Titanium and zinc oxide nanoparticles are proton-coupled electron transfer agents

Area of Science:

• Surface Chemistry
• Photocatalysis
• Energy Conversion

Background:

• Oxidation-reduction reactions on metal oxide surfaces are vital for solar energy, photocatalysis, and geochemistry.
• Current models often describe these as simple electron transfers, potentially overlooking key mechanisms.

Purpose of the Study:

• To investigate the mechanism of oxidation-reduction reactions at reduced TiO(2) and ZnO nanoparticle surfaces.
• To determine if electron and proton transfers are coupled in these interfacial reactions.

Main Methods:

• Utilized reduced titanium dioxide (TiO(2)) and zinc oxide (ZnO) nanoparticles in solution.
• Analyzed reactions with phenoxyl and nitroxyl radicals to observe electron and proton transfer dynamics.

Main Results:

• Demonstrated that TiO(2) and ZnO nanoparticles transfer both an electron and a proton to radicals.
• Identified these interfacial reactions as rapid and quantitative proton-coupled electron transfer (PCET).

Conclusions:

• The conventional description of electron transfer in metal oxide surface reactions is incomplete.
• Metal oxide surfaces act as proton-coupled electron transfer (PCET) reagents, a critical insight for developing chemical energy technologies reliant on e(-)/H(+) coupling.