A Tap-Water-Driven Triboelectric Nanogenerator for Pulsed Electrical Assistance of Photoelectrochemical Water Splitting

Abstract A tap-water-driven triboelectric nanogenerator (TAPTENG) system based on a reciprocating sliding triboelectric nanogenerator was developed as an external bias source for photoelectrochemical (PEC) water splitting. The TAPTENG converts the rotational motion of a water turbine into reciprocating sliding motion through a Scotch yoke-inspired mechanism, enabling stable triboelectric power generation under flowing tap water. The system generated an open-circuit voltage of 31 V and a short-circuit current of 1.1 μA at approximately 3 Hz (180 rpm), corresponding to normal household tap-water flow conditions, and successfully powered 50 LEDs. The generated electrical output was applied to a TiO2 nanorod (NR)/p-Si photocathode under simulated solar illumination. Linear sweep voltammetry showed stable PEC operation, while the TAPTENG bias increased the photocurrent density across the measured potential range. Differential photocurrent analysis revealed a maximum enhancement of 1.39 mA cm−2 at −1.0 V vs. RHE, corresponding to a 5.4% increase compared with the TAPTENG-off condition. The enhancement gradually decreased at more positive potentials, indicating that the triboelectric bias is more effective under kinetically limited cathodic conditions. These results demonstrate that mechanically generated pulsed triboelectric bias can effectively assist PEC charge-transfer processes without disrupting the intrinsic electrochemical behavior of the system. This work provides a practical strategy for coupling small-scale water-driven mechanical energy harvesting with solar hydrogen production.