Enhanced Photochemical Hydrogen Evolution from Fe_4S_4-Based Biomimetic Chalcogels Containing M~(2+) (M = Pt, Zn, Co, Ni, Sn) Centers

摘要

Naturally abundant enzymes often feature active sites comprising transition metal duster units that catalyze chemical processes and reduce small molecules as well as protons. We introduce a family of new chalcogenide aerogels (chalcogels), aiming to model the function of active sites and the structural features of a larger protective framework New metal incorporated iron sulfur tin sulfide chalcogels referred to as ternary chalcogels and specifically the chalcogels M-ITS-cg3, fully integrate biological redox-active Fe_4S_4 dusters into a semiconducting porous framework by bridging them with Sn_4S_(10) linking units. In the M-ITS-cg3 system we can tailor the electro- and photocatalytic properties of chalcogels through the control of spatial distance of redox-active Fe_4S_4 centers using additional linking metal ions, M~(2+) (Pt, Zn, Co, Ni, Sn). The presence of a third metal does not change the structural properties of the biomimetic chalcogels but modifies and even enhances their functional performance. M-ITS-cg3s exhibit electrocatalytic activity in proton reduction that arises from the Fe_4S_4 dusters but is tuned inductively by M~(2+). The metal ions alter the reduction potential of Fe_4S_4 in a favorable manner for photochemical hydrogen production. The Pt incorporated ITS-cg3 shows the greatest improvement in the overall hydrogen yield compared to the binary ITS-cg3. The ability to manipulate the properties of biomimetic chalcogels through synthetic control of the composition, while retaining both structural and functional properties, illustrates the chalcogels' flexibility and potential in carrying out useful electrochemical and photochemical reactions.