An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due ...An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due to the synergistically enhanced kinetics on enriched active sites and reconfigured electronic band structure. Here this work introduces hierarchical heterostructures into a NiMo@NiS/MoS_(2)@Ni_(2)S_(2)/MoO_(x)(NiMoS) composite by one-pot controlled moderative sulfidation. The optimal solvent composition and addition of NaOH enable NiMoS to own loose and porous structures, smaller nanoparticle sizes, optimal phase composition and chemical states of elements, improving the OER activity of NiMoS. To achieve current densities of 50 and 100 mA cm^(-1), small overpotentials of 275 and 306 mV are required respectively, together with a minor Tafel slope of 58 mV dec^(-1), which outperforms most reported sulfide catalysts and IrO_(2). The synergistic effects in the hierarchical heterostructures expose more active sites,adjust the electronic band structure, and enable the fast charge transfer kinetics, which construct an optimized local coordination environment for high OER electrocatalytic activity. Furthermore, the hierarchical heterostructures suppress the distinct lowering of electrical conductivity and collapse of pristine structures resulted from the metal oxidation and synchronous S leaching during OER, yielding competitive catalytic stability.展开更多
After the oilfield development enters the period of extra-high water cut, the permeability of the area near the well is reduced due to the erosion and dissolution of cement by water. At the same time, due to the frequ...After the oilfield development enters the period of extra-high water cut, the permeability of the area near the well is reduced due to the erosion and dissolution of cement by water. At the same time, due to the frequent production of layer adjustment, there is a phenomenon of multiple layers drilled in a well, which increases the construction difficulty. According to the difference of oil-water density, there is also a high water cut section in one interval, and there is a phenomenon that the oil-bearing section is in the upper part and the water-bearing section is in the lower part. According to the research results of "universal distribution and local enrichment" of the remaining oil in geological institute, the material basis of deep digging potential still exists in the high water cut rear stratified section. Guided by the concept of moderate sand control, through the analysis of oil well sand production, the application of remaining oil distribution, the research and application of water control and sand control technology in complex well conditions, and the research of moderate water control technology with complementary advantages, a set of technology suitable for combining sand control and water control in Gudao Oilfield has finally been formed. The application of this technology has achieved the purpose of simplifying downhole string and prolonging water control period.展开更多
基金financial supports from the National Natural Science Foundation of China (52004155,51690164, and 51805321)the China Postdoctoral Science Foundation (2020M681261)the Science and Technology Commission of Shanghai Municipality (19XD1401600 and 19010500300)。
文摘An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due to the synergistically enhanced kinetics on enriched active sites and reconfigured electronic band structure. Here this work introduces hierarchical heterostructures into a NiMo@NiS/MoS_(2)@Ni_(2)S_(2)/MoO_(x)(NiMoS) composite by one-pot controlled moderative sulfidation. The optimal solvent composition and addition of NaOH enable NiMoS to own loose and porous structures, smaller nanoparticle sizes, optimal phase composition and chemical states of elements, improving the OER activity of NiMoS. To achieve current densities of 50 and 100 mA cm^(-1), small overpotentials of 275 and 306 mV are required respectively, together with a minor Tafel slope of 58 mV dec^(-1), which outperforms most reported sulfide catalysts and IrO_(2). The synergistic effects in the hierarchical heterostructures expose more active sites,adjust the electronic band structure, and enable the fast charge transfer kinetics, which construct an optimized local coordination environment for high OER electrocatalytic activity. Furthermore, the hierarchical heterostructures suppress the distinct lowering of electrical conductivity and collapse of pristine structures resulted from the metal oxidation and synchronous S leaching during OER, yielding competitive catalytic stability.
文摘After the oilfield development enters the period of extra-high water cut, the permeability of the area near the well is reduced due to the erosion and dissolution of cement by water. At the same time, due to the frequent production of layer adjustment, there is a phenomenon of multiple layers drilled in a well, which increases the construction difficulty. According to the difference of oil-water density, there is also a high water cut section in one interval, and there is a phenomenon that the oil-bearing section is in the upper part and the water-bearing section is in the lower part. According to the research results of "universal distribution and local enrichment" of the remaining oil in geological institute, the material basis of deep digging potential still exists in the high water cut rear stratified section. Guided by the concept of moderate sand control, through the analysis of oil well sand production, the application of remaining oil distribution, the research and application of water control and sand control technology in complex well conditions, and the research of moderate water control technology with complementary advantages, a set of technology suitable for combining sand control and water control in Gudao Oilfield has finally been formed. The application of this technology has achieved the purpose of simplifying downhole string and prolonging water control period.
