High temperature recrystallization of kersterite Cu2ZnSnS4 towards enhanced photocatalytic H2 evolution

•Kesterite Cu2ZnSnS4 (CZTS) was used as photocatalyst for H2 evolution.•High temperature recrystallization (HTR) was used to enhance H2 evolution.•The crystallinity and specific surface area are two key factors that affected H2 evolution.•HTR was proved to be an efficient approach that enhanced the surface specific activity.

Kesterite Cu2ZnSnS4 (CZTS) with different crystallinities were obtained by high temperature recrystallization of as-prepared kesterite CZTS nanocrystals under elevated temperature. The effect of temperature on the crystallinity, crystallite size and specific surface area, thus the photocatalytic H2 evolution activity were discussed in detail. The maximum photocatalytic H2 evolution rate was achieved under an intermediate annealing temperature (450 and 550 °C), which show moderate crystallinity and specific surface area. However, the surface specific activity of CZTS, namely the amount of H2 evolution per surface area, show the highest value when the annealing temperature increased up to 750 °C. A rapid cooling process which induces the improvement of crystallinity without significant loss of specific surface area was used to further enhance the photocatalytic H2 evolution activity of CZTS.

Graphical abstractThe recrystallization of kesterite CZTS nanocrystals under high temperature was proved to be an efficient approach that enhanced the surface specific activity of H2 evolution of CZTS.Figure optionsDownload full-size imageDownload as PowerPoint slide