Synthesis of carbon nitrides from carbon dioxide

Provided are methods of converting carbon dioxide to carbon nitrides. In a first reaction, carbon dioxide may be reacted with metal nitrides, such as Li.sub.3N, to form carbon nitrides in a fast and exothermic reaction. Also provided are methods of using product metal cyanamides from the first reaction to subsequently generate additional carbon nitrides.https://digitalcommons.mtu.edu/patents/1005/thumbnail.jp

An Investigation of Students\u27 Media Preferences in Learning Mathematical Concepts

Besides the traditional face-to-face learning medium, online media are now available for students in various learning environments. The delivery of coursework through online media is on the increase in colleges and universities. However, research on the use of online learning media in beginning collegiate level foundational mathematics courses for non-mathematics and non-science majors is limited. Therefore, the purpose of this study was to investigate, within a foundational mathematics course, connections between media used for instruction in hybrid and online enhanced face-to-face learning environments and students’ media preferences. The online Web Course Tools (WebCT) Vista template used in this study was designed by the researcher and her colleague as a part of the hybrid fellowship project for a two-year college. Applying transactional distance theory and engagement theory, designers carefully analyzed each concept and determined which concepts would be delivered most effectively in each learning medium. This study was quantitative in nature. During Fall 2005, thirty-eight students in the Introduction to Mathematical Modeling course at a community college in the southeast participated in the final study. Students in the hybrid sections comprised the treatment group while students in the online face-to-face section comprised the control group. Throughout the semester, all students were asked to respond to questions on the following instruments: Assignment Feedback, Quiz Feedback, Test Feedback, and Project Feedback. Chi-Square analysis showed that significant differences were found in the majority of items on the Test Feedback instrument related to the linear and quadratic modules. In general, the treatment group preferred online learning at least half of the time and believed online resources provide the basic resources for learning the subject matter. Students’ written responses from the treatment group indicated that both online learner-content interactions, and in-class learner-instructor interactions supplemented the learning of mathematics. The control group preferred predominantly face-to-face learning and believed that learning primarily took place in a physical setting. The findings showed that the proportion of students who completed the course using the hybrid and face-to-face learning environments was not significantly different. Therefore, the data showed the success rate for both learning environments was about the same

MoS2 as a co-catalyst for photocatalytic hydrogen production from water

Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly active, inexpensive, and earth-abundant materials as photocatalysts. As a presentative layer-structured transition metal dichalcogenides, molybdenum disulfide (MoS2) is attracting intensive attention due to its unique electro and photo properties. In this article, we comprehensively review the recent research efforts of exploring MoS2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO2, and others. It is shown that MoS2–semiconductor composites are promising photocatalysts for hydrogen evolution from water under visible light irradiation

Degradation issues and stabilization strategies of protonic ceramic electrolysis cells for steam electrolysis

Protonic ceramic electrolysis cells (PCECs) are attractive electrochemical devices for converting electrical energy to chemicals due to their high conversion efficiency, favorable thermodynamics, fast kinetics, and inexpensive materials. Compared with conventional oxygen ion-conducting solid oxide electrolysis cells, PCECs operate at a lower operating temperature and a favorable operation mode, thus expecting high durability. However, the degradation of PCECs is still significant, hampering their development. In this review, the typical degradations of PCECs are summarized, with emphasis on the chemical stability of the electrolytes and the air electrode materials. Moreover, the degradation mechanism and influencing factors are assessed deeply. Finally, the emerging strategies for inhibiting long-term degradations, including chemical composition modifications and microstructure tuning, are explored

Thermo-photo catalytic anode process for carbonate-superstructured solid fuel cells

Converting hydrocarbons and greenhouse gases (i.e., carbon dioxide, CO2) directly into electricity through fuel cells at intermediate temperatures (450 to 550 °C) remains a significant challenge, primarily due to the sluggish activation of C-H and C=O bonds. Here, we demonstrated a unique strategy to address this issue, in which light illumination was introduced into the thermal catalytic CO2reforming of ethane in the anode as a unique thermo-photo anode process for carbonate-superstructured solid fuel cells. The light-enhanced fuel activation led to excellent cell performance with a record-high peak power density of 168 mW cm-2at an intermediate temperature of 550 °C. Furthermore, no degradation was observed during ~50 h operation. Such a successful integration of photo energy into the fuel cell system provides a new direction for the development of efficient fuel cells

Recent advances in graphene-based materials for fuel cell applications

The unique chemical and physical properties of graphene and its derivatives (graphene oxide, heteroatom-doped graphene, and functionalized graphene) have stimulated tremendous efforts and made significant progress in fuel cell applications. This review focuses on the latest advances in the use of graphene-based materials in electrodes, electrolytes, and bipolar plates for fuel cells. The understanding of structure-activity relationships of metal-free heteroatom-doped graphene and graphene-supported catalysts was highlighted. The performances and advantages of graphene-based materials in membranes and bipolar plates were summarized. We also outlined the challenges and perspectives in using graphene-based materials for fuel cell applications