Leaf-like hematite-decorated flexible carbon-textile for enhancing mass transfer at triphasic interfaces in photoanodes.

Photoelectrodes play a critical role in photoelectrochemical (PEC) reactions. However, the sluggish mass/electron transfer kinetics at the triphasic interface and inherent structural rigid features significantly limit their practical and scalable applications. In this work, we used the confinement effect of nanofibers to uniformly nucleate and grow leaf-like α-FeO nanoarrays on the surface of flexible, porous carbon textile-based photoelectrodes by a mild hydrothermal method. This strategy significantly enhances the bubble desorption while maintaining a high density of electrochemically active sites for electrolyte infiltration. This new PEC photoanode structure exhibits a current density of 0.4 mA cm under visible-light irradiation, which is 8 times higher than that of α-FeO arrays on traditional F-doped tin oxide (FTO) glass. The α-FeO@oxidized carbon cloth also demonstrates excellent oxygen evolution reaction (OER) activity in the PEC system, with an overpotential of 193 mV at 10 mA cm, a low Tafel slope of 42 mV dec, and an oxygen production rate of 1.76 mmol g h. Moreover, the flexible, free-standing PEC photoanode can withstand extreme working conditions such as folding and twisting, and can be designed into various shapes to expose a larger active surface. This work demonstrates a new photoanode strategy that solves the problems of slow triphasic interface mass transfer and rigidity, and provides great prospects for portable and wearable PEC devices.