A photocapacitor based on a perovskite solar cell and PANI/CNT supercapacitor with large capacitance was integrated using a CNT bridge.

Based on porous carbon nanotube/polyaniline composite (CNT/PANI) and poly(vinyl alcohol) gel, we fabricated centimeter-sized hydrocapacitors with dual functions of energy conversion and storage with an efficient lowcost method. Owning to excellent hydrophily and large specific capacitance of CNT/PANI, the hydrocapacitors can easily convert energy from water movement induced by capillarity, gravity, or air pressure difference into electricity and store the generated electricity. Especially, sandwich-like hydrocapacitors outputted large current of 1.65 mA through an external load of 100 Ω, and hydrocapacitors showed good extendibility by connecting in series. To explain the mechanism of hydrocapacitors in this work, a possible model based on capillarity and traditional streaming potential was proposed and discussed. Hydrocapacitors here also provide a reference for future integration of nanogenerators and energy storage parts.

As a distinctive type of energy devices, supercapacitors have received great attention because of their practical applications in recent years. In this work, a selfcharging phenomenon induced by gravity is reported in paperlike supercapacitors, which consisted of two polyaniline/ carbon nanotube composite (PANI/CNT) electrodes and a polyvinyl alcohol/H 2 SO 4 (PVA/H 2 SO 4 ) gel electrolyte. Without external electric power supply, the PANI/CNT supercapacitors could provide a maximal output voltage of 0.15 V in ambient environment (24 °C, relative humidity about 60%). Concentration gradient-induced potential difference was excluded for our experiments. Our investigation reveals that the self-charging phenomenon in these supercapacitors can be explained by the gravity-induced streaming potential. As this phenomenon has not been reported before, we hope it could provide new ideas for self-charging energy storage devices.

High-performance piezo-phototronic multijunction solar cells based on single-type two-dimensional materials,

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Intrinsic polarization has been demonstrated in layered structures to reduce the energy gap. Here we demonstrate that strain-induced polarization can increase energy gap and induce a metallic-to-semiconducting phase transition in zigzag nanoribbons of single-layered transitionmetal dichalcogenides, such as MoS2, MoSe2, WS2 and WSe2. This study provides a guidance for designing quantum piezotronic devices.

No abstract

To deepen our understanding of reservoir heterogeneity, seepage barriers in the study area were divided into interlayer, intralayer, and planar levels based on their spatial distribution characteristics and then investigated by taking the third member of the Neogene Guantao Formation in the block M of the Gudao oilfield as an example. Based on their genesis characteristics, the interlayer seepage barriers were divided into the overbank sand-overbank sand type, overbank sand-channel type, isolated channel superposition type, and channel shallow-cut type. The planar seepage barriers were categorized into the channel boundary type, abandoned channel type, channel-overbank sand type, and floodplain mudstone type. The intralayer seepage barriers were classified into the mudstone type and physical property type. Classifying multiple levels of different types of seepage barriers led to the refinement of their spatial characteristics. The strength of seepage barriers was characterized using the “seepage barrier coefficient” and “reservoir quality coefficient,” and the small-valued coefficients of the interlayer and intralayer seepage barriers indicated that these seepage barriers are characterized by large thickness, high mudstone content, poor physical properties, and weak seepage ability. The strength of the planar seepage barriers was dependent on the sedimentary facies types and channel stages, and the difference between planar seepage barriers was characterized using the reservoir quality coefficient. The seepage barriers were described based on the multilevel classification of seepage barrier categories, the intralayer seepage barriers with a lateral accretion pattern in the meandering river point bars were identified and described, and the distribution characteristics of seepage barriers were summarized at multiple levels. The method of “hierarchical analysis, skeleton construction, and category fitting” was used to establish 3D models of different levels of seepage barriers, and a modeling method based on the characteristics of intralayer seepage barriers under the constraint of architecture pattern was used to model intralayer seepage barriers with a lateral accretion pattern. In the monitoring of water injection profiles, it was found that the extent of blockage achieved by seepage barriers affects the water injection volume and thus controls the fluid transport pattern. Due to the development characteristics of the seepage barrier in the formation, there are some differences in injection production efficiency under different well pattern matching modes. The research on the distribution characteristics of different levels of seepage barrier categories provides a reliable geological basis for improving the injection-production relationship.