The development of bifunctional electro-catalysts with high efficiency toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic media still remains challenge. Herein, we report a seed-mediated...

Hybridizing Pd-based electrocatalysts with Ni-based species has been recognized as an effective pathway to enhance the catalytic performance for methanol oxidation reaction (MOR). However, doping Ni-based species with heterogeneous valence...

The metropolitan area is the inevitable trend of urbanization towards an advanced form. The pattern of urban radiation is the key to building a metro area and promoting high-quality regional development. In order to effectively promote the rationalization of metropolitan areas and regional integration development, this paper takes the Yangtze River Delta (YRD) region as an example, calculates the intensity of city centrality (ICC) based on the statistical data, and explores the radiation pattern and spatial relationship of cities at different levels by using methods such as the extended breaking point model and the hierarchical Voronoi diagram. The research results show that: (1) The ICC in the YRD shows a spatial pattern of “high in the east and low in the west, high in the middle and low in the north and south”. (2) The ICC value of “strong-strong” adjacent cities shows the tendency of the radiation range to shrink and that the radiation direction is perpendicular to both sides. The “strong-weak” adjacent cities’ radiation range and direction show an expansion–contraction trend. The radiation range and direction of “weak-weak” adjacent cities exhibit disorder. (3) Because the ICC is hierarchical, urban radiation is a polycentric, nested circle structure. Shanghai is the first-level center, and Hangzhou, Nanjing, Ningbo, Hefei, and Xuzhou are the second-level centers. (4) The sequence of the spatial morphological complexity and stability in each circle, from complex to simple, is the Hangzhou circle, the Shanghai circle, the Xuzhou circle, the Hefei circle, and the Nanjing circle. The spatial morphological characteristics of the Ningbo circle do not meet the morphological dimension conditions. The study of the polycentric circle structure is of practical significance for the enhancement of the radiation driving effect of the central city and the expansion and improvement of the metropolitan area.

Concave nanostructure with highly branched architecture and abundant step atoms is one kind of desirable materials for energy conversion devices. However, current synthetic strategies for non‐noble metal‐based NiCoP concave nanostructure still remain challenging. Herein, we demonstrate a site‐selective chemical etching and subsequent phosphorating strategy to fabricate highly branched NiCoP concave nanocrosses (HB‐NiCoP CNCs). The HB‐NiCoP CNCs are consisted of six axial arms in three‐dimensional space and each protruding arm is equipped with high‐density atomic steps, ledges and kinks. As an electrocatalyst towards oxygen evolution reaction, the HB‐NiCoP CNCs exhibit remarkably enhanced activity and stability, with small overpotential of 289 mV to reach 10 mA cm−2, surpassing the NiCoP nanocages and commercial RuO2. The superior OER performance of HB‐NiCoP CNCs is originated from the highly branched concave structure, the synergistic effect between bimetal Ni and Co atoms, as well as the electronic structure modulation from P.