Solar Energy Storage by a Heterostructured BiVO₄–PbO_<i>x</i> Photocapacitive Device

Abstract

The development of solar energy storage strategies is a key step for handling the inherent variability of sunlight within a global solar-based energy model. In the present study, we have developed a photocapacitive device based on the heterostructured BiVO 4 –PbO x system. BiVO 4 provides the photoactive core of the device, while PbO x nanoparticles (formed by the controlled oxidation of colloidal PbS quantum dots) furnish a capacitive platform by redox pseudocapacitance. The synergistic coupling of these two systems leads to high capacitance under illumination, which can be subsequently released in the dark. This integrated device exhibits excellent behavior in terms of solar light harvesting (band gap in the visible region ∼2.4 eV), with a specific capacitance of 6 mF cm –2 (4.5 mF cm –2 at discharge current density of 0.015 mA cm –2 ), high open-circuit potential (1.5 V vs RHE), and stable charge–discharge cycling during 100 cycles, opening promising research avenues in the development of novel solar energy conversion–storage strategies.