Tuning the photocatalytic performance of halide perovskites for efficient solar hydrogen production: A DFT study of CsGeCl3-xXx (X= Br, I)

Photoelectrochemical water splitting holds immense potential for sustainable hydrogen production to address mounting energy demands. However, the development of efficient and cost-effective photocatalysts remains a significant challenge. Perovskites, recognized for their cost-effectiveness and tunable characteristics, show potential as viable candidates in this context. Our investigation is the first to mark the photocatalytic efficacy of CsGeCl₃. The findings reveal a modest solar-to-hydrogen (STH) efficiency of 0.74 % due to its wide bandgap energy. Halide mixing with iodine and bromine significantly improves the STH efficiencies, reaching approximately 8.47 %. In addition, applying uniaxial compressive stress further boosts the efficiency to 14.6 %. In this study, we employed the density functional theory (DFT) through the WIEN2k software to scrutinize the structural, electronic, optical, photocatalytic, and thermoelectric properties of all the studied structures. Furthermore, the study evaluated the compounds' capacity for CO₂ photoreduction, susceptibility to degradation, and the influence of pH on their photocatalytic performance. The insights gained from this work contribute to the development of efficient and cost-effective perovskite-based photocatalysts for renewable hydrogen production.