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.