(661q) DFT Insights into Photocatalytic H2s Splitting over Metal Sulfide Photocatalysts for Green Hydrogen Generation

The extraction and combustion of traditional fossil fuels generates vast amounts of greenhouse gases contributing to climate change. Problems derived from climate change dictate the reestablishment in energy production and utilization. In this direction, converting solar energy through photocatalysis into suitable fuels such as hydrogen by water splitting or H₂S splitting is an intriguing strategy to alleviate energy crisis and environmental problems. However, seeking sound solutions to improve the solar harvesting efficiency, achieving higher quantum yields and selectivity, still poses great challenges in this field. Therefore, it is essential to understand how to improve the solar light utilization and conversion efficiency based on existing technologies and materials, or searching for alternative ones. Along that effort, DFT calculation is an indispensable tool to provide guidance to effectively select or design photocatalysts for improving hydrogen generation efficiency.

This work focuses on the study of H₂S decomposition, since it is thermochemically a more favorable route for H₂ generation compare to H₂O splitting. In this contribution, we will present and discuss the adsorption and dissociation of H₂S molecule on CdS-based catalysts and other metal sulfide catalysts, screening out the best photcatalysts and co-catalysts for high efficient hydrogen production. We have performed spin-polarized DFT-D3 calculations to evaluate the stability and electronic structures of different catalyst surfaces and gain a quantum-level understanding of H₂S splitting in these catalyst surfaces, validated with measurements obtained from experiments and thermochemical computational approaches. Results demonstrated that the DFT-D3 method captures the vdW force of interlayer interactions, and improves the prediction of band gap, with the predicted values showing good agreement with experimental data. Our study has focused on the adsorption behavior and dissociation mechanism, as well as the effects of generating h+/e- during the photocatalysis process on the adsorption and desorption steps.

We acknowledge support from Khalifa University (project RC2-2019-007).