7.2% efficient polycrystalline silicon photoelectrode

After etching, n-type cast polycrystalline silicon photoanodes immersed in a solution of methanol and a substituted ferrocene reagent exhibit photoelectrode efficiencies of 7.2%±0.7% under simulated AM2 illumination. Scanning laser spot data indicate that the grain boundaries are active; however, the semiconductor/liquid contact does not display the severe shunting effects which are observed at a polycrystalline Si/Pt Schottky barrier. Evidence for an interfacial oxide on the operating polycrystalline Si photoanode is presented. Some losses in short circuit current can be ascribed to bulk semiconductor properties; however, despite these losses, photoanodes fabricated from polycrystalline substrates exhibit efficiencies comparable to those of single crystal material. Two major conclusions of our studies are that improved photoelectrode behavior in the polycrystalline silicon/methanol system will primarily result from changes in bulk electrode properties and from grain boundary passivation, and that Fermi level pinning by surface states does not prevent the design of efficient silicon-based liquid junctions

A 14% efficient nonaqueous semiconductor/liquid junction solar cell

We describe the most efficient semiconductor/liquid junction solar cell reported to date. Under W‐halogen (ELH) illumination, the device is a 14% efficient two‐electrode solar cell fabricated from an n‐type silicon photoanode in contact with a nonaqueous electrolyte solution. The cell′s central feature is an ultrathin electrolyte layer which simultaneously reduces losses which result from electrode polarization, electrolyte light absorption, and electrolyte resistance. The thin electrolyte layer also eliminates the need for forced convection of the redox couple and allows for precise control over the amount of water (and other electrolyte impurities) exposed to the semiconductor. After one month of continuous operation under ELH light at 100 mW/cm^2, which corresponds to the passage of over 70 000 C/cm^2, thin‐layer cells retained over 90% of their efficiency. In addition, when made with Wacker Silso cast polycrystalline Si, cells yield an efficiency of 9.8% under simulated AMl illumination. The thin‐layer cells employ no external compensation yet surpass their corresponding experimental (three‐electrode) predecessors in efficiency

Kindling the Spark of Black Male Genius through Education

This essay examines the nature of inopportunity associated with blackmaleness, synthesizes the narratives of the other contributors to this issue of the journal, and offers recommendations for how education can support Black males' academic, social, and cultural maturation. While African American males face daunting economic and educational challenges, James and Lewis argue that they can navigate through them to obtain academic and career success while still maintaining their identity as Black males

Photoelectrochemical water splitting: silicon photocathodes for hydrogen evolution

The development of low cost, scalable, renewable energy technologies is one of today's most pressing scientific challenges. We report on progress towards the development of a photoelectrochemical water-splitting system that will use sunlight and water as the inputs to produce renewable hydrogen with oxygen as a by-product. This system is based on the design principle of incorporating two separate, photosensitive inorganic semiconductor/liquid junctions to collectively generate the 1.7-1.9 V at open circuit needed to support both the oxidation of H_2O (or OH^-) and the reduction of H^+ (or H_2O). Si microwire arrays are a promising photocathode material because the high aspect-ratio electrode architecture allows for the use of low cost, earth-abundant materials without sacrificing energy-conversion efficiency, due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surfacearea design of the rod-based semiconductor array inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. Arrays of Si microwires grown using the Vapor Liquid Solid (VLS) mechanism have been shown to have desirable electronic light absorption properties. We have demonstrated that these arrays can be coated with earth-abundant metallic catalysts and used for photoelectrochemical production of hydrogen. This development is a step towards the demonstration of a complete artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, and scalable

Recognizing and promoting interdisciplinary collaboration, leadership, and impact: award for interdisciplinary excellence in mathematics education (IEME award)

The presentation of the Award for Excellence in Mathematics Education to Roger E. Howe in 2015 officially launched the award, with the goal of recognizing work of lasting significance and impact in advancing mathematics education as an interdisciplinary field, linking mathematics, educational studies, and practice. From the beginning, this unique award has emphasized interdisciplinarity in mathematics education, highlighting the importance of boundary-crossing collaborations among mathematicians, mathematics educators, scholars in other related fields, and practitioners of mathematics. To emphasize the importance of interdisciplinary collaboration in mathematics education, starting in 2019, the name of the award is changed from “Excellence in Mathematics Education” to “Interdisciplinary Excellence in Mathematics Education”

Physical Model Study, CSO Diversion through Bottom Outlet Slot, Site DS-4 Upper Rouge Tunnel System

https://deepblue.lib.umich.edu/bitstream/2027.42/154196/1/39015101405218.pd

A Physical Model Investigation of Sediment Deposition and Circulation Patterns for Kalamazoo Lake (a.k.a. Saugatuck Harbor)

https://deepblue.lib.umich.edu/bitstream/2027.42/154164/1/39015099114913.pd

The Role of Mentors/Advisors in the Doctoral Training of African American Students at Predominately White Universities: Implications for Doctoral Training

The purpose of this study is to examine the relationship and the importance of connecting the African American doctoral students and their advisors in the mentor roles. More specifically, this study brings to the forefront the importance as well as the impact of mentors/advisors and their roles in facilitating academic success for African American doctoral students. Many African American doctoral students are typically misunderstood and misdirected in the types of support that they may need to succeed in graduate school (Gallien & Peterson, 2005). Mentors/advisors and the roles that they have are essential to the success of African American doctoral students. The support structures surrounding the mentor/advisor relationship in this research are essential to how it relates to the needs of the African American doctoral student on a predominately White campus. Given the findings, recommendations are provided for future research and for administrators at predominately White Institutions