posted on 2022-01-25, 15:13authored byXiaomin Ren, Chunzhi Li, Jiali Liu, He Li, Liujie Bing, Shiyang Bai, Guoyong Xue, Yanbin Shen, Qihua Yang
The particle size of co-catalysts
significantly affects the activity
of semiconductors in photocatalysis. Herein, we report that the photocatalytic
H2 evolution (PHE) activity of a visible light responsive
covalent organic framework (COF) layer supported on SiO2 nanoparticles was greatly promoted from 47.7 to 85.5 μmol/h
by decreasing the particle size of the Pd co-catalyst from 3.3 nm
to single atoms/clusters. A PHE rate of 156 mmol gCOF–1 h–1 and apparent quantum efficiency
up to 7.3% were achieved with the Pd SAs/Cs co-catalyst. The relationship
between the activity of Pd in H2 dissociation, proton reduction,
and PHE rate suggests that the promotion effect of Pd SAs/Cs is mainly
attributed to their enhancement in charge separation of COF layers
rather than proton reduction. Furthermore, a photoactive film was
fabricated and steady production of H2 was achieved under
visible light irradiation and static conditions. The optimization
of the particle size of co-catalysts provides an efficient method
for enhancing the photocatalytic activity of semiconductors.