Evaporation-driven hydrovoltaic energy harvesting with surface-modified carbonized silk fabrics: Mechanisms and wearable applications

Evaporation-driven hydrovoltaic energy harvesting offers a sustainable and promising solution for wearable energy applications. Herein, we report an optimized hydrovoltaic generator based on acid-treated carbonized silk fabrics (ACSF), further functionalized with sodium p-styrene sulfonate (SSS) via in-situ polymerization. The incorporation of oxygen-containing groups (e.g., –COOH and –OH) and sulfonic acid groups (–SO₃H) significantly enhanced the hydrophilicity, surface charge density, and ion transport efficiency of the fabrics. As a result, the optimized PACSF reaches an open-circuit voltage (V oc ) of 288 mV and a short-circuit current (I sc ) of 35 μA under ambient evaporation conditions. V oc and I sc further increases to 0.56 V and 39 μA with artificial sweat. Moreover, an Al C electrode configuration enables a current density of ~560 μA cm −2 together with a power density of ~366 μW cm −3 . The evaporation-driven mechanism was systematically investigated, demonstrating the critical role of surface functionalization in modulating water transport dynamics and charge transfer. PACSF devices exhibited excellent durability, scalability, and tunable electrical output, enabling practical applications in low-power wearable electronics. This work provides insights into the design of hydrovoltaic materials and their potential for integration into wearable energy systems.