Photoelectrochemical Water Oxidation over Novel Semiconducting Zinc-Based Metal-Thiolate Framework.

Designing an efficient catalyst for a sustainable photoelectrochemical water oxidation reaction is very challenging in the context of renewable energy research. Here, we have introduced a new semiconducting porous zinc-thiolate framework via successful stitching of an "N" donor linker with a triazine-based tristhiolate secondary building unit in the overall architecture. The introduction of both linker and tristhiolate ligand synergistically modifies the architecture by making it a rigid, crystalline, three-dimensional, thermally stable, and porous framework. Our novel zinc-thiolate framework is used as an n-type semiconductor as revealed from the solid-state UV-vis DRS spectroscopic analysis, ac and dc conductivity analysis, and Mott-Schottky plot. This n-type semiconductor-based zinc-thiolate framework is utilized in the photoelectrochemical water oxidation reaction. It displayed a very high efficiency for a visible-light-driven oxygen evolution reaction (OER) in a KOH medium using standard Ag/AgCl as the reference electrode. The superiority of this material was further revealed from the low onset potential (0.822 mV vs RHE), high photocurrent density (0.204 mA cm), good stability, and high O evolution rate (77 μmol g of oxygen evolution within 2 h), and a good efficiency (ABPE 0.42%, IPCE 29.6% and APCE 34.5%). Furthermore, the porosity in the overall framework seems to be a blessing to the photoelectrochemical performance due to better mass diffusion of the electrolyte. A detailed mechanism for the OER reaction was analyzed through density functional theory analysis suggesting the potential future of this Zn-thiolate framework for achieving a high efficiency in the sustainable water oxidation reaction.