Dual-Vacancy-Engineered ZnIn2S4 Nanosheets for Harnessing Low-Frequency Vibration Induced Piezoelectric Polarization Coupled with Static Dipole Field to Enhance Photocatalytic H2 Evolution

This study delves into the realm of chemically complex materials, focusing on Zinc Indium Sulfide (ZnIn 2 S 4 , ZIS) for efficient photocatalytic water splitting into hydrogen (H 2 ) and oxygen (H 2 ). Recognizing the pivotal role of microstructures in chemically complex materials, our research emphasizes the impact of defects in ZIS, a material with multiple principal chemical components, on its H 2 production efficiency. We explore the optimization of material defects, particularly sulfur (S) and indium (In) vacancies, under external stress to enhance H 2 production through dipole and piezoelectric effects. To unravel the intricate process-structure-property relationships in ZIS, we utilize a multi-scale computational approach. Density Functional Theory (DFT) is employed to calculate dipole moment, dielectric, elastic, and piezoelectric properties under varying defect compositions. These properties are then integrated into a continuum model developed through Finite Element Analysis (FEA), bridging mechanical and electrical phenomena to simulate the electric potential distribution (voltage) in both pristine and defective ZIS. Our simulations demonstrate a marked increase in voltage, induced by internal dipole moments and piezoelectric effects, especially pronounced along the (100) and (010) crystal orientations in defective ZIS. This enhanced voltage leads to improved charge separation, substantially increasing the H 2 production rate upon electron excitation and generation of electron/hole pairs. Our findings contribute vital insights into the microstructural influences on the photocatalytic performance of ZIS, offering design principles for advanced materials in renewable energy applications. This study exemplifies the power of computational techniques in elucidating the complex interplay between microstructure and properties in chemically complex materials, aligning with the core focus of this symposium. Figure 1