RESUMO
NiFe-based oxo-hydroxides are highly active for the oxygen evolution reaction but require complex synthesis and are poorly durable when deposited on foreign supports. Herein we demonstrate that easily processable, Earth-abundant and cheap Fe-Ni alloys spontaneously develop a highly active NiFe oxo-hydroxide surface, exsolved upon electrochemical activation. While the manufacturing process and the initial surface state of the alloys do not impact the oxygen evolution reaction performance, the growth/composition of the NiFe oxo-hydroxide surface layer depends on the alloying elements and initial atomic Fe/Ni ratio, hence driving oxygen evolution reaction activity. Whatever the initial Fe/Ni ratio of the Fe-Ni alloy (varying between 0.004 and 7.4), the best oxygen evolution reaction performance (beyond that of commercial IrO2) and durability was obtained for a surface Fe/Ni ratio between 0.2 and 0.4 and includes numerous active sites (high NiIII/NiII capacitive response) and high efficiency (high Fe/Ni ratio). This knowledge paves the way to active and durable Fe-Ni alloy oxygen-evolving electrodes for alkaline water electrolysers.
RESUMO
Autism is now thought to be present right from birth. Although usually not officially diagnosed until after the child's second birthday, parents often report disturbances before then. The age of detection of disturbances varies and may be linked to differences in the severity of the autism and its associated retardation. This study evaluates the developmental characteristics of 193 children with pervasive developmental disorder, using the same standard procedures for all subjects. Our goal was to determine the relationship between age of parental recognition of disturbances and disorder severity. The results indicated mainly a link between early abnormalities, associated medical condition and severity measured on cognitive tests. They suggest systematic screening for signs of autism in very young children.