Toward photocatalytic hydrogen generation over BiVO_(4) by controlling particle size

Owing to excellent light absorption and high activity fo r oxygen evolution,monoclinic bismuth vanadate(BiVO_(4)) is regarded as an ideal candidate for photocatalytic water splitting.However,its application is limited by the large particle size in micrometer scale,as well as the slightly positive conduction band.In this work,we successfully synthesized nano-BiVO_(4) with particle size ranged from 27 nm to 57 nm by wet chemical method based on electrostatic spinning method.Unlike bulk BiVO_(4),the nano-sized BiVO_(4) possesses the ability to generate hydrogen by water splitting,and the activity could reach up to1.66 μmol h^(-1) g^(-1) with the assistance of Pt.The enhanced activity is mainly attributed to the improvements resulted from reduced particle size,which includes elevated conduction band,enlarged specific surface area and promoted charge separation.This work provides a simple method for synthesizing photocatalyst with small particle size and high yield.

Reservoir characteristics and well-logging evaluation of the Lower Cambrian shales in southeast Chongqing, China

To accurately identify the reservoir characteristics and main controlling factors of the Cambrian Niutitang black shale in the southeast Chongqing,a series of systematic measurements were conducted on core samples from Well Yuke-1 and Well Youke-1.The measurements include clay mineral analysis,XRD analysis,petrophysical properties,specific surface area,pore diameter and TOC,as well as R_(o) and maceral compositions.The Niutitang shale reservoir contains detrital minerals and clay minerals averagely of 51.34%and 32.74%,respectively.The average effective porosity and permeability are 1.2%and 8.0×10^(-3)mD,respectively,typically of ultra-low porosity and permeability.Mesopores are dominant,accounting for approximately 73%of the total pore volume.The average BET specific surface area is 7.75m^(2)/g and the average pore diameter is 5.3nm.The average TOC is 2.29%and the average R_(o) is 3.12%,indicating that the organic matter is in over-maturity stage.Statistical analyses of the measurements show that the micropore volume is positively correlated with TOC but negatively correlated with the total content of clay minerals;the mesopore volume is positively correlated with TOC,the total content of clay minerals and the con­tent of carbonate minerals;the macropore volume is positively correlated with TOC and the con­tent of carbonate minerals,weakly positively correlated with the content of detrital minerals but negatively correlated with the total content of clay minerals.The porosity and TOC of the Niuti­tang shale are computed using the conventional well-logging method for the Yuke-1 and Youke-1 wells,and the porosities are quite consistent with the core analysis resultsr,but in the shallow res­ervoir that contains no oil and gas,the TOC exhibits no correlation with the core analysis results.

Petrophysical Characteristics of Silurian Mudstones from Central Taurides in Southern Turkey

This study used a range of integrated and complementary experiments to examine porestructure,fluid-shale wetting characteristics,sample size-dependent porosity towards different fluids,and imbibition behavior,as well as the relationships between these properties and the mineralogy of Silurian mudstones in the Central Taurides of Turkey.Working with different sample-sizes,the experiments consisted of helium pycnometry,low-pressure nitrogen physisorption isotherm,mercury intrusion porosimetry,fluid immersion porosimetry,liquid displacement,fluid droplet wettability and contact angle measurements,and spontaneous imbibition of fluids;four fluids with different hydrophilicity were used to assess the characteristics of fluid-shale interaction and its influence on porestructure.Results show that studied mudstones can be grouped into three rock types:siliceous,carbonate-dominated,and mixed mudstones.Siliceous and mixed mudstones have higher porosities,pore-throat diameters,surface areas and tortuosities than the carbonate-dominated mudstones,regardless of sample sizes and fluids used.With low permeabilities and medium pore-throat sizes for the siliceous and mixed mudstones,the wettability and imbibition results show that these mudstones are both oil-wet and moderately-to-high water-wet.In contrast,the carbonate-dominated mudstones exhibit oil-wet characteristics.These results indicate that studied siliceous and mixed mudstones in the Central Taurides seem to have appropriate petrophysical properties in the context of reservoir quality.