S, N co-doped carbon dots induced effective chlorine ion repulsion in TiO2 nanorod clusters for photoelectrochemical seawater splitting

Abstract

It is essential to promote seawater photoelectrolysis technologies for reducing the dependency on fossil fuels and alleviating the freshwater resources shortage. However, the undesirable chloride oxidation reaction (CER) on the anode side has seriously limited their application. Here, S, N co-doped carbon dots (S, N-CDs) were prepared and successfully decorated on the surface of TiO2 nanorod clusters photoanode via hydrothermal process to inhibit the CER in photoelectrochemical (PEC) seawater splitting. The prepared S, N-CDs/TiO2 photoanode exhibited a photocurrent density of 34.4 μA cm−1 (at 1.23 V RHE), which was around 3 times for that of pure TiO2. More importantly, it exhibited a lower ClO− yield. After 1 h of continuous operation, the concentration of the ClO− was only 6 μM in the final reaction liquid, which was nearly half of that for pure TiO2. It was suggested that S, N-CDs could be potential ideal electrode materials in PEC seawater splitting systems, due to effectively chlorine-repulsing, improving photoelectric properties.