Electrocatalytic oxidation of methanol on CoNi electrodeposited materials

Cobalt-nickel bimetallic materials electrodeposited on Si/Ti/Ni substrates were evaluated for the oxidation of methanol in alkaline media. CoNi samples were prepared potentiostatically selecting conditions adequate to achieve the desired Co/Ni ratio. All samples were characterized by X-ray fluorescence and cyclic voltammetry to determine their composition and electrochemical behaviour. The electrocatalytical performance of prepared samples was evaluated also by cyclic voltammetry using methanol solutions in alkaline media. Material composition, methanol and NaOH concentration, and temperature were the variables studied. The results indicate that a cobalt excess inhibits the methanol oxidation. In the same way, a significant enhancement of the oxidation current was observed on increasing the NaOH concentration up to 0.5 M, but for higher concentrations the electrocatalytic performance of these materials decreases. With regard to the increase of MeOH concentration or temperature, both variables are related to an improvement of the electrocatalytic performance. Finally, the effect of platinum skin on the CoNi deposits was evaluated, concluding that it favours MeOH oxidation but does not protect the substrate surface from the damage exerted by excessive NaOH concentration

Electrocatalytic oxidation of methanol on CoNi electrodeposited materials

Cobalt-nickel bimetallic materials electrodeposited on Si/Ti/Ni substrates were evaluated for the oxidation of methanol in alkaline media. CoNi samples were prepared potentiostatically selecting conditions adequate to achieve the desired Co/Ni ratio. All samples were characterized by X-ray fluorescence and cyclic voltammetry to determine their composition and electrochemical behaviour. The electrocatalytical performance of prepared samples was evaluated also by cyclic voltammetry using methanol solutions in alkaline media. Material composition, methanol and NaOH concentration, and temperature were the variables studied. The results indicate that a cobalt excess inhibits the methanol oxidation. In the same way, a significant enhancement of the oxidation current was observed on increasing the NaOH concentration up to 0.5 M, but for higher concentrations the electrocatalytic performance of these materials decreases. With regard to the increase of MeOH concentration or temperature, both variables are related to an improvement of the electrocatalytic performance. Finally, the effect of platinum skin on the CoNi deposits was evaluated, concluding that it favours MeOH oxidation but does not protect the substrate surface from the damage exerted by excessive NaOH concentration

Farming Practices in the Early Neolithic According to Agricultural Tools: Evidence from La Draga Site (Northeastern Iberia)

La Draga is an open-air settlement located on the shoreline of Lake Banyoles in the Northeast of the Iberian Peninsula. To date, two occupation phases have been differentiated, both attributed to the Early Neolithic (5300–4900 cal BC). The proximity of the lake has meant that a large part of the site has been covered by the water table; as a consequence organic materials are well preserved. The preservation of wooden artefacts offers an excellent opportunity to study the techniques and crafts developed in the first Neolithic villages. This chapter presents the wooden tools related to agricultural practices. This assemblage consists of 45 pointed sticks, 24 of which can be interpreted as digging sticks according to ethnographic and archaeological parallels and the results of a specific experimental program, and 7 sickle handles, one of which holds a flint blade still inserted in its original position. The information these implements provide for the knowledge of the first agriculture is discussed and compared with data supplied by several archaeobotanical proxies. The two approaches are seen to contribute complementary data allowing a more comprehensive reconstruction of the farming practices of Early Neolithic communities in the Western Mediterranean.Peer reviewe