EDTA-assisted synthesis of amorphous BiSx nanodots for improving photocatalytic hydrogen-evolution rate of TiO2

Abstract

Compared with crystalline metal sulfides, amorphous metal sulfides can expose more unsaturated S atoms as hydrogen-production active centers to enhance photocatalytic hydrogen-evolution activity of photocatalysts. Therefore, it is of great significance to explore simple and mild strategies to fabricate new amorphous metal sulfides for improving H2-production performance. In this work, the amorphous BiSx nanodots with the size of 0.5–2 nm as a novel and effective H2-evolution cocatalyst were successfully and homogeneously loaded on TiO2 surface to extremely facilitate the photocatalytic H2-production performance. The BiSx/TiO2 photocatalyst was obtained by an EDTA-assisted two-step process, which was including the adsorption of the Bi(Ш)-EDTA ions on TiO2 and the in-situ formation of amorphous BiSx nanodots. It is found that the BiSx/TiO2(1.0 wt%) photocatalyst achieved the maximum photocatalytic hydrogen-production performance (803.2 μmol h−1 g−1, AQE= 3.86%), which was 83.6 and 1.6 folds of the blank TiO2 and crystalline Bi2S3-modified TiO2 (c-Bi2S3/TiO2), respectively. Importantly, the above amorphous BiSx nanodots can serve as a general cocatalyst to promote the H2-generation activity of other typical photocatalysts (g-C3N4 and CdS). The boosted photocatalytic H2-production performances are attributed to that the amorphous BiSx nanodots can provide more unsaturated active S atoms as the efficient H2-evolution active sites for promoting H2-evolution rate. This study provides a new insight for exploiting novel metal sulfide cocatalyst in the field of photocatalytic hydrogen evolution.