N-Doped carbon dots: a metal-free co-catalyst on hematite nanorod arrays toward efficient photoelectrochemical water oxidation

In this communication, we demonstrate the use of N-doped carbon dots (N-CDs) as a co-catalyst for hematite (alpha-Fe2O3) nanorod arrays on a Ti sheet for photoelectrochemical water oxidation. Under simulated light irradiation, the photocurrent density of the resulting N-CDs@alpha-Fe2O3/Ti as a photoanode exhibits a 3.4 times increase with a 280 mV cathode shift of the onset potential relative to that of pristine alpha-Fe2O3/Ti, with excellent photostability. The up-conversion fluorescent properties of N-CDs enable the absorption of longer wavelength irradiation with emission of short wavelength light to excite alpha-Fe2O3, leading to the generation of more electron-hole pairs.