Reversible Stacking of 2D ZnIn2S4 Atomic Layers for Enhanced Photocatalytic Hydrogen Evolution

It is technically challenging to reversibly tune the layer number of 2D materials in the solution. Herein, a facile concentration modulation strategy is demonstrated to reversibly tailor the aggregation state of 2D ZnIn2S4 (ZIS) atomic layers, and they are implemented for effective photocatalytic hydrogen (H-2) evolution. By adjusting the colloidal concentration of ZIS (ZIS-X, X = 0.09, 0.25, or 3.0 mg mL(-1)), ZIS atomic layers exhibit the significant aggregation of (006) facet stacking in the solution, leading to the bandgap shift from 3.21 to 2.66 eV. The colloidal stacked layers are further assembled into hollow microsphere after freeze-drying the solution into solid powders, which can be redispersed into colloidal solution with reversibility. The photocatalytic hydrogen evolution of ZIS-X colloids is evaluated, and the slightly aggregated ZIS-0.25 displays the enhanced photocatalytic H-2 evolution rates (1.11 mu mol m(-2) h(-1)). The charge-transfer/recombination dynamics are characterized by time-resolved photoluminescence (TRPL) spectroscopy, and ZIS-0.25 displays the longest lifetime (5.55 mu s), consistent with the best photocatalytic performance. This work provides a facile, consecutive, and reversible strategy for regulating the photo-electrochemical properties of 2D ZIS, which is beneficial for efficient solar energy conversion.

Automated summary

A concentration modulation strategy is used to reversibly tailor the aggregation state of 2D ZnIn2S4 atomic layers for efficient photocatalytic hydrogen evolution. By adjusting the colloidal concentration, the bandgap of ZIS atomic layers can be shifted, and they can be assembled into hollow microspheres that can be redispersed reversibly. The ZIS-0.25 colloids exhibit the best photocatalytic performance and the longest lifetime, providing a facile and reversible strategy for regulating the photo-electrochemical properties of 2D ZIS.