A study published in Advanced Materials by Wiley-VCH GmbH, with researchers from the Changchun University of Technology and the Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, demonstrated a new method to significantly improve the performance and longevity of devices that generate electricity from atmospheric moisture. By integrating a light-sensitive component, the team created a device that overcomes a major limitation of conventional moisture electricity generators (MEGs).

MEGs operate by harnessing the natural movement of ions, driven by a concentration gradient created as the device absorbs water from the air. However, a persistent challenge has been performance decay. Over time, ions accumulate and saturate the gradient, which diminishes the driving force for ion migration and drastically reduces electrical output.

To address this, the researchers designed a photon moisture electricity generator (P-MEG). The key innovation was a photosensitive layer electrode made from a heterojunction of mesoporous titanium dioxide sensitized with CdS/CdSe quantum dots. This layer was combined with a proton-conducting hydrogel and a bottom moisture-absorbing layer.

The team found that when illuminated, the photosensitive layer generated electron-hole pairs. The excited electrons then participated in a reduction reaction, converting accumulated protons (H⁺) at the electrode interface into hydrogen gas (H₂). This process continuously consumed ions on one side, thereby reconstructing the ion concentration gradient that is essential for sustained power generation. The production of H₂ was directly confirmed using gas chromatography, and a measurable increase in the local pH near the electrode provided further evidence for the consumption of H⁺ ions.

Experimental results showed that this light-induced mechanism substantially enhanced the device's electrical output. Under 80% relative humidity, illumination increased the P-MEG's output voltage from 0.55 to 0.65 V, boosted the current density from 17.5 to 34.5 µA cm⁻², and raised the power density from 8.26 to 26.7 µW cm⁻². The device also exhibited a stable, repeatable current response under intermittent light and maintained a stable voltage output over five days in a natural day-night cycle.

The P-MEG demonstrated functionality in diverse conditions. It powered small electronics like LEDs and sensors, responded to human breathing for potential health monitoring, and even operated in sub-zero environments, generating a voltage of 0.56 V in a snowy setting at -22 °C.

This work provides a viable strategy to break the ion saturation bottleneck in moisture-enabled energy harvesting. The synergistic use of light and moisture opens a pathway for developing more stable and efficient power sources for wearable electronics and environmental sensors.