The development of cost-effective hydroxide exchange membrane fuel cells is limited by the lack of high-performance and low-cost anode hydrogen oxidation reaction catalysts. Here we report a Pt-free catalyst Ru7Ni3/C, which exhibits excellent hydrogen oxidation reaction activity in both rotating disk electrode and membrane electrode assembly measurements. The hydrogen oxidation reaction mass activity and specific activity of Ru7Ni3/C, as measured in rotating disk experiments, is about 21 and 25 times that of Pt/C, and 3 and 5 times that of PtRu/C, respectively. The hydroxide exchange membrane fuel cell with Ru7Ni3/C anode can deliver a high peak power density of 2.03 W cm−2 in H2/O2 and 1.23 W cm−2 in H2/air (CO2-free) at 95 °C, surpassing that using PtRu/C anode catalyst, and good durability with less than 5% voltage loss over 100 h of operation. The weakened hydrogen binding of Ru by alloying with Ni and enhanced water adsorption by the presence of surface Ni oxides lead to the high hydrogen oxidation reaction activity of Ru7Ni3/C. By using the Ru7Ni3/C catalyst, the anode cost can be reduced by 85% of the current state-of-the-art PtRu/C, making it highly promising in economical hydroxide exchange membrane fuel cells.
Social media are acknowledged as an important information source that influences tourists’ travel choices. However, qualitative studies that take an inductive approach to identify the roles of social media by investigating how social media affect travel choices are limited. By interviewing 21 tourists who had recently taken trips, this article aimed to identify the roles that social media played in the tourists’ choices of six travel components (destination, transportation, accommodation, food and dining activities, attractions, as well as shopping and leisure activities). Four roles have been identified: Need Generator, Supporter, Guider and Approver. Theoretical and practical implications along with future research suggestions are discussed.
Novel BiTe/graphene quantum dots (BiTe/GQDs) hybrid nanosheets with a unique structure that GQDs are homogeneously embedded in the BiTe nanosheet matrix have been synthesized by a simple solution-based synthesis strategy. A significantly reduced thermal conductivity and enhanced powder factor are observed in the BiTe/GQDs hybrid nanosheets, which is ascribed to the optimized thermoelectric transport properties of the BiTe/GQDs interface. Furthermore, by varying the size of the GQDs, the thermoelectric performance of BiTe/GQDs hybrid nanostructures could be further enhanced, which could be attributed to the optimization of the density and dispersion manner of the GQDs in the BiTe matrix. A maximum ZT of 0.55 is obtained at 425 K for the BiTe/GQDs-20 nm, which is higher than that of BiTe without hybrid nanostrucure. This work provides insights for the structural design and synthesis of BiTe-based hybrid thermoelectric materials, which will be important for future development of broadly functional material systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.