Indian scientists have developed a sunlight-powered, self-charging energy storage device that can both capture and store solar energy within a single integrated system. The innovation, known as a photo-capacitor, marks a significant step towards clean, low-cost and self-sustaining power solutions for portable, wearable and off-grid applications.

The device has been developed by researchers at the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous institute under the Department of Science and Technology. Unlike conventional solar systems that rely on separate units for energy harvesting and storage, the photo-capacitor combines both functions, reducing system complexity, energy losses and overall footprint.

The research team, led by Dr Kavita Pandey, used binder-free nickel–cobalt oxide (NiCo?O?) nanowires grown directly on nickel foam through an in-situ hydrothermal process. The nanowires form a highly porous, conductive three-dimensional network that efficiently absorbs sunlight while simultaneously storing electrical charge.

Under illumination, the NiCo?O? electrode demonstrated a 54 per cent increase in capacitance, rising from 570 to 880 mF cm?² at a current density of 15 mA cm?². The electrode retained about 85 per cent of its capacity even after 10,000 charge–discharge cycles, highlighting its durability for long-term use.

To assess real-world performance, the researchers developed an asymmetric photo-supercapacitor using activated carbon as the negative electrode. The device delivered a stable output of 1.2 volts, maintained 88 per cent capacitance after 1,000 photo-charging cycles, and operated reliably under a wide range of lighting conditions, from indoor illumination to high solar intensity.

The study also included theoretical simulations that explained the material’s high efficiency. Nickel substitution in the cobalt oxide framework narrowed the band gap and induced half-metallic behaviour, enabling faster charge transport and improved conductivity—key advantages for photo-assisted energy storage.

Published in Sustainable Energy & Fuels by the Royal Society of Chemistry, the research introduces a new class of smart, photo-rechargeable energy storage devices. The innovation is expected to support India’s clean energy ambitions by enabling decentralised, grid-independent power systems and reducing reliance on conventional batteries and fossil fuels.