Enhanced hydrogen evolution reaction in Sr doped BiFeO_(3) by achieving the coexistence of ferroelectricity and ferromagnetism at room temperature

The perovskite transition metal oxide(TMO) has been considered in electrocatalysis for the modern clean energy technologies as its high electrochemical activity and low cost. The atomic scale engineering to the local stoichiometry of single crystal TMO provides a clue of the relation between electronic structure and catalytic performance. Here we report a hydrogen evolution reaction(HER) activity enhancement ~ 1761% of Bi_(0.85)Sr_(0.15)FeO_3 compared to the pure BiFeO_3. By the systemic investigation of the Sr doping level of Bi_(1-x)Sr_xFeO_3(BSFO), it is found that the HER enhancement originates from the improvement of ferromagnetism of BSFO without obvious scarification of the ferroelectricity at the room temperature. The multiple ferroic orderings in BSFO are beneficial for HER activity, which offers the strengthen of hybridization of Fe 3d and O2 p orbitals from the view of ferromagnetism, and the assistance of electron drift by spontaneous electric polarization. Our study not only affords the strategy of developing multiple ferroic orderings in TMO, but also facilitates the atomic scale understanding of the improved HER activity.

D-Ocean： an unstructured data management system for data ocean environment

Together with the big data movement, many organizations collect their own big data and build distinctive applications. In order to provide smart services upon big data, massive variable data should be well linked and organized to form Data Ocean, which specially emphasizes the deep exploration of the relationships among unstructured data to support smart services. Currently, almost all of these applications have to deal with unstructured data by integrating various analysis and search techniques upon massive storage and processing infrastructure at the application level, which greatly increase the difficulty and cost of application development. This paper presents D-Ocean, an unstructured data management system for data ocean environment. D-Ocean has an open and scalable architecture, which consists of a core platform, pluggable components and auxiliary tools. It exploits a unified storage framework to store data in different kinds of data stores, integrates batch and incremental processing mechanisms to process unstructured data, and provides a combined search engine to conduct compound queries. Furthermore, a so-called RAISE process modeling is proposed to support the whole process of Repository, Analysis, Index, Search and Environment modeling, which can greatly simplify application development. The experiments and use cases in production demonstrate the efficiency and usability of D-Ocean.