Influence of the preparation method and the support on H2O 2electrogeneration using cerium oxide nanoparticles

This work describes the influence of the preparation method and the carbon support using a low contentof cerium oxide nanoparticles (CeO2/C 4%) on H2O2electrogeneration via the oxygen reduction reac-tion (ORR). For this purpose, the polymeric precursor (PPM) and sol-gel (SGM) methods with Vulcan XC72R (V) and Printex L6 (P) supports were employed. The materials were characterized by X-ray diffrac-tion (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TheXRD analysis identified two phases comprising CeO2and CeO 2-x. The smallest mean crystallite size wasexhibited for the 4% CeO2/C PPM P material, which was estimated using the Debye-Scherrer equation tobe 6 nm and 4 nm for the CeO2and the CeO 2-xphases, respectively, and was determined by TEM to be5.9 nm. XPS analysis was utilized to compare the oxygen content of the 4% CeO2/C PPM P to Printex L6.The electrochemical analysis was accomplished using a rotating ring-disk electrode. The results showedthat the 4% CeO2/C specimen, prepared by PPM and supported on Printex L6, was the best electrocatalystfor H2O2production in 1 mol L -1NaOH. This material showed the highest ring current, producing 88%H2O2and transferring 2.2 electrons per O 2molecule via the ORR at the lowest onset potential. Addition-ally, the ring-current of the 4% CeO2/C PPM P material was higher than that of Vulcan XC 72R and PrintexL6, the reference materials for H2O 2production, indicating the highest electrocatalytic activity for the 4%CeO2/C PPM P material. © 2013 Elsevier Ltd. All rights reserved.

Informe de la Reunión del Grupo Especial de Trabajo Establecido en Virtud de la Resolución 553(XXVI) = Report of the Meeting of the Ad Hoc Working Group Established Pursuant to Resolution 553(XXVI) = Rapport de la Réunion du Groupe de Travail Spécial Créé aux Termes de la Résolution 553(XXVI)

Incluye Bibliografía

Reunión de Representantes de Países Miembros de la CEPAL ante las Naciones Unidas para Conocer el Informe de la Reunión del Grupo Especial de Trabajo = Meeting of Representatives of States Members of ECLAC to the United Nations to Hear the Report of the Meeting of the ad hoc Working Group = Réunion des Représentants des Pays Membres de la CEPALC auprès Nations Unies Visant à Prendre Connaissance du Rapport de la Réunion du Groupe de Travail Spécial

Rev.1 sólo en español

Informe del Grupo de Trabajo Intersecretarial sobre Recursos Hídricos en América Latina = Report of the Inter-Secretariat Working Group on Water Resources in Latin America

Incluye Bibliografía

Working Group on the Methodology for the Study of International Migration: introductory paper for the meeting

Se detallan los antecedentes del proceso de constitucion del grupo de trabajo sobre la metodologia para el estudio de la migracion internacional y se plantean algunas bases para la discusion en la primera reunion de dicho grupo a realizarse en Helsinki en septiembre de 1978. Se aportan datos sobre la labor desarrollada por el Centro Latinoamericano de Demografia (CELADE) en el estudio de las migraciones internacionales en los paises latinoamericanos. Se inserta la agenda de la reunion de Helsinki.