Lotus-leaf-like Bi2O2CO3 nanosheet combined with Mo2S3 for higher photocatalytic hydrogen evolution

• Two-dimensional layered stack structure Mo 2 S 3 /Bi 2 O 2 CO 3 composite successfully prepared； • The construction of unconventional n-n heterojunction effectively efficiently inhibits the recombination of electron-hole pairs; • The synergistic effect of Bi 2 O 2 CO 3 with a lotus-leaf like Mo 2 S 3 nanosheets jointly promote the improvement of the hydrogen production performance. The exploration of multiple composite with heterojunction structures to replace single catalysts with insufficient capacity is significant for the photocatalytic evolution of high-yield hydrogen. In this case, the Mo 2 S 3 /Bi 2 O 2 CO 3 composite with a unique n-n heterojunction and two-dimensional (2D) spatial structure was successfully prepared for the first time using the hydrothermal-physical mixture method. The percentage of Bi 2 O 2 CO 3 in the composite can be easily adjusted by changing the amount of Bi 2 O 2 CO 3 introduced into the physical mixing process. With a mass percentage of Bi 2 O 2 CO 3 attained 3% to Mo 2 S 3 , the composite Mo 2 S 3 /Bi 2 O 2 CO 3 with n-n heterojunction exhibited the highest photocatalytic effect among all as-prepared samples, with a photocatalytic effect 5 times higher than pure Mo 2 S 3 . The presence of Bi 2 O 2 CO 3 and the synergistic interactions of n-n heterojunction significantly reduced the dispersity of short-rod shaped Mo 2 S 3 , as well as the recombination of photogenerated charge carriers. As a result, electron circulation was improved, and photocatalytic hydrogen evolution activity under visible light was improved. In addition to improving the photocatalytic hydrogen evolution effect, the composite Mo 2 S 3 /Bi 2 O 2 CO 3 has been found to have excellent stability, which is a noteworthy feature. A series of characterization results and semiconductor energy band structure were used to investigate the possible photocatalytic hydrogen evolution mechanism in the Eosin-Y (EY) sensitized Mo 2 S 3 /Bi 2 O 2 CO 3 system.