Search

Operando synchrotron radiation photoelectron spectroscopy in the tender X-ray energy range has been used to obtain information on the energy-band relations of semiconductor and metal-covered semiconductor surfaces while in direct contact with aqueous electrolytes under potentiostatic control. The system that was investigated consists of highly doped Si substrates that were conformally coated with ∼70 nm titania films produced by atomic-layer deposition. TiO2/electrolyte and Si/TiO2/Ni/electrolyte interfaces were then analyzed by synchrotron radiation photoelectron spectroscopy. The PES data allows for determination of the flat-band position and identification of potential regions in which Fermi level pinning, depletion, or accumulation occurred. Operando X-ray absorption spectroscopy (XAS) techniques were additionally used to investigate the properties of heterogeneous electrocatalysts for the oxygen-evolution reaction. Operando XAS including the pre-edge, edge and EXAFS regions allowed the development of a detailed picture of the catalysts under operating conditions, and elucidated the changes in the physical and electronic structure of the catalyst that accompanied increases in the applied potential. Specifically, XAS data, combined with DFT studies, indicated that the activity of the electrocatalyst correlated with the formation of Fe dopant sites in γ-NiOOH.

Operando synchrotron radiation photoelectron spectroscopy in the tender X-ray energy range has been used to obtain information on the energy-band relations of semiconductor and metal-covered semiconductor surfaces while in direct contact with aqueous electrolytes under potentiostatic control. The system that was investigated consists of highly doped Si substrates that were conformally coated with ∼70 nm titania films produced by atomic-layer deposition. TiO2/electrolyte and Si/TiO2/Ni/electrolyte interfaces were then analyzed by synchrotron radiation photoelectron spectroscopy. The PES data allows for determination of the flat-band position and identification of potential regions in which Fermi level pinning, depletion, or accumulation occurred. Operando X-ray absorption spectroscopy (XAS) techniques were additionally used to investigate the properties of heterogeneous electrocatalysts for the oxygen-evolution reaction. Operando XAS including the pre-edge, edge and EXAFS regions allowed the development of a detailed picture of the catalysts under operating conditions, and elucidated the changes in the physical and electronic structure of the catalyst that accompanied increases in the applied potential. Specifically, XAS data, combined with DFT studies, indicated that the activity of the electrocatalyst correlated with the formation of Fe dopant sites in γ-NiOOH.

Small-band-gap (Eg < 2 eV) semiconductors must be stabilized for use in integrated devices that convert solar energy into the bonding energy of a reduced fuel, specifically H2(g) or a reduced-carbon species such as CH3OH or CH4. To sustainably and scalably complete the fuel cycle, electrons must be liberated through the oxidation of water to O2(g). Strongly acidic or strongly alkaline electrolytes are needed to enable efficient and intrinsically safe operation of a full solar-driven water-splitting system. However, under water-oxidation conditions, the small-band-gap semiconductors required for efficient cell operation are unstable, either dissolving or forming insulating surface oxides. We describe herein recent progress in the protection of semiconductor photoanodes under such operational conditions. We specifically describe the properties of two protective overlayers, TiO2/Ni and NiOx, both of which have demonstrated the ability to protect otherwise unstable semiconductors for >100 h of continuous solar-driven water oxidation when in contact with a highly alkaline aqueous electrolyte (1.0 M KOH(aq)). The stabilization of various semiconductor photoanodes is reviewed in the context of the electronic characteristics and a mechanistic analysis of the TiO2 films, along with a discussion of the optical, catalytic, and electronic nature of NiOx films for stabilization of semiconductor photoanodes for water oxidation.

Small-band-gap (Eg < 2 eV) semiconductors must be stabilized for use in integrated devices that convert solar energy into the bonding energy of a reduced fuel, specifically H2(g) or a reduced-carbon species such as CH3OH or CH4. To sustainably and scalably complete the fuel cycle, electrons must be liberated through the oxidation of water to O2(g). Strongly acidic or strongly alkaline electrolytes are needed to enable efficient and intrinsically safe operation of a full solar-driven water-splitting system. However, under water-oxidation conditions, the small-band-gap semiconductors required for efficient cell operation are unstable, either dissolving or forming insulating surface oxides. We describe herein recent progress in the protection of semiconductor photoanodes under such operational conditions. We specifically describe the properties of two protective overlayers, TiO2/Ni and NiOx, both of which have demonstrated the ability to protect otherwise unstable semiconductors for >100 h of continuous solar-driven water oxidation when in contact with a highly alkaline aqueous electrolyte (1.0 M KOH(aq)). The stabilization of various semiconductor photoanodes is reviewed in the context of the electronic characteristics and a mechanistic analysis of the TiO2 films, along with a discussion of the optical, catalytic, and electronic nature of NiOx films for stabilization of semiconductor photoanodes for water oxidation.

