Boosting Hydrogen Production via Water Splitting: An ITO Plus g-C₃N₄ Nanomaterial Enabled Polymer Optical Fiber Design

Hydrogen production via photocatalytic (PC) and photoelectrochemical (PEC) water splitting holds significant promise for sustainable energy. Traditional reactor designs, however, are hindered by inefficient light delivery and utilization, high equipment costs, and a large physical footprint. Our study introduces a modified polymer optical fiber (POF) incorporated PEC system, where indium tin oxide (ITO) and graphite carbon nitride (g-C 3 N 4 ) nanomaterial coated POF acts as both a light delivery source and optoelectrode. The unique inside-out light delivery approach significantly enhances light utilization (24-fold larger than bare POF) and achieves high photocurrent density (0.2 mA cm –2 ), leading to a rapid hydrogen production rate of 344 μmol h –1 g –1, up to 15 times higher than most existing reactor designs. Our optoelectrode system also offers a geometric space capacity of 2670 m 2 m –3, >25 times larger than conventional flat-electrode PEC designs. This research introduces a versatile optical fiber electrode platform, enabling compact and efficient light-driven water splitting.