Defining stratigraphic oil and gas plays by modifying structural plays:A case study from the Xihu Sag,east China Sea Shelf Basin

The study focuses on an area of relatively mature oil and gas exploration located in the western slope of the Xihu Sag,East China Sea Shelf Basin.Three stratigraphic oil and gas plays are introduced to replenish the shrinking prospect inventory in the area.The reservoirs of these plays are traditional pay intervals of the Eocene Pinghu Formation and Baoshi Formation composed of tide-dominated delta front,tidal flat and delta front sand bar facies.By investigating conventional seismic data,seismic inversion volumes,and well log data,multiple tidal-influenced delta front channels,beach sand packages have been mapped out in different reservoir sand intervals of the Pinghu Formation and Baoshi Formation.We recognize four types of stratigraphic terminations:channel flank pinch-outs,axial pinch-outs of sand-fills,channel mouth sand bar pinch-outs,and onlap pinch-outs for the Baoshi Formation.Both the depositional facies and relatively low sand-shale ratio of the reservoir formations favor the occurrence of stratigraphic terminations.The closure mechanism of all these plays are similar to the traditional structure plays in the area:fault blocks or fault-bounded rollover anticlines,except that one or more closing faults are replaced by these stratigraphic terminations.Several small-sized closures should exist but the relatively large ones are centered around a major intra-slope rise,raising the exploration potential in this maturely explored area.The new exploration drilling campaign has so far tested the play of delta front channel facies,with three out of four wells commercially successful.These play concepts open up a novel approach to identify new traps in the study area and many other rift basins with similar settings in eastern China.

Space-confined growth of monolayer ReSe2 under a graphene layer on Au foils

Vertical heterostructures based on two-dimensional(2D)materials have attracted widespread interest for their numerous applications in electronic and optoelectronic devices.Herein,we report the direct construct!on of an abnormal graphene/ReSe2 stack on Au foils by a two-step chemical vapor deposition(CVD)strategy.During the second growth stage,mono layer ReSe2 is found to prefere ntially evolve at the irUerface between the first-grown graphene layer and the Au substrate.The unusual stacking behavior is unraveled by in-situ"cutting open"the upper graphene from the defects to expose the lower ReSe2 using scanning tunneling microscopy(STM).From combination of these results with density functional theory calculations,the domain boundaries and edge sites of graphene are proposed to be adsorption sites for Re and Se precursors,further facilitating the growth of ReSe2 at the van der Waals gap of graphene/Au.This work hereby offers an intriguing strategy for obtaining vertical 2D heterostructures featured with an ultra-clean interface and a designed stacking geometry.

Scalable salt-templated directed synthesis of high-quality MoS_(2) nanosheets powders towards energetic and environmental applications

Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have emerged as perfect platforms for developing applications in nano-electronics,catalysis,energy storage and environmental-related fields due to their superior properties.However,the low-cost,batch production of high-quality 2D TMDCs remains a huge challenge with the existing synthetic strategies.Herein,we present a scalable chemical vapor deposition(CVD)approach for the batch production of high-quality MoS_(2) nanosheet powders,by using naturally abundant,water-soluble and recyclable NaCl crystal powders as templates.The high-quality MoS_(2) nanosheets powders are achieved by a facile water dissolution-filtration process,by virtue of the excellent dispersibility of the as-grown products in water.The internal mechanism for the scalable synthesis strategy is explored.The applications of the MoS_(2) nanosheets powders are also demonstrated as catalysts or adsorbents in hydrogen evolution reaction(HER)and organic dyes adsorption,respectively.This work should hereby pave ways for the mass production and application of powdery TMDCs in energetic and environmental related fields.

Salt-assisted growth and ultrafast photocarrier dynamics of large-sized monolayer ReSe2

Owing to its anisotropic optical and electrical properties,rhenium diselenide(ReSe2)has garnered considerable attention recently as a candidate material for polarization-sensitive photodetectors.However,the direct and controllable synthesis of large-sized ReSe2 with a uniform thickness is still a great challenge.Herein,we have refined the synthesis method to obtain uniform monolayer ReSe2 flakes with a size of up to^106μm on sapphire via an ambient-pressure chemical vapor deposition technique using Na promoter from sodium chloride.Interestingly,optical pump-probe spectroscopy revealed a fast switching from saturable absorption(SA)to absorption enhancement(AE)in subpicosecond time scale,followed by a slower decay induced by exciton recombination.Furthermore,both AE and SA signals exhibited clear angular dependence with a periodicity of 180°,which reflected the dichroism in nonlinear absorption dynamics.In addition,the photocarrier dynamics including free-carrier transport and subpicosecond relaxation due to exciton formation or surface trapping was probed using time resolved terahertz spectroscopy.We believe that our study serves as a reference for atomically controlled synthesis of large-sized ReSe2 and provides useful insights on its optoelectronic properties for novel device applications.

Application of chemical vapor-deposited monolayer ReSe2 in the electrocatalytic hydrogen evolution reaction

Controlled synthesis of structurally anisotropic rhenium diselenide （ReSe2） with macroscopically uniform and strictly monolayer thickness as well as tunable domain shape/size is of great interest for electronics-, optoelectronics-, and electrocatalysis-related applications. Herein, we describe the controlled synthesis of uniform monolayer ReSe2 flakes with variable morphology （sunflower- or truncated-triangle-shaped） on SiO2/Si substrates using different ambient-pressure chemical vapor deposition （CVD） setups. The prepared polycrystalline ReSe2 flakes were transferred intact onto Au foil electrodes and tested for activity in the hydrogen evolution reaction （HER）. Interestingly, compared to the compact truncated-triangle-shaped ReSe2 flakes, their edge-abundant sunflower-shaped counterparts exhibited superior electrocatalytic HER activity, featuring a relatively low Tafel slope of - 76 mV/dec and an exchange current density of 10.5 μA/cm2. Thus, our work demonstrates that CVD-grown ReSe2 is a promising two- dimensional anisotropic material for applications in the electrocatalytic HER.