability of Si-based PEC cells in operation, metal−insulator−
semiconductor (MIS) structures have been widely employed. In
this work, we employ simple and highly scalable processes to
fabricate high-performance, extremely stable Si-based MIS photoanodes,
and demonstrate their application to the fabrication of
wafer-scale photoanodes. Localized conduction paths formed via an
Al/SiO2 thin-film reaction enable low-resistance charge extraction
even through thick insulating layers, yielding photoanodes with excellent stability. To improve the efficiency, we demonstrate a twostep
Ni/NiFe electrodeposition process to create efficient oxygen evolution reaction catalysts. The Ni/NiFe catalyst allows for a high
Schottky barrier between Si and Ni, lowering the photoanode onset potential, while the NiFe surface layer improves the catalytic
performance. An unassisted solar-driven water splitting system incorporating a wafer-scale photoanode and monocrystalline Si solar
cells is demonstrated and yields a solar-to-hydrogen conversion efficiency of 6.9% under simulated AM 1.5G sunlight illumination.This research was primarily supported by the National Science
Foundation (grant CBET-2109842). The authors acknowledge
the use of the facilities and instrumentation supported by
Texas Materials Institute, and by the National Science
Foundation through the Center for Dynamics and Control of
Materials: an NSF MRSEC under Cooperative Agreement nos.
DMR-1720595 and DMR-2308817. This work was performed
in part at the University of Texas Microelectronics Research
Center, a member of the National Nanotechnology Coordinated
Infrastructure (NNCI), which is supported by the
National Science Foundation (grant ECCS-2025227).Center for Dynamics and Control of Material
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Massively Scalable Self-Assembly of Nano and Microparticle Monolayers via Aerosol Assisted Deposition
Get PDFAn extremely rapid process for self-assembling well-ordered, nano, and
microparticle monolayers via a novel aerosolized method is presented. The
novel technique can reach monolayer self-assembly rates as high as 268 cm2
min−1 from a single aerosolizing source and methods to reach faster
monolayer self-assembly rates are outlined. A new physical mechanism
describing the self-assembly process is presented and new insights enabling
high-efficiency nanoparticle monolayer self-assembly are developed. In
addition, well-ordered monolayer arrays from particles of various sizes,
surface functionality, and materials are fabricated. This new technique enables
a 93× increase in monolayer self-assembly rates compared to the current
state of the art and has the potential to provide an extremely low-cost option
for submicron nanomanufacturing.This work was primarily supported
by The Center for Dynamics and Control of Materials (CDCM) under
National Science Foundation award numbers DMR-1720595 and DMR-
2308817. This work was performed in part at the University of Texas at
Austin’s Microelectronics Research Center, amember of the National Nanotechnology
Coordinated Infrastructure (NNCI), which is supported by
the National Science Foundation grant (grants ECCS-1542159 and ECCS-
2025227). This research was partially supported by the U.S. National Science
Foundation through Award #1828974 and the Robert A. Welch Foundation
(Grant F-1464).Electrical and Computer Engineerin
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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