Activation of Peroxide to 1 O 2 and *OH on High Work Function Semiconductors: Influence of Doping, Defects, and Electrochemistry

Singlet oxygen ( 1 O 2 ) generation through simple disproportionation of H 2 O 2 is one of the cleanest, safest, and most easily accessible means of achieving a potent oxidizing action that can be exploited for a wide range of applications, from antimicrobial surfaces to many heterogeneous chemical transformations. However, most catalysts known to date for this reaction operate under highly alkaline conditions and lose potency under neutral conditions. This study reports the discovery of a new class of oxide catalysts with high electron affinity and work function, namely, LaSrMnO 3, La 2 NiO 4, δ-MnO 2, and V 2 O 5, which have high efficiency for H 2 O 2 disproportionation into 1 O 2 without the production of the *OH radical under circumneutral pH conditions. Studies of these oxides with a wide range of oxygen vacancy (V O ) defects as potential catalytic sites for H 2 O 2 disproportionation show that V O defects quenches the catalytic activity in V 2 O 5, which is shown to be due to the electronic effect where increasing V O defects leads to an increased Burstein–Moss (B-M) shift of Fermi energy well into the conduction band (CB), making injection of e – from H 2 O 2 unfavorable. The increasing presence of Mn III defects in manganites enhances 1 O 2 production due to increased work function. The study provides a roadmap for the engineering of powerful 1 O 2 generators for use as selective oxidative catalysts.