The electrical and spectroscopic properties of the TiO2/Ni protection layer system, which enables stabilization of otherwise corroding photoanodes, have been investigated in contact with electrolyte solutions by scanning-probe microscopy, electrochemistry and in-situ ambient pressure X-ray photoelectron spectroscopy (AP-XPS). Specifically, the energy-band relations of the p+-Si/ALD-TiO2/Ni interface have been determined for a selected range of Ni thicknesses. AP-XPS measurements using tender X-rays were performed in a three-electrode electrochemical arrangement under potentiostatic controlto obtain information from the semiconductor near-surface region, the electrochemical double layer (ECDL) and the electrolyte beyond the ECDL. The degree of conductivity depended on the chemical state of the Ni on the TiO2 surface. At low loadings of Ni, the Ni was present primarily as an oxide layer and the samples were not conductive, although the TiO2 XPS core levels nonetheless displayed behavior indicative of a metal-electrolyte junction. In contrast, as the Ni thickness increased, the Ni phase was primarily metallic and the electrochemical behavior became highly conductive, with the AP-XPS data indicative of a metal-electrolyte junction. Electrochemical and microtopographical methods have been employed to better define the nature of the TiO2/Ni electrodes and to contextualize the AP-XPS results.

The experience of Iona College in implementing a curriculum integrating technology with science in a liberal arts curriculum is outlined. Development of a curriculum development plan including computer, energy, environmental, and health sequences, problems of integrating the curriculum, and faculty involvement are discussed. (MSE)

Contract comics are relatively new on the legal horizon. They have attracted attention from various legal disciplines and from legal practice. Their novelty and growing significance open up numerous questions: biographical, terminological, classificatory, methodological, theoretical, and disciplinary. They also raise questions about technology and media, codes and communication, and the senses. My findings are threefold: first, contract comics implicitly challenge the predominantly text-only approach to contract law. As such, they need to be understood and anchored in a broader legal discourse, one that extends to and draws on established basic legal disciplines (eg, legal iconography, legal theory, legal semiotics, law and the humanities) and on emerging ones (eg, multisensory law and its branches visual law and audio-visual law (working terms)). Second, contract comics can be associated with other visual, audio-visual, and multisensory legal phenomena. Third, contract comics, indispensable to non-verbocentric communication, also provide an excellent example of representing and communicating non-contractual legal contents. [ABSTRACT FROM AUTHOR]

Outdoor recreation provides vital interactions between humans and ecological systems with a range of mental and physical benefits for people. Despite the increased number of studies using crowdsourced online data to assess how people interact with the landscape during recreational activities, the focus remains largely on mapping the spatial distribution of visitors or analyzing the content of shared images and little work has been done to quantify the perceptions and emotions people assign to the landscape. In this study, we used crowdsourced textual data from an outdoor activity-sharing platform (Wikiloc), and applied Natural Language Processing (NLP) methods and correlation analysis to capture hikers' perceptions associated with landscape features and physical outdoor activities. Our results indicate eight clusters based on the semantic similarity between words ranging from four clusters describing landscape features ("ecosystems, animals & plants", "geodiversity", "climate & weather", and "built cultural heritage"), to one cluster describing the range of physical outdoor activities and three clusters indicating hikers' perceptions and emotions ("aesthetics", "joy & restoration" and "physical effort sensation"). The association analysis revealed that the cluster "ecosystems, animals & plants" is likely to stimulate all three identified perceptions, suggesting that these natural features are important for hikers during their outdoor experience. Moreover, hikers strongly associate the cluster "outdoor physical activities" with both "joy & restoration" and "physical effort sensation" perceptions, highlighting the health and well-being benefits of physical activities in natural landscapes. Our study shows the potential of Wikiloc as a valuable data source to assess human-nature interactions and how textual data can provide significant advances in understanding peoples' preferences and perceptions while recreating. These findings can help inform outdoor recreation planners in the study region by focusing on the elements of the landscape that peoples perceive to be important (i.e. "ecosystems, animals & plants"). • The textual content of social media offers insights on human-nature interactions. • Wikiloc text and word2vec model were used to assess hikers' preferences and perceptions. • We identify the landscape features that stimulate hikers' perceptions. • Ecosystem and landscape features were associated with all types of perceptions. • Understanding hikers' perceptions can assist landscape management and planning. [ABSTRACT FROM AUTHOR]