# Enhancing hydrovoltaic power generation through coupled heat and light-driven surface charge dynamics

## TL;DR

This paper introduces a new framework for evaporation-driven energy devices that improves electricity generation by controlling surface charge dynamics and achieving 1V output.

## Contribution

A unified framework decouples and controls interfacial processes in hydrovoltaic systems, revealing capacitive and thermal mechanisms as key to energy conversion.

## Key findings

- Capacitive photocharging and thermal surface equilibria dominate energy conversion in EDHV systems.
- The device achieves 1 V open-circuit voltage and 0.25 W/m² power density.
- Material engineering, such as silicon doping and dielectric choice, enhances performance.

## Abstract

Harnessing natural evaporation offers a sustainable pathway for next-generation energy technologies. We present a unified physical and experimental framework for evaporation-driven hydrovoltaic (EDHV) systems that decouples and controls the key interfacial processes underlying electricity generation from heat and sunlight. An intermediate ion-conducting layer separates the evaporative top interface from the silicon–dielectric nanopillar array, enabling independent modulation of evaporation, ion transport, and interfacial chemical equilibrium. This strategy enhances performance and clarifies mechanisms governing thermal and photo-induced charge generation, improving ion migration and electricity output. We develop a predictive equivalent-circuit model that captures process coupling through an analytically derived transfer capacitance. Our results show that capacitive photocharging and thermally modulated surface equilibria—rather than faradaic or photothermal effects—dominate energy conversion. The device achieves 1 V open-circuit voltage and 0.25 W/m² power density, with silicon doping and dielectric choice further boosting performance. These findings inform EDHV optimization across environmental and material conditions.

A framework for evaporation-driven hydrovoltaic devices decouples interfacial processes, revealing capacitive, thermal, and surface-charge mechanisms that boost energy generation, enabling 1 V output and improved performance via material engineering.