Aggregation-based phase transition tailored heterophase junctions of AgInS2 for boosting photocatalytic H2 evolution

Due to high defect tolerance and multiphase allowance, AgInS2 (AIS) quantum dots (QDs) provide chances for designing new type junctions via tailoring defects, size, or phase structure. These new type junctions potentially enhance photoelectric performance, such as photocatalytic H-2 evolution (PHE). Here, ultra -small AIS QDs (-1 nm) with well-defined exciton absorption were prepared aqueously via a reverse hot-injection procedure for the first time. A coalescence or fast aggregation-based growth was observed for coarsening at 95 or 135 celcius, respectively. XRD and TEM investigations revealed that the tetragonal -orthorhombic (t-o) phase transition occurred via aggregation-based growth. The studies on phase tran-sition kinetics resulted in fine-tailoring on AIS polymorphs, favoring t-o AIS junctions. UV-vis absorption spectra confirm the double absorption edge of the t-o heterophase junction with enhanced visible absorption. Steady and transient PL spectra suggest improvements in carriers' separation/transfer in this t-o junction. As a result, the optimized t-o AIS shows superior photocatalytic H2 evolution rates of 1022 lmol. g(-1). h(-1), 51.1 times that of t-AIS or 3.8 times that of o-AIS. This work is expected to provide new insight for designing ternary alloyed QDs with strongly coupled interfaces for effective H2 generations. (C) 2022 Published by Elsevier Inc.

Automated summary

This study reports the preparation of ultra-small AgInS2 quantum dots via a reverse hot-injection method in an aqueous solution. The fine-tailoring of AIS polymorphs through phase transition kinetics leads to the formation of optimized t-o AIS, which exhibits superior photocatalytic H2 generation performance.