Factors Influencing the Supply Efficiency of Basic Public Service at County Level

In this paper,we use DEA-Tobit model to conduct empirical study on the governmental supply efficiency of public service in Chongqing's 38 counties and the influencing factors during the period 2008-2011.The results show that the supply efficiency of basic public service at county level is generally low,and there is significant regional differences and strong volatility;per capita GDP,population density and population size,and level of education of the residents,are significantly correlated with the supply efficiency of basic public service at county level,but traffic density,urbanization level,and the proportion of government spending on public service to total fiscal expenditure,have no significant effects on the efficiency of basic public service at county level.Based on this,we propose some policy recommendations for enhancing the level of local economic development and the level of education,and reasonably guiding the residents'agglomeration.

Single-Site Cu-Doped PdSn Wavy Nanowires for Highly Active,Stable,and CO-Tolerant Ethanol Oxidation Electrocatalysis

Developing a catalyst to break the tradeoff relation-ship between the catalytic activity and antipoisoning property toward the ethanol oxidation reaction(EOR)is of critical importance to the development of direct ethanol fuel cells(DEFCs),but remains challenging.Here,we developed a unique class of single-site Cu-doped PdSn wavy nanowires(denoted as SS Cu−PdSn WNWs)with promoted activity and durability toward alkaline EOR.Detailed characterizations reveal the atomic isolation of Cu species dispersed on the surface of the PdSn WNWs with distinct wavy structure and grain boundaries.The created SS Cu−PdSn WNWs exhibit an enhanced EOR performance in terms of mass activity,which is higher than those of PdSn WNWs,commercial Pd black,and commercial Pd/C,respectively.Moreover,the SS Cu−PdSn WNWs can also show improved stability as compared to other catalysts due to the improved antipoisoning property from the unique surface anchoring structure.Further investigations demonstrate that the doped SS Cu can strongly inhibit the adsorption of CO and promote the reaction process of EOR.DFT results reveal that the doped Cu shifts down the d-band center of PdSn,thereby modifying the adsorption of intermediates and reducing the reaction barrier of EOR.This work maps a pathway for optimally boosting EOR performance with surface engineering via atomic doping.

Atomically isolated Pd sites within Pd-S nanocrystals enable trifunctional catalysis for direct,electrocatalytic and photocatalytic syntheses of H_(2)O_(2)

Although high-efficiency production of hydrogen peroxide(H_(2)O_(2))can be realized separately by means of direct,electrochemical,and photocatalytic synthesis,developing versatile catalysts is particularly challenging yet desirable.Herein,for the first time we reported that palladium-sulphur nanocrystals(Pd-S NCs)can be adopted as robust and universal catalysts,which can realize the efficient O_(2) conversion by three methods.As a result,Pd-S NCs exhibit an excellent selectivity(89.5%)to H_(2)O_(2)with high productivity(133.6 mol·kgcat^(−1)·h^(−1))in the direct synthesis,along with the significantly enhanced H_(2)O_(2)production activity and stability via electrocatalytic and photocatalytic syntheses.It is demonstrated that the isolated Pd sites can enhance the adsorption of O_(2) and inhibit its O–O bond dissociation,improving H_(2)O_(2)selectivity and reducing H_(2)O_(2)degradation.Further study confirms that the difference in surface atom composition and arrangement is the key factor for different ORR mechanisms on Pd NCs and Pd-S NCs.

A top–down strategy to realize the synthesis of small-sized L10 - platinum-based intermetallic compounds for selective hydrogenation

The synthesis of Pt-based nanoparticles(NPs)with ultrasmall feature and tailored structure is of great importance for catalysis yet challenging.In this work,we demonstrate a facile top–down strategy for the fabrication of small-sized Pt-based intermetallic compounds(IMCs)with L10 structure through the evaporation of Cd under high temperature.Impressively,such thermal treatment can be used as a versatile strategy for creating binary,ternary,quaternary,quinary,and senary L10-Pt-based IMCs.Moreover,the small-sized Pt-based IMCs display high stability against high temperature of 700℃,which can serve as active and selective catalyst for the selective hydrogenation of 4-nitrophenylacetylene.This work may not only provide a versatile top–down strategy for fabricating highly stable small-sized Pt-based NPs with L10 structure,but also promote their extensive applications in catalysis and beyond.

Facet and dimensionality control of Pt nanostructures for efficient oxygen reduction and methanol oxidation electrocatalysts

The control of the size, composition, and shape of platinum nanocrystals has attracted much attention recently, mostly due to their unique properties and related catalytic functionalities. However, the realization of platinum nanocrystals with controlled exposed facets and dimensionality remains a significant challenge. Herein, we show an efficient synthetic strategy to selectively prepare highly controllable platinum nanocrystals with distinct dimensionalities from onedimensional nanowires to zero-dimensional octahedra. Although the synthesis of platinum nanowires has been reported multiple times, the synthetic approach reported herein is much more novel and robust and ultimately results in high yields of high-quality platinum nanowires. Such dimensionality tuning on {111} facet dominated platinum nanocrystals allows us to firstly investigate the effect of the number of edges/corners on the electrocatalytic properties. Our results show that the synthesized platinum nanocrystals exhibit very interesting dimensionality-dependent electrocatalytic activity towards both the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR), in which one-dimensional platinum nanowires with minimized edges/corners show enhanced electrocatalytic activities with respect to zero-dimensional platinum octahedra. Our dimensionality tuning also provides Pt nanowires with superior durability for the oxygen reduction reaction with negligible activity decay over the course of 30,000 potential sweeps. The present work highlights that the {111} facet bound platinum nanowires with minimized edges/corners are indeed promising candidates as electrocatalysts with excellent activity and superior durability. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.