Size and Crystallinity‐Dependent Photocatalytic Performance of MIL‐53(Fe) and MIL‐53(Fe)/g‐C₃N₄ Composite

ABSTRACT MIL‐53(Fe) is a novel photocatalytic material that has been developed over the past decade; however, significant efforts are still required to fully optimize its photocatalytic performance in order to meet the requirements of practical applications. In this paper, we investigated the effects of size and crystallinity on the photocatalytic performance of MIL‐53(Fe) and its composites x‐MIL‐53(Fe)/g‐C 3 N 4 (x‐MIL‐Fe/CN). During the hydrothermal synthesis process, the control over particle size was achieved by adjusting the amount of acetic acid (HAc). Ball milling was utilized to manipulate both the size and crystallinity of MIL‐53(Fe). Photocatalytic experiments demonstrated that MIL‐53(Fe) and 15‐MIL‐Fe/CN, characterized by the smallest particle sizes and great crystallinity, exhibited the highest photocatalytic activity. This enhancement in photocatalytic activity can be attributed to the reduced band gap and lower recombination rate of photogenerated carriers. Notably, the hydrogen evolution rate for 15‐MIL‐Fe/CN reached up to 4950 μmol·g −1 ·h −1 , but MIL‐53(Fe) achieved a 98% degradation of methyl orange within 60 min